Commit graph

197 commits

Author SHA1 Message Date
Fuad Tabba
ef06fd16d4 bpf, arm64: Force 8-byte alignment for JIT buffer to prevent atomic tearing
struct bpf_plt contains a u64 target field. Currently, the BPF JIT
allocator requests an alignment of 4 bytes (sizeof(u32)) for the JIT
buffer.

Because the base address of the JIT buffer can be 4-byte aligned (e.g.,
ending in 0x4 or 0xc), the relative padding logic in build_plt() fails
to ensure that target lands on an 8-byte boundary.

This leads to two issues:
1. UBSAN reports misaligned-access warnings when dereferencing the
   structure.
2. More critically, target is updated concurrently via WRITE_ONCE() in
   bpf_arch_text_poke() while the JIT'd code executes ldr. On arm64,
   64-bit loads/stores are only guaranteed to be single-copy atomic if
   they are 64-bit aligned. A misaligned target risks a torn read,
   causing the JIT to jump to a corrupted address.

Fix this by increasing the allocation alignment requirement to 8 bytes
(sizeof(u64)) in bpf_jit_binary_pack_alloc(). This anchors the base of
the JIT buffer to an 8-byte boundary, allowing the relative padding math
in build_plt() to correctly align the target field.

Fixes: b2ad54e153 ("bpf, arm64: Implement bpf_arch_text_poke() for arm64")
Signed-off-by: Fuad Tabba <tabba@google.com>
Acked-by: Will Deacon <will@kernel.org>
Link: https://lore.kernel.org/r/20260226075525.233321-1-tabba@google.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2026-02-26 11:19:00 -08:00
Linus Torvalds
bf4afc53b7 Convert 'alloc_obj' family to use the new default GFP_KERNEL argument
This was done entirely with mindless brute force, using

    git grep -l '\<k[vmz]*alloc_objs*(.*, GFP_KERNEL)' |
        xargs sed -i 's/\(alloc_objs*(.*\), GFP_KERNEL)/\1)/'

to convert the new alloc_obj() users that had a simple GFP_KERNEL
argument to just drop that argument.

Note that due to the extreme simplicity of the scripting, any slightly
more complex cases spread over multiple lines would not be triggered:
they definitely exist, but this covers the vast bulk of the cases, and
the resulting diff is also then easier to check automatically.

For the same reason the 'flex' versions will be done as a separate
conversion.

Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2026-02-21 17:09:51 -08:00
Kees Cook
69050f8d6d treewide: Replace kmalloc with kmalloc_obj for non-scalar types
This is the result of running the Coccinelle script from
scripts/coccinelle/api/kmalloc_objs.cocci. The script is designed to
avoid scalar types (which need careful case-by-case checking), and
instead replace kmalloc-family calls that allocate struct or union
object instances:

Single allocations:	kmalloc(sizeof(TYPE), ...)
are replaced with:	kmalloc_obj(TYPE, ...)

Array allocations:	kmalloc_array(COUNT, sizeof(TYPE), ...)
are replaced with:	kmalloc_objs(TYPE, COUNT, ...)

Flex array allocations:	kmalloc(struct_size(PTR, FAM, COUNT), ...)
are replaced with:	kmalloc_flex(*PTR, FAM, COUNT, ...)

(where TYPE may also be *VAR)

The resulting allocations no longer return "void *", instead returning
"TYPE *".

Signed-off-by: Kees Cook <kees@kernel.org>
2026-02-21 01:02:28 -08:00
Linus Torvalds
136114e0ab mm.git review status for linus..mm-nonmm-stable
Total patches:       107
 Reviews/patch:       1.07
 Reviewed rate:       67%
 
 - The 2 patch series "ocfs2: give ocfs2 the ability to reclaim
   suballocator free bg" from Heming Zhao saves disk space by teaching
   ocfs2 to reclaim suballocator block group space.
 
 - The 4 patch series "Add ARRAY_END(), and use it to fix off-by-one
   bugs" from Alejandro Colomar adds the ARRAY_END() macro and uses it in
   various places.
 
 - The 2 patch series "vmcoreinfo: support VMCOREINFO_BYTES larger than
   PAGE_SIZE" from Pnina Feder makes the vmcore code future-safe, if
   VMCOREINFO_BYTES ever exceeds the page size.
 
 - The 7 patch series "kallsyms: Prevent invalid access when showing
   module buildid" from Petr Mladek cleans up kallsyms code related to
   module buildid and fixes an invalid access crash when printing
   backtraces.
 
 - The 3 patch series "Address page fault in
   ima_restore_measurement_list()" from Harshit Mogalapalli fixes a
   kexec-related crash that can occur when booting the second-stage kernel
   on x86.
 
 - The 6 patch series "kho: ABI headers and Documentation updates" from
   Mike Rapoport updates the kexec handover ABI documentation.
 
 - The 4 patch series "Align atomic storage" from Finn Thain adds the
   __aligned attribute to atomic_t and atomic64_t definitions to get
   natural alignment of both types on csky, m68k, microblaze, nios2,
   openrisc and sh.
 
 - The 2 patch series "kho: clean up page initialization logic" from
   Pratyush Yadav simplifies the page initialization logic in
   kho_restore_page().
 
 - The 6 patch series "Unload linux/kernel.h" from Yury Norov moves
   several things out of kernel.h and into more appropriate places.
 
 - The 7 patch series "don't abuse task_struct.group_leader" from Oleg
   Nesterov removes the usage of ->group_leader when it is "obviously
   unnecessary".
 
 - The 5 patch series "list private v2 & luo flb" from Pasha Tatashin
   adds some infrastructure improvements to the live update orchestrator.
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Merge tag 'mm-nonmm-stable-2026-02-12-10-48' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

Pull non-MM updates from Andrew Morton:

 - "ocfs2: give ocfs2 the ability to reclaim suballocator free bg" saves
   disk space by teaching ocfs2 to reclaim suballocator block group
   space (Heming Zhao)

 - "Add ARRAY_END(), and use it to fix off-by-one bugs" adds the
   ARRAY_END() macro and uses it in various places (Alejandro Colomar)

 - "vmcoreinfo: support VMCOREINFO_BYTES larger than PAGE_SIZE" makes
   the vmcore code future-safe, if VMCOREINFO_BYTES ever exceeds the
   page size (Pnina Feder)

 - "kallsyms: Prevent invalid access when showing module buildid" cleans
   up kallsyms code related to module buildid and fixes an invalid
   access crash when printing backtraces (Petr Mladek)

 - "Address page fault in ima_restore_measurement_list()" fixes a
   kexec-related crash that can occur when booting the second-stage
   kernel on x86 (Harshit Mogalapalli)

 - "kho: ABI headers and Documentation updates" updates the kexec
   handover ABI documentation (Mike Rapoport)

 - "Align atomic storage" adds the __aligned attribute to atomic_t and
   atomic64_t definitions to get natural alignment of both types on
   csky, m68k, microblaze, nios2, openrisc and sh (Finn Thain)

 - "kho: clean up page initialization logic" simplifies the page
   initialization logic in kho_restore_page() (Pratyush Yadav)

 - "Unload linux/kernel.h" moves several things out of kernel.h and into
   more appropriate places (Yury Norov)

 - "don't abuse task_struct.group_leader" removes the usage of
   ->group_leader when it is "obviously unnecessary" (Oleg Nesterov)

 - "list private v2 & luo flb" adds some infrastructure improvements to
   the live update orchestrator (Pasha Tatashin)

* tag 'mm-nonmm-stable-2026-02-12-10-48' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (107 commits)
  watchdog/hardlockup: simplify perf event probe and remove per-cpu dependency
  procfs: fix missing RCU protection when reading real_parent in do_task_stat()
  watchdog/softlockup: fix sample ring index wrap in need_counting_irqs()
  kcsan, compiler_types: avoid duplicate type issues in BPF Type Format
  kho: fix doc for kho_restore_pages()
  tests/liveupdate: add in-kernel liveupdate test
  liveupdate: luo_flb: introduce File-Lifecycle-Bound global state
  liveupdate: luo_file: Use private list
  list: add kunit test for private list primitives
  list: add primitives for private list manipulations
  delayacct: fix uapi timespec64 definition
  panic: add panic_force_cpu= parameter to redirect panic to a specific CPU
  netclassid: use thread_group_leader(p) in update_classid_task()
  RDMA/umem: don't abuse current->group_leader
  drm/pan*: don't abuse current->group_leader
  drm/amd: kill the outdated "Only the pthreads threading model is supported" checks
  drm/amdgpu: don't abuse current->group_leader
  android/binder: use same_thread_group(proc->tsk, current) in binder_mmap()
  android/binder: don't abuse current->group_leader
  kho: skip memoryless NUMA nodes when reserving scratch areas
  ...
2026-02-12 12:13:01 -08:00
Linus Torvalds
f17b474e36 bpf-next-7.0
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Merge tag 'bpf-next-7.0' of git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next

Pull bpf updates from Alexei Starovoitov:

 - Support associating BPF program with struct_ops (Amery Hung)

 - Switch BPF local storage to rqspinlock and remove recursion detection
   counters which were causing false positives (Amery Hung)

 - Fix live registers marking for indirect jumps (Anton Protopopov)

 - Introduce execution context detection BPF helpers (Changwoo Min)

 - Improve verifier precision for 32bit sign extension pattern
   (Cupertino Miranda)

 - Optimize BTF type lookup by sorting vmlinux BTF and doing binary
   search (Donglin Peng)

 - Allow states pruning for misc/invalid slots in iterator loops (Eduard
   Zingerman)

 - In preparation for ASAN support in BPF arenas teach libbpf to move
   global BPF variables to the end of the region and enable arena kfuncs
   while holding locks (Emil Tsalapatis)

 - Introduce support for implicit arguments in kfuncs and migrate a
   number of them to new API. This is a prerequisite for cgroup
   sub-schedulers in sched-ext (Ihor Solodrai)

 - Fix incorrect copied_seq calculation in sockmap (Jiayuan Chen)

 - Fix ORC stack unwind from kprobe_multi (Jiri Olsa)

 - Speed up fentry attach by using single ftrace direct ops in BPF
   trampolines (Jiri Olsa)

 - Require frozen map for calculating map hash (KP Singh)

 - Fix lock entry creation in TAS fallback in rqspinlock (Kumar
   Kartikeya Dwivedi)

 - Allow user space to select cpu in lookup/update operations on per-cpu
   array and hash maps (Leon Hwang)

 - Make kfuncs return trusted pointers by default (Matt Bobrowski)

 - Introduce "fsession" support where single BPF program is executed
   upon entry and exit from traced kernel function (Menglong Dong)

 - Allow bpf_timer and bpf_wq use in all programs types (Mykyta
   Yatsenko, Andrii Nakryiko, Kumar Kartikeya Dwivedi, Alexei
   Starovoitov)

 - Make KF_TRUSTED_ARGS the default for all kfuncs and clean up their
   definition across the tree (Puranjay Mohan)

 - Allow BPF arena calls from non-sleepable context (Puranjay Mohan)

 - Improve register id comparison logic in the verifier and extend
   linked registers with negative offsets (Puranjay Mohan)

 - In preparation for BPF-OOM introduce kfuncs to access memcg events
   (Roman Gushchin)

 - Use CFI compatible destructor kfunc type (Sami Tolvanen)

 - Add bitwise tracking for BPF_END in the verifier (Tianci Cao)

 - Add range tracking for BPF_DIV and BPF_MOD in the verifier (Yazhou
   Tang)

 - Make BPF selftests work with 64k page size (Yonghong Song)

* tag 'bpf-next-7.0' of git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next: (268 commits)
  selftests/bpf: Fix outdated test on storage->smap
  selftests/bpf: Choose another percpu variable in bpf for btf_dump test
  selftests/bpf: Remove test_task_storage_map_stress_lookup
  selftests/bpf: Update task_local_storage/task_storage_nodeadlock test
  selftests/bpf: Update task_local_storage/recursion test
  selftests/bpf: Update sk_storage_omem_uncharge test
  bpf: Switch to bpf_selem_unlink_nofail in bpf_local_storage_{map_free, destroy}
  bpf: Support lockless unlink when freeing map or local storage
  bpf: Prepare for bpf_selem_unlink_nofail()
  bpf: Remove unused percpu counter from bpf_local_storage_map_free
  bpf: Remove cgroup local storage percpu counter
  bpf: Remove task local storage percpu counter
  bpf: Change local_storage->lock and b->lock to rqspinlock
  bpf: Convert bpf_selem_unlink to failable
  bpf: Convert bpf_selem_link_map to failable
  bpf: Convert bpf_selem_unlink_map to failable
  bpf: Select bpf_local_storage_map_bucket based on bpf_local_storage
  selftests/xsk: fix number of Tx frags in invalid packet
  selftests/xsk: properly handle batch ending in the middle of a packet
  bpf: Prevent reentrance into call_rcu_tasks_trace()
  ...
2026-02-10 11:26:21 -08:00
Linus Torvalds
45bf4bc87c arm64 updates for 7.0
ACPI:
  - Add interrupt signalling support to the AGDI handler.
  - Add Catalin and myself to the arm64 ACPI MAINTAINERS entry.
 
 CPU features:
 - Drop Kconfig options for PAN and LSE (these are detected at runtime).
 - Add support for 64-byte single-copy atomic instructions (LS64/LS64V).
 - Reduce MTE overhead when executing in the kernel on Ampere CPUs.
 - Ensure POR_EL0 value exposed via ptrace is up-to-date.
 - Fix error handling on GCS allocation failure.
 
 CPU frequency:
 - Add CPU hotplug support to the FIE setup in the AMU driver.
 
 Entry code:
 - Minor optimisations and cleanups to the syscall entry path.
 - Preparatory rework for moving to the generic syscall entry code.
 
 Hardware errata:
 - Work around Spectre-BHB on TSV110 processors.
 - Work around broken CMO propagation on some systems with the SI-L1
   interconnect.
 
 Miscellaneous:
 - Disable branch profiling for arch/arm64/ to avoid issues with noinstr.
 - Minor fixes and cleanups (kexec + ubsan, WARN_ONCE() instead of
   WARN_ON(), reduction of boolean expression).
 - Fix custom __READ_ONCE() implementation for LTO builds when operating
   on non-atomic types.
 
 Perf and PMUs:
 - Support for CMN-600AE.
 - Be stricter about supported hardware in the CMN driver.
 - Support for DSU-110 and DSU-120.
 - Support for the cycles event in the DSU driver (alongside the
   dedicated cycles counter).
 - Use IRQF_NO_THREAD instead of IRQF_ONESHOT in the cxlpmu driver.
 - Use !bitmap_empty() as a faster alternative to bitmap_weight().
 - Fix SPE error handling when failing to resume profiling.
 
 Selftests:
 - Add support for the FORCE_TARGETS option to the arm64 kselftests.
 - Avoid nolibc-specific my_syscall() function.
 - Add basic test for the LS64 HWCAP.
 - Extend fp-pidbench to cover additional workload patterns.
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Merge tag 'arm64-upstream' of git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux

Pull arm64 updates from Will Deacon:
 "There's a little less than normal, probably due to LPC & Christmas/New
  Year meaning that a few series weren't quite ready or reviewed in
  time. It's still useful across the board, despite the only real
  feature being support for the LS64 feature enabling 64-byte atomic
  accesses to endpoints that support it.

  ACPI:
   - Add interrupt signalling support to the AGDI handler
   - Add Catalin and myself to the arm64 ACPI MAINTAINERS entry

  CPU features:
   - Drop Kconfig options for PAN and LSE (these are detected at runtime)
   - Add support for 64-byte single-copy atomic instructions (LS64/LS64V)
   - Reduce MTE overhead when executing in the kernel on Ampere CPUs
   - Ensure POR_EL0 value exposed via ptrace is up-to-date
   - Fix error handling on GCS allocation failure

  CPU frequency:
   - Add CPU hotplug support to the FIE setup in the AMU driver

  Entry code:
   - Minor optimisations and cleanups to the syscall entry path
   - Preparatory rework for moving to the generic syscall entry code

  Hardware errata:
   - Work around Spectre-BHB on TSV110 processors
   - Work around broken CMO propagation on some systems with the SI-L1
     interconnect

  Miscellaneous:
   - Disable branch profiling for arch/arm64/ to avoid issues with
     noinstr
   - Minor fixes and cleanups (kexec + ubsan, WARN_ONCE() instead of
     WARN_ON(), reduction of boolean expression)
   - Fix custom __READ_ONCE() implementation for LTO builds when
     operating on non-atomic types

  Perf and PMUs:
   - Support for CMN-600AE
   - Be stricter about supported hardware in the CMN driver
   - Support for DSU-110 and DSU-120
   - Support for the cycles event in the DSU driver (alongside the
     dedicated cycles counter)
   - Use IRQF_NO_THREAD instead of IRQF_ONESHOT in the cxlpmu driver
   - Use !bitmap_empty() as a faster alternative to bitmap_weight()
   - Fix SPE error handling when failing to resume profiling

  Selftests:
   - Add support for the FORCE_TARGETS option to the arm64 kselftests
   - Avoid nolibc-specific my_syscall() function
   - Add basic test for the LS64 HWCAP
   - Extend fp-pidbench to cover additional workload patterns"

* tag 'arm64-upstream' of git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux: (43 commits)
  perf/arm-cmn: Reject unsupported hardware configurations
  perf: arm_spe: Properly set hw.state on failures
  arm64/gcs: Fix error handling in arch_set_shadow_stack_status()
  arm64: Fix non-atomic __READ_ONCE() with CONFIG_LTO=y
  arm64: poe: fix stale POR_EL0 values for ptrace
  kselftest/arm64: Raise default number of loops in fp-pidbench
  kselftest/arm64: Add a no-SVE loop after SVE in fp-pidbench
  perf/cxlpmu: Replace IRQF_ONESHOT with IRQF_NO_THREAD
  arm64: mte: Set TCMA1 whenever MTE is present in the kernel
  arm64/ptrace: Return early for ptrace_report_syscall_entry() error
  arm64/ptrace: Split report_syscall()
  arm64: Remove unused _TIF_WORK_MASK
  kselftest/arm64: Add missing file in .gitignore
  arm64: errata: Workaround for SI L1 downstream coherency issue
  kselftest/arm64: Add HWCAP test for FEAT_LS64
  arm64: Add support for FEAT_{LS64, LS64_V}
  KVM: arm64: Enable FEAT_{LS64, LS64_V} in the supported guest
  arm64: Provide basic EL2 setup for FEAT_{LS64, LS64_V} usage at EL0/1
  KVM: arm64: Handle DABT caused by LS64* instructions on unsupported memory
  KVM: arm64: Add documentation for KVM_EXIT_ARM_LDST64B
  ...
2026-02-09 20:28:45 -08:00
Leon Hwang
e3aa56b3ac bpf, arm64: Add fsession support
Implement fsession support in the arm64 BPF JIT trampoline.

Extend the trampoline stack layout to store function metadata and
session cookies, and pass the appropriate metadata to fentry and
fexit programs. This mirrors the existing x86 behavior and enables
session cookies on arm64.

Acked-by: Puranjay Mohan <puranjay@kernel.org>
Tested-by: Puranjay Mohan <puranjay@kernel.org>
Signed-off-by: Leon Hwang <leon.hwang@linux.dev>
Link: https://lore.kernel.org/r/20260131144950.16294-3-leon.hwang@linux.dev
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2026-01-31 13:51:04 -08:00
Marc Zyngier
6191b25d8b arm64: Unconditionally enable LSE support
LSE atomics have been in the architecture since ARMv8.1 (released in
2014), and are hopefully supported by all modern toolchains.

Drop the optional nature of LSE support in the kernel, and always
compile the support in, as this really is very little code. LL/SC
still is the default, and the switch to LSE is done dynamically.

Signed-off-by: Marc Zyngier <maz@kernel.org>
Signed-off-by: Will Deacon <will@kernel.org>
2026-01-22 10:16:41 +00:00
Petr Mladek
cd6735896d kallsyms/bpf: rename __bpf_address_lookup() to bpf_address_lookup()
bpf_address_lookup() has been used only in kallsyms_lookup_buildid().  It
was supposed to set @modname and @modbuildid when the symbol was in a
module.

But it always just cleared @modname because BPF symbols were never in a
module.  And it did not clear @modbuildid because the pointer was not
passed.

The wrapper is no longer needed.  Both @modname and @modbuildid are now
always initialized to NULL in kallsyms_lookup_buildid().

Remove the wrapper and rename __bpf_address_lookup() to
bpf_address_lookup() because this variant is used everywhere.

[akpm@linux-foundation.org: fix loongarch]
Link: https://lkml.kernel.org/r/20251128135920.217303-6-pmladek@suse.com
Fixes: 9294523e37 ("module: add printk formats to add module build ID to stacktraces")
Signed-off-by: Petr Mladek <pmladek@suse.com>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Cc: Aaron Tomlin <atomlin@atomlin.com>
Cc: Daniel Borkman <daniel@iogearbox.net>
Cc: Daniel Gomez <da.gomez@samsung.com>
Cc: John Fastabend <john.fastabend@gmail.com>
Cc: Kees Cook <kees@kernel.org>
Cc: Luis Chamberalin <mcgrof@kernel.org>
Cc: Marc Rutland <mark.rutland@arm.com>
Cc: "Masami Hiramatsu (Google)" <mhiramat@kernel.org>
Cc: Petr Pavlu <petr.pavlu@suse.com>
Cc: Sami Tolvanen <samitolvanen@google.com>
Cc: Steven Rostedt (Google) <rostedt@goodmis.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2026-01-20 19:44:22 -08:00
Puranjay Mohan
f785a31395 bpf: arm64: Fix sparse warnings
ctx->image is declared as __le32 because arm64 instructions are LE
regardless of CPU's runtime endianness. emit_u32_data() emits raw data
and not instructions so cast the value to __le32 to fix the sparse
warning.

Cast function pointer to void * before doing arithmetic.

Signed-off-by: Puranjay Mohan <puranjay@kernel.org>
Link: https://lore.kernel.org/r/20251219191310.3204425-1-puranjay@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2025-12-21 16:57:23 -08:00
Ondrej Mosnacek
189e5deb94 bpf, arm64: Do not audit capability check in do_jit()
Analogically to the x86 commit 881a9c9cb7 ("bpf: Do not audit
capability check in do_jit()"), change the capable() call to
ns_capable_noaudit() in order to avoid spurious SELinux denials in audit
log.

The commit log from that commit applies here as well:
"""
The failure of this check only results in a security mitigation being
applied, slightly affecting performance of the compiled BPF program. It
doesn't result in a failed syscall, an thus auditing a failed LSM
permission check for it is unwanted. For example with SELinux, it causes
a denial to be reported for confined processes running as root, which
tends to be flagged as a problem to be fixed in the policy. Yet
dontauditing or allowing CAP_SYS_ADMIN to the domain may not be
desirable, as it would allow/silence also other checks - either going
against the principle of least privilege or making debugging potentially
harder.

Fix it by changing it from capable() to ns_capable_noaudit(), which
instructs the LSMs to not audit the resulting denials.
"""

Fixes: f300769ead ("arm64: bpf: Only mitigate cBPF programs loaded by unprivileged users")
Signed-off-by: Ondrej Mosnacek <omosnace@redhat.com>
Link: https://lore.kernel.org/r/20251204125916.441021-1-omosnace@redhat.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2025-12-09 23:25:11 -08:00
Linus Torvalds
015e7b0b0e bpf-next-6.19
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Merge tag 'bpf-next-6.19' of git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next

Pull bpf updates from Alexei Starovoitov:

 - Convert selftests/bpf/test_tc_edt and test_tc_tunnel from .sh to
   test_progs runner (Alexis Lothoré)

 - Convert selftests/bpf/test_xsk to test_progs runner (Bastien
   Curutchet)

 - Replace bpf memory allocator with kmalloc_nolock() in
   bpf_local_storage (Amery Hung), and in bpf streams and range tree
   (Puranjay Mohan)

 - Introduce support for indirect jumps in BPF verifier and x86 JIT
   (Anton Protopopov) and arm64 JIT (Puranjay Mohan)

 - Remove runqslower bpf tool (Hoyeon Lee)

 - Fix corner cases in the verifier to close several syzbot reports
   (Eduard Zingerman, KaFai Wan)

 - Several improvements in deadlock detection in rqspinlock (Kumar
   Kartikeya Dwivedi)

 - Implement "jmp" mode for BPF trampoline and corresponding
   DYNAMIC_FTRACE_WITH_JMP. It improves "fexit" program type performance
   from 80 M/s to 136 M/s. With Steven's Ack. (Menglong Dong)

 - Add ability to test non-linear skbs in BPF_PROG_TEST_RUN (Paul
   Chaignon)

 - Do not let BPF_PROG_TEST_RUN emit invalid GSO types to stack (Daniel
   Borkmann)

 - Generalize buildid reader into bpf_dynptr (Mykyta Yatsenko)

 - Optimize bpf_map_update_elem() for map-in-map types (Ritesh
   Oedayrajsingh Varma)

 - Introduce overwrite mode for BPF ring buffer (Xu Kuohai)

* tag 'bpf-next-6.19' of git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next: (169 commits)
  bpf: optimize bpf_map_update_elem() for map-in-map types
  bpf: make kprobe_multi_link_prog_run always_inline
  selftests/bpf: do not hardcode target rate in test_tc_edt BPF program
  selftests/bpf: remove test_tc_edt.sh
  selftests/bpf: integrate test_tc_edt into test_progs
  selftests/bpf: rename test_tc_edt.bpf.c section to expose program type
  selftests/bpf: Add success stats to rqspinlock stress test
  rqspinlock: Precede non-head waiter queueing with AA check
  rqspinlock: Disable spinning for trylock fallback
  rqspinlock: Use trylock fallback when per-CPU rqnode is busy
  rqspinlock: Perform AA checks immediately
  rqspinlock: Enclose lock/unlock within lock entry acquisitions
  bpf: Remove runqslower tool
  selftests/bpf: Remove usage of lsm/file_alloc_security in selftest
  bpf: Disable file_alloc_security hook
  bpf: check for insn arrays in check_ptr_alignment
  bpf: force BPF_F_RDONLY_PROG on insn array creation
  bpf: Fix exclusive map memory leak
  selftests/bpf: Make CS length configurable for rqspinlock stress test
  selftests/bpf: Add lock wait time stats to rqspinlock stress test
  ...
2025-12-03 16:54:54 -08:00
Linus Torvalds
44fc84337b arm64 updates for 6.19:
Core features:
 
  - Basic Arm MPAM (Memory system resource Partitioning And Monitoring)
    driver under drivers/resctrl/ which makes use of the fs/rectrl/ API
 
 Perf and PMU:
 
  - Avoid cycle counter on multi-threaded CPUs
 
  - Extend CSPMU device probing and add additional filtering support for
    NVIDIA implementations
 
  - Add support for the PMUs on the NoC S3 interconnect
 
  - Add additional compatible strings for new Cortex and C1 CPUs
 
  - Add support for data source filtering to the SPE driver
 
  - Add support for i.MX8QM and "DB" PMU in the imx PMU driver
 
 Memory managemennt:
 
  - Avoid broadcast TLBI if page reused in write fault
 
  - Elide TLB invalidation if the old PTE was not valid
 
  - Drop redundant cpu_set_*_tcr_t0sz() macros
 
  - Propagate pgtable_alloc() errors outside of __create_pgd_mapping()
 
  - Propagate return value from __change_memory_common()
 
 ACPI and EFI:
 
  - Call EFI runtime services without disabling preemption
 
  - Remove unused ACPI function
 
 Miscellaneous:
 
  - ptrace support to disable streaming on SME-only systems
 
  - Improve sysreg generation to include a 'Prefix' descriptor
 
  - Replace __ASSEMBLY__ with __ASSEMBLER__
 
  - Align register dumps in the kselftest zt-test
 
  - Remove some no longer used macros/functions
 
  - Various spelling corrections
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Merge tag 'arm64-upstream' of git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux

Pull arm64 updates from Catalin Marinas:
 "These are the arm64 updates for 6.19.

  The biggest part is the Arm MPAM driver under drivers/resctrl/.
  There's a patch touching mm/ to handle spurious faults for huge pmd
  (similar to the pte version). The corresponding arm64 part allows us
  to avoid the TLB maintenance if a (huge) page is reused after a write
  fault. There's EFI refactoring to allow runtime services with
  preemption enabled and the rest is the usual perf/PMU updates and
  several cleanups/typos.

  Summary:

  Core features:

   - Basic Arm MPAM (Memory system resource Partitioning And Monitoring)
     driver under drivers/resctrl/ which makes use of the fs/rectrl/ API

  Perf and PMU:

   - Avoid cycle counter on multi-threaded CPUs

   - Extend CSPMU device probing and add additional filtering support
     for NVIDIA implementations

   - Add support for the PMUs on the NoC S3 interconnect

   - Add additional compatible strings for new Cortex and C1 CPUs

   - Add support for data source filtering to the SPE driver

   - Add support for i.MX8QM and "DB" PMU in the imx PMU driver

  Memory managemennt:

   - Avoid broadcast TLBI if page reused in write fault

   - Elide TLB invalidation if the old PTE was not valid

   - Drop redundant cpu_set_*_tcr_t0sz() macros

   - Propagate pgtable_alloc() errors outside of __create_pgd_mapping()

   - Propagate return value from __change_memory_common()

  ACPI and EFI:

   - Call EFI runtime services without disabling preemption

   - Remove unused ACPI function

  Miscellaneous:

   - ptrace support to disable streaming on SME-only systems

   - Improve sysreg generation to include a 'Prefix' descriptor

   - Replace __ASSEMBLY__ with __ASSEMBLER__

   - Align register dumps in the kselftest zt-test

   - Remove some no longer used macros/functions

   - Various spelling corrections"

* tag 'arm64-upstream' of git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux: (94 commits)
  arm64/mm: Document why linear map split failure upon vm_reset_perms is not problematic
  arm64/pageattr: Propagate return value from __change_memory_common
  arm64/sysreg: Remove unused define ARM64_FEATURE_FIELD_BITS
  KVM: arm64: selftests: Consider all 7 possible levels of cache
  KVM: arm64: selftests: Remove ARM64_FEATURE_FIELD_BITS and its last user
  arm64: atomics: lse: Remove unused parameters from ATOMIC_FETCH_OP_AND macros
  Documentation/arm64: Fix the typo of register names
  ACPI: GTDT: Get rid of acpi_arch_timer_mem_init()
  perf: arm_spe: Add support for filtering on data source
  perf: Add perf_event_attr::config4
  perf/imx_ddr: Add support for PMU in DB (system interconnects)
  perf/imx_ddr: Get and enable optional clks
  perf/imx_ddr: Move ida_alloc() from ddr_perf_init() to ddr_perf_probe()
  dt-bindings: perf: fsl-imx-ddr: Add compatible string for i.MX8QM, i.MX8QXP and i.MX8DXL
  arm64: remove duplicate ARCH_HAS_MEM_ENCRYPT
  arm64: mm: use untagged address to calculate page index
  MAINTAINERS: new entry for MPAM Driver
  arm_mpam: Add kunit tests for props_mismatch()
  arm_mpam: Add kunit test for bitmap reset
  arm_mpam: Add helper to reset saved mbwu state
  ...
2025-12-02 17:03:55 -08:00
Menglong Dong
ae4a3160d1 bpf: specify the old and new poke_type for bpf_arch_text_poke
In the origin logic, the bpf_arch_text_poke() assume that the old and new
instructions have the same opcode. However, they can have different opcode
if we want to replace a "call" insn with a "jmp" insn.

Therefore, add the new function parameter "old_t" along with the "new_t",
which are used to indicate the old and new poke type. Meanwhile, adjust
the implement of bpf_arch_text_poke() for all the archs.

"BPF_MOD_NOP" is added to make the code more readable. In
bpf_arch_text_poke(), we still check if the new and old address is NULL to
determine if nop insn should be used, which I think is more safe.

Signed-off-by: Menglong Dong <dongml2@chinatelecom.cn>
Link: https://lore.kernel.org/r/20251118123639.688444-6-dongml2@chinatelecom.cn
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2025-11-24 09:47:03 -08:00
Puranjay Mohan
f4a66cf1cb bpf: arm64: Add support for indirect jumps
Add support for a new instruction

	BPF_JMP|BPF_X|BPF_JA, SRC=0, DST=Rx, off=0, imm=0

which does an indirect jump to a location stored in Rx.  The register
Rx should have type PTR_TO_INSN. This new type assures that the Rx
register contains a value (or a range of values) loaded from a
correct jump table – map of type instruction array.

ARM64 JIT supports indirect jumps to all registers through the A64_BR()
macro, use it to implement this new instruction.

Signed-off-by: Puranjay Mohan <puranjay@kernel.org>
Reviewed-by: Anton Protopopov <a.s.protopopov@gmail.com>
Acked-by: Xu Kuohai <xukuohai@huawei.com>
Link: https://lore.kernel.org/r/20251117130732.11107-3-puranjay@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2025-11-21 16:40:21 -08:00
Puranjay Mohan
84b1c40d5b bpf: arm64: Add support for instructions array
Add support for the instructions array map type in the arm64 JIT by
calling bpf_prog_update_insn_ptrs() with the offsets that map
xlated_offset to the jited_offset in the final image. arm64 JIT already
has this offset array which was being used for
bpf_prog_fill_jited_linfo() and can be used directly for
bpf_prog_update_insn_ptrs.

Signed-off-by: Puranjay Mohan <puranjay@kernel.org>
Reviewed-by: Anton Protopopov <a.s.protopopov@gmail.com>
Acked-by: Xu Kuohai <xukuohai@huawei.com>
Link: https://lore.kernel.org/r/20251117130732.11107-2-puranjay@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2025-11-21 16:40:21 -08:00
mrigendrachaubey
96ac403ea2 arm64: Fix typos and spelling errors in comments
This patch corrects several minor typographical and spelling errors
in comments across multiple arm64 source files.

No functional changes.

Signed-off-by: mrigendrachaubey <mrigendra.chaubey@gmail.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
2025-11-12 17:06:21 +00:00
Puranjay Mohan
be708ed300 bpf/arm64: Fix BPF_ST into arena memory
The arm64 JIT supports BPF_ST with BPF_PROBE_MEM32 (arena) by using the
tmp2 register to hold the dst + arena_vm_base value and using tmp2 as the
new dst register. But this is broken because in case is_lsi_offset()
returns false the tmp2 will be clobbered by emit_a64_mov_i(1, tmp2, off,
ctx); and hence the emitted store instruction will be of the form:
	strb    w10, [x11, x11]
Fix this by using the third temporary register to hold the dst +
arena_vm_base.

Fixes: 339af577ec ("bpf: Add arm64 JIT support for PROBE_MEM32 pseudo instructions.")
Signed-off-by: Puranjay Mohan <puranjay@kernel.org>
Link: https://lore.kernel.org/r/20251030121715.55214-1-puranjay@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2025-10-31 11:20:53 -07:00
Linus Torvalds
ae28ed4578 bpf-next-6.18
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Merge tag 'bpf-next-6.18' of git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next

Pull bpf updates from Alexei Starovoitov:

 - Support pulling non-linear xdp data with bpf_xdp_pull_data() kfunc
   (Amery Hung)

   Applied as a stable branch in bpf-next and net-next trees.

 - Support reading skb metadata via bpf_dynptr (Jakub Sitnicki)

   Also a stable branch in bpf-next and net-next trees.

 - Enforce expected_attach_type for tailcall compatibility (Daniel
   Borkmann)

 - Replace path-sensitive with path-insensitive live stack analysis in
   the verifier (Eduard Zingerman)

   This is a significant change in the verification logic. More details,
   motivation, long term plans are in the cover letter/merge commit.

 - Support signed BPF programs (KP Singh)

   This is another major feature that took years to materialize.

   Algorithm details are in the cover letter/marge commit

 - Add support for may_goto instruction to s390 JIT (Ilya Leoshkevich)

 - Add support for may_goto instruction to arm64 JIT (Puranjay Mohan)

 - Fix USDT SIB argument handling in libbpf (Jiawei Zhao)

 - Allow uprobe-bpf program to change context registers (Jiri Olsa)

 - Support signed loads from BPF arena (Kumar Kartikeya Dwivedi and
   Puranjay Mohan)

 - Allow access to union arguments in tracing programs (Leon Hwang)

 - Optimize rcu_read_lock() + migrate_disable() combination where it's
   used in BPF subsystem (Menglong Dong)

 - Introduce bpf_task_work_schedule*() kfuncs to schedule deferred
   execution of BPF callback in the context of a specific task using the
   kernel’s task_work infrastructure (Mykyta Yatsenko)

 - Enforce RCU protection for KF_RCU_PROTECTED kfuncs (Kumar Kartikeya
   Dwivedi)

 - Add stress test for rqspinlock in NMI (Kumar Kartikeya Dwivedi)

 - Improve the precision of tnum multiplier verifier operation
   (Nandakumar Edamana)

 - Use tnums to improve is_branch_taken() logic (Paul Chaignon)

 - Add support for atomic operations in arena in riscv JIT (Pu Lehui)

 - Report arena faults to BPF error stream (Puranjay Mohan)

 - Search for tracefs at /sys/kernel/tracing first in bpftool (Quentin
   Monnet)

 - Add bpf_strcasecmp() kfunc (Rong Tao)

 - Support lookup_and_delete_elem command in BPF_MAP_STACK_TRACE (Tao
   Chen)

* tag 'bpf-next-6.18' of git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next: (197 commits)
  libbpf: Replace AF_ALG with open coded SHA-256
  selftests/bpf: Add stress test for rqspinlock in NMI
  selftests/bpf: Add test case for different expected_attach_type
  bpf: Enforce expected_attach_type for tailcall compatibility
  bpftool: Remove duplicate string.h header
  bpf: Remove duplicate crypto/sha2.h header
  libbpf: Fix error when st-prefix_ops and ops from differ btf
  selftests/bpf: Test changing packet data from kfunc
  selftests/bpf: Add stacktrace map lookup_and_delete_elem test case
  selftests/bpf: Refactor stacktrace_map case with skeleton
  bpf: Add lookup_and_delete_elem for BPF_MAP_STACK_TRACE
  selftests/bpf: Fix flaky bpf_cookie selftest
  selftests/bpf: Test changing packet data from global functions with a kfunc
  bpf: Emit struct bpf_xdp_sock type in vmlinux BTF
  selftests/bpf: Task_work selftest cleanup fixes
  MAINTAINERS: Delete inactive maintainers from AF_XDP
  bpf: Mark kfuncs as __noclone
  selftests/bpf: Add kprobe multi write ctx attach test
  selftests/bpf: Add kprobe write ctx attach test
  selftests/bpf: Add uprobe context ip register change test
  ...
2025-09-30 17:58:11 -07:00
Kees Cook
23ef9d4397 kcfi: Rename CONFIG_CFI_CLANG to CONFIG_CFI
The kernel's CFI implementation uses the KCFI ABI specifically, and is
not strictly tied to a particular compiler. In preparation for GCC
supporting KCFI, rename CONFIG_CFI_CLANG to CONFIG_CFI (along with
associated options).

Use new "transitional" Kconfig option for old CONFIG_CFI_CLANG that will
enable CONFIG_CFI during olddefconfig.

Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Reviewed-by: Nathan Chancellor <nathan@kernel.org>
Link: https://lore.kernel.org/r/20250923213422.1105654-3-kees@kernel.org
Signed-off-by: Kees Cook <kees@kernel.org>
2025-09-24 14:29:14 -07:00
Puranjay Mohan
eab2a71f3a bpf, arm64: Add support for signed arena loads
Add support for signed loads from arena which are internally converted
to loads with mode set BPF_PROBE_MEM32SX by the verifier. The
implementation is similar to BPF_PROBE_MEMSX and BPF_MEMSX but for
BPF_PROBE_MEM32SX, arena_vm_base is added to the src register to form
the address.

Signed-off-by: Puranjay Mohan <puranjay@kernel.org>
Link: https://lore.kernel.org/r/20250923110157.18326-3-puranjay@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2025-09-23 12:00:22 -07:00
Kumar Kartikeya Dwivedi
a91ae3c893 bpf, x86: Add support for signed arena loads
Currently, signed load instructions into arena memory are unsupported.
The compiler is free to generate these, and on GCC-14 we see a
corresponding error when it happens. The hurdle in supporting them is
deciding which unused opcode to use to mark them for the JIT's own
consumption. After much thinking, it appears 0xc0 / BPF_NOSPEC can be
combined with load instructions to identify signed arena loads. Use
this to recognize and JIT them appropriately, and remove the verifier
side limitation on the program if the JIT supports them.

Co-developed-by: Puranjay Mohan <puranjay@kernel.org>
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Signed-off-by: Puranjay Mohan <puranjay@kernel.org>
Link: https://lore.kernel.org/r/20250923110157.18326-2-puranjay@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2025-09-23 12:00:22 -07:00
Hengqi Chen
6ff4a0fa3e bpf, arm64: Call bpf_jit_binary_pack_finalize() in bpf_jit_free()
The current implementation seems incorrect and does NOT match the
comment above, use bpf_jit_binary_pack_finalize() instead.

Fixes: 1dad391dae ("bpf, arm64: use bpf_prog_pack for memory management")
Acked-by: Puranjay Mohan <puranjay@kernel.org>
Signed-off-by: Hengqi Chen <hengqi.chen@gmail.com>
Acked-by: Song Liu <song@kernel.org>
Acked-by: Puranjay Mohan <puranjay@kernel.org>
Link: https://lore.kernel.org/r/20250916232653.101004-1-hengqi.chen@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2025-09-17 11:20:32 -07:00
Puranjay Mohan
5c5240d020 bpf: Report arena faults to BPF stderr
Begin reporting arena page faults and the faulting address to BPF
program's stderr, this patch adds support in the arm64 and x86-64 JITs,
support for other archs can be added later.

The fault handlers receive the 32 bit address in the arena region so
the upper 32 bits of user_vm_start is added to it before printing the
address. This is what the user would expect to see as this is what is
printed by bpf_printk() is you pass it an address returned by
bpf_arena_alloc_pages();

Signed-off-by: Puranjay Mohan <puranjay@kernel.org>
Acked-by: Yonghong Song <yonghong.song@linux.dev>
Link: https://lore.kernel.org/r/20250911145808.58042-4-puranjay@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2025-09-11 13:00:43 -07:00
Puranjay Mohan
0460484244 bpf: arm64: simplify exception table handling
BPF loads with BPF_PROBE_MEM(SX) can load from unsafe pointers and the
JIT adds an exception table entry for the JITed instruction which allows
the exeption handler to set the destination register of the load to zero
and continue execution from the next instruction.

As all arm64 instructions are AARCH64_INSN_SIZE size, the exception
handler can just increment the pc by AARCH64_INSN_SIZE without needing
the exact address of the instruction following the the faulting
instruction.

Simplify the exception table usage in arm64 JIT by only saving the
destination register in ex->fixup and drop everything related to
the fixup_offset. The fault handler is modified to add AARCH64_INSN_SIZE
to the pc.

Signed-off-by: Puranjay Mohan <puranjay@kernel.org>
Acked-by: Yonghong Song <yonghong.song@linux.dev>
Acked-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Acked-by: Xu Kuohai <xukuohai@huawei.com>
Link: https://lore.kernel.org/r/20250911145808.58042-2-puranjay@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2025-09-11 13:00:43 -07:00
Hengqi Chen
929adf8838 bpf, arm64: Remove duplicated bpf_flush_icache()
The bpf_flush_icache() is done by bpf_arch_text_copy() already.
Remove the duplicated one in arch_prepare_bpf_trampoline().

Signed-off-by: Hengqi Chen <hengqi.chen@gmail.com>
Acked-by: Puranjay Mohan <puranjay@kernel.org>
Link: https://lore.kernel.org/r/20250904075703.49404-1-hengqi.chen@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2025-09-04 09:02:23 -07:00
Puranjay Mohan
16175375da bpf, arm64: Add JIT support for timed may_goto
When verifier sees a timed may_goto instruction, it emits a call to
arch_bpf_timed_may_goto() with a stack offset in BPF_REG_AX (arm64 r9)
and expects a count value to be returned in the same register. The
verifier doesn't save or restore any registers before emitting this
call.

arch_bpf_timed_may_goto() should act as a trampoline to call
bpf_check_timed_may_goto() with AAPCS64 calling convention.

To support this custom calling convention, implement
arch_bpf_timed_may_goto() in assembly and make sure BPF caller saved
registers are saved and restored, call bpf_check_timed_may_goto with
arm64 calling convention where first argument and return value both are
in x0, then put the result back into BPF_REG_AX before returning.

Signed-off-by: Puranjay Mohan <puranjay@kernel.org>
Acked-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Acked-by: Xu Kuohai <xukuohai@huawei.com>
Link: https://lore.kernel.org/r/20250827113245.52629-2-puranjay@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2025-08-27 17:16:22 -07:00
Puranjay Mohan
710618c760 arm64/cfi,bpf: Support kCFI + BPF on arm64
Currently, bpf_dispatcher_*_func() is marked with `__nocfi` therefore
calling BPF programs from this interface doesn't cause CFI warnings.

When BPF programs are called directly from C: from BPF helpers or
struct_ops, CFI warnings are generated.

Implement proper CFI prologues for the BPF programs and callbacks and
drop __nocfi for arm64. Fix the trampoline generation code to emit kCFI
prologue when a struct_ops trampoline is being prepared.

Signed-off-by: Puranjay Mohan <puranjay12@gmail.com>
Co-developed-by: Maxwell Bland <mbland@motorola.com>
Signed-off-by: Maxwell Bland <mbland@motorola.com>
Co-developed-by: Sami Tolvanen <samitolvanen@google.com>
Signed-off-by: Sami Tolvanen <samitolvanen@google.com>
Tested-by: Dao Huang <huangdao1@oppo.com>
Acked-by: Will Deacon <will@kernel.org>
Link: https://lore.kernel.org/r/20250801001004.1859976-8-samitolvanen@google.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2025-07-31 18:23:54 -07:00
Puranjay Mohan
6c17a882d3 bpf, arm64: JIT support for private stack
The private stack is allocated in bpf_int_jit_compile() with 16-byte
alignment. It includes additional guard regions to detect stack
overflows and underflows at runtime.

Memory layout:

              +------------------------------------------------------+
              |                                                      |
              |  16 bytes padding (overflow guard - stack top)       |
              |  [ detects writes beyond top of stack ]              |
     BPF FP ->+------------------------------------------------------+
              |                                                      |
              |  BPF private stack (sized by verifier)               |
              |  [ 16-byte aligned ]                                 |
              |                                                      |
BPF PRIV SP ->+------------------------------------------------------+
              |                                                      |
              |  16 bytes padding (underflow guard - stack bottom)   |
              |  [ detects accesses before start of stack ]          |
              |                                                      |
              +------------------------------------------------------+

On detection of an overflow or underflow, the kernel emits messages
like:

    BPF private stack overflow/underflow detected for prog <prog_name>

After commit bd737fcb64 ("bpf, arm64: Get rid of fpb"), Jited BPF
programs use the stack in two ways:

1. Via the BPF frame pointer (top of stack), using negative offsets.
2. Via the stack pointer (bottom of stack), using positive offsets in
   LDR/STR instructions.

When a private stack is used, ARM64 callee-saved register x27 replaces
the stack pointer. The BPF frame pointer usage remains unchanged; but
it now points to the top of the private stack.

Relevant tests (Enabled in following patch):

 #415/1   struct_ops_private_stack/private_stack:OK
 #415/2   struct_ops_private_stack/private_stack_fail:OK
 #415/3   struct_ops_private_stack/private_stack_recur:OK
 #415     struct_ops_private_stack:OK
 #549/1   verifier_private_stack/Private stack, single prog:OK
 #549/2   verifier_private_stack/Private stack, subtree > MAX_BPF_STACK:OK
 #549/3   verifier_private_stack/No private stack:OK
 #549/4   verifier_private_stack/Private stack, callback:OK
 #549/5   verifier_private_stack/Private stack, exception in main prog:OK
 #549/6   verifier_private_stack/Private stack, exception in subprog:OK
 #549/7   verifier_private_stack/Private stack, async callback, not nested:OK
 #549/8   verifier_private_stack/Private stack, async callback, potential nesting:OK
 #549     verifier_private_stack:OK
 Summary: 2/11 PASSED, 0 SKIPPED, 0 FAILED

Signed-off-by: Puranjay Mohan <puranjay@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Yonghong Song <yonghong.song@linux.dev>
Link: https://lore.kernel.org/bpf/20250724120257.7299-3-puranjay@kernel.org
2025-07-26 21:26:56 +02:00
Puranjay Mohan
b114fcee76 bpf, arm64: Fix fp initialization for exception boundary
In the ARM64 BPF JIT when prog->aux->exception_boundary is set for a BPF
program, find_used_callee_regs() is not called because for a program
acting as exception boundary, all callee saved registers are saved.
find_used_callee_regs() sets `ctx->fp_used = true;` when it sees FP
being used in any of the instructions.

For programs acting as exception boundary, ctx->fp_used remains false
even if frame pointer is used by the program and therefore, FP is not
set-up for such programs in the prologue. This can cause the kernel to
crash due to a pagefault.

Fix it by setting ctx->fp_used = true for exception boundary programs as
fp is always saved in such programs.

Fixes: 5d4fa9ec56 ("bpf, arm64: Avoid blindly saving/restoring all callee-saved registers")
Signed-off-by: Puranjay Mohan <puranjay@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Xu Kuohai <xukuohai@huawei.com>
Link: https://lore.kernel.org/bpf/20250722133410.54161-2-puranjay@kernel.org
2025-07-26 21:23:38 +02:00
Alexis Lothoré (eBPF Foundation)
dc704d0cfa bpf, arm64: remove structs on stack constraint
While introducing support for 9+ arguments for tracing programs on
ARM64, commit 9014cf56f1 ("bpf, arm64: Support up to 12 function
arguments") has also introduced a constraint preventing BPF trampolines
from being generated if the target function consumes a struct argument
passed on stack, because of uncertainties around the exact struct
location: if the struct has been marked as packed or with a custom
alignment, this info is not reflected in BTF data, and so generated
tracing trampolines could read the target function arguments at wrong
offsets.

This issue is not specific to ARM64: there has been an attempt (see [1])
to bring the same constraint to other architectures JIT compilers. But
discussions following this attempt led to the move of this constraint
out of the kernel (see [2]): instead of preventing the kernel from
generating trampolines for those functions consuming structs on stack,
it is simpler to just make sure that those functions with uncertain
struct arguments location are not encoded in BTF information, and so
that one can not even attempt to attach a tracing program to such
function. The task is then deferred to pahole (see [3]).

Now that the constraint is handled by pahole, remove it from the arm64
JIT compiler to keep it simple.

[1] https://lore.kernel.org/bpf/20250613-deny_trampoline_structs_on_stack-v1-0-5be9211768c3@bootlin.com/
[2] https://lore.kernel.org/bpf/CAADnVQ+sj9XhscN9PdmTzjVa7Eif21noAUH3y1K6x5bWcL-5pg@mail.gmail.com/
[3] https://lore.kernel.org/bpf/20250707-btf_skip_structs_on_stack-v3-0-29569e086c12@bootlin.com/

Signed-off-by: Alexis Lothoré (eBPF Foundation) <alexis.lothore@bootlin.com>
Link: https://lore.kernel.org/r/20250709-arm64_relax_jit_comp-v1-1-3850fe189092@bootlin.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2025-07-16 18:28:30 -07:00
Luis Gerhorst
dff883d9e9 bpf, arm64, powerpc: Change nospec to include v1 barrier
This changes the semantics of BPF_NOSPEC (previously a v4-only barrier)
to always emit a speculation barrier that works against both Spectre v1
AND v4. If mitigation is not needed on an architecture, the backend
should set bpf_jit_bypass_spec_v4/v1().

As of now, this commit only has the user-visible implication that unpriv
BPF's performance on PowerPC is reduced. This is the case because we
have to emit additional v1 barrier instructions for BPF_NOSPEC now.

This commit is required for a future commit to allow us to rely on
BPF_NOSPEC for Spectre v1 mitigation. As of this commit, the feature
that nospec acts as a v1 barrier is unused.

Commit f5e81d1117 ("bpf: Introduce BPF nospec instruction for
mitigating Spectre v4") noted that mitigation instructions for v1 and v4
might be different on some archs. While this would potentially offer
improved performance on PowerPC, it was dismissed after the following
considerations:

* Only having one barrier simplifies the verifier and allows us to
  easily rely on v4-induced barriers for reducing the complexity of
  v1-induced speculative path verification.

* For the architectures that implemented BPF_NOSPEC, only PowerPC has
  distinct instructions for v1 and v4. Even there, some insns may be
  shared between the barriers for v1 and v4 (e.g., 'ori 31,31,0' and
  'sync'). If this is still found to impact performance in an
  unacceptable way, BPF_NOSPEC can be split into BPF_NOSPEC_V1 and
  BPF_NOSPEC_V4 later. As an optimization, we can already skip v1/v4
  insns from being emitted for PowerPC with this setup if
  bypass_spec_v1/v4 is set.

Vulnerability-status for BPF_NOSPEC-based Spectre mitigations (v4 as of
this commit, v1 in the future) is therefore:

* x86 (32-bit and 64-bit), ARM64, and PowerPC (64-bit): Mitigated - This
  patch implements BPF_NOSPEC for these architectures. The previous
  v4-only version was supported since commit f5e81d1117 ("bpf:
  Introduce BPF nospec instruction for mitigating Spectre v4") and
  commit b7540d6250 ("powerpc/bpf: Emit stf barrier instruction
  sequences for BPF_NOSPEC").

* LoongArch: Not Vulnerable - Commit a6f6a95f25 ("LoongArch, bpf: Fix
  jit to skip speculation barrier opcode") is the only other past commit
  related to BPF_NOSPEC and indicates that the insn is not required
  there.

* MIPS: Vulnerable (if unprivileged BPF is enabled) -
  Commit a6f6a95f2580 ("LoongArch, bpf: Fix jit to skip speculation
  barrier opcode") indicates that it is not vulnerable, but this
  contradicts the kernel and Debian documentation. Therefore, I assume
  that there exist vulnerable MIPS CPUs (but maybe not from Loongson?).
  In the future, BPF_NOSPEC could be implemented for MIPS based on the
  GCC speculation_barrier [1]. For now, we rely on unprivileged BPF
  being disabled by default.

* Other: Unknown - To the best of my knowledge there is no definitive
  information available that indicates that any other arch is
  vulnerable. They are therefore left untouched (BPF_NOSPEC is not
  implemented, but bypass_spec_v1/v4 is also not set).

I did the following testing to ensure the insn encoding is correct:

* ARM64:
  * 'dsb nsh; isb' was successfully tested with the BPF CI in [2]
  * 'sb' locally using QEMU v7.2.15 -cpu max (emitted sb insn is
    executed for example with './test_progs -t verifier_array_access')

* PowerPC: The following configs were tested locally with ppc64le QEMU
  v8.2 '-machine pseries -cpu POWER9':
  * STF_BARRIER_EIEIO + CONFIG_PPC_BOOK32_64
  * STF_BARRIER_SYNC_ORI (forced on) + CONFIG_PPC_BOOK32_64
  * STF_BARRIER_FALLBACK (forced on) + CONFIG_PPC_BOOK32_64
  * CONFIG_PPC_E500 (forced on) + STF_BARRIER_EIEIO
  * CONFIG_PPC_E500 (forced on) + STF_BARRIER_SYNC_ORI (forced on)
  * CONFIG_PPC_E500 (forced on) + STF_BARRIER_FALLBACK (forced on)
  * CONFIG_PPC_E500 (forced on) + STF_BARRIER_NONE (forced on)
  Most of those cobinations should not occur in practice, but I was not
  able to get an PPC e6500 rootfs (for testing PPC_E500 without forcing
  it on). In any case, this should ensure that there are no unexpected
  conflicts between the insns when combined like this. Individual v1/v4
  barriers were already emitted elsewhere.

Hari's ack is for the PowerPC changes only.

[1] https://gcc.gnu.org/git/?p=gcc.git;a=commit;h=29b74545531f6afbee9fc38c267524326dbfbedf
    ("MIPS: Add speculation_barrier support")
[2] https://github.com/kernel-patches/bpf/pull/8576

Signed-off-by: Luis Gerhorst <luis.gerhorst@fau.de>
Acked-by: Hari Bathini <hbathini@linux.ibm.com>
Cc: Henriette Herzog <henriette.herzog@rub.de>
Cc: Maximilian Ott <ott@cs.fau.de>
Cc: Milan Stephan <milan.stephan@fau.de>
Link: https://lore.kernel.org/r/20250603211703.337860-1-luis.gerhorst@fau.de
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2025-06-09 20:11:09 -07:00
Luis Gerhorst
03c68a0f8c bpf, arm64, powerpc: Add bpf_jit_bypass_spec_v1/v4()
JITs can set bpf_jit_bypass_spec_v1/v4() if they want the verifier to
skip analysis/patching for the respective vulnerability. For v4, this
will reduce the number of barriers the verifier inserts. For v1, it
allows more programs to be accepted.

The primary motivation for this is to not regress unpriv BPF's
performance on ARM64 in a future commit where BPF_NOSPEC is also used
against Spectre v1.

This has the user-visible change that v1-induced rejections on
non-vulnerable PowerPC CPUs are avoided.

For now, this does not change the semantics of BPF_NOSPEC. It is still a
v4-only barrier and must not be implemented if bypass_spec_v4 is always
true for the arch. Changing it to a v1 AND v4-barrier is done in a
future commit.

As an alternative to bypass_spec_v1/v4, one could introduce NOSPEC_V1
AND NOSPEC_V4 instructions and allow backends to skip their lowering as
suggested by commit f5e81d1117 ("bpf: Introduce BPF nospec instruction
for mitigating Spectre v4"). Adding bpf_jit_bypass_spec_v1/v4() was
found to be preferable for the following reason:

* bypass_spec_v1/v4 benefits non-vulnerable CPUs: Always performing the
  same analysis (not taking into account whether the current CPU is
  vulnerable), needlessly restricts users of CPUs that are not
  vulnerable. The only use case for this would be portability-testing,
  but this can later be added easily when needed by allowing users to
  force bypass_spec_v1/v4 to false.

* Portability is still acceptable: Directly disabling the analysis
  instead of skipping the lowering of BPF_NOSPEC(_V1/V4) might allow
  programs on non-vulnerable CPUs to be accepted while the program will
  be rejected on vulnerable CPUs. With the fallback to speculation
  barriers for Spectre v1 implemented in a future commit, this will only
  affect programs that do variable stack-accesses or are very complex.

For PowerPC, the SEC_FTR checking in bpf_jit_bypass_spec_v4() is based
on the check that was previously located in the BPF_NOSPEC case.

For LoongArch, it would likely be safe to set both
bpf_jit_bypass_spec_v1() and _v4() according to
commit a6f6a95f2580 ("LoongArch, bpf: Fix jit to skip speculation
barrier opcode"). This is omitted here as I am unable to do any testing
for LoongArch.

Hari's ack concerns the PowerPC part only.

Signed-off-by: Luis Gerhorst <luis.gerhorst@fau.de>
Acked-by: Hari Bathini <hbathini@linux.ibm.com>
Cc: Henriette Herzog <henriette.herzog@rub.de>
Cc: Maximilian Ott <ott@cs.fau.de>
Cc: Milan Stephan <milan.stephan@fau.de>
Link: https://lore.kernel.org/r/20250603211318.337474-1-luis.gerhorst@fau.de
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2025-06-09 20:11:09 -07:00
Linus Torvalds
90b83efa67 bpf-next-6.16
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Merge tag 'bpf-next-6.16' of git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next

Pull bpf updates from Alexei Starovoitov:

 - Fix and improve BTF deduplication of identical BTF types (Alan
   Maguire and Andrii Nakryiko)

 - Support up to 12 arguments in BPF trampoline on arm64 (Xu Kuohai and
   Alexis Lothoré)

 - Support load-acquire and store-release instructions in BPF JIT on
   riscv64 (Andrea Parri)

 - Fix uninitialized values in BPF_{CORE,PROBE}_READ macros (Anton
   Protopopov)

 - Streamline allowed helpers across program types (Feng Yang)

 - Support atomic update for hashtab of BPF maps (Hou Tao)

 - Implement json output for BPF helpers (Ihor Solodrai)

 - Several s390 JIT fixes (Ilya Leoshkevich)

 - Various sockmap fixes (Jiayuan Chen)

 - Support mmap of vmlinux BTF data (Lorenz Bauer)

 - Support BPF rbtree traversal and list peeking (Martin KaFai Lau)

 - Tests for sockmap/sockhash redirection (Michal Luczaj)

 - Introduce kfuncs for memory reads into dynptrs (Mykyta Yatsenko)

 - Add support for dma-buf iterators in BPF (T.J. Mercier)

 - The verifier support for __bpf_trap() (Yonghong Song)

* tag 'bpf-next-6.16' of git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next: (135 commits)
  bpf, arm64: Remove unused-but-set function and variable.
  selftests/bpf: Add tests with stack ptr register in conditional jmp
  bpf: Do not include stack ptr register in precision backtracking bookkeeping
  selftests/bpf: enable many-args tests for arm64
  bpf, arm64: Support up to 12 function arguments
  bpf: Check rcu_read_lock_trace_held() in bpf_map_lookup_percpu_elem()
  bpf: Avoid __bpf_prog_ret0_warn when jit fails
  bpftool: Add support for custom BTF path in prog load/loadall
  selftests/bpf: Add unit tests with __bpf_trap() kfunc
  bpf: Warn with __bpf_trap() kfunc maybe due to uninitialized variable
  bpf: Remove special_kfunc_set from verifier
  selftests/bpf: Add test for open coded dmabuf_iter
  selftests/bpf: Add test for dmabuf_iter
  bpf: Add open coded dmabuf iterator
  bpf: Add dmabuf iterator
  dma-buf: Rename debugfs symbols
  bpf: Fix error return value in bpf_copy_from_user_dynptr
  libbpf: Use mmap to parse vmlinux BTF from sysfs
  selftests: bpf: Add a test for mmapable vmlinux BTF
  btf: Allow mmap of vmlinux btf
  ...
2025-05-28 15:52:42 -07:00
Alexei Starovoitov
c5cebb241e bpf, arm64: Remove unused-but-set function and variable.
Remove unused-but-set function and variable to fix the build warning:
   arch/arm64/net/bpf_jit_comp.c: In function 'arch_bpf_trampoline_size':
    2547 |  int nregs, ret;
         |      ^~~~~

Fixes: 9014cf56f1 ("bpf, arm64: Support up to 12 function arguments")
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Xu Kuohai <xukuohai@huawei.com>
Link: https://lore.kernel.org/bpf/20250528002704.21197-1-alexei.starovoitov@gmail.com

Closes: https://lore.kernel.org/oe-kbuild-all/202505280643.h0qYcSCM-lkp@intel.com/
2025-05-27 20:16:57 -07:00
Xu Kuohai
9014cf56f1 bpf, arm64: Support up to 12 function arguments
Currently ARM64 bpf trampoline supports up to 8 function arguments.
According to the statistics from commit
473e3150e3 ("bpf, x86: allow function arguments up to 12 for TRACING"),
there are about 200 functions accept 9 to 12 arguments, so adding support
for up to 12 function arguments.

Due to bpf only supporting function arguments up to 16 bytes, according to
AAPCS64, starting from the first argument, each argument is first
attempted to be loaded to 1 or 2 smallest registers from x0-x7, if there
are no enough registers to hold the entire argument, then all remaining
arguments starting from this one are pushed to the stack for passing.
There are some non-trivial cases for which it is not possible to
correctly read arguments from/write arguments to the stack: for example
struct variables may have custom packing/alignment attributes that are
invisible in BTF info. Such cases are denied for now to make sure not to
read incorrect values.

Signed-off-by: Xu Kuohai <xukuohai@huawei.com>
Co-developed-by: Alexis Lothoré (eBPF Foundation) <alexis.lothore@bootlin.com>
Signed-off-by: Alexis Lothoré (eBPF Foundation) <alexis.lothore@bootlin.com>
Link: https://lore.kernel.org/r/20250527-many_args_arm64-v3-1-3faf7bb8e4a2@bootlin.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2025-05-27 10:50:31 -07:00
James Morse
f300769ead arm64: bpf: Only mitigate cBPF programs loaded by unprivileged users
Support for eBPF programs loaded by unprivileged users is typically
disabled. This means only cBPF programs need to be mitigated for BHB.

In addition, only mitigate cBPF programs that were loaded by an
unprivileged user. Privileged users can also load the same program
via eBPF, making the mitigation pointless.

Signed-off-by: James Morse <james.morse@arm.com>
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
2025-05-08 15:29:03 +01:00
James Morse
0dfefc2ea2 arm64: bpf: Add BHB mitigation to the epilogue for cBPF programs
A malicious BPF program may manipulate the branch history to influence
what the hardware speculates will happen next.

On exit from a BPF program, emit the BHB mititgation sequence.

This is only applied for 'classic' cBPF programs that are loaded by
seccomp.

Signed-off-by: James Morse <james.morse@arm.com>
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
2025-05-08 15:28:35 +01:00
Peilin Ye
9bb12368d5 bpf, arm64: Support load-acquire and store-release instructions
Support BPF load-acquire (BPF_LOAD_ACQ) and store-release
(BPF_STORE_REL) instructions in the arm64 JIT compiler.  For example
(assuming little-endian):

  db 10 00 00 00 01 00 00  r0 = load_acquire((u64 *)(r1 + 0x0))
  95 00 00 00 00 00 00 00  exit

  opcode (0xdb): BPF_ATOMIC | BPF_DW | BPF_STX
  imm (0x00000100): BPF_LOAD_ACQ

The JIT compiler would emit an LDAR instruction for the above, e.g.:

  ldar  x7, [x0]

Similarly, consider the following 16-bit store-release:

  cb 21 00 00 10 01 00 00  store_release((u16 *)(r1 + 0x0), w2)
  95 00 00 00 00 00 00 00  exit

  opcode (0xcb): BPF_ATOMIC | BPF_H | BPF_STX
  imm (0x00000110): BPF_STORE_REL

An STLRH instruction would be emitted, e.g.:

  stlrh  w1, [x0]

For a complete mapping:

  load-acquire     8-bit  LDARB
 (BPF_LOAD_ACQ)   16-bit  LDARH
                  32-bit  LDAR (32-bit)
                  64-bit  LDAR (64-bit)
  store-release    8-bit  STLRB
 (BPF_STORE_REL)  16-bit  STLRH
                  32-bit  STLR (32-bit)
                  64-bit  STLR (64-bit)

Arena accesses are supported.
bpf_jit_supports_insn(..., /*in_arena=*/true) always returns true for
BPF_LOAD_ACQ and BPF_STORE_REL instructions, as they don't depend on
ARM64_HAS_LSE_ATOMICS.

Acked-by: Xu Kuohai <xukuohai@huawei.com>
Signed-off-by: Peilin Ye <yepeilin@google.com>
Link: https://lore.kernel.org/r/51664a1300710238ba2d4d95142b57a52c4f0cae.1741049567.git.yepeilin@google.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2025-03-15 11:48:29 -07:00
Peilin Ye
880442305a bpf: Introduce load-acquire and store-release instructions
Introduce BPF instructions with load-acquire and store-release
semantics, as discussed in [1].  Define 2 new flags:

  #define BPF_LOAD_ACQ    0x100
  #define BPF_STORE_REL   0x110

A "load-acquire" is a BPF_STX | BPF_ATOMIC instruction with the 'imm'
field set to BPF_LOAD_ACQ (0x100).

Similarly, a "store-release" is a BPF_STX | BPF_ATOMIC instruction with
the 'imm' field set to BPF_STORE_REL (0x110).

Unlike existing atomic read-modify-write operations that only support
BPF_W (32-bit) and BPF_DW (64-bit) size modifiers, load-acquires and
store-releases also support BPF_B (8-bit) and BPF_H (16-bit).  As an
exception, however, 64-bit load-acquires/store-releases are not
supported on 32-bit architectures (to fix a build error reported by the
kernel test robot).

An 8- or 16-bit load-acquire zero-extends the value before writing it to
a 32-bit register, just like ARM64 instruction LDARH and friends.

Similar to existing atomic read-modify-write operations, misaligned
load-acquires/store-releases are not allowed (even if
BPF_F_ANY_ALIGNMENT is set).

As an example, consider the following 64-bit load-acquire BPF
instruction (assuming little-endian):

  db 10 00 00 00 01 00 00  r0 = load_acquire((u64 *)(r1 + 0x0))

  opcode (0xdb): BPF_ATOMIC | BPF_DW | BPF_STX
  imm (0x00000100): BPF_LOAD_ACQ

Similarly, a 16-bit BPF store-release:

  cb 21 00 00 10 01 00 00  store_release((u16 *)(r1 + 0x0), w2)

  opcode (0xcb): BPF_ATOMIC | BPF_H | BPF_STX
  imm (0x00000110): BPF_STORE_REL

In arch/{arm64,s390,x86}/net/bpf_jit_comp.c, have
bpf_jit_supports_insn(..., /*in_arena=*/true) return false for the new
instructions, until the corresponding JIT compiler supports them in
arena.

[1] https://lore.kernel.org/all/20240729183246.4110549-1-yepeilin@google.com/

Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Acked-by: Ilya Leoshkevich <iii@linux.ibm.com>
Cc: kernel test robot <lkp@intel.com>
Signed-off-by: Peilin Ye <yepeilin@google.com>
Link: https://lore.kernel.org/r/a217f46f0e445fbd573a1a024be5c6bf1d5fe716.1741049567.git.yepeilin@google.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2025-03-15 11:48:28 -07:00
Song Liu
239860828f bpf: arm64: Silence "UBSAN: negation-overflow" warning
With UBSAN, test_bpf.ko triggers warnings like:

UBSAN: negation-overflow in arch/arm64/net/bpf_jit_comp.c:1333:28
negation of -2147483648 cannot be represented in type 's32' (aka 'int'):

Silence these warnings by casting imm to u32 first.

Reported-by: Breno Leitao <leitao@debian.org>
Signed-off-by: Song Liu <song@kernel.org>
Tested-by: Breno Leitao <leitao@debian.org>
Link: https://lore.kernel.org/r/20250218080240.2431257-1-song@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2025-02-23 13:04:02 -08:00
Peilin Ye
8c21f88407 bpf, arm64: Emit A64_{ADD,SUB}_I when possible in emit_{lse,ll_sc}_atomic()
Currently in emit_{lse,ll_sc}_atomic(), if there is an offset, we add it
to the base address by doing e.g.:

  if (off) {
          emit_a64_mov_i(1, tmp, off, ctx);
          emit(A64_ADD(1, tmp, tmp, dst), ctx);
  [...]

As pointed out by Xu, we can use emit_a64_add_i() (added in the previous
patch) instead, which tries to combine the above into a single A64_ADD_I
or A64_SUB_I when possible.

Suggested-by: Xu Kuohai <xukuohai@huaweicloud.com>
Signed-off-by: Peilin Ye <yepeilin@google.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Xu Kuohai <xukuohai@huawei.com>
Link: https://lore.kernel.org/bpf/9ad3034a62361d91a99af24efa03f48c4c9e13ea.1735868489.git.yepeilin@google.com
2025-01-06 15:07:41 +01:00
Peilin Ye
66bb58ac06 bpf, arm64: Factor out emit_a64_add_i()
As suggested by Xu, factor out emit_a64_add_i() for later use. No
functional change.

Suggested-by: Xu Kuohai <xukuohai@huaweicloud.com>
Signed-off-by: Peilin Ye <yepeilin@google.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Xu Kuohai <xukuohai@huawei.com>
Link: https://lore.kernel.org/bpf/fedbaca80e6d8bd5bcba1ac5320dfbbdab14472e.1735868489.git.yepeilin@google.com
2025-01-06 15:07:26 +01:00
Peilin Ye
0a5807219a bpf, arm64: Simplify if logic in emit_lse_atomic()
Delete that unnecessary outer if clause. No functional change.

Signed-off-by: Peilin Ye <yepeilin@google.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Xu Kuohai <xukuohai@huawei.com>
Link: https://lore.kernel.org/bpf/e8520e5503a489e2dea8526077976ae5a0ab1849.1735868489.git.yepeilin@google.com
2025-01-06 15:07:20 +01:00
Linus Torvalds
5c00ff742b - The series "zram: optimal post-processing target selection" from
Sergey Senozhatsky improves zram's post-processing selection algorithm.
   This leads to improved memory savings.
 
 - Wei Yang has gone to town on the mapletree code, contributing several
   series which clean up the implementation:
 
 	- "refine mas_mab_cp()"
 	- "Reduce the space to be cleared for maple_big_node"
 	- "maple_tree: simplify mas_push_node()"
 	- "Following cleanup after introduce mas_wr_store_type()"
 	- "refine storing null"
 
 - The series "selftests/mm: hugetlb_fault_after_madv improvements" from
   David Hildenbrand fixes this selftest for s390.
 
 - The series "introduce pte_offset_map_{ro|rw}_nolock()" from Qi Zheng
   implements some rationaizations and cleanups in the page mapping code.
 
 - The series "mm: optimize shadow entries removal" from Shakeel Butt
   optimizes the file truncation code by speeding up the handling of shadow
   entries.
 
 - The series "Remove PageKsm()" from Matthew Wilcox completes the
   migration of this flag over to being a folio-based flag.
 
 - The series "Unify hugetlb into arch_get_unmapped_area functions" from
   Oscar Salvador implements a bunch of consolidations and cleanups in the
   hugetlb code.
 
 - The series "Do not shatter hugezeropage on wp-fault" from Dev Jain
   takes away the wp-fault time practice of turning a huge zero page into
   small pages.  Instead we replace the whole thing with a THP.  More
   consistent cleaner and potentiall saves a large number of pagefaults.
 
 - The series "percpu: Add a test case and fix for clang" from Andy
   Shevchenko enhances and fixes the kernel's built in percpu test code.
 
 - The series "mm/mremap: Remove extra vma tree walk" from Liam Howlett
   optimizes mremap() by avoiding doing things which we didn't need to do.
 
 - The series "Improve the tmpfs large folio read performance" from
   Baolin Wang teaches tmpfs to copy data into userspace at the folio size
   rather than as individual pages.  A 20% speedup was observed.
 
 - The series "mm/damon/vaddr: Fix issue in
   damon_va_evenly_split_region()" fro Zheng Yejian fixes DAMON splitting.
 
 - The series "memcg-v1: fully deprecate charge moving" from Shakeel Butt
   removes the long-deprecated memcgv2 charge moving feature.
 
 - The series "fix error handling in mmap_region() and refactor" from
   Lorenzo Stoakes cleanup up some of the mmap() error handling and
   addresses some potential performance issues.
 
 - The series "x86/module: use large ROX pages for text allocations" from
   Mike Rapoport teaches x86 to use large pages for read-only-execute
   module text.
 
 - The series "page allocation tag compression" from Suren Baghdasaryan
   is followon maintenance work for the new page allocation profiling
   feature.
 
 - The series "page->index removals in mm" from Matthew Wilcox remove
   most references to page->index in mm/.  A slow march towards shrinking
   struct page.
 
 - The series "damon/{self,kunit}tests: minor fixups for DAMON debugfs
   interface tests" from Andrew Paniakin performs maintenance work for
   DAMON's self testing code.
 
 - The series "mm: zswap swap-out of large folios" from Kanchana Sridhar
   improves zswap's batching of compression and decompression.  It is a
   step along the way towards using Intel IAA hardware acceleration for
   this zswap operation.
 
 - The series "kasan: migrate the last module test to kunit" from
   Sabyrzhan Tasbolatov completes the migration of the KASAN built-in tests
   over to the KUnit framework.
 
 - The series "implement lightweight guard pages" from Lorenzo Stoakes
   permits userapace to place fault-generating guard pages within a single
   VMA, rather than requiring that multiple VMAs be created for this.
   Improved efficiencies for userspace memory allocators are expected.
 
 - The series "memcg: tracepoint for flushing stats" from JP Kobryn uses
   tracepoints to provide increased visibility into memcg stats flushing
   activity.
 
 - The series "zram: IDLE flag handling fixes" from Sergey Senozhatsky
   fixes a zram buglet which potentially affected performance.
 
 - The series "mm: add more kernel parameters to control mTHP" from
   Maíra Canal enhances our ability to control/configuremultisize THP from
   the kernel boot command line.
 
 - The series "kasan: few improvements on kunit tests" from Sabyrzhan
   Tasbolatov has a couple of fixups for the KASAN KUnit tests.
 
 - The series "mm/list_lru: Split list_lru lock into per-cgroup scope"
   from Kairui Song optimizes list_lru memory utilization when lockdep is
   enabled.
 -----BEGIN PGP SIGNATURE-----
 
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 jkeuAQCkl+BmeYHE6uG0hi3pRxkupseR6DEOAYIiTv0/l8/GggD/Z3jmEeqnZaNq
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 =JfWR
 -----END PGP SIGNATURE-----

Merge tag 'mm-stable-2024-11-18-19-27' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

Pull MM updates from Andrew Morton:

 - The series "zram: optimal post-processing target selection" from
   Sergey Senozhatsky improves zram's post-processing selection
   algorithm. This leads to improved memory savings.

 - Wei Yang has gone to town on the mapletree code, contributing several
   series which clean up the implementation:
	- "refine mas_mab_cp()"
	- "Reduce the space to be cleared for maple_big_node"
	- "maple_tree: simplify mas_push_node()"
	- "Following cleanup after introduce mas_wr_store_type()"
	- "refine storing null"

 - The series "selftests/mm: hugetlb_fault_after_madv improvements" from
   David Hildenbrand fixes this selftest for s390.

 - The series "introduce pte_offset_map_{ro|rw}_nolock()" from Qi Zheng
   implements some rationaizations and cleanups in the page mapping
   code.

 - The series "mm: optimize shadow entries removal" from Shakeel Butt
   optimizes the file truncation code by speeding up the handling of
   shadow entries.

 - The series "Remove PageKsm()" from Matthew Wilcox completes the
   migration of this flag over to being a folio-based flag.

 - The series "Unify hugetlb into arch_get_unmapped_area functions" from
   Oscar Salvador implements a bunch of consolidations and cleanups in
   the hugetlb code.

 - The series "Do not shatter hugezeropage on wp-fault" from Dev Jain
   takes away the wp-fault time practice of turning a huge zero page
   into small pages. Instead we replace the whole thing with a THP. More
   consistent cleaner and potentiall saves a large number of pagefaults.

 - The series "percpu: Add a test case and fix for clang" from Andy
   Shevchenko enhances and fixes the kernel's built in percpu test code.

 - The series "mm/mremap: Remove extra vma tree walk" from Liam Howlett
   optimizes mremap() by avoiding doing things which we didn't need to
   do.

 - The series "Improve the tmpfs large folio read performance" from
   Baolin Wang teaches tmpfs to copy data into userspace at the folio
   size rather than as individual pages. A 20% speedup was observed.

 - The series "mm/damon/vaddr: Fix issue in
   damon_va_evenly_split_region()" fro Zheng Yejian fixes DAMON
   splitting.

 - The series "memcg-v1: fully deprecate charge moving" from Shakeel
   Butt removes the long-deprecated memcgv2 charge moving feature.

 - The series "fix error handling in mmap_region() and refactor" from
   Lorenzo Stoakes cleanup up some of the mmap() error handling and
   addresses some potential performance issues.

 - The series "x86/module: use large ROX pages for text allocations"
   from Mike Rapoport teaches x86 to use large pages for
   read-only-execute module text.

 - The series "page allocation tag compression" from Suren Baghdasaryan
   is followon maintenance work for the new page allocation profiling
   feature.

 - The series "page->index removals in mm" from Matthew Wilcox remove
   most references to page->index in mm/. A slow march towards shrinking
   struct page.

 - The series "damon/{self,kunit}tests: minor fixups for DAMON debugfs
   interface tests" from Andrew Paniakin performs maintenance work for
   DAMON's self testing code.

 - The series "mm: zswap swap-out of large folios" from Kanchana Sridhar
   improves zswap's batching of compression and decompression. It is a
   step along the way towards using Intel IAA hardware acceleration for
   this zswap operation.

 - The series "kasan: migrate the last module test to kunit" from
   Sabyrzhan Tasbolatov completes the migration of the KASAN built-in
   tests over to the KUnit framework.

 - The series "implement lightweight guard pages" from Lorenzo Stoakes
   permits userapace to place fault-generating guard pages within a
   single VMA, rather than requiring that multiple VMAs be created for
   this. Improved efficiencies for userspace memory allocators are
   expected.

 - The series "memcg: tracepoint for flushing stats" from JP Kobryn uses
   tracepoints to provide increased visibility into memcg stats flushing
   activity.

 - The series "zram: IDLE flag handling fixes" from Sergey Senozhatsky
   fixes a zram buglet which potentially affected performance.

 - The series "mm: add more kernel parameters to control mTHP" from
   Maíra Canal enhances our ability to control/configuremultisize THP
   from the kernel boot command line.

 - The series "kasan: few improvements on kunit tests" from Sabyrzhan
   Tasbolatov has a couple of fixups for the KASAN KUnit tests.

 - The series "mm/list_lru: Split list_lru lock into per-cgroup scope"
   from Kairui Song optimizes list_lru memory utilization when lockdep
   is enabled.

* tag 'mm-stable-2024-11-18-19-27' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (215 commits)
  cma: enforce non-zero pageblock_order during cma_init_reserved_mem()
  mm/kfence: add a new kunit test test_use_after_free_read_nofault()
  zram: fix NULL pointer in comp_algorithm_show()
  memcg/hugetlb: add hugeTLB counters to memcg
  vmstat: call fold_vm_zone_numa_events() before show per zone NUMA event
  mm: mmap_lock: check trace_mmap_lock_$type_enabled() instead of regcount
  zram: ZRAM_DEF_COMP should depend on ZRAM
  MAINTAINERS/MEMORY MANAGEMENT: add document files for mm
  Docs/mm/damon: recommend academic papers to read and/or cite
  mm: define general function pXd_init()
  kmemleak: iommu/iova: fix transient kmemleak false positive
  mm/list_lru: simplify the list_lru walk callback function
  mm/list_lru: split the lock to per-cgroup scope
  mm/list_lru: simplify reparenting and initial allocation
  mm/list_lru: code clean up for reparenting
  mm/list_lru: don't export list_lru_add
  mm/list_lru: don't pass unnecessary key parameters
  kasan: add kunit tests for kmalloc_track_caller, kmalloc_node_track_caller
  kasan: change kasan_atomics kunit test as KUNIT_CASE_SLOW
  kasan: use EXPORT_SYMBOL_IF_KUNIT to export symbols
  ...
2024-11-23 09:58:07 -08:00
Mike Rapoport (Microsoft)
0c3beacf68 asm-generic: introduce text-patching.h
Several architectures support text patching, but they name the header
files that declare patching functions differently.

Make all such headers consistently named text-patching.h and add an empty
header in asm-generic for architectures that do not support text patching.

Link: https://lkml.kernel.org/r/20241023162711.2579610-4-rppt@kernel.org
Signed-off-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Acked-by: Geert Uytterhoeven <geert@linux-m68k.org> # m68k
Acked-by: Arnd Bergmann <arnd@arndb.de>
Reviewed-by: Luis Chamberlain <mcgrof@kernel.org>
Tested-by: kdevops <kdevops@lists.linux.dev>
Cc: Andreas Larsson <andreas@gaisler.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Ard Biesheuvel <ardb@kernel.org>
Cc: Borislav Petkov (AMD) <bp@alien8.de>
Cc: Brian Cain <bcain@quicinc.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Christophe Leroy <christophe.leroy@csgroup.eu>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Dinh Nguyen <dinguyen@kernel.org>
Cc: Guo Ren <guoren@kernel.org>
Cc: Helge Deller <deller@gmx.de>
Cc: Huacai Chen <chenhuacai@kernel.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Johannes Berg <johannes@sipsolutions.net>
Cc: John Paul Adrian Glaubitz <glaubitz@physik.fu-berlin.de>
Cc: Kent Overstreet <kent.overstreet@linux.dev>
Cc: Liam R. Howlett <Liam.Howlett@Oracle.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Cc: Matt Turner <mattst88@gmail.com>
Cc: Max Filippov <jcmvbkbc@gmail.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Michal Simek <monstr@monstr.eu>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Palmer Dabbelt <palmer@dabbelt.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Richard Weinberger <richard@nod.at>
Cc: Russell King <linux@armlinux.org.uk>
Cc: Song Liu <song@kernel.org>
Cc: Stafford Horne <shorne@gmail.com>
Cc: Steven Rostedt (Google) <rostedt@goodmis.org>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Uladzislau Rezki (Sony) <urezki@gmail.com>
Cc: Vineet Gupta <vgupta@kernel.org>
Cc: Will Deacon <will@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2024-11-07 14:25:15 -08:00
Xu Kuohai
87cb58aebd bpf, arm64: Remove garbage frame for struct_ops trampoline
The callsite layout for arm64 fentry is:

mov x9, lr
nop

When a bpf prog is attached, the nop instruction is patched to a call
to bpf trampoline:

mov x9, lr
bl <bpf trampoline>

So two return addresses are passed to bpf trampoline: the return address
for the traced function/prog, stored in x9, and the return address for
the bpf trampoline itself, stored in lr. To obtain a full and accurate
call stack, the bpf trampoline constructs two fake function frames using
x9 and lr.

However, struct_ops progs are invoked directly as function callbacks,
meaning that x9 is not set as it is in the fentry callsite. In this case,
the frame constructed using x9 is garbage. The following stack trace for
struct_ops, captured by perf sampling, illustrates this issue, where
tcp_ack+0x404 is a garbage frame:

ffffffc0801a04b4 bpf_prog_50992e55a0f655a9_bpf_cubic_cong_avoid+0x98 (bpf_prog_50992e55a0f655a9_bpf_cubic_cong_avoid)
ffffffc0801a228c [unknown] ([kernel.kallsyms]) // bpf trampoline
ffffffd08d362590 tcp_ack+0x798 ([kernel.kallsyms]) // caller for bpf trampoline
ffffffd08d3621fc tcp_ack+0x404 ([kernel.kallsyms]) // garbage frame
ffffffd08d36452c tcp_rcv_established+0x4ac ([kernel.kallsyms])
ffffffd08d375c58 tcp_v4_do_rcv+0x1f0 ([kernel.kallsyms])
ffffffd08d378630 tcp_v4_rcv+0xeb8 ([kernel.kallsyms])

To fix it, construct only one frame using lr for struct_ops.

The above stack trace also indicates that there is no kernel symbol for
struct_ops bpf trampoline. This will be addressed in a follow-up patch.

Fixes: efc9909fdc ("bpf, arm64: Add bpf trampoline for arm64")
Signed-off-by: Xu Kuohai <xukuohai@huawei.com>
Acked-by: Puranjay Mohan <puranjay@kernel.org>
Tested-by: Puranjay Mohan <puranjay@kernel.org>
Link: https://lore.kernel.org/r/20241025085220.533949-1-xukuohai@huaweicloud.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2024-10-25 09:11:40 -07:00
Peter Collingbourne
a552e2ef5f bpf, arm64: Fix address emission with tag-based KASAN enabled
When BPF_TRAMP_F_CALL_ORIG is enabled, the address of a bpf_tramp_image
struct on the stack is passed during the size calculation pass and
an address on the heap is passed during code generation. This may
cause a heap buffer overflow if the heap address is tagged because
emit_a64_mov_i64() will emit longer code than it did during the size
calculation pass. The same problem could occur without tag-based
KASAN if one of the 16-bit words of the stack address happened to
be all-ones during the size calculation pass. Fix the problem by
assuming the worst case (4 instructions) when calculating the size
of the bpf_tramp_image address emission.

Fixes: 19d3c179a3 ("bpf, arm64: Fix trampoline for BPF_TRAMP_F_CALL_ORIG")
Signed-off-by: Peter Collingbourne <pcc@google.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Xu Kuohai <xukuohai@huawei.com>
Link: https://linux-review.googlesource.com/id/I1496f2bc24fba7a1d492e16e2b94cf43714f2d3c
Link: https://lore.kernel.org/bpf/20241018221644.3240898-1-pcc@google.com
2024-10-21 09:45:19 +02:00
Xu Kuohai
ddbe9ec550 bpf, arm64: Jit BPF_CALL to direct call when possible
Currently, BPF_CALL is always jited to indirect call. When target is
within the range of direct call, BPF_CALL can be jited to direct call.

For example, the following BPF_CALL

    call __htab_map_lookup_elem

is always jited to indirect call:

    mov     x10, #0xffffffffffff18f4
    movk    x10, #0x821, lsl #16
    movk    x10, #0x8000, lsl #32
    blr     x10

When the address of target __htab_map_lookup_elem is within the range of
direct call, the BPF_CALL can be jited to:

    bl      0xfffffffffd33bc98

This patch does such jit optimization by emitting arm64 direct calls for
BPF_CALL when possible, indirect calls otherwise.

Without this patch, the jit works as follows.

1. First pass
   A. Determine jited position and size for each bpf instruction.
   B. Computed the jited image size.

2. Allocate jited image with size computed in step 1.

3. Second pass
   A. Adjust jump offset for jump instructions
   B. Write the final image.

This works because, for a given bpf prog, regardless of where the jited
image is allocated, the jited result for each instruction is fixed. The
second pass differs from the first only in adjusting the jump offsets,
like changing "jmp imm1" to "jmp imm2", while the position and size of
the "jmp" instruction remain unchanged.

Now considering whether to jit BPF_CALL to arm64 direct or indirect call
instruction. The choice depends solely on the jump offset: direct call
if the jump offset is within 128MB, indirect call otherwise.

For a given BPF_CALL, the target address is known, so the jump offset is
decided by the jited address of the BPF_CALL instruction. In other words,
for a given bpf prog, the jited result for each BPF_CALL is determined
by its jited address.

The jited address for a BPF_CALL is the jited image address plus the
total jited size of all preceding instructions. For a given bpf prog,
there are clearly no BPF_CALL instructions before the first BPF_CALL
instruction. Since the jited result for all other instructions other
than BPF_CALL are fixed, the total jited size preceding the first
BPF_CALL is also fixed. Therefore, once the jited image is allocated,
the jited address for the first BPF_CALL is fixed.

Now that the jited result for the first BPF_CALL is fixed, the jited
results for all instructions preceding the second BPF_CALL are fixed.
So the jited address and result for the second BPF_CALL are also fixed.

Similarly, we can conclude that the jited addresses and results for all
subsequent BPF_CALL instructions are fixed.

This means that, for a given bpf prog, once the jited image is allocated,
the jited address and result for all instructions, including all BPF_CALL
instructions, are fixed.

Based on the observation, with this patch, the jit works as follows.

1. First pass
   Estimate the maximum jited image size. In this pass, all BPF_CALLs
   are jited to arm64 indirect calls since the jump offsets are unknown
   because the jited image is not allocated.

2. Allocate jited image with size estimated in step 1.

3. Second pass
   A. Determine the jited result for each BPF_CALL.
   B. Determine jited address and size for each bpf instruction.

4. Third pass
   A. Adjust jump offset for jump instructions.
   B. Write the final image.

Signed-off-by: Xu Kuohai <xukuohai@huawei.com>
Reviewed-by: Puranjay Mohan <puranjay@kernel.org>
Link: https://lore.kernel.org/r/20240903094407.601107-1-xukuohai@huaweicloud.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2024-09-04 11:51:06 -07:00
Xu Kuohai
5d4fa9ec56 bpf, arm64: Avoid blindly saving/restoring all callee-saved registers
The arm64 jit blindly saves/restores all callee-saved registers, making
the jited result looks a bit too compliated. For example, for an empty
prog, the jited result is:

   0:   bti jc
   4:   mov     x9, lr
   8:   nop
   c:   paciasp
  10:   stp     fp, lr, [sp, #-16]!
  14:   mov     fp, sp
  18:   stp     x19, x20, [sp, #-16]!
  1c:   stp     x21, x22, [sp, #-16]!
  20:   stp     x26, x25, [sp, #-16]!
  24:   mov     x26, #0
  28:   stp     x26, x25, [sp, #-16]!
  2c:   mov     x26, sp
  30:   stp     x27, x28, [sp, #-16]!
  34:   mov     x25, sp
  38:   bti j 		// tailcall target
  3c:   sub     sp, sp, #0
  40:   mov     x7, #0
  44:   add     sp, sp, #0
  48:   ldp     x27, x28, [sp], #16
  4c:   ldp     x26, x25, [sp], #16
  50:   ldp     x26, x25, [sp], #16
  54:   ldp     x21, x22, [sp], #16
  58:   ldp     x19, x20, [sp], #16
  5c:   ldp     fp, lr, [sp], #16
  60:   mov     x0, x7
  64:   autiasp
  68:   ret

Clearly, there is no need to save/restore unused callee-saved registers.
This patch does this change, making the jited image to only save/restore
the callee-saved registers it uses.

Now the jited result of empty prog is:

   0:   bti jc
   4:   mov     x9, lr
   8:   nop
   c:   paciasp
  10:   stp     fp, lr, [sp, #-16]!
  14:   mov     fp, sp
  18:   stp     xzr, x26, [sp, #-16]!
  1c:   mov     x26, sp
  20:   bti j		// tailcall target
  24:   mov     x7, #0
  28:   ldp     xzr, x26, [sp], #16
  2c:   ldp     fp, lr, [sp], #16
  30:   mov     x0, x7
  34:   autiasp
  38:   ret

Since bpf prog saves/restores its own callee-saved registers as needed,
to make tailcall work correctly, the caller needs to restore its saved
registers before tailcall, and the callee needs to save its callee-saved
registers after tailcall. This extra restoring/saving instructions
increases preformance overhead.

[1] provides 2 benchmarks for tailcall scenarios. Below is the perf
number measured in an arm64 KVM guest. The result indicates that the
performance difference before and after the patch in typical tailcall
scenarios is negligible.

- Before:

 Performance counter stats for './test_progs -t tailcalls' (5 runs):

           4313.43 msec task-clock                       #    0.874 CPUs utilized               ( +-  0.16% )
               574      context-switches                 #  133.073 /sec                        ( +-  1.14% )
                 0      cpu-migrations                   #    0.000 /sec
               538      page-faults                      #  124.727 /sec                        ( +-  0.57% )
       10697772784      cycles                           #    2.480 GHz                         ( +-  0.22% )  (61.19%)
       25511241955      instructions                     #    2.38  insn per cycle              ( +-  0.08% )  (66.70%)
        5108910557      branches                         #    1.184 G/sec                       ( +-  0.08% )  (72.38%)
           2800459      branch-misses                    #    0.05% of all branches             ( +-  0.51% )  (72.36%)
                        TopDownL1                 #     0.60 retiring                    ( +-  0.09% )  (66.84%)
                                                  #     0.21 frontend_bound              ( +-  0.15% )  (61.31%)
                                                  #     0.12 bad_speculation             ( +-  0.08% )  (50.11%)
                                                  #     0.07 backend_bound               ( +-  0.16% )  (33.30%)
        8274201819      L1-dcache-loads                  #    1.918 G/sec                       ( +-  0.18% )  (33.15%)
            468268      L1-dcache-load-misses            #    0.01% of all L1-dcache accesses   ( +-  4.69% )  (33.16%)
            385383      LLC-loads                        #   89.345 K/sec                       ( +-  5.22% )  (33.16%)
             38296      LLC-load-misses                  #    9.94% of all LL-cache accesses    ( +- 42.52% )  (38.69%)
        6886576501      L1-icache-loads                  #    1.597 G/sec                       ( +-  0.35% )  (38.69%)
           1848585      L1-icache-load-misses            #    0.03% of all L1-icache accesses   ( +-  4.52% )  (44.23%)
        9043645883      dTLB-loads                       #    2.097 G/sec                       ( +-  0.10% )  (44.33%)
            416672      dTLB-load-misses                 #    0.00% of all dTLB cache accesses  ( +-  5.15% )  (49.89%)
        6925626111      iTLB-loads                       #    1.606 G/sec                       ( +-  0.35% )  (55.46%)
             66220      iTLB-load-misses                 #    0.00% of all iTLB cache accesses  ( +-  1.88% )  (55.50%)
   <not supported>      L1-dcache-prefetches
   <not supported>      L1-dcache-prefetch-misses

            4.9372 +- 0.0526 seconds time elapsed  ( +-  1.07% )

 Performance counter stats for './test_progs -t flow_dissector' (5 runs):

          10924.50 msec task-clock                       #    0.945 CPUs utilized               ( +-  0.08% )
               603      context-switches                 #   55.197 /sec                        ( +-  1.13% )
                 0      cpu-migrations                   #    0.000 /sec
               566      page-faults                      #   51.810 /sec                        ( +-  0.42% )
       27381270695      cycles                           #    2.506 GHz                         ( +-  0.18% )  (60.46%)
       56996583922      instructions                     #    2.08  insn per cycle              ( +-  0.21% )  (66.11%)
       10321647567      branches                         #  944.816 M/sec                       ( +-  0.17% )  (71.79%)
           3347735      branch-misses                    #    0.03% of all branches             ( +-  3.72% )  (72.15%)
                        TopDownL1                 #     0.52 retiring                    ( +-  0.13% )  (66.74%)
                                                  #     0.27 frontend_bound              ( +-  0.14% )  (61.27%)
                                                  #     0.14 bad_speculation             ( +-  0.19% )  (50.36%)
                                                  #     0.07 backend_bound               ( +-  0.42% )  (33.89%)
       18740797617      L1-dcache-loads                  #    1.715 G/sec                       ( +-  0.43% )  (33.71%)
          13715669      L1-dcache-load-misses            #    0.07% of all L1-dcache accesses   ( +- 32.85% )  (33.34%)
           4087551      LLC-loads                        #  374.164 K/sec                       ( +- 29.53% )  (33.26%)
            267906      LLC-load-misses                  #    6.55% of all LL-cache accesses    ( +- 23.90% )  (38.76%)
       15811864229      L1-icache-loads                  #    1.447 G/sec                       ( +-  0.12% )  (38.73%)
           2976833      L1-icache-load-misses            #    0.02% of all L1-icache accesses   ( +-  9.73% )  (44.22%)
       20138907471      dTLB-loads                       #    1.843 G/sec                       ( +-  0.18% )  (44.15%)
            732850      dTLB-load-misses                 #    0.00% of all dTLB cache accesses  ( +- 11.18% )  (49.64%)
       15895726702      iTLB-loads                       #    1.455 G/sec                       ( +-  0.15% )  (55.13%)
            152075      iTLB-load-misses                 #    0.00% of all iTLB cache accesses  ( +-  4.71% )  (54.98%)
   <not supported>      L1-dcache-prefetches
   <not supported>      L1-dcache-prefetch-misses

           11.5613 +- 0.0317 seconds time elapsed  ( +-  0.27% )

- After:

 Performance counter stats for './test_progs -t tailcalls' (5 runs):

           4278.78 msec task-clock                       #    0.871 CPUs utilized               ( +-  0.15% )
               569      context-switches                 #  132.982 /sec                        ( +-  0.58% )
                 0      cpu-migrations                   #    0.000 /sec
               539      page-faults                      #  125.970 /sec                        ( +-  0.43% )
       10588986432      cycles                           #    2.475 GHz                         ( +-  0.20% )  (60.91%)
       25303825043      instructions                     #    2.39  insn per cycle              ( +-  0.08% )  (66.48%)
        5110756256      branches                         #    1.194 G/sec                       ( +-  0.07% )  (72.03%)
           2719569      branch-misses                    #    0.05% of all branches             ( +-  2.42% )  (72.03%)
                        TopDownL1                 #     0.60 retiring                    ( +-  0.22% )  (66.31%)
                                                  #     0.22 frontend_bound              ( +-  0.21% )  (60.83%)
                                                  #     0.12 bad_speculation             ( +-  0.26% )  (50.25%)
                                                  #     0.06 backend_bound               ( +-  0.17% )  (33.52%)
        8163648527      L1-dcache-loads                  #    1.908 G/sec                       ( +-  0.33% )  (33.52%)
            694979      L1-dcache-load-misses            #    0.01% of all L1-dcache accesses   ( +- 30.53% )  (33.52%)
           1902347      LLC-loads                        #  444.600 K/sec                       ( +- 48.84% )  (33.69%)
             96677      LLC-load-misses                  #    5.08% of all LL-cache accesses    ( +- 43.48% )  (39.30%)
        6863517589      L1-icache-loads                  #    1.604 G/sec                       ( +-  0.37% )  (39.17%)
           1871519      L1-icache-load-misses            #    0.03% of all L1-icache accesses   ( +-  6.78% )  (44.56%)
        8927782813      dTLB-loads                       #    2.087 G/sec                       ( +-  0.14% )  (44.37%)
            438237      dTLB-load-misses                 #    0.00% of all dTLB cache accesses  ( +-  6.00% )  (49.75%)
        6886906831      iTLB-loads                       #    1.610 G/sec                       ( +-  0.36% )  (55.08%)
             67568      iTLB-load-misses                 #    0.00% of all iTLB cache accesses  ( +-  3.27% )  (54.86%)
   <not supported>      L1-dcache-prefetches
   <not supported>      L1-dcache-prefetch-misses

            4.9114 +- 0.0309 seconds time elapsed  ( +-  0.63% )

 Performance counter stats for './test_progs -t flow_dissector' (5 runs):

          10948.40 msec task-clock                       #    0.942 CPUs utilized               ( +-  0.05% )
               615      context-switches                 #   56.173 /sec                        ( +-  1.65% )
                 1      cpu-migrations                   #    0.091 /sec                        ( +- 31.62% )
               567      page-faults                      #   51.788 /sec                        ( +-  0.44% )
       27334194328      cycles                           #    2.497 GHz                         ( +-  0.08% )  (61.05%)
       56656528828      instructions                     #    2.07  insn per cycle              ( +-  0.08% )  (66.67%)
       10270389422      branches                         #  938.072 M/sec                       ( +-  0.10% )  (72.21%)
           3453837      branch-misses                    #    0.03% of all branches             ( +-  3.75% )  (72.27%)
                        TopDownL1                 #     0.52 retiring                    ( +-  0.16% )  (66.55%)
                                                  #     0.27 frontend_bound              ( +-  0.09% )  (60.91%)
                                                  #     0.14 bad_speculation             ( +-  0.08% )  (49.85%)
                                                  #     0.07 backend_bound               ( +-  0.16% )  (33.33%)
       18982866028      L1-dcache-loads                  #    1.734 G/sec                       ( +-  0.24% )  (33.34%)
           8802454      L1-dcache-load-misses            #    0.05% of all L1-dcache accesses   ( +- 52.30% )  (33.31%)
           2612962      LLC-loads                        #  238.661 K/sec                       ( +- 29.78% )  (33.45%)
            264107      LLC-load-misses                  #   10.11% of all LL-cache accesses    ( +- 18.34% )  (39.07%)
       15793205997      L1-icache-loads                  #    1.443 G/sec                       ( +-  0.15% )  (39.09%)
           3930802      L1-icache-load-misses            #    0.02% of all L1-icache accesses   ( +-  3.72% )  (44.66%)
       20097828496      dTLB-loads                       #    1.836 G/sec                       ( +-  0.09% )  (44.68%)
            961757      dTLB-load-misses                 #    0.00% of all dTLB cache accesses  ( +-  3.32% )  (50.15%)
       15838728506      iTLB-loads                       #    1.447 G/sec                       ( +-  0.09% )  (55.62%)
            167652      iTLB-load-misses                 #    0.00% of all iTLB cache accesses  ( +-  1.28% )  (55.52%)
   <not supported>      L1-dcache-prefetches
   <not supported>      L1-dcache-prefetch-misses

           11.6173 +- 0.0268 seconds time elapsed  ( +-  0.23% )

[1] https://lore.kernel.org/bpf/20200724123644.5096-1-maciej.fijalkowski@intel.com/

Signed-off-by: Xu Kuohai <xukuohai@huawei.com>
Link: https://lore.kernel.org/r/20240826071624.350108-3-xukuohai@huaweicloud.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2024-08-28 08:41:33 -07:00