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linux/kernel/bpf
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Alexei Starovoitov 98d7ca374b bpf: Track delta between "linked" registers. 
Compilers can generate the code
  r1 = r2
  r1 += 0x1
  if r2 < 1000 goto ...
  use knowledge of r2 range in subsequent r1 operations

So remember constant delta between r2 and r1 and update r1 after 'if' condition.

Unfortunately LLVM still uses this pattern for loops with 'can_loop' construct:
for (i = 0; i < 1000 && can_loop; i++)

The "undo" pass was introduced in LLVM
https://reviews.llvm.org/D121937
to prevent this optimization, but it cannot cover all cases.
Instead of fighting middle end optimizer in BPF backend teach the verifier
about this pattern.

Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Link: https://lore.kernel.org/bpf/20240613013815.953-3-alexei.starovoitov@gmail.com
2024-06-14 21:52:39 +02:00
..
preload bpf: make preloaded map iterators to display map elements count 2023-07-06 12:42:25 -07:00
arena.c The usual shower of singleton fixes and minor series all over MM, 2024-05-19 09:21:03 -07:00
arraymap.c bpf: Do not walk twice the map on free 2024-04-30 16:28:33 +02:00
bloom_filter.c bpf: Check bloom filter map value size 2024-03-27 09:56:17 -07:00
bpf_cgrp_storage.c bpf: Enable bpf_cgrp_storage for cgroup1 non-attach case 2023-12-08 17:08:18 -08:00
bpf_inode_storage.c Networking changes for 6.4. 2023-04-26 16:07:23 -07:00
bpf_iter.c bpf: move sleepable flag from bpf_prog_aux to bpf_prog 2024-03-11 16:41:25 -07:00
bpf_local_storage.c bpf: Fix order of args in call to bpf_map_kvcalloc 2024-05-18 10:46:16 -07:00
bpf_lru_list.c bpf: Address KCSAN report on bpf_lru_list 2023-05-12 12:01:03 -07:00
bpf_lru_list.h bpf: lru: Remove unused declaration bpf_lru_promote() 2023-08-08 17:21:42 -07:00
bpf_lsm.c bpf: Minor clean-up to sleepable_lsm_hooks BTF set 2024-02-01 18:37:45 +01:00
bpf_struct_ops.c bpf: support epoll from bpf struct_ops links. 2024-05-30 15:34:13 -07:00
bpf_task_storage.c bpf: Teach verifier that certain helpers accept NULL pointer. 2023-04-04 16:57:16 -07:00
btf.c bpf: verifier: Relax caller requirements for kfunc projection type args 2024-06-12 11:01:31 -07:00
cgroup.c bpf: Allow helper bpf_get_[ns_]current_pid_tgid() for all prog types 2024-03-19 14:24:07 -07:00
cgroup_iter.c bpf: Let verifier consider {task,cgroup} is trusted in bpf_iter_reg 2023-11-07 15:24:25 -08:00
core.c Modules changes for v6.10-rc1 2024-05-15 14:05:08 -07:00
cpumap.c bpf: report RCU QS in cpumap kthread 2024-03-20 21:05:43 -07:00
cpumask.c bpf: Allow invoking kfuncs from BPF_PROG_TYPE_SYSCALL progs 2024-04-05 10:56:09 -07:00
crypto.c bpf: crypto: make state and IV dynptr nullable 2024-06-13 16:33:04 -07:00
devmap.c bpf, devmap: Remove unnecessary if check in for loop 2024-06-03 17:09:23 +02:00
disasm.c bpf: add special internal-only MOV instruction to resolve per-CPU addrs 2024-04-03 10:29:55 -07:00
disasm.h bpf: Relicense disassembler as GPL-2.0-only OR BSD-2-Clause 2021-09-02 14:49:23 +02:00
dispatcher.c bpf: Use arch_bpf_trampoline_size 2023-12-06 17:17:20 -08:00
hashtab.c bpf: Do not walk twice the hash map on free 2024-04-30 16:28:46 +02:00
helpers.c bpf: Fix bpf_dynptr documentation comments 2024-06-13 11:18:43 -07:00
inode.c bpf: Support symbolic BPF FS delegation mount options 2024-01-24 16:21:02 -08:00
Kconfig bpf: remove CONFIG_BPF_JIT dependency on CONFIG_MODULES of 2024-05-14 00:36:29 -07:00
link_iter.c bpf: Add bpf_link iterator 2022-05-10 11:20:45 -07:00
local_storage.c cgroup changes for v6.4-rc1 2023-04-29 10:05:22 -07:00
log.c bpf: Track delta between "linked" registers. 2024-06-14 21:52:39 +02:00
lpm_trie.c bpf: Avoid kfree_rcu() under lock in bpf_lpm_trie. 2024-03-29 11:10:41 -07:00
Makefile bpf: crypto: fix build when CONFIG_CRYPTO=m 2024-05-01 13:32:26 -07:00
map_in_map.c bpf: save extended inner map info for percpu array maps as well 2024-05-15 09:34:54 -07:00
map_in_map.h bpf: Add map and need_defer parameters to .map_fd_put_ptr() 2023-12-04 17:50:26 -08:00
map_iter.c bpf: treewide: Annotate BPF kfuncs in BTF 2024-01-31 20:40:56 -08:00
memalloc.c mm: memcg: add NULL check to obj_cgroup_put() 2024-04-25 20:55:43 -07:00
mmap_unlock_work.h bpf: Introduce helper bpf_find_vma 2021-11-07 11:54:51 -08:00
mprog.c bpf: Handle bpf_mprog_query with NULL entry 2023-10-06 17:11:20 -07:00
net_namespace.c net: Add includes masked by netdevice.h including uapi/bpf.h 2021-12-29 20:03:05 -08:00
offload.c Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2023-09-21 21:49:45 +02:00
percpu_freelist.c bpf: Initialize same number of free nodes for each pcpu_freelist 2022-11-11 12:05:14 -08:00
percpu_freelist.h bpf: Use raw_spin_trylock() for pcpu_freelist_push/pop in NMI 2020-10-06 00:04:11 +02:00
prog_iter.c bpf: Refactor bpf_iter_reg to have separate seq_info member 2020-07-25 20:16:32 -07:00
queue_stack_maps.c bpf: Avoid deadlock when using queue and stack maps from NMI 2023-09-11 19:04:49 -07:00
reuseport_array.c bpf: Centralize permissions checks for all BPF map types 2023-06-19 14:04:04 +02:00
ringbuf.c bpf: Fold smp_mb__before_atomic() into atomic_set_release() 2023-10-24 14:26:07 +02:00
stackmap.c bpf: Fix stackmap overflow check on 32-bit arches 2024-03-07 20:06:25 -08:00
syscall.c bpf-next-for-netdev 2024-06-10 18:02:14 -07:00
sysfs_btf.c btf: Avoid weak external references 2024-04-16 16:35:13 +02:00
task_iter.c bpf: Fix an issue due to uninitialized bpf_iter_task 2024-02-19 12:28:15 +01:00
tcx.c bpf, tcx: Get rid of tcx_link_const 2023-10-23 15:01:53 -07:00
tnum.c bpf: simplify tnum output if a fully known constant 2023-12-02 11:36:51 -08:00
token.c bpf,token: Use BIT_ULL() to convert the bit mask 2024-01-29 20:04:55 -08:00
trampoline.c Networking changes for 6.10. 2024-05-14 19:42:24 -07:00
verifier.c bpf: Track delta between "linked" registers. 2024-06-14 21:52:39 +02:00