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Catalin Marinas 8a85b31312 arm64: gcs: Do not set PTE_SHARED on GCS mappings if FEAT_LPA2 is enabled
When FEAT_LPA2 is enabled, bits 8-9 of the PTE replace the
shareability attribute with bits 50-51 of the output address. The
_PAGE_GCS{,_RO} definitions include the PTE_SHARED bits as 0b11 (this
matches the other _PAGE_* definitions) but using this macro directly
leads to the following panic when enabling GCS on a system/model with
LPA2:

  Unable to handle kernel paging request at virtual address fffff1ffc32d8008
  Mem abort info:
    ESR = 0x0000000096000004
    EC = 0x25: DABT (current EL), IL = 32 bits
    SET = 0, FnV = 0
    EA = 0, S1PTW = 0
    FSC = 0x04: level 0 translation fault
  Data abort info:
    ISV = 0, ISS = 0x00000004, ISS2 = 0x00000000
    CM = 0, WnR = 0, TnD = 0, TagAccess = 0
    GCS = 0, Overlay = 0, DirtyBit = 0, Xs = 0
  swapper pgtable: 4k pages, 52-bit VAs, pgdp=0000000060f4d000
  [fffff1ffc32d8008] pgd=100000006184b003, p4d=0000000000000000
  Internal error: Oops: 0000000096000004 [#1]  SMP
  CPU: 0 UID: 0 PID: 513 Comm: gcs_write_fault Tainted: G   M                7.0.0-rc1 #1 PREEMPT
  Tainted: [M]=MACHINE_CHECK
  Hardware name: QEMU QEMU Virtual Machine, BIOS 2025.02-8+deb13u1 11/08/2025
  pstate: 03402005 (nzcv daif +PAN -UAO +TCO +DIT -SSBS BTYPE=--)
  pc : zap_huge_pmd+0x168/0x468
  lr : zap_huge_pmd+0x2c/0x468
  sp : ffff800080beb660
  x29: ffff800080beb660 x28: fff00000c2058180 x27: ffff800080beb898
  x26: fff00000c2058180 x25: ffff800080beb820 x24: 00c800010b600f41
  x23: ffffc1ffc30af1a8 x22: fff00000c2058180 x21: 0000ffff8dc00000
  x20: fff00000c2bc6370 x19: ffff800080beb898 x18: ffff800080bebb60
  x17: 0000000000000000 x16: 0000000000000000 x15: 0000000000000007
  x14: 000000000000000a x13: 0000aaaacbbbffff x12: 0000000000000000
  x11: 0000ffff8ddfffff x10: 00000000000001fe x9 : 0000ffff8ddfffff
  x8 : 0000ffff8de00000 x7 : 0000ffff8da00000 x6 : fff00000c2bc6370
  x5 : 0000ffff8da00000 x4 : 000000010b600000 x3 : ffffc1ffc0000000
  x2 : fff00000c2058180 x1 : fffff1ffc32d8000 x0 : 000000c00010b600
  Call trace:
   zap_huge_pmd+0x168/0x468 (P)
   unmap_page_range+0xd70/0x1560
   unmap_single_vma+0x48/0x80
   unmap_vmas+0x90/0x180
   unmap_region+0x88/0xe4
   vms_complete_munmap_vmas+0xf8/0x1e0
   do_vmi_align_munmap+0x158/0x180
   do_vmi_munmap+0xac/0x160
   __vm_munmap+0xb0/0x138
   vm_munmap+0x14/0x20
   gcs_free+0x70/0x80
   mm_release+0x1c/0xc8
   exit_mm_release+0x28/0x38
   do_exit+0x190/0x8ec
   do_group_exit+0x34/0x90
   get_signal+0x794/0x858
   arch_do_signal_or_restart+0x11c/0x3e0
   exit_to_user_mode_loop+0x10c/0x17c
   el0_da+0x8c/0x9c
   el0t_64_sync_handler+0xd0/0xf0
   el0t_64_sync+0x198/0x19c
  Code: aa1603e2 d34cfc00 cb813001 8b011861 (f9400420)

Similarly to how the kernel handles protection_map[], use a
gcs_page_prot variable to store the protection bits and clear PTE_SHARED
if LPA2 is enabled.

Also remove the unused PAGE_GCS{,_RO} macros.

Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Fixes: 6497b66ba6 ("arm64/mm: Map pages for guarded control stack")
Reported-by: Emanuele Rocca <emanuele.rocca@arm.com>
Cc: stable@vger.kernel.org
Cc: Mark Brown <broonie@kernel.org>
Cc: Will Deacon <will@kernel.org>
Reviewed-by: David Hildenbrand (Arm) <david@kernel.org>
Signed-off-by: Will Deacon <will@kernel.org>
2026-02-25 19:53:57 +00:00
arch arm64: gcs: Do not set PTE_SHARED on GCS mappings if FEAT_LPA2 is enabled 2026-02-25 19:53:57 +00:00
block Convert remaining multi-line kmalloc_obj/flex GFP_KERNEL uses 2026-02-22 08:26:33 -08:00
certs Convert 'alloc_obj' family to use the new default GFP_KERNEL argument 2026-02-21 17:09:51 -08:00
crypto x509: select CONFIG_CRYPTO_LIB_SHA256 2026-02-22 12:09:23 -08:00
Documentation RTC for 7.0 2026-02-22 09:43:11 -08:00
drivers RTC for 7.0 2026-02-22 09:43:11 -08:00
fs fsverity fixes for v7.0-rc1 2026-02-22 13:12:04 -08:00
include fsverity fixes for v7.0-rc1 2026-02-22 13:12:04 -08:00
init Convert 'alloc_flex' family to use the new default GFP_KERNEL argument 2026-02-21 17:09:51 -08:00
io_uring Convert 'alloc_flex' family to use the new default GFP_KERNEL argument 2026-02-21 17:09:51 -08:00
ipc Convert 'alloc_obj' family to use the new default GFP_KERNEL argument 2026-02-21 17:09:51 -08:00
kernel Convert remaining multi-line kmalloc_obj/flex GFP_KERNEL uses 2026-02-22 08:26:33 -08:00
lib Crypto library fix for v7.0-rc1 2026-02-22 13:09:33 -08:00
LICENSES LICENSES: Add modern form of the LGPL-2.1 tags to the usage guide section 2025-10-22 07:58:19 +02:00
mm Convert remaining multi-line kmalloc_obj/flex GFP_KERNEL uses 2026-02-22 08:26:33 -08:00
net Convert remaining multi-line kmalloc_obj/flex GFP_KERNEL uses 2026-02-22 08:26:33 -08:00
rust Rust fixes for v7.0-rc1 2026-02-22 08:43:31 -08:00
samples USB / Thunderbolt changes for 7.0-rc1 2026-02-17 09:36:43 -08:00
scripts Convert 'alloc_obj' family to use the new default GFP_KERNEL argument 2026-02-21 17:09:51 -08:00
security Convert remaining multi-line kmalloc_obj/flex GFP_KERNEL uses 2026-02-22 08:26:33 -08:00
sound Convert remaining multi-line kmalloc_obj/flex GFP_KERNEL uses 2026-02-22 08:26:33 -08:00
tools Rust fixes for v7.0-rc1 2026-02-22 08:43:31 -08:00
usr kbuild: uapi: drop dependency on CC_CAN_LINK 2026-01-16 15:02:11 -07:00
virt Convert 'alloc_obj' family to use the new default GFP_KERNEL argument 2026-02-21 17:09:51 -08:00
.clang-format Devicetree updates for v7.0: 2026-02-11 18:27:08 -08:00
.clippy.toml rust: clean Rust 1.88.0's warning about clippy::disallowed_macros configuration 2025-05-07 00:11:47 +02:00
.cocciconfig
.editorconfig editorconfig: add rst extension 2026-01-26 19:07:09 -08:00
.get_maintainer.ignore MAINTAINERS: remove Alyssa Rosenzweig 2025-09-18 21:17:31 +02:00
.gitattributes .gitattributes: set diff driver for Rust source code files 2023-05-31 17:48:25 +02:00
.gitignore rust: kbuild: add proc macro library support 2025-11-24 17:15:36 +01:00
.mailmap Landlock update for v7.0-rc1 2026-02-11 15:57:08 -08:00
.pylintrc docs: Move the python libraries to tools/lib/python 2025-11-18 09:22:40 -07:00
.rustfmt.toml rust: add .rustfmt.toml 2022-09-28 09:02:20 +02:00
COPYING COPYING: state that all contributions really are covered by this file 2020-02-10 13:32:20 -08:00
CREDITS CREDITS: Add -next to Stephen Rothwell's entry 2026-02-22 12:11:33 -08:00
Kbuild sched: Make migrate_{en,dis}able() inline 2025-09-25 09:57:16 +02:00
Kconfig io_uring: Rename KConfig to Kconfig 2025-02-19 14:53:27 -07:00
MAINTAINERS EFI fixes for v7.0 #1 2026-02-20 12:04:40 -08:00
Makefile Linux 7.0-rc1 2026-02-22 13:18:59 -08:00
README docs: add AI Coding Assistants documentation 2026-01-06 14:55:06 -07:00

Linux kernel
============

The Linux kernel is the core of any Linux operating system. It manages hardware,
system resources, and provides the fundamental services for all other software.

Quick Start
-----------

* Report a bug: See Documentation/admin-guide/reporting-issues.rst
* Get the latest kernel: https://kernel.org
* Build the kernel: See Documentation/admin-guide/quickly-build-trimmed-linux.rst
* Join the community: https://lore.kernel.org/

Essential Documentation
-----------------------

All users should be familiar with:

* Building requirements: Documentation/process/changes.rst
* Code of Conduct: Documentation/process/code-of-conduct.rst
* License: See COPYING

Documentation can be built with make htmldocs or viewed online at:
https://www.kernel.org/doc/html/latest/


Who Are You?
============

Find your role below:

* New Kernel Developer - Getting started with kernel development
* Academic Researcher - Studying kernel internals and architecture
* Security Expert - Hardening and vulnerability analysis
* Backport/Maintenance Engineer - Maintaining stable kernels
* System Administrator - Configuring and troubleshooting
* Maintainer - Leading subsystems and reviewing patches
* Hardware Vendor - Writing drivers for new hardware
* Distribution Maintainer - Packaging kernels for distros
* AI Coding Assistant - LLMs and AI-powered development tools


For Specific Users
==================

New Kernel Developer
--------------------

Welcome! Start your kernel development journey here:

* Getting Started: Documentation/process/development-process.rst
* Your First Patch: Documentation/process/submitting-patches.rst
* Coding Style: Documentation/process/coding-style.rst
* Build System: Documentation/kbuild/index.rst
* Development Tools: Documentation/dev-tools/index.rst
* Kernel Hacking Guide: Documentation/kernel-hacking/hacking.rst
* Core APIs: Documentation/core-api/index.rst

Academic Researcher
-------------------

Explore the kernel's architecture and internals:

* Researcher Guidelines: Documentation/process/researcher-guidelines.rst
* Memory Management: Documentation/mm/index.rst
* Scheduler: Documentation/scheduler/index.rst
* Networking Stack: Documentation/networking/index.rst
* Filesystems: Documentation/filesystems/index.rst
* RCU (Read-Copy Update): Documentation/RCU/index.rst
* Locking Primitives: Documentation/locking/index.rst
* Power Management: Documentation/power/index.rst

Security Expert
---------------

Security documentation and hardening guides:

* Security Documentation: Documentation/security/index.rst
* LSM Development: Documentation/security/lsm-development.rst
* Self Protection: Documentation/security/self-protection.rst
* Reporting Vulnerabilities: Documentation/process/security-bugs.rst
* CVE Procedures: Documentation/process/cve.rst
* Embargoed Hardware Issues: Documentation/process/embargoed-hardware-issues.rst
* Security Features: Documentation/userspace-api/seccomp_filter.rst

Backport/Maintenance Engineer
-----------------------------

Maintain and stabilize kernel versions:

* Stable Kernel Rules: Documentation/process/stable-kernel-rules.rst
* Backporting Guide: Documentation/process/backporting.rst
* Applying Patches: Documentation/process/applying-patches.rst
* Subsystem Profile: Documentation/maintainer/maintainer-entry-profile.rst
* Git for Maintainers: Documentation/maintainer/configure-git.rst

System Administrator
--------------------

Configure, tune, and troubleshoot Linux systems:

* Admin Guide: Documentation/admin-guide/index.rst
* Kernel Parameters: Documentation/admin-guide/kernel-parameters.rst
* Sysctl Tuning: Documentation/admin-guide/sysctl/index.rst
* Tracing/Debugging: Documentation/trace/index.rst
* Performance Security: Documentation/admin-guide/perf-security.rst
* Hardware Monitoring: Documentation/hwmon/index.rst

Maintainer
----------

Lead kernel subsystems and manage contributions:

* Maintainer Handbook: Documentation/maintainer/index.rst
* Pull Requests: Documentation/maintainer/pull-requests.rst
* Managing Patches: Documentation/maintainer/modifying-patches.rst
* Rebasing and Merging: Documentation/maintainer/rebasing-and-merging.rst
* Development Process: Documentation/process/maintainer-handbooks.rst
* Maintainer Entry Profile: Documentation/maintainer/maintainer-entry-profile.rst
* Git Configuration: Documentation/maintainer/configure-git.rst

Hardware Vendor
---------------

Write drivers and support new hardware:

* Driver API Guide: Documentation/driver-api/index.rst
* Driver Model: Documentation/driver-api/driver-model/driver.rst
* Device Drivers: Documentation/driver-api/infrastructure.rst
* Bus Types: Documentation/driver-api/driver-model/bus.rst
* Device Tree Bindings: Documentation/devicetree/bindings/
* Power Management: Documentation/driver-api/pm/index.rst
* DMA API: Documentation/core-api/dma-api.rst

Distribution Maintainer
-----------------------

Package and distribute the kernel:

* Stable Kernel Rules: Documentation/process/stable-kernel-rules.rst
* ABI Documentation: Documentation/ABI/README
* Kernel Configuration: Documentation/kbuild/kconfig.rst
* Module Signing: Documentation/admin-guide/module-signing.rst
* Kernel Parameters: Documentation/admin-guide/kernel-parameters.rst
* Tainted Kernels: Documentation/admin-guide/tainted-kernels.rst

AI Coding Assistant
-------------------

CRITICAL: If you are an LLM or AI-powered coding assistant, you MUST read and
follow the AI coding assistants documentation before contributing to the Linux
kernel:

* Documentation/process/coding-assistants.rst

This documentation contains essential requirements about licensing, attribution,
and the Developer Certificate of Origin that all AI tools must comply with.


Communication and Support
=========================

* Mailing Lists: https://lore.kernel.org/
* IRC: #kernelnewbies on irc.oftc.net
* Bugzilla: https://bugzilla.kernel.org/
* MAINTAINERS file: Lists subsystem maintainers and mailing lists
* Email Clients: Documentation/process/email-clients.rst