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 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 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
code
Clone this repository
https://tangled.org/tjh.dev/kernel
git@gordian.tjh.dev:tjh.dev/kernel
For self-hosted knots, clone URLs may differ based on your setup.
TCR2_ELx.E0POE is set during smp_init().
However, this bit is not reprogrammed when the CPU enters suspension and
later resumes via cpu_resume(), as __cpu_setup() does not re-enable E0POE
and there is no save/restore logic for the TCR2_ELx system register.
As a result, the E0POE feature no longer works after cpu_resume().
To address this, save and restore TCR2_EL1 in the cpu_suspend()/cpu_resume()
path, rather than adding related logic to __cpu_setup(), taking into account
possible future extensions of the TCR2_ELx feature.
Fixes: bf83dae90fbc ("arm64: enable the Permission Overlay Extension for EL0")
Cc: <stable@vger.kernel.org> # 6.12.x
Signed-off-by: Yeoreum Yun <yeoreum.yun@arm.com>
Reviewed-by: Anshuman Khandual <anshuman.khandual@arm.com>
Reviewed-by: Kevin Brodsky <kevin.brodsky@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Running KASAN KUnit tests with {HW,SW}_TAGS mode triggers a fault in
change_memory_common():
Call trace:
change_memory_common+0x168/0x210 (P)
set_memory_ro+0x20/0x48
vmalloc_helpers_tags+0xe8/0x338
kunit_try_run_case+0x74/0x188
kunit_generic_run_threadfn_adapter+0x30/0x70
kthread+0x11c/0x200
ret_from_fork+0x10/0x20
---[ end trace 0000000000000000 ]---
# vmalloc_helpers_tags: try faulted
not ok 67 vmalloc_helpers_tags
Commit a06494adb7ef ("arm64: mm: use untagged address to calculate page index")
fixed a KASAN warning in the BPF subsystem by adding kasan_reset_tag() to
the index calculation. In the execmem flow:
bpf_prog_pack_alloc()
-> bpf_jit_alloc_exec()
-> execmem_alloc()
The returned address from execmem_vmalloc/execmem_cache_alloc is passed
through kasan_reset_tag(), so start has no tag while area->addr still
retains the original tag. The fix correctly handled this case by resetting
the tag on area->addr:
(start - (unsigned long)kasan_reset_tag(area->addr)) >> PAGE_SHIFT
However, in normal vmalloc paths, both start and area->addr have matching
tags(or no tags). Resetting only area->addr causes a mismatch when
subtracting a tagged address from an untagged one, resulting in an
incorrect index.
Fix this by resetting tags on both addresses in the index calculation.
This ensures correct results regardless of the tag state of either address.
Tested with KASAN KUnit tests under CONFIG_KASAN_GENERIC,
CONFIG_KASAN_SW_TAGS, and CONFIG_KASAN_HW_TAGS - all pass. Also verified
the original BPF KASAN warning from [1] is still fixed.
[1] https://lore.kernel.org/all/20251118164115.GA3977565@ax162/
Fixes: a06494adb7ef ("arm64: mm: use untagged address to calculate page index")
Signed-off-by: Jiayuan Chen <jiayuan.chen@shopee.com>
Signed-off-by: Jiayuan Chen <jiayuan.chen@linux.dev>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Dan has reported two uses of uninitialized variables in __ris_msmon_read().
If an unknown monitor type is encountered then the local variable, now, is
used uninitialized. Fix this by returning early on error. If a non-mbwu
monitor is being read then the local variable, overflow, is not initialized
but still read. Initialize it to false as overflow is not relevant for csu
monitors.
Fixes: 823e7c3712c5 ("arm_mpam: Add mpam_msmon_read() to read monitor value")
Fixes: 9e5afb7c3283 ("arm_mpam: Use long MBWU counters if supported")
Reported-by: kernel test robot <lkp@intel.com>
Reported-by: Dan Carpenter <dan.carpenter@linaro.org>
Closes: https://lore.kernel.org/r/202512091519.RBwiJcSq-lkp@intel.com/
Closes: https://lore.kernel.org/r/202512100547.N7QPYgfb-lkp@intel.com/
Signed-off-by: Ben Horgan <ben.horgan@arm.com>
Reviewed-by: Jonathan Cameron <jonathan.cameron@huawei.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
As EFI runtime services can now be run without disabling preemption remove
the check for non preemptible in current_in_efi(). Without this change,
firmware errors that were previously recovered from by
__efi_runtime_kernel_fixup_exception() will lead to a kernel oops.
Fixes: a5baf582f4c0 ("arm64/efi: Call EFI runtime services without disabling preemption")
Signed-off-by: Ben Horgan <ben.horgan@arm.com>
Reviewed-by: Yeoreum Yun <yeoreum.yun@arm.com>
Acked-by: Ard Biesheuvel <ardb@kernel.org>
Reviewed-by: Richard Lyu <richard.lyu@suse.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Since commit eb972eab0794 ("lkdtm/bugs: Add cases for BUG and PANIC
occurring in hardirq context"), building with clang for x86_64 results
in the following warnings:
vmlinux.o: warning: objtool: lkdtm_PANIC_IN_HARDIRQ(): unexpected end of section .text.lkdtm_PANIC_IN_HARDIRQ
vmlinux.o: warning: objtool: lkdtm_BUG_IN_HARDIRQ(): unexpected end of section .text.lkdtm_BUG_IN_HARDIRQ
caused by busy "while (wait_for_...);" loops. Add READ_ONCE() and
cpu_relax() to better indicate the intention and avoid any unwanted
compiler optimisations.
Fixes: eb972eab0794 ("lkdtm/bugs: Add cases for BUG and PANIC occurring in hardirq context")
Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202512190111.jxFSqxUH-lkp@intel.com/
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
When we exec a new task we forget to flush the set of locked GCS mode bits.
Since we do flush the rest of the state this means that if GCS is locked
the new task will be unable to enable GCS, it will be locked as being
disabled. Add the expected flush.
Fixes: fc84bc5378a8 ("arm64/gcs: Context switch GCS state for EL0")
Cc: <stable@vger.kernel.org> # 6.13.x
Reported-by: Yury Khrustalev <Yury.Khrustalev@arm.com>
Signed-off-by: Mark Brown <broonie@kernel.org>
Tested-by: Yury Khrustalev <yury.khrustalev@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Since commit 7137a203b251 ("arm64/fpsimd: Permit kernel mode NEON with
IRQs off"), the only condition under which the fallback path is taken
for FP/SIMD preserve/restore across a EFI runtime call is when it is
called from hardirq or NMI context.
In practice, this only happens when the EFI pstore driver is called to
dump the kernel log buffer into a EFI variable under a panic, oops or
emergency_restart() condition, and none of these can be expected to
result in a return to user space for the task in question.
This means that the existing EFI-specific logic for preserving and
restoring SVE/SME state is pointless, and can be removed.
Instead, kill the task, so that an exceedingly unlikely inadvertent
return to user space does not proceed with a corrupted FP/SIMD state.
Also, retain the preserve and restore of the base FP/SIMD state, as that
might belong to kernel mode use of FP/SIMD. (Note that EFI runtime calls
are never invoked reentrantly, even in this case, and so any interrupted
kernel mode FP/SIMD usage will be unrelated to EFI)
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Add lkdtm cases to trigger a BUG() or panic() from hardirq context. This
is useful for testing pstore behavior being invoked from such contexts.
Reviewed-by: Kees Cook <kees@kernel.org>
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
TL;DR: checking force_pte_mapping() in arch_kfence_init_pool() is
sufficient
Commit ce2b3a50ad92 ("arm64: mm: Don't sleep in
split_kernel_leaf_mapping() when in atomic context") recently added
an arm64 implementation of arch_kfence_init_pool() to ensure that
the KFENCE pool is PTE-mapped. Assuming that the pool was not
initialised early, block splitting is necessary if the linear
mapping is not fully PTE-mapped, in other words if
force_pte_mapping() is false.
arch_kfence_init_pool() currently makes another check: whether
BBML2-noabort is supported, i.e. whether we are *able* to split
block mappings. This check is however unnecessary, because
force_pte_mapping() is always true if KFENCE is enabled and
BBML2-noabort is not supported. This must be the case by design,
since KFENCE requires PTE-mapped pages in all cases. We can
therefore remove that check.
The situation is different in split_kernel_leaf_mapping(), as that
function is called unconditionally regardless of the configuration.
If BBML2-noabort is not supported, it cannot do anything and bails
out. If force_pte_mapping() is true, there is nothing to do and it
also bails out, but these are independent checks.
Commit 53357f14f924 ("arm64: mm: Tidy up force_pte_mapping()")
grouped these checks into a helper, split_leaf_mapping_possible().
This isn't so helpful as only split_kernel_leaf_mapping() should
check both. Revert the parts of that commit that introduced the
helper, reintroducing the more accurate comments in
split_kernel_leaf_mapping().
Signed-off-by: Kevin Brodsky <kevin.brodsky@arm.com>
Reviewed-by: Ryan Roberts <ryan.roberts@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Pull SCSI fixes from James Bottomley:
"The only core fix is in doc; all the others are in drivers, with the
biggest impacts in libsas being the rollback on error handling and in
ufs coming from a couple of error handling fixes, one causing a crash
if it's activated before scanning and the other fixing W-LUN
resumption"
* tag 'scsi-misc' of git://git.kernel.org/pub/scm/linux/kernel/git/jejb/scsi:
scsi: ufs: qcom: Fix confusing cleanup.h syntax
scsi: libsas: Add rollback handling when an error occurs
scsi: device_handler: Return error pointer in scsi_dh_attached_handler_name()
scsi: ufs: core: Fix a deadlock in the frequency scaling code
scsi: ufs: core: Fix an error handler crash
scsi: Revert "scsi: libsas: Fix exp-attached device scan after probe failure scanned in again after probe failed"
scsi: ufs: core: Fix RPMB link error by reversing Kconfig dependencies
scsi: qla4xxx: Use time conversion macros
scsi: qla2xxx: Enable/disable IRQD_NO_BALANCING during reset
scsi: ipr: Enable/disable IRQD_NO_BALANCING during reset
scsi: imm: Fix use-after-free bug caused by unfinished delayed work
scsi: target: sbp: Remove KMSG_COMPONENT macro
scsi: core: Correct documentation for scsi_device_quiesce()
scsi: mpi3mr: Prevent duplicate SAS/SATA device entries in channel 1
scsi: target: Reset t_task_cdb pointer in error case
scsi: ufs: core: Fix EH failure after W-LUN resume error
Pull ceph updates from Ilya Dryomov:
"We have a patch that adds an initial set of tracepoints to the MDS
client from Max, a fix that hardens osdmap parsing code from myself
(marked for stable) and a few assorted fixups"
* tag 'ceph-for-6.19-rc1' of https://github.com/ceph/ceph-client:
rbd: stop selecting CRC32, CRYPTO, and CRYPTO_AES
ceph: stop selecting CRC32, CRYPTO, and CRYPTO_AES
libceph: make decode_pool() more resilient against corrupted osdmaps
libceph: Amend checking to fix `make W=1` build breakage
ceph: Amend checking to fix `make W=1` build breakage
ceph: add trace points to the MDS client
libceph: fix log output race condition in OSD client
Initializing automatic __free variables to NULL without need (e.g.
branches with different allocations), followed by actual allocation is
in contrary to explicit coding rules guiding cleanup.h:
"Given that the "__free(...) = NULL" pattern for variables defined at
the top of the function poses this potential interdependency problem the
recommendation is to always define and assign variables in one statement
and not group variable definitions at the top of the function when
__free() is used."
Code does not have a bug, but is less readable and uses discouraged
coding practice, so fix that by moving declaration to the place of
assignment.
Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@oss.qualcomm.com>
Reviewed-by: Manivannan Sadhasivam <mani@kernel.org>
Link: https://patch.msgid.link/20251208020807.5043-2-krzysztof.kozlowski@oss.qualcomm.com
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Pull tomoyo update from Tetsuo Handa:
"Trivial optimization"
* tag 'tomoyo-pr-20251212' of git://git.code.sf.net/p/tomoyo/tomoyo:
tomoyo: Use local kmap in tomoyo_dump_page()
None of the RBD code directly requires CRC32, CRYPTO, or CRYPTO_AES.
These options are needed by CEPH_LIB code and they are selected there
directly.
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
Reviewed-by: Dongsheng Yang <dongsheng.yang@linux.dev>
In sas_register_phys(), if an error is triggered in the loop process, we
need to roll back the resources that have already been requested.
Add sas_unregister_phys() when an error occurs in sas_register_ha().
[mkp: a few coding style tweaks and address John's comment]
Signed-off-by: Chaohai Chen <wdhh6@aliyun.com>
Reviewed-by: John Garry <john.g.garry@oracle.com>
Link: https://patch.msgid.link/20251206060616.69216-1-wdhh6@aliyun.com
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Pull CPU hotplug fix from Ingo Molnar:
- Fix CPU hotplug callbacks to disable interrupts on UP kernels
* tag 'smp-urgent-2025-12-12' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
cpu: Make atomic hotplug callbacks run with interrupts disabled on UP