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
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Pull LoongArch updates from Huacai Chen:
- Select HAVE_CMPXCHG_{LOCAL,DOUBLE}
- Add 128-bit atomic cmpxchg support
- Add HOTPLUG_SMT implementation
- Wire up memfd_secret system call
- Fix boot errors and unwind errors for KASAN
- Use BPF prog pack allocator and add BPF arena support
- Update dts files to add nand controllers
- Some bug fixes and other small changes
* tag 'loongarch-7.0' of git://git.kernel.org/pub/scm/linux/kernel/git/chenhuacai/linux-loongson:
LoongArch: dts: loongson-2k1000: Add nand controller support
LoongArch: dts: loongson-2k0500: Add nand controller support
LoongArch: BPF: Implement bpf_addr_space_cast instruction
LoongArch: BPF: Implement PROBE_MEM32 pseudo instructions
LoongArch: BPF: Use BPF prog pack allocator
LoongArch: Use IS_ERR_PCPU() macro for KGDB
LoongArch: Rework KASAN initialization for PTW-enabled systems
LoongArch: Disable instrumentation for setup_ptwalker()
LoongArch: Remove some extern variables in source files
LoongArch: Guard percpu handler under !CONFIG_PREEMPT_RT
LoongArch: Handle percpu handler address for ORC unwinder
LoongArch: Use %px to print unmodified unwinding address
LoongArch: Prefer top-down allocation after arch_mem_init()
LoongArch: Add HOTPLUG_SMT implementation
LoongArch: Make cpumask_of_node() robust against NUMA_NO_NODE
LoongArch: Wire up memfd_secret system call
LoongArch: Replace seq_printf() with seq_puts() for simple strings
LoongArch: Add 128-bit atomic cmpxchg support
LoongArch: Add detection for SC.Q support
LoongArch: Select HAVE_CMPXCHG_LOCAL in Kconfig
Pull memblock updates from Mike Rapoport:
- update tools/include/linux/mm.h to fix memblock tests compilation
- drop redundant struct page* parameter from memblock_free_pages() and
get struct page from the pfn
- add underflow detection for size calculation in memtest and warn
about underflow when VM_DEBUG is enabled
* tag 'memblock-v7.0-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/rppt/memblock:
mm/memtest: add underflow detection for size calculation
memblock: drop redundant 'struct page *' argument from memblock_free_pages()
memblock test: include <linux/sizes.h> from tools mm.h stub
The module is supported, enable it.
Signed-off-by: Binbin Zhou <zhoubinbin@loongson.cn>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
Pull fbdev updates from Helge Deller:
"It's now easily possible to replace the framebuffer penguin boot logo
with an own logo at compile time (Vincent Mailhol)
The hyperv framebuffer driver has been removed, since the hyperv DRM
driver now seems to provide equal functionality.
Various console_conditional_schedule() calls across the console
drivers (fbcon, printk, vt) have been removed since they are no longer
necessary.
All other patches are either fixes in au1100fb, au1200fb, ffb, rivafb,
vt8500lcdfb and of_display_timing, or minor cleanups in the fbcon and
omapfb drivers"
* tag 'fbdev-for-7.0-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/deller/linux-fbdev: (32 commits)
fbcon: Declare struct fb_info.fbcon_par as of type struct fbcon_par
fbcon: Remove struct fbcon_display.inverse
fbdev: au1200fb: Fix a memory leak in au1200fb_drv_probe()
fbdev: ffb: fix corrupted video output on Sun FFB1
fbdev: of_display_timing: Fix device node reference leak in of_get_display_timings()
staging: fbtft: Make framebuffer registration message debug-only
staging: fbtft: Fix build failure when CONFIG_FB_DEVICE=n
fbdev: au1100fb: Check return value of clk_enable() in .resume()
printk, vt, fbcon: Remove console_conditional_schedule()
fbdev: fix fb_pad_unaligned_buffer mask
fbdev: of: display_timing: fix refcount leak in of_get_display_timings()
fbdev: vt8500lcdfb: fix missing dma_free_coherent()
video/logo: don't select LOGO_LINUX_MONO and LOGO_LINUX_VGA16 by default
video/logo: move logo selection logic to Kconfig
video/logo: remove logo_mac_clut224
sh: defconfig: remove CONFIG_LOGO_SUPERH_*
newport_con: depend on LOGO_LINUX_CLUT224 instead of LOGO_SGI_CLUT224
video/logo: allow custom logo
video/logo: add a type parameter to the logo makefile function
video/logo: remove orphan .pgm Makefile rule
...
The computation:
end = start + (size - (start_phys_aligned - start_phys)) / incr
could theoretically underflow if size < offset, leading to a massive
iteration.
Add VM_WARN_ON_ONCE() to detect cases where the region size is smaller
than the alignment offset. While this should never happen in practice
due to memblock guarantees, the warning helps catch potential bugs in
early memory initialization code.
Suggested-by: Mike Rapoport <rppt@kernel.org>
Signed-off-by: Kevin Lourenco <klourencodev@gmail.com>
Link: https://patch.msgid.link/20251229161321.9079-1-klourencodev@gmail.com
Signed-off-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
The module is supported, enable it.
Signed-off-by: Binbin Zhou <zhoubinbin@loongson.cn>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
Pull capabilities updates from Serge Hallyn:
- add KUnit tests for some core capabilities helpers
- avoid emitting IPC audit messages when there's not
actually a permission being denied
* tag 'caps-pr-20260213' of git://git.kernel.org/pub/scm/linux/kernel/git/sergeh/linux:
ipc: don't audit capability check in ipc_permissions()
security: Add KUnit tests for kuid_root_in_ns and vfsuid_root_in_currentns
The only correct type for the field fbcon_par in struct fb_info
is struct fbcon_par. Declare is as such. The field is a pointer
to fbcon-private data.
Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Signed-off-by: Helge Deller <deller@gmx.de>
memblock_free_pages() currently takes both a struct page * and the
corresponding PFN. The page pointer is always derived from the PFN at
call sites (pfn_to_page(pfn)), making the parameter redundant and also
allowing accidental mismatches between the two arguments.
Simplify the interface by removing the struct page * argument and
deriving the page locally from the PFN, after the deferred struct page
initialization check. This keeps the behavior unchanged while making
the helper harder to misuse.
Signed-off-by: Shengming Hu <hu.shengming@zte.com.cn>
Reviewed-by: David Hildenbrand (Red Hat) <david@kernel.org>
Link: https://patch.msgid.link/tencent_F741CE6ECC49EE099736685E60C0DBD4A209@qq.com
Signed-off-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
LLVM generates bpf_addr_space_cast instruction while translating pointers
between native (zero) address space and __attribute__((address_space(N))).
The addr_space=0 is reserved as bpf_arena address space.
rY = addr_space_cast(rX, 0, 1) is processed by the verifier and converted
to normal 32-bit move: wX = wY
rY = addr_space_cast(rX, 1, 0) has to be converted by JIT.
With this, the following test cases passed:
$ ./test_progs -a arena_htab,arena_list,arena_strsearch,verifier_arena,verifier_arena_large
#4/1 arena_htab/arena_htab_llvm:OK
#4/2 arena_htab/arena_htab_asm:OK
#4 arena_htab:OK
#5/1 arena_list/arena_list_1:OK
#5/2 arena_list/arena_list_1000:OK
#5 arena_list:OK
#7/1 arena_strsearch/arena_strsearch:OK
#7 arena_strsearch:OK
#507/1 verifier_arena/basic_alloc1:OK
#507/2 verifier_arena/basic_alloc2:OK
#507/3 verifier_arena/basic_alloc3:OK
#507/4 verifier_arena/basic_reserve1:OK
#507/5 verifier_arena/basic_reserve2:OK
#507/6 verifier_arena/reserve_twice:OK
#507/7 verifier_arena/reserve_invalid_region:OK
#507/8 verifier_arena/iter_maps1:OK
#507/9 verifier_arena/iter_maps2:OK
#507/10 verifier_arena/iter_maps3:OK
#507 verifier_arena:OK
#508/1 verifier_arena_large/big_alloc1:OK
#508/2 verifier_arena_large/access_reserved:OK
#508/3 verifier_arena_large/request_partially_reserved:OK
#508/4 verifier_arena_large/free_reserved:OK
#508/5 verifier_arena_large/big_alloc2:OK
#508 verifier_arena_large:OK
Summary: 5/20 PASSED, 0 SKIPPED, 0 FAILED
Acked-by: Tiezhu Yang <yangtiezhu@loongson.cn>
Tested-by: Vincent Li <vincent.mc.li@gmail.com>
Signed-off-by: Hengqi Chen <hengqi.chen@gmail.com>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
Pull rpmsg updates from Bjorn Andersson:
- Fix a race in rpmsg driver_override_show() and use the existing
helper to implement the store()
- Implement support for EPOLLOUT in the virtio rpmsg driver
* tag 'rpmsg-v7.0' of git://git.kernel.org/pub/scm/linux/kernel/git/remoteproc/linux:
rpmsg: core: fix race in driver_override_show() and use core helper
rpmsg: virtio: EPOLLOUT support
The IPC sysctls implement the ctl_table_root::permissions hook and
they override the file access mode based on the CAP_CHECKPOINT_RESTORE
capability, which is being checked regardless of whether any access is
actually denied or not, so if an LSM denies the capability, an audit
record may be logged even when access is in fact granted.
It wouldn't be viable to restructure the sysctl permission logic to only
check the capability when the access would be actually denied if it's
not granted. Thus, do the same as in net_ctl_permissions()
(net/sysctl_net.c) - switch from ns_capable() to ns_capable_noaudit(),
so that the check never emits an audit record.
Fixes: 0889f44e2810 ("ipc: Check permissions for checkpoint_restart sysctls at open time")
Signed-off-by: Ondrej Mosnacek <omosnace@redhat.com>
Acked-by: Alexey Gladkov <legion@kernel.org>
Acked-by: Serge Hallyn <serge@hallyn.com>
Signed-off-by: Serge Hallyn <sergeh@kernel.org>
The field inverse in struct fbcon_display is unused. Remove it.
Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Cc: <stable@vger.kernel.org> # v6.0+
Signed-off-by: Helge Deller <deller@gmx.de>
memblock test compilation fails:
memblock.c: In function ‘memblock_validate_numa_coverage’:
memblock.c:784:58: error: ‘SZ_1M’ undeclared (first use in this function)
784 | mem_size_mb = memblock_phys_mem_size() / SZ_1M;
| ^~~~~
The SZ_1M is defined in sizes.h, but it is not included by stub version of
mm.h in tools/include/linux.
Add include of sizes.h to tools/include/linux/mm.h to fix the compilation
of memblock tests.
Link: https://patch.msgid.link/20251228183942.3628918-1-rppt@kernel.org
Signed-off-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Reviewed-by: Anshuman Khandual <anshuman.khandual@arm.com>
Add support for `{LDX,STX,ST} | PROBE_MEM32 | {B,H,W,DW}` instructions.
They are similar to PROBE_MEM instructions with the following differences:
* PROBE_MEM32 supports store.
* PROBE_MEM32 relies on the verifier to clear upper 32-bit of the
src/dst register
* PROBE_MEM32 adds 64-bit kern_vm_start address (which is stored in S6
in the prologue). Due to bpf_arena constructions such S6 + reg +
off16 access is guaranteed to be within arena virtual range, so no
address check at run-time.
* S6 is a free callee-saved register, so it is used to store arena_vm_start
* PROBE_MEM32 allows ST and STX. If they fault the store is a nop. When
LDX faults the destination register is zeroed.
To support these on LoongArch, we employ the t2/t3 registers to store the
intermediate results of reg_arena + src/dst reg and use the t2/t3 registers
as the new src/dst reg. This allows us to reuse most of the existing code.
Acked-by: Tiezhu Yang <yangtiezhu@loongson.cn>
Tested-by: Vincent Li <vincent.mc.li@gmail.com>
Signed-off-by: Hengqi Chen <hengqi.chen@gmail.com>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
Pull remoteproc updates from Bjorn Andersson:
- Fix a memory remapping issue and make a few life-cycle improvements
in the i.MX HiFi remoteproc driver
- Add support the System Manager CPU and LMM APIs and use this to
support i.MX95
- Rework the handling of the Mediatek SCP clock to avoid a potential
circular deadlock in the clock providers
- Refactor the Qualcomm secure-world helpers and add support in the
Qualcomm PAS remoteproc driver for reading a resource-table from
secure world. Use this to configure the IOMMU on newer targets where
Linux runs in EL2
* tag 'rproc-v7.0' of git://git.kernel.org/pub/scm/linux/kernel/git/remoteproc/linux:
remoteproc: imx_rproc: Fix invalid loaded resource table detection
remoteproc: mediatek: Break lock dependency to `prepare_lock`
remoteproc: imx_rproc: Add support for i.MX95
remoteproc: imx_rproc: Add support for System Manager CPU API
remoteproc: imx_rproc: Add support for System Manager LMM API
remoteproc: imx_rproc: Introduce prepare ops for imx_rproc_dcfg
remoteproc: imx_rproc: Add runtime ops copy to support dynamic behavior
dt-bindings: remoteproc: fsl,imx-rproc: Add support for i.MX95
dt-bindings: remoteproc: Add HSM M4F core on TI K3 SoCs
remoteproc: xlnx_r5: Simplify with scoped for each OF child loop
remoteproc: mtk_scp: Simplify with scoped for each OF child loop
remoteproc: imx_dsp_rproc: Only reset carveout memory at RPROC_OFFLINE state
dt-bindings: remoteproc: qcom,sm8550-pas: Drop SM8750 ADSP from if-branch
dt-bindings: remoteproc: qcom,adsp: Allow cx-supply on qcom,sdm845-slpi-pas
remoteproc: imx_dsp_rproc: Fix multiple start/stop operations
remoteproc: imx_rproc: Use strstarts for "rsc-table" check
remoteproc: imx_dsp_rproc: Wait for suspend ACK only if WAIT_FW_CONFIRMATION is set
remoteproc: imx_dsp_rproc: Rename macro to reflect multiple contexts
remoteproc: imx_dsp_rproc: Skip RP_MBOX_SUSPEND_SYSTEM when mailbox TX channel is uninitialized
dt-bindings: remoteproc: Fix dead link to Keystone DSP GPIO binding