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
Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
1444865
3
929
Clone this repository
https://tangled.org/tjh.dev/kernel
https://tangled.org/did:plc:65gha4t3avpfpzmvpbwovss7/kernel
git@gordian.tjh.dev:tjh.dev/kernel
git@gordian.tjh.dev:did:plc:65gha4t3avpfpzmvpbwovss7/kernel
For self-hosted knots, clone URLs may differ based on your setup.
Download tar.gz
The module is supported, enable it.
Signed-off-by: Binbin Zhou <zhoubinbin@loongson.cn>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
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>
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>
Use bpf_jit_binary_pack_alloc() for BPF JIT binaries. The BPF prog pack
allocator creates a pair of RW and RX buffers. The BPF JIT writes the
program into the RW buffer. When the JIT is done, the program is copied
to the final RX buffer with bpf_jit_binary_pack_finalize().
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>
In commit a759e37fb467 ("err.h: add ERR_PTR_PCPU(), PTR_ERR_PCPU() and
IS_ERR_PCPU() macros"), specialized macros were added to check an error
within a __percpu pointer, so use them instead of manually casting with
__force, like all other users of register_wide_hw_breakpoint().
Signed-off-by: Carlos López <clopez@suse.de>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
kasan_init_generic() indicates that kasan is fully initialized, so it
should be put at end of kasan_init().
Otherwise bringing up the primary CPU failed when CONFIG_KASAN is set
on PTW-enabled systems, here are the call chains:
kernel_entry()
start_kernel()
setup_arch()
kasan_init()
kasan_init_generic()
The reason is PTW-enabled systems have speculative accesses which means
memory accesses to the shadow memory after kasan_init() may be executed
by hardware before. However, accessing shadow memory is safe only after
kasan fully initialized because kasan_init() uses a temporary PGD table
until we have populated all levels of shadow page tables and writen the
PGD register. Moving kasan_init_generic() later can defer the occasion
of kasan_enabled(), so as to avoid speculative accesses on shadow pages.
After moving kasan_init_generic() to the end, kasan_init() can no longer
call kasan_mem_to_shadow() for shadow address conversion because it will
always return kasan_early_shadow_page. On the other hand, we should keep
the current logic of kasan_mem_to_shadow() for both the early and final
stage because there may be instrumentation before kasan_init().
To solve this, we factor out a new mem_to_shadow() function from current
kasan_mem_to_shadow() for the shadow address conversion in kasan_init().
Cc: stable@vger.kernel.org
Signed-off-by: Tiezhu Yang <yangtiezhu@loongson.cn>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
According to Documentation/dev-tools/kasan.rst, software KASAN modes use
compiler instrumentation to insert validity checks. Such instrumentation
might be incompatible with some parts of the kernel, and therefore needs
to be disabled, just use the attribute __no_sanitize_address to disable
instrumentation for the low level function setup_ptwalker().
Otherwise bringing up the secondary CPUs failed when CONFIG_KASAN is set
(especially when PTW is enabled), here are the call chains:
smpboot_entry()
start_secondary()
cpu_probe()
per_cpu_trap_init()
tlb_init()
setup_tlb_handler()
setup_ptwalker()
The reason is the PGD registers are configured in setup_ptwalker(), but
KASAN instrumentation may cause TLB exceptions before that.
Cc: stable@vger.kernel.org
Signed-off-by: Tiezhu Yang <yangtiezhu@loongson.cn>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
There are declarations of the variable "eentry", "pcpu_handlers[]" and
"exception_handlers[]" in asm/setup.h, the source files already include
this header file directly or indirectly, so no need to declare them in
the source files, just remove the code.
Cc: stable@vger.kernel.org
Signed-off-by: Tiezhu Yang <yangtiezhu@loongson.cn>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
After commit 88fd2b70120d ("LoongArch: Fix sleeping in atomic context for
PREEMPT_RT"), it should guard percpu handler under !CONFIG_PREEMPT_RT to
avoid redundant operations.
Cc: stable@vger.kernel.org
Signed-off-by: Tiezhu Yang <yangtiezhu@loongson.cn>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
After commit 4cd641a79e69 ("LoongArch: Remove unnecessary checks for ORC
unwinder"), the system can not boot normally under some configs (such as
enable KASAN), there are many error messages "cannot find unwind pc".
The kernel boots normally with the defconfig, so no problem found out at
the first time. Here is one way to reproduce:
cd linux
make mrproper defconfig -j"$(nproc)"
scripts/config -e KASAN
make olddefconfig all -j"$(nproc)"
sudo make modules_install
sudo make install
sudo reboot
The address that can not unwind is not a valid kernel address which is
between "pcpu_handlers[cpu]" and "pcpu_handlers[cpu] + vec_sz" due to
the code of eentry was copied to the new area of pcpu_handlers[cpu] in
setup_tlb_handler(), handle this special case to get the valid address
to unwind normally.
Cc: stable@vger.kernel.org
Signed-off-by: Tiezhu Yang <yangtiezhu@loongson.cn>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
Currently, use %p to prevent leaking information about the kernel memory
layout when printing the PC address, but the kernel log messages are not
useful to debug problem if bt_address() returns 0. Given that the type of
"pc" variable is unsigned long, it should use %px to print the unmodified
unwinding address.
Cc: stable@vger.kernel.org
Signed-off-by: Tiezhu Yang <yangtiezhu@loongson.cn>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
Currently we use bottom-up allocation after sparse_init(), the reason is
sparse_init() need a lot of memory, and bottom-up allocation may exhaust
precious low memory (below 4GB). On the other hand, SWIOTLB and CMA need
low memories for DMA32, so swiotlb_init() and dma_contiguous_reserve()
need bottom-up allocation.
Since swiotlb_init() and dma_contiguous_reserve() are both called in
arch_mem_init(), we no longer need bottom-up allocation after that. So
we set the allocation policy to top-down at the end of arch_mem_init(),
in order to avoid later memory allocations (such as KASAN) exhaust low
memory.
This solve at least two problems:
1. Some buggy BIOSes use 0xfd000000~0xfe000000 for secondary CPUs, but
didn't reserve this range, which causes smpboot failures.
2. Some DMA32 devices, such as Loongson-DRM and OHCI, cannot work with
KASAN enabled.
Cc: stable@vger.kernel.org
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
For benchmarking or debugging purpose, we usually want to control SMT
via boot parameter and sysfs knobs. So add HOTPLUG_SMT implementation.
1. Boot parameters:
nosmt: Disable SMT, can be enabled via sysfs knobs.
nosmt=force: Disable SMT, cannot be enabled via sysfs knobs.
2. Runtime sysfs controls:
Write "on", "off", "forceoff" or the number of SMT threads (1, 2, ...)
to /sys/devices/system/cpu/smt/control.
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
The arch definition of cpumask_of_node() cannot handle NUMA_NO_NODE -
which is a valid index - so add a check for this.
Cc: stable@vger.kernel.org
Signed-off-by: John Garry <john.g.garry@oracle.com>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
LoongArch supports ARCH_HAS_SET_DIRECT_MAP, therefore wire up the
memfd_secret system call, which just depends on it.
Acked-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Acked-by: David Hildenbrand (Red Hat) <david@kernel.org>
Signed-off-by: Lain "Fearyncess" Yang <fearyncess@aosc.io>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
Fix warnings like: "Prefer seq_puts to seq_printf" by checkpatch.pl.
Replace seq_printf() calls with seq_puts() in show_cpuinfo() when
outputting simple constant strings without format specifiers.
This improves performance slightly as seq_puts() avoids parsing the
format string.
Signed-off-by: George Guo <guodongtai@kylinos.cn>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
README