kernel/linux
0
Fork 0
mirror of https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ synced 2026-09-26 18:16:26 +00:00
Code Issues Releases Packages Activity
No description
1,215,118 commits 116 branches 5,779 tags 5.5 GiB
  • C 96.9%
  • Assembly 0.9%
  • Rust 0.6%
  • Shell 0.6%
  • Python 0.5%
  • Other 0.3%
Find a file
Deepak Gupta be97d0db5f
 riscv: VMAP_STACK overflow detection thread-safe 
commit 31da94c25a ("riscv: add VMAP_STACK overflow detection") added
support for CONFIG_VMAP_STACK. If overflow is detected, CPU switches to
`shadow_stack` temporarily before switching finally to per-cpu
`overflow_stack`.

If two CPUs/harts are racing and end up in over flowing kernel stack, one
or both will end up corrupting each other state because `shadow_stack` is
not per-cpu. This patch optimizes per-cpu overflow stack switch by
directly picking per-cpu `overflow_stack` and gets rid of `shadow_stack`.

Following are the changes in this patch

 - Defines an asm macro to obtain per-cpu symbols in destination
   register.
 - In entry.S, when overflow is detected, per-cpu overflow stack is
   located using per-cpu asm macro. Computing per-cpu symbol requires
   a temporary register. x31 is saved away into CSR_SCRATCH
   (CSR_SCRATCH is anyways zero since we're in kernel).

Please see Links for additional relevant disccussion and alternative
solution.

Tested by `echo EXHAUST_STACK > /sys/kernel/debug/provoke-crash/DIRECT`
Kernel crash log below

 Insufficient stack space to handle exception!/debug/provoke-crash/DIRECT
 Task stack:     [0xff20000010a98000..0xff20000010a9c000]
 Overflow stack: [0xff600001f7d98370..0xff600001f7d99370]
 CPU: 1 PID: 205 Comm: bash Not tainted 6.1.0-rc2-00001-g328a1f96f7b9 #34
 Hardware name: riscv-virtio,qemu (DT)
 epc : __memset+0x60/0xfc
  ra : recursive_loop+0x48/0xc6 [lkdtm]
 epc : ffffffff808de0e4 ra : ffffffff0163a752 sp : ff20000010a97e80
  gp : ffffffff815c0330 tp : ff600000820ea280 t0 : ff20000010a97e88
  t1 : 000000000000002e t2 : 3233206874706564 s0 : ff20000010a982b0
  s1 : 0000000000000012 a0 : ff20000010a97e88 a1 : 0000000000000000
  a2 : 0000000000000400 a3 : ff20000010a98288 a4 : 0000000000000000
  a5 : 0000000000000000 a6 : fffffffffffe43f0 a7 : 00007fffffffffff
  s2 : ff20000010a97e88 s3 : ffffffff01644680 s4 : ff20000010a9be90
  s5 : ff600000842ba6c0 s6 : 00aaaaaac29e42b0 s7 : 00fffffff0aa3684
  s8 : 00aaaaaac2978040 s9 : 0000000000000065 s10: 00ffffff8a7cad10
  s11: 00ffffff8a76a4e0 t3 : ffffffff815dbaf4 t4 : ffffffff815dbaf4
  t5 : ffffffff815dbab8 t6 : ff20000010a9bb48
 status: 0000000200000120 badaddr: ff20000010a97e88 cause: 000000000000000f
 Kernel panic - not syncing: Kernel stack overflow
 CPU: 1 PID: 205 Comm: bash Not tainted 6.1.0-rc2-00001-g328a1f96f7b9 #34
 Hardware name: riscv-virtio,qemu (DT)
 Call Trace:
 [<ffffffff80006754>] dump_backtrace+0x30/0x38
 [<ffffffff808de798>] show_stack+0x40/0x4c
 [<ffffffff808ea2a8>] dump_stack_lvl+0x44/0x5c
 [<ffffffff808ea2d8>] dump_stack+0x18/0x20
 [<ffffffff808dec06>] panic+0x126/0x2fe
 [<ffffffff800065ea>] walk_stackframe+0x0/0xf0
 [<ffffffff0163a752>] recursive_loop+0x48/0xc6 [lkdtm]
 SMP: stopping secondary CPUs
 ---[ end Kernel panic - not syncing: Kernel stack overflow ]---

Cc: Guo Ren <guoren@kernel.org>
Cc: Jisheng Zhang <jszhang@kernel.org>
Link: https://lore.kernel.org/linux-riscv/Y347B0x4VUNOd6V7@xhacker/T/#t
Link: https://lore.kernel.org/lkml/20221124094845.1907443-1-debug@rivosinc.com/
Signed-off-by: Deepak Gupta <debug@rivosinc.com>
Co-developed-by: Sami Tolvanen <samitolvanen@google.com>
Signed-off-by: Sami Tolvanen <samitolvanen@google.com>
Acked-by: Guo Ren <guoren@kernel.org>
Tested-by: Nathan Chancellor <nathan@kernel.org>
Link: https://lore.kernel.org/r/20230927224757.1154247-9-samitolvanen@google.com
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
History 2023-10-27 14:43:05 -07:00
arch riscv: VMAP_STACK overflow detection thread-safe 2023-10-27 14:43:05 -07:00
block block: fix pin count management when merging same-page segments 2023-09-06 07:32:27 -06:00
certs certs: Reference revocation list for all keyrings 2023-08-17 20:12:41 +00:00
crypto This update includes the following changes: 2023-08-29 11:23:29 -07:00
Documentation drm ci for 6.6-rc1 2023-09-10 11:55:26 -07:00
drivers drm ci for 6.6-rc1 2023-09-10 11:55:26 -07:00
fs six smb3 client fixes, one fix for nls Kconfig, one minor spnego registry update 2023-09-09 19:56:23 -07:00
include six smb3 client fixes, one fix for nls Kconfig, one minor spnego registry update 2023-09-09 19:56:23 -07:00
init workqueue: Changes for v6.6 2023-09-01 16:06:32 -07:00
io_uring Revert "io_uring: fix IO hang in io_wq_put_and_exit from do_exit()" 2023-09-07 09:41:49 -06:00
ipc Add x86 shadow stack support 2023-08-31 12:20:12 -07:00
kernel RISC-V Patches for the 6.6 Merge Window, Part 2 (try 2) 2023-09-09 14:25:11 -07:00
lib iov_iter: Kunit tests for page extraction 2023-09-09 15:11:49 -07:00
LICENSES LICENSES: Add the copyleft-next-0.3.1 license 2022-11-08 15:44:01 +01:00
mm LoongArch changes for v6.6 2023-09-08 12:16:52 -07:00
net Including fixes from netfilter and bpf. 2023-09-07 18:33:07 -07:00
rust Documentation work keeps chugging along; stuff for 6.6 includes: 2023-08-30 20:05:42 -07:00
samples VFIO updates for v6.6-rc1 2023-08-30 20:36:01 -07:00
scripts Fix preemption delays in the SGX code, remove unnecessarily UAPI-exported code, 2023-09-10 10:39:31 -07:00
security Landlock updates for v6.6-rc1 2023-09-08 12:06:51 -07:00
sound sound fixes for 6.6-rc1 2023-09-08 13:07:50 -07:00
tools perf tools changes for v6.6: 2023-09-09 20:06:17 -07:00
usr initramfs: Encode dependency on KBUILD_BUILD_TIMESTAMP 2023-06-06 17:54:49 +09:00
virt ARM: 2023-09-07 13:52:20 -07:00
.clang-format iommu: Add for_each_group_device() 2023-05-23 08:15:51 +02:00
.cocciconfig scripts: add Linux .cocciconfig for coccinelle 2016-07-22 12:13:39 +02:00
.get_maintainer.ignore get_maintainer: add Alan to .get_maintainer.ignore 2022-08-20 15:17:44 -07:00
.gitattributes .gitattributes: set diff driver for Rust source code files 2023-05-31 17:48:25 +02:00
.gitignore kbuild: rpm-pkg: rename binkernel.spec to kernel.spec 2023-07-25 00:59:33 +09:00
.mailmap for-linus-2023083101 2023-09-01 12:31:44 -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 USB: Remove Wireless USB and UWB documentation 2023-08-09 14:17:32 +02:00
Kbuild Kbuild updates for v6.1 2022-10-10 12:00:45 -07:00
Kconfig kbuild: ensure full rebuild when the compiler is updated 2020-05-12 13:28:33 +09:00
MAINTAINERS drm ci for 6.6-rc1 2023-09-10 11:55:26 -07:00
Makefile Linux 6.6-rc1 2023-09-10 16:28:41 -07:00
README Drop all 00-INDEX files from Documentation/ 2018-09-09 15:08:58 -06:00

README 

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

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.