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Mark Rutland 51005a59bc lkdtm/bugs: add test for hung smp_call_function_single() 
The CONFIG_CSD_LOCK_WAIT_DEBUG option enables debugging of hung
smp_call_function*() calls (e.g. when the target CPU gets stuck within
the callback function). Testing this option requires triggering such
hangs.

This patch adds an lkdtm test with a hung smp_call_function_single()
callback, which can be used to test CONFIG_CSD_LOCK_WAIT_DEBUG and NMI
backtraces (as CONFIG_CSD_LOCK_WAIT_DEBUG will attempt an NMI backtrace
of the hung target CPU).

On arm64 using pseudo-NMI, this looks like:

| # mount -t debugfs none /sys/kernel/debug/
| # echo SMP_CALL_LOCKUP > /sys/kernel/debug/provoke-crash/DIRECT
| lkdtm: Performing direct entry SMP_CALL_LOCKUP
| smp: csd: Detected non-responsive CSD lock (#1) on CPU#1, waiting 5000000176 ns for CPU#00 __lkdtm_SMP_CALL_LOCKUP+0x0/0x8(0x0).
| smp:     csd: CSD lock (#1) handling this request.
| Sending NMI from CPU 1 to CPUs 0:
| NMI backtrace for cpu 0
| CPU: 0 PID: 0 Comm: swapper/0 Not tainted 6.9.0-rc4-00001-gfdfd281212ec #1
| Hardware name: linux,dummy-virt (DT)
| pstate: 60401005 (nZCv daif +PAN -UAO -TCO -DIT +SSBS BTYPE=--)
| pc : __lkdtm_SMP_CALL_LOCKUP+0x0/0x8
| lr : __flush_smp_call_function_queue+0x1b0/0x290
| sp : ffff800080003f30
| pmr_save: 00000060
| x29: ffff800080003f30 x28: ffffa4ce961a4900 x27: 0000000000000000
| x26: fff000003fcfa0c0 x25: ffffa4ce961a4900 x24: ffffa4ce959aa140
| x23: ffffa4ce959aa140 x22: 0000000000000000 x21: ffff800080523c40
| x20: 0000000000000000 x19: 0000000000000000 x18: fff05b31aa323000
| x17: fff05b31aa323000 x16: ffff800080000000 x15: 0000330fc3fe6b2c
| x14: 0000000000000000 x13: 0000000000000000 x12: 0000000000000279
| x11: 0000000000000040 x10: fff000000302d0a8 x9 : fff000000302d0a0
| x8 : fff0000003400270 x7 : 0000000000000000 x6 : ffffa4ce9451b810
| x5 : 0000000000000000 x4 : fff05b31aa323000 x3 : ffff800080003f30
| x2 : fff05b31aa323000 x1 : ffffa4ce959aa140 x0 : 0000000000000000
| Call trace:
|  __lkdtm_SMP_CALL_LOCKUP+0x0/0x8
|  generic_smp_call_function_single_interrupt+0x14/0x20
|  ipi_handler+0xb8/0x178
|  handle_percpu_devid_irq+0x84/0x130
|  generic_handle_domain_irq+0x2c/0x44
|  gic_handle_irq+0x118/0x240
|  call_on_irq_stack+0x24/0x4c
|  do_interrupt_handler+0x80/0x84
|  el1_interrupt+0x44/0xc0
|  el1h_64_irq_handler+0x18/0x24
|  el1h_64_irq+0x78/0x7c
|  default_idle_call+0x40/0x60
|  do_idle+0x23c/0x2d0
|  cpu_startup_entry+0x38/0x3c
|  kernel_init+0x0/0x1d8
|  start_kernel+0x51c/0x608
|  __primary_switched+0x80/0x88
| CPU: 1 PID: 128 Comm: sh Not tainted 6.9.0-rc4-00001-gfdfd281212ec #1
| Hardware name: linux,dummy-virt (DT)
| Call trace:
|  dump_backtrace+0x90/0xe8
|  show_stack+0x18/0x24
|  dump_stack_lvl+0xac/0xe8
|  dump_stack+0x18/0x24
|  csd_lock_wait_toolong+0x268/0x338
|  smp_call_function_single+0x1dc/0x2f0
|  lkdtm_SMP_CALL_LOCKUP+0xcc/0xfc
|  lkdtm_do_action+0x1c/0x38
|  direct_entry+0xbc/0x14c
|  full_proxy_write+0x60/0xb4
|  vfs_write+0xd0/0x35c
|  ksys_write+0x70/0x104
|  __arm64_sys_write+0x1c/0x28
|  invoke_syscall+0x48/0x114
|  el0_svc_common.constprop.0+0x40/0xe0
|  do_el0_svc+0x1c/0x28
|  el0_svc+0x38/0x108
|  el0t_64_sync_handler+0x120/0x12c
|  el0t_64_sync+0x1a4/0x1a8
| smp: csd: Continued non-responsive CSD lock (#1) on CPU#1, waiting 10000064272 ns for CPU#00 __lkdtm_SMP_CALL_LOCKUP+0x0/0x8(0x0).
| smp:     csd: CSD lock (#1) handling this request.
| smp: csd: Continued non-responsive CSD lock (#1) on CPU#1, waiting 15000064384 ns for CPU#00 __lkdtm_SMP_CALL_LOCKUP+0x0/0x8(0x0).
| smp:     csd: CSD lock (#1) handling this request.

Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Acked-by: Paul E. McKenney <paulmck@kernel.org>
Cc: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/20240515120828.375585-1-mark.rutland@arm.com
Signed-off-by: Kees Cook <kees@kernel.org>
History 2024-06-17 11:17:31 -07:00
arch Miscellaneous topology parsing fixes: 2024-06-02 09:32:34 -07:00
block blk-throttle: Fix incorrect display of io.max 2024-05-30 19:44:29 -06:00
certs kbuild: use $(src) instead of $(srctree)/$(src) for source directory 2024-05-10 04:34:52 +09:00
crypto This push fixes a bug in the new ecc P521 code as well as a buggy 2024-05-20 08:47:54 -07:00
Documentation dma-mapping fixes for Linux 6.10 2024-05-31 12:14:55 -07:00
drivers lkdtm/bugs: add test for hung smp_call_function_single() 2024-06-17 11:17:31 -07:00
fs 2 small smb3 fixes 2024-06-01 14:35:57 -07:00
include TTY fix for 6.10-rc2 2024-06-01 08:53:39 -07:00
init Driver core changes for 6.10-rc1 2024-05-22 12:13:40 -07:00
io_uring io_uring/net: assign kmsg inq/flags before buffer selection 2024-05-30 14:04:37 -06:00
ipc Mainly singleton patches, documented in their respective changelogs. 2024-05-19 14:02:03 -07:00
kernel Kbuild fixes for v6.10 2024-06-01 09:33:55 -07:00
lib kunit/fortify: Remove __kmalloc_node() test 2024-05-31 13:47:41 -07:00
LICENSES LICENSES: Add the copyleft-next-0.3.1 license 2022-11-08 15:44:01 +01:00
mm 16 hotfixes, 11 of which are cc:stable. 2024-05-25 15:10:33 -07:00
net Including fixes from bpf and netfilter. 2024-05-30 08:33:04 -07:00
rust LoongArch changes for v6.10 2024-05-22 09:43:07 -07:00
samples tracing/treewide: Remove second parameter of __assign_str() 2024-05-22 20:14:47 -04:00
scripts dt-bindings: kbuild: Fix dt_binding_check on unconfigured build 2024-05-30 01:15:58 +09:00
security landlock: Fix d_parent walk 2024-05-31 16:41:52 +02:00
sound ALSA: seq: ump: Fix swapped song position pointer data 2024-05-31 09:51:44 +02:00
tools lkdtm/bugs: add test for hung smp_call_function_single() 2024-06-17 11:17:31 -07:00
usr kbuild: use $(src) instead of $(srctree)/$(src) for source directory 2024-05-10 04:34:52 +09:00
virt The usual shower of singleton fixes and minor series all over MM, 2024-05-19 09:21:03 -07:00
.clang-format clang-format: Update with v6.7-rc4's for_each macro list 2023-12-08 23:54:38 +01:00
.cocciconfig scripts: add Linux .cocciconfig for coccinelle 2016-07-22 12:13:39 +02:00
.editorconfig Add .editorconfig file for basic formatting 2023-12-28 16:22:47 +09:00
.get_maintainer.ignore Add Jeff Kirsher to .get_maintainer.ignore 2024-03-08 11:36:54 +00:00
.gitattributes .gitattributes: set diff driver for Rust source code files 2023-05-31 17:48:25 +02:00
.gitignore kbuild: create a list of all built DTB files 2024-02-19 18:20:39 +09:00
.mailmap mailmap: update entry for Kees Cook 2024-05-31 08:58:36 -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 MAINTAINERS: Drop Gustavo Pimentel as PCI DWC Maintainer 2024-03-27 13:41:02 -05:00
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 sound fixes for 6.10-rc2 2024-05-31 12:11:44 -07:00
Makefile Linux 6.10-rc2 2024-06-02 15:44:56 -07:00
README README: Fix spelling 2024-03-18 03:36:32 -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 reStructuredText 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.