linux/Documentation/dev-tools
Barry Song dc9586823f scripts/gdb: document lx_current is only supported by x86
Patch series "scripts/gdb: clarify the platforms supporting lx_current and add arm64 support", v2.

lx_current depends on per_cpu current_task variable which exists on x86
only.  so it actually works on x86 only.  the 1st patch documents this
clearly; the 2nd patch adds support for arm64.

This patch (of 2):

x86 is the only architecture which has per_cpu current_task:

  arch$ git grep current_task | grep -i per_cpu
  x86/include/asm/current.h:DECLARE_PER_CPU(struct task_struct *, current_task);
  x86/kernel/cpu/common.c:DEFINE_PER_CPU(struct task_struct *, current_task) ____cacheline_aligned =
  x86/kernel/cpu/common.c:EXPORT_PER_CPU_SYMBOL(current_task);
  x86/kernel/cpu/common.c:DEFINE_PER_CPU(struct task_struct *, current_task) = &init_task;
  x86/kernel/cpu/common.c:EXPORT_PER_CPU_SYMBOL(current_task);
  x86/kernel/smpboot.c:	per_cpu(current_task, cpu) = idle;

On other architectures, lx_current() will lead to a python exception:

  (gdb) p $lx_current().pid
  Python Exception <class 'gdb.error'> No symbol "current_task" in current context.:
  Error occurred in Python: No symbol "current_task" in current context.

To avoid more people struggling and wasting time in other architectures,
document it.

Link: https://lkml.kernel.org/r/20210314203444.15188-1-song.bao.hua@hisilicon.com
Link: https://lkml.kernel.org/r/20210314203444.15188-2-song.bao.hua@hisilicon.com
Signed-off-by: Barry Song <song.bao.hua@hisilicon.com>
Cc: Jan Kiszka <jan.kiszka@siemens.com>
Cc: Kieran Bingham <kbingham@kernel.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-05-07 00:26:33 -07:00
..
kunit Documentation: kunit: add tips for using current->kunit_test 2021-04-07 16:40:37 -06:00
checkpatch.rst docs: document all error message types in checkpatch 2021-03-25 11:47:42 -06:00
coccinelle.rst Documentation: Coccinelle: Improve command example for debugging patches 2020-12-03 15:45:18 -07:00
gcov.rst docs/gcov: Convert two tags to ref in dev-tools/gov.rst 2021-04-08 11:19:43 -06:00
gdb-kernel-debugging.rst scripts/gdb: document lx_current is only supported by x86 2021-05-07 00:26:33 -07:00
index.rst Documentation: dev-tools: Add Testing Overview 2021-04-15 14:53:02 -06:00
kasan.rst kasan: docs: update tests section 2021-04-30 11:20:42 -07:00
kcov.rst Documentation: fix typos found in process, dev-tools, and doc-guide subdirectories 2020-12-03 15:55:04 -07:00
kcsan.rst kcsan: Add missing license and copyright headers 2021-03-08 14:27:43 -08:00
kfence.rst kfence: report sensitive information based on no_hash_pointers 2021-02-26 09:41:02 -08:00
kgdb.rst Documentation: kgdb: Fix a typo 2020-11-18 13:47:17 -07:00
kmemleak.rst mm,kmemleak-test.c: move kmemleak-test.c to samples dir 2020-10-13 18:38:27 -07:00
kselftest.rst Documentation: kselftest: fix path to test module files 2021-04-02 16:17:18 -06:00
sparse.rst doc: add link to sparse's home page/internal docs 2020-07-05 14:32:56 -06:00
testing-overview.rst Documentation: dev-tools: Add Testing Overview 2021-04-15 14:53:02 -06:00
ubsan.rst ubsan: remove UBSAN_MISC in favor of individual options 2020-12-15 22:46:19 -08:00