* [merged] scripts-gdb-document-lx_current-is-only-supported-by-x86.patch removed from -mm tree
@ 2021-05-08 22:53 akpm
0 siblings, 0 replies; only message in thread
From: akpm @ 2021-05-08 22:53 UTC (permalink / raw)
To: corbet, jan.kiszka, kbingham, mm-commits, song.bao.hua
The patch titled
Subject: scripts/gdb: document lx_current is only supported by x86
has been removed from the -mm tree. Its filename was
scripts-gdb-document-lx_current-is-only-supported-by-x86.patch
This patch was dropped because it was merged into mainline or a subsystem tree
------------------------------------------------------
From: Barry Song <song.bao.hua@hisilicon.com>
Subject: 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>
---
Documentation/dev-tools/gdb-kernel-debugging.rst | 2 +-
scripts/gdb/linux/cpus.py | 10 ++++++++--
2 files changed, 9 insertions(+), 3 deletions(-)
--- a/Documentation/dev-tools/gdb-kernel-debugging.rst~scripts-gdb-document-lx_current-is-only-supported-by-x86
+++ a/Documentation/dev-tools/gdb-kernel-debugging.rst
@@ -114,7 +114,7 @@ Examples of using the Linux-provided gdb
[ 0.000000] BIOS-e820: [mem 0x000000000009fc00-0x000000000009ffff] reserved
....
-- Examine fields of the current task struct::
+- Examine fields of the current task struct(supported by x86 only)::
(gdb) p $lx_current().pid
$1 = 4998
--- a/scripts/gdb/linux/cpus.py~scripts-gdb-document-lx_current-is-only-supported-by-x86
+++ a/scripts/gdb/linux/cpus.py
@@ -156,6 +156,13 @@ Note that VAR has to be quoted as string
PerCpu()
+def get_current_task(cpu):
+ if utils.is_target_arch("x86"):
+ var_ptr = gdb.parse_and_eval("¤t_task")
+ return per_cpu(var_ptr, cpu).dereference()
+ else:
+ raise gdb.GdbError("Sorry, obtaining the current task is not yet "
+ "supported with this arch")
class LxCurrentFunc(gdb.Function):
"""Return current task.
@@ -167,8 +174,7 @@ number. If CPU is omitted, the CPU of th
super(LxCurrentFunc, self).__init__("lx_current")
def invoke(self, cpu=-1):
- var_ptr = gdb.parse_and_eval("¤t_task")
- return per_cpu(var_ptr, cpu).dereference()
+ return get_current_task(cpu)
LxCurrentFunc()
_
Patches currently in -mm which might be from song.bao.hua@hisilicon.com are
^ permalink raw reply [flat|nested] only message in thread
only message in thread, other threads:[~2021-05-08 22:54 UTC | newest]
Thread overview: (only message) (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2021-05-08 22:53 [merged] scripts-gdb-document-lx_current-is-only-supported-by-x86.patch removed from -mm tree akpm
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).