All of lore.kernel.org
 help / color / mirror / Atom feed
From: root <chenggang.qin@gmail.com>
To: linux-kernel@vger.kernel.org
Cc: Chenggang Qin <chenggang.qcg@taobao.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	Arjan van de Ven <arjan@linux.intel.com>,
	David Ahern <dsahern@gmail.com>, Ingo Molnar <mingo@redhat.com>,
	Mike Galbraith <efault@gmx.de>, Namhyung Kim <namhyung@gmail.com>,
	Paul Mackerras <paulus@samba.org>,
	Peter Zijlstra <a.p.zijlstra@chello.nl>,
	Wu Fengguang <fengguang.wu@intel.com>,
	Yanmin Zhang <yanmin.zhang@intel.com>
Subject: [PATCH] perf core: Use KSTK_ESP() instead of pt_regs->sp while output user regs
Date: Tue, 23 Dec 2014 14:22:25 +0800	[thread overview]
Message-ID: <1419315745-20767-1-git-send-email-user@chenggang-laptop> (raw)

From: Chenggang Qin <chenggang.qcg@taobao.com>

For x86_64, the exact value of user stack's esp should be got by KSTK_ESP(current).
current->thread.usersp is copied from PDA while enter ring0. 
Now, we output the value of sp from pt_regs. But pt_regs->sp has changed before
it was pushed into kernel stack.

So, we cannot get the correct callchain while unwind some user stacks.
For example, if the stack contains __lll_unlock_wake()/__lll_lock_wait(), the
callchain will break some times with the latest version of libunwind.
The root cause is the sp that is used by libunwind may be wrong.

If we use KSTK_ESP(current), the correct callchain can be got everytime.
Other architectures also have KSTK_ESP() macro.

Signed-off-by: Chenggang Qin <chenggang.qcg@taobao.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Arjan van de Ven <arjan@linux.intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Namhyung Kim <namhyung@gmail.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Wu Fengguang <fengguang.wu@intel.com>
Cc: Yanmin Zhang <yanmin.zhang@intel.com>

---
 arch/x86/kernel/perf_regs.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/arch/x86/kernel/perf_regs.c b/arch/x86/kernel/perf_regs.c
index e309cc5..5da8df8 100644
--- a/arch/x86/kernel/perf_regs.c
+++ b/arch/x86/kernel/perf_regs.c
@@ -60,6 +60,9 @@ u64 perf_reg_value(struct pt_regs *regs, int idx)
 	if (WARN_ON_ONCE(idx >= ARRAY_SIZE(pt_regs_offset)))
 		return 0;
 
+	if (idx == PERF_REG_X86_SP)
+		return KSTK_ESP(current);
+
 	return regs_get_register(regs, pt_regs_offset[idx]);
 }
 
-- 
1.9.1


             reply	other threads:[~2014-12-23  6:22 UTC|newest]

Thread overview: 23+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2014-12-23  6:22 root [this message]
2014-12-23  8:30 ` Andy Lutomirski
     [not found] ` <c027bde0-5f4f-441f-8d45-3e7f6f702231@alibaba-inc.com>
2014-12-25 15:48   ` 答复:[PATCH] " Andy Lutomirski
2014-12-25 16:21     ` Andy Lutomirski
2014-12-30 19:03     ` Peter Zijlstra
2014-12-30 23:29       ` Andy Lutomirski
2014-12-31  2:00         ` Andy Lutomirski
2015-01-02 16:11           ` Jan Beulich
2015-01-02 18:03             ` Andy Lutomirski
2015-01-05  8:47               ` Jan Beulich
2015-01-04 16:10       ` Jiri Olsa
2015-01-04 17:18         ` Andy Lutomirski
2015-01-04 17:41           ` Jiri Olsa
2015-01-04 18:36             ` [PATCH 0/2] perf: Improve user regs sampling Andy Lutomirski
2015-01-04 18:36               ` [PATCH 1/2] perf: Move task_pt_regs sampling into arch code Andy Lutomirski
2015-01-05 14:07                 ` Peter Zijlstra
2015-01-05 16:13                   ` Andy Lutomirski
2015-01-05 16:44                     ` Peter Zijlstra
2015-01-05 18:28                       ` Andy Lutomirski
2015-01-09 12:32                 ` [tip:perf/urgent] " tip-bot for Andy Lutomirski
2015-01-04 18:36               ` [PATCH 2/2] x86_64, perf: Improve user regs sampling Andy Lutomirski
2015-01-09 12:32                 ` [tip:perf/urgent] perf/x86_64: " tip-bot for Andy Lutomirski
2015-01-05 10:46               ` [PATCH 0/2] perf: " Jiri Olsa

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=1419315745-20767-1-git-send-email-user@chenggang-laptop \
    --to=chenggang.qin@gmail.com \
    --cc=a.p.zijlstra@chello.nl \
    --cc=akpm@linux-foundation.org \
    --cc=arjan@linux.intel.com \
    --cc=chenggang.qcg@taobao.com \
    --cc=dsahern@gmail.com \
    --cc=efault@gmx.de \
    --cc=fengguang.wu@intel.com \
    --cc=linux-kernel@vger.kernel.org \
    --cc=mingo@redhat.com \
    --cc=namhyung@gmail.com \
    --cc=paulus@samba.org \
    --cc=yanmin.zhang@intel.com \
    --subject='Re: [PATCH] perf core: Use KSTK_ESP() instead of pt_regs->sp while output user regs' \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.