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Message-Id: <20170323120701.e9cc77190ad489e6472c872a@kernel.org>
Date: Thu, 23 Mar 2017 12:07:01 +0900
From: Masami Hiramatsu <mhiramat@...nel.org>
To: Steven Rostedt <rostedt@...dmis.org>
Cc: linux-kernel@...r.kernel.org, Ingo Molnar <mingo@...nel.org>,
Andrew Morton <akpm@...ux-foundation.org>,
Thomas Gleixner <tglx@...utronix.de>,
Peter Zijlstra <peterz@...radead.org>,
Masami Hiramatsu <mhiramat@...nel.org>,
"H. Peter Anvin" <hpa@...or.com>,
Andy Lutomirski <luto@...capital.net>,
Josh Poimboeuf <jpoimboe@...hat.com>,
Linus Torvalds <torvalds@...ux-foundation.org>
Subject: Re: [PATCH 3/6] ftrace/x86_32: Add stack frame pointer to
ftrace_caller
On Tue, 21 Mar 2017 21:35:05 -0400
Steven Rostedt <rostedt@...dmis.org> wrote:
> From: "Steven Rostedt (VMware)" <rostedt@...dmis.org>
>
> The function hook ftrace_caller does not create its own stack frame, and
> this causes the ftrace stack trace to miss the first function when doing
> stack traces.
>
> # echo schedule:stacktrace > /sys/kernel/tracing/set_ftrace_filter
>
> Before:
> <idle>-0 [002] .N.. 29.865807: <stack trace>
> => cpu_startup_entry
> => start_secondary
> => startup_32_smp
> <...>-7 [001] .... 29.866509: <stack trace>
> => kthread
> => ret_from_fork
> <...>-1 [000] .... 29.865377: <stack trace>
> => poll_schedule_timeout
> => do_select
> => core_sys_select
> => SyS_select
> => do_fast_syscall_32
> => entry_SYSENTER_32
>
> After:
> <idle>-0 [002] .N.. 31.234853: <stack trace>
> => do_idle
> => cpu_startup_entry
> => start_secondary
> => startup_32_smp
> <...>-7 [003] .... 31.235140: <stack trace>
> => rcu_gp_kthread
> => kthread
> => ret_from_fork
> <...>-1819 [000] .... 31.264172: <stack trace>
> => schedule_hrtimeout_range
> => poll_schedule_timeout
> => do_sys_poll
> => SyS_ppoll
> => do_fast_syscall_32
> => entry_SYSENTER_32
>
Looks good to me.
Reviewed-by: Masami Hiramatsu <mhiramat@...nel.org>
Thank you,
> Reviewed-by: Josh Poimboeuf <jpoimboe@...hat.com>
> Signed-off-by: Steven Rostedt (VMware) <rostedt@...dmis.org>
> ---
> arch/x86/kernel/ftrace_32.S | 12 ++++++++++--
> 1 file changed, 10 insertions(+), 2 deletions(-)
>
> diff --git a/arch/x86/kernel/ftrace_32.S b/arch/x86/kernel/ftrace_32.S
> index 1889a74823ce..f991e723c3e4 100644
> --- a/arch/x86/kernel/ftrace_32.S
> +++ b/arch/x86/kernel/ftrace_32.S
> @@ -18,12 +18,19 @@ ENTRY(mcount)
> END(mcount)
>
> ENTRY(ftrace_caller)
> +
> + pushl %ebp
> + movl %esp, %ebp
> +
> pushl %eax
> pushl %ecx
> pushl %edx
> pushl $0 /* Pass NULL as regs pointer */
> - movl 4*4(%esp), %eax
> - movl 0x4(%ebp), %edx
> + movl 5*4(%esp), %eax
> + /* Copy original ebp into %edx */
> + movl 4*4(%esp), %edx
> + /* Get the parent ip */
> + movl 0x4(%edx), %edx
> movl function_trace_op, %ecx
> subl $MCOUNT_INSN_SIZE, %eax
>
> @@ -35,6 +42,7 @@ ftrace_call:
> popl %edx
> popl %ecx
> popl %eax
> + popl %ebp
> .Lftrace_ret:
> #ifdef CONFIG_FUNCTION_GRAPH_TRACER
> .globl ftrace_graph_call
> --
> 2.10.2
>
>
--
Masami Hiramatsu <mhiramat@...nel.org>
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