On Tue, 21 Mar 2017 21:35:05 -0400
Steven Rostedt wrote:
> From: "Steven Rostedt (VMware)"
>
> 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:
> -0 [002] .N..29.865807:
> => cpu_startup_entry
> => start_secondary
> => startup_32_smp
><...>-7 [001] 29.866509:
> => kthread
> => ret_from_fork
><...>-1 [000] 29.865377:
> => poll_schedule_timeout
> => do_select
> => core_sys_select
> => SyS_select
> => do_fast_syscall_32
> => entry_SYSENTER_32
>
> After:
> -0 [002] .N..31.234853:
> => do_idle
> => cpu_startup_entry
> => start_secondary
> => startup_32_smp
><...>-7 [003] 31.235140:
> => rcu_gp_kthread
> => kthread
> => ret_from_fork
><...>-1819 [000] 31.264172:
> => 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
Thank you,
> Reviewed-by: Josh Poimboeuf
> Signed-off-by: Steven Rostedt (VMware)
> ---
> 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 $0 /* Pass NULL as regs pointer */
> - movl4*4(%esp), %eax
> - movl0x4(%ebp), %edx
> + movl5*4(%esp), %eax
> + /* Copy original ebp into %edx */
> + movl4*4(%esp), %edx
> + /* Get the parent ip */
> + movl0x4(%edx), %edx
> movlfunction_trace_op, %ecx
> subl$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
