x86/ftrace: Add stack frame pointer to ftrace_caller

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

Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Reviewed-by: Josh Poimboeuf <jpoimboe@redhat.com>
Reviewed-by: Masami Hiramatsu <mhiramat@kernel.org>
Reviewed-by: Ingo Molnar <mingo@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: http://lkml.kernel.org/r/20170323143445.771707773@goodmis.org
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

diff --git a/arch/x86/kernel/ftrace_32.S b/arch/x86/kernel/ftrace_32.S
index 2b160f238a4296aac2e7eb75bb789bffa491deac..a4e2872971c00169a29d4f1f1e05a6f2c1d16b46 100644 (file)
--- a/arch/x86/kernel/ftrace_32.S
+++ b/arch/x86/kernel/ftrace_32.S
@@ -16,12 +16,19 @@ 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
 
@@ -33,6 +40,7 @@ ftrace_call:
        popl    %edx
        popl    %ecx
        popl    %eax
+       popl    %ebp
 .Lftrace_ret:
 #ifdef CONFIG_FUNCTION_GRAPH_TRACER
 .globl ftrace_graph_call