diff options
| author | Josh Poimboeuf <jpoimboe@redhat.com> | 2016-08-19 14:53:00 +0300 |
|---|---|---|
| committer | Ingo Molnar <mingo@kernel.org> | 2016-08-24 13:15:15 +0300 |
| commit | 471bd10f5e2880bd91a2627d887f6062494cfe9c (patch) | |
| tree | 5995297863d15d7a8b44f78889f23975c98bf709 /arch/x86/include/asm/ftrace.h | |
| parent | 408fe5de2f2767059a9561e0ae6d4385d1b39dac (diff) | |
| download | linux-471bd10f5e2880bd91a2627d887f6062494cfe9c.tar.xz | |
ftrace/x86: Implement HAVE_FUNCTION_GRAPH_RET_ADDR_PTR
Use the more reliable version of ftrace_graph_ret_addr() so we no longer
have to worry about the unwinder getting out of sync with the function
graph ret_stack index, which can happen if the unwinder skips any frames
before calling ftrace_graph_ret_addr().
This fixes this issue (and several others like it):
$ cat /proc/self/stack
[<ffffffff810489a2>] save_stack_trace_tsk+0x22/0x40
[<ffffffff81311a89>] proc_pid_stack+0xb9/0x110
[<ffffffff813127c4>] proc_single_show+0x54/0x80
[<ffffffff812be088>] seq_read+0x108/0x3e0
[<ffffffff812923d7>] __vfs_read+0x37/0x140
[<ffffffff812929d9>] vfs_read+0x99/0x140
[<ffffffff81293f28>] SyS_read+0x58/0xc0
[<ffffffff818af97c>] entry_SYSCALL_64_fastpath+0x1f/0xbd
[<ffffffffffffffff>] 0xffffffffffffffff
$ echo function_graph > /sys/kernel/debug/tracing/current_tracer
$ cat /proc/self/stack
[<ffffffff818b2428>] return_to_handler+0x0/0x27
[<ffffffff810394cc>] print_context_stack+0xfc/0x100
[<ffffffff818b2428>] return_to_handler+0x0/0x27
[<ffffffff8103891b>] dump_trace+0x12b/0x350
[<ffffffff818b2428>] return_to_handler+0x0/0x27
[<ffffffff810489a2>] save_stack_trace_tsk+0x22/0x40
[<ffffffff818b2428>] return_to_handler+0x0/0x27
[<ffffffff81311a89>] proc_pid_stack+0xb9/0x110
[<ffffffff818b2428>] return_to_handler+0x0/0x27
[<ffffffff813127c4>] proc_single_show+0x54/0x80
[<ffffffff818b2428>] return_to_handler+0x0/0x27
[<ffffffff812be088>] seq_read+0x108/0x3e0
[<ffffffff818b2428>] return_to_handler+0x0/0x27
[<ffffffff812923d7>] __vfs_read+0x37/0x140
[<ffffffff818b2428>] return_to_handler+0x0/0x27
[<ffffffff812929d9>] vfs_read+0x99/0x140
[<ffffffffffffffff>] 0xffffffffffffffff
Enabling function graph tracing causes the stack trace to change in two
ways:
First, the real call addresses are confusingly interspersed with
'return_to_handler' addresses. This issue will be fixed by the next
patch.
Second, the stack trace is offset by two frames, because the unwinder
skipped the first two frames and got out of sync with the ret_stack
index. This patch fixes this issue.
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Acked-by: Steven Rostedt <rostedt@goodmis.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Byungchul Park <byungchul.park@lge.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Nilay Vaish <nilayvaish@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/a6d623e36f8d08f9a17bd74d804d201177a23afd.1471607358.git.jpoimboe@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'arch/x86/include/asm/ftrace.h')
| -rw-r--r-- | arch/x86/include/asm/ftrace.h | 2 |
1 files changed, 2 insertions, 0 deletions
diff --git a/arch/x86/include/asm/ftrace.h b/arch/x86/include/asm/ftrace.h index 37f67cbba1c6..eccd0ac6bc38 100644 --- a/arch/x86/include/asm/ftrace.h +++ b/arch/x86/include/asm/ftrace.h @@ -14,6 +14,8 @@ #define ARCH_SUPPORTS_FTRACE_OPS 1 #endif +#define HAVE_FUNCTION_GRAPH_RET_ADDR_PTR + #ifndef __ASSEMBLY__ extern void mcount(void); extern atomic_t modifying_ftrace_code; |