diff options
| author | Borislav Petkov <bp@suse.de> | 2019-10-21 17:18:23 +0200 |
|---|---|---|
| committer | Borislav Petkov <bp@suse.de> | 2019-10-25 10:52:22 +0200 |
| commit | 0f42c1ad44d437f75b840b572376fd538fbb9643 (patch) | |
| tree | b86501365601e861b13c80f35ea0487d3cab0d0b /arch/x86/kernel/ftrace_64.S | |
| parent | 13fbe784ef6e58d0267a6e183f90ce7826d7d885 (diff) | |
x86/ftrace: Get rid of function_hook
History lesson courtesy of Steve:
"When ftrace first was introduced to the kernel, it used gcc's
mcount profiling mechanism. The mcount mechanism would add a call to
"mcount" at the start of every function but after the stack frame was
set up. Later, in gcc 4.6, gcc introduced -mfentry, that would create a
call to "__fentry__" instead of "mcount", before the stack frame was
set up. In order to handle both cases, ftrace defined a macro
"function_hook" that would be either "mcount" or "__fentry__" depending
on which one was being used.
The Linux kernel no longer supports the "mcount" method, thus there's
no reason to keep the "function_hook" define around. Simply use
"__fentry__", as there is no ambiguity to the name anymore."
Drop it everywhere.
Signed-off-by: Borislav Petkov <bp@suse.de>
Acked-by: Jiri Slaby <jslaby@suse.cz>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: linux-doc@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: "Steven Rostedt (VMware)" <rostedt@goodmis.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: x86@kernel.org
Link: http://lkml.kernel.org/r/20191018124800.0a7006bb@gandalf.local.home
Diffstat (limited to 'arch/x86/kernel/ftrace_64.S')
| -rw-r--r-- | arch/x86/kernel/ftrace_64.S | 13 |
1 files changed, 6 insertions, 7 deletions
diff --git a/arch/x86/kernel/ftrace_64.S b/arch/x86/kernel/ftrace_64.S index 69c8d1b9119e..6e8961ca3605 100644 --- a/arch/x86/kernel/ftrace_64.S +++ b/arch/x86/kernel/ftrace_64.S @@ -14,9 +14,6 @@ .code64 .section .entry.text, "ax" -# define function_hook __fentry__ -EXPORT_SYMBOL(__fentry__) - #ifdef CONFIG_FRAME_POINTER /* Save parent and function stack frames (rip and rbp) */ # define MCOUNT_FRAME_SIZE (8+16*2) @@ -132,9 +129,10 @@ EXPORT_SYMBOL(__fentry__) #ifdef CONFIG_DYNAMIC_FTRACE -SYM_FUNC_START(function_hook) +SYM_FUNC_START(__fentry__) retq -SYM_FUNC_END(function_hook) +SYM_FUNC_END(__fentry__) +EXPORT_SYMBOL(__fentry__) SYM_FUNC_START(ftrace_caller) /* save_mcount_regs fills in first two parameters */ @@ -248,7 +246,7 @@ SYM_FUNC_END(ftrace_regs_caller) #else /* ! CONFIG_DYNAMIC_FTRACE */ -SYM_FUNC_START(function_hook) +SYM_FUNC_START(__fentry__) cmpq $ftrace_stub, ftrace_trace_function jnz trace @@ -279,7 +277,8 @@ trace: restore_mcount_regs jmp fgraph_trace -SYM_FUNC_END(function_hook) +SYM_FUNC_END(__fentry__) +EXPORT_SYMBOL(__fentry__) #endif /* CONFIG_DYNAMIC_FTRACE */ #ifdef CONFIG_FUNCTION_GRAPH_TRACER |