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| 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_32.S | |
| parent | x86/asm: Replace WEAK uses by SYM_INNER_LABEL_ALIGN (diff) | |
| download | linux-0f42c1ad44d437f75b840b572376fd538fbb9643.tar.xz linux-0f42c1ad44d437f75b840b572376fd538fbb9643.zip | |
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_32.S')
| -rw-r--r-- | arch/x86/kernel/ftrace_32.S | 8 |
1 files changed, 3 insertions, 5 deletions
diff --git a/arch/x86/kernel/ftrace_32.S b/arch/x86/kernel/ftrace_32.S index 8ed1f5d371f0..e8a9f8370112 100644 --- a/arch/x86/kernel/ftrace_32.S +++ b/arch/x86/kernel/ftrace_32.S @@ -12,18 +12,16 @@ #include <asm/frame.h> #include <asm/asm-offsets.h> -# define function_hook __fentry__ -EXPORT_SYMBOL(__fentry__) - #ifdef CONFIG_FRAME_POINTER # define MCOUNT_FRAME 1 /* using frame = true */ #else # define MCOUNT_FRAME 0 /* using frame = false */ #endif -SYM_FUNC_START(function_hook) +SYM_FUNC_START(__fentry__) ret -SYM_FUNC_END(function_hook) +SYM_FUNC_END(__fentry__) +EXPORT_SYMBOL(__fentry__) SYM_CODE_START(ftrace_caller) |