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| author | Steven Rostedt <rostedt@goodmis.org> | 2016-10-24 21:01:48 +0200 |
|---|---|---|
| committer | Thomas Gleixner <tglx@linutronix.de> | 2016-10-26 12:38:17 +0200 |
| commit | 5de0a8c0c240338cb5b73363b0673c6aa804bb1c (patch) | |
| tree | 29581fb848137b041427007cc9603435383bd29b /arch/x86/kernel/mcount_64.S | |
| parent | x86/quirks: Hide maybe-uninitialized warning (diff) | |
| download | linux-5de0a8c0c240338cb5b73363b0673c6aa804bb1c.tar.xz linux-5de0a8c0c240338cb5b73363b0673c6aa804bb1c.zip | |
x86: Fix export for mcount and __fentry__
Commit 784d5699eddc5 ("x86: move exports to actual definitions") removed the
EXPORT_SYMBOL(__fentry__) and EXPORT_SYMBOL(mcount) from x8664_ksyms_64.c,
and added EXPORT_SYMBOL(function_hook) in mcount_64.S instead. The problem
is that function_hook isn't a function at all, but a macro that is defined
as either mcount or __fentry__ depending on the support from gcc.
Originally, I thought this was a macro issue, like what __stringify()
is used for. But the problem is a bit deeper. The Makefile.build has
some magic that does post processing of files to create the CRC
bindings. It does some searches for EXPORT_SYMBOL() and because it
finds a macro name and not the actual functions, this causes
function_hook not to be converted into mcount or __fentry__ and they
are missed.
Instead of adding more magic to Makefile.build, just add
EXPORT_SYMBOL() for mcount and __fentry__ where the ifdef is used.
Since this is assembly and not C, it doesn't require being set after
the function is defined.
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Tested-by: Borislav Petkov <bp@alien8.de>
Cc: Gabriel C <nix.or.die@gmail.com>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Al Viro <viro@ZenIV.linux.org.uk>
Link: http://lkml.kernel.org/r/20161024150148.4f9d90e4@gandalf.local.home
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Diffstat (limited to 'arch/x86/kernel/mcount_64.S')
| -rw-r--r-- | arch/x86/kernel/mcount_64.S | 3 |
1 files changed, 2 insertions, 1 deletions
diff --git a/arch/x86/kernel/mcount_64.S b/arch/x86/kernel/mcount_64.S index efe73aacf966..7b0d3da52fb4 100644 --- a/arch/x86/kernel/mcount_64.S +++ b/arch/x86/kernel/mcount_64.S @@ -18,8 +18,10 @@ #ifdef CC_USING_FENTRY # define function_hook __fentry__ +EXPORT_SYMBOL(__fentry__) #else # define function_hook mcount +EXPORT_SYMBOL(mcount) #endif /* All cases save the original rbp (8 bytes) */ @@ -295,7 +297,6 @@ trace: jmp fgraph_trace END(function_hook) #endif /* CONFIG_DYNAMIC_FTRACE */ -EXPORT_SYMBOL(function_hook) #endif /* CONFIG_FUNCTION_TRACER */ #ifdef CONFIG_FUNCTION_GRAPH_TRACER |