• Steven Rostedt's avatar
    x86: Fix export for mcount and __fentry__ · 5de0a8c0
    Steven Rostedt authored
    Commit 784d5699 ("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: default avatarSteven Rostedt <rostedt@goodmis.org>
    Tested-by: default avatarBorislav 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.homeSigned-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
    5de0a8c0
mcount_64.S 7.93 KB