objtool: Add STACK_FRAME_NON_STANDARD() macro

Add a new macro, STACK_FRAME_NON_STANDARD(), which is used to denote a
function which does something unusual related to its stack frame.  Use
of the macro prevents objtool from emitting a false positive warning.

Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Bernd Petrovitsch <bernd@petrovitsch.priv.at>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Chris J Arges <chris.j.arges@canonical.com>
Cc: Jiri Slaby <jslaby@suse.cz>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Michal Marek <mmarek@suse.cz>
Cc: Namhyung Kim <namhyung@gmail.com>
Cc: Pedro Alves <palves@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: live-patching@vger.kernel.org
Link: http://lkml.kernel.org/r/34487a17b23dba43c50941599d47054a9584b219.1456719558.git.jpoimboe@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Josh Poimboeuf 2016-02-28 22:22:35 -06:00 committed by Ingo Molnar
parent c0dd671686
commit 9a99417acb
2 changed files with 27 additions and 1 deletions

View file

@ -343,7 +343,10 @@ SECTIONS
/* Sections to be discarded */
DISCARDS
/DISCARD/ : { *(.eh_frame) }
/DISCARD/ : {
*(.eh_frame)
*(__func_stack_frame_non_standard)
}
}

23
include/linux/frame.h Normal file
View file

@ -0,0 +1,23 @@
#ifndef _LINUX_FRAME_H
#define _LINUX_FRAME_H
#ifdef CONFIG_STACK_VALIDATION
/*
* This macro marks the given function's stack frame as "non-standard", which
* tells objtool to ignore the function when doing stack metadata validation.
* It should only be used in special cases where you're 100% sure it won't
* affect the reliability of frame pointers and kernel stack traces.
*
* For more information, see tools/objtool/Documentation/stack-validation.txt.
*/
#define STACK_FRAME_NON_STANDARD(func) \
static void __used __section(__func_stack_frame_non_standard) \
*__func_stack_frame_non_standard_##func = func
#else /* !CONFIG_STACK_VALIDATION */
#define STACK_FRAME_NON_STANDARD(func)
#endif /* CONFIG_STACK_VALIDATION */
#endif /* _LINUX_FRAME_H */