]> git.proxmox.com Git - mirror_ubuntu-disco-kernel.git/commit
locking/rwsem/x86: Add stack frame dependency for ____down_write()
authorJosh Poimboeuf <jpoimboe@redhat.com>
Thu, 13 Oct 2016 21:26:15 +0000 (16:26 -0500)
committerIngo Molnar <mingo@kernel.org>
Tue, 18 Oct 2016 10:21:16 +0000 (12:21 +0200)
commit55a76b59b5fef408442e16121faa9eb00a65fd50
tree20716520fdd5960572e15f6b0dbac064e7b9ca34
parent1001354ca34179f3db924eb66672442a173147dc
locking/rwsem/x86: Add stack frame dependency for ____down_write()

Arnd reported the following objtool warning:

  kernel/locking/rwsem.o: warning: objtool: down_write_killable()+0x16: call without frame pointer save/setup

The warning means gcc placed the ____down_write() inline asm (and its
call instruction) before the frame pointer setup in
down_write_killable(), which breaks frame pointer convention and can
result in incorrect stack traces.

Force the stack frame to be created before the call instruction by
listing the stack pointer as an output operand in the inline asm
statement.

Reported-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1188b7015f04baf361e59de499ee2d7272c59dce.1476393828.git.jpoimboe@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
arch/x86/include/asm/rwsem.h