Commit-ID: 4544ba8c6b1743499cabb682897a469911845f15 Gitweb: http://git.kernel.org/tip/4544ba8c6b1743499cabb682897a469911845f15 Author: Borislav Petkov <[email protected]> AuthorDate: Mon, 16 May 2016 11:34:28 +0200 Committer: Ingo Molnar <[email protected]> CommitDate: Mon, 16 May 2016 12:35:40 +0200
locking/rwsem: Fix comment on register clobbering Document explicitly that %edx can get clobbered on the slow path, on 32-bit kernels. Something I learned the hard way. :-\ Suggested-by: Linus Torvalds <[email protected]> Signed-off-by: Borislav Petkov <[email protected]> Cc: Alexander Shishkin <[email protected]> Cc: Andy Lutomirski <[email protected]> Cc: Arnaldo Carvalho de Melo <[email protected]> Cc: Borislav Petkov <[email protected]> Cc: Brian Gerst <[email protected]> Cc: Denys Vlasenko <[email protected]> Cc: Guenter Roeck <[email protected]> Cc: H. Peter Anvin <[email protected]> Cc: Jiri Olsa <[email protected]> Cc: Peter Zijlstra <[email protected]> Cc: Stephane Eranian <[email protected]> Cc: Thomas Gleixner <[email protected]> Cc: Vince Weaver <[email protected]> Cc: [email protected] Link: http://lkml.kernel.org/r/[email protected] Signed-off-by: Ingo Molnar <[email protected]> --- arch/x86/lib/rwsem.S | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) diff --git a/arch/x86/lib/rwsem.S b/arch/x86/lib/rwsem.S index a37462a..bf2c607 100644 --- a/arch/x86/lib/rwsem.S +++ b/arch/x86/lib/rwsem.S @@ -29,8 +29,10 @@ * there is contention on the semaphore. * * %eax contains the semaphore pointer on entry. Save the C-clobbered - * registers (%eax, %edx and %ecx) except %eax whish is either a return - * value or just clobbered.. + * registers (%eax, %edx and %ecx) except %eax which is either a return + * value or just gets clobbered. Same is true for %edx so make sure GCC + * reloads it after the slow path, by making it hold a temporary, for + * example see ____down_write(). */ #define save_common_regs \
