From: Arnd Bergmann <arnd@xxxxxxxx> This patch has been added to the v4.1 stable tree. If you have any objections, please let us know. =============== [ Upstream commit 7206f9bf108eb9513d170c73f151367a1bdf3dbf ] The x86 version of insb/insw/insl uses an inline assembly that does not have the target buffer listed as an output. This can confuse the compiler, leading it to think that a subsequent access of the buffer is uninitialized: drivers/net/wireless/wl3501_cs.c: In function ‘wl3501_mgmt_scan_confirm’: drivers/net/wireless/wl3501_cs.c:665:9: error: ‘sig.status’ is used uninitialized in this function [-Werror=uninitialized] drivers/net/wireless/wl3501_cs.c:668:12: error: ‘sig.cap_info’ may be used uninitialized in this function [-Werror=maybe-uninitialized] drivers/net/sb1000.c: In function 'sb1000_rx': drivers/net/sb1000.c:775:9: error: 'st[0]' is used uninitialized in this function [-Werror=uninitialized] drivers/net/sb1000.c:776:10: error: 'st[1]' may be used uninitialized in this function [-Werror=maybe-uninitialized] drivers/net/sb1000.c:784:11: error: 'st[1]' may be used uninitialized in this function [-Werror=maybe-uninitialized] I tried to mark the exact input buffer as an output here, but couldn't figure it out. As suggested by Linus, marking all memory as clobbered however is good enough too. For the outs operations, I also add the memory clobber, to force the input to be written to local variables. This is probably already guaranteed by the "asm volatile", but it can't hurt to do this for symmetry. Suggested-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx> Signed-off-by: Arnd Bergmann <arnd@xxxxxxxx> Acked-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx> Cc: Borislav Petkov <bp@xxxxxxx> Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx> Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx> Cc: Tom Lendacky <thomas.lendacky@xxxxxxx> Link: http://lkml.kernel.org/r/20170719125310.2487451-5-arnd@xxxxxxxx Link: https://lkml.org/lkml/2017/7/12/605 Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx> Signed-off-by: Sasha Levin <alexander.levin@xxxxxxxxxxx> --- arch/x86/include/asm/io.h | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/arch/x86/include/asm/io.h b/arch/x86/include/asm/io.h index 34a5b93704d3..b36deb1d9561 100644 --- a/arch/x86/include/asm/io.h +++ b/arch/x86/include/asm/io.h @@ -301,13 +301,13 @@ static inline unsigned type in##bwl##_p(int port) \ static inline void outs##bwl(int port, const void *addr, unsigned long count) \ { \ asm volatile("rep; outs" #bwl \ - : "+S"(addr), "+c"(count) : "d"(port)); \ + : "+S"(addr), "+c"(count) : "d"(port) : "memory"); \ } \ \ static inline void ins##bwl(int port, void *addr, unsigned long count) \ { \ asm volatile("rep; ins" #bwl \ - : "+D"(addr), "+c"(count) : "d"(port)); \ + : "+D"(addr), "+c"(count) : "d"(port) : "memory"); \ } BUILDIO(b, b, char) -- 2.11.0