| Message ID | 20170719125310.2487451-5-arnd@arndb.de |
|---|---|
| State | Accepted |
| Commit | 7206f9bf108eb9513d170c73f151367a1bdf3dbf |
| Headers | show |
| Series | x86: randconfig warning fixes | expand |
[adding Linus to Cc, apparently git send-email ignores the Suggested-by tag for the cc-list] On Wed, Jul 19, 2017 at 2:53 PM, Arnd Bergmann <arnd@arndb.de> wrote: > 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. > > Link: https://lkml.org/lkml/2017/7/12/605 > Suggested-by: Linus Torvalds <torvalds@linux-foundation.org> > Signed-off-by: Arnd Bergmann <arnd@arndb.de> > --- > v2: replace broken original RFC patch with one that probably works. > The crazy stack usage I reported in teh wl3501_cs driver with > my original patch is gone too now. > --- > 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 e080a39b2108..4bc6f459a8b6 100644 > --- a/arch/x86/include/asm/io.h > +++ b/arch/x86/include/asm/io.h > @@ -328,13 +328,13 @@ 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) > -- > 2.9.0 >
On Wed, Jul 19, 2017 at 5:53 AM, Arnd Bergmann <arnd@arndb.de> wrote: > > 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. Ack, obviously looks fine to me. Linus
diff --git a/arch/x86/include/asm/io.h b/arch/x86/include/asm/io.h index e080a39b2108..4bc6f459a8b6 100644 --- a/arch/x86/include/asm/io.h +++ b/arch/x86/include/asm/io.h @@ -328,13 +328,13 @@ 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)
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. Link: https://lkml.org/lkml/2017/7/12/605 Suggested-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Arnd Bergmann <arnd@arndb.de> --- v2: replace broken original RFC patch with one that probably works. The crazy stack usage I reported in teh wl3501_cs driver with my original patch is gone too now. --- arch/x86/include/asm/io.h | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) -- 2.9.0