On Sun, Mar 10, 2019 at 11:37 PM Jeff King <peff@xxxxxxxx> wrote: > > On Mon, Mar 11, 2019 at 11:00:25AM +0900, Junio C Hamano wrote: > > > Jeffrey Walton <noloader@xxxxxxxxx> writes: > > > > > I think this is the patch for sha1dc/sha1.c . It stops using unaligned > > > accesses by default, but still honors SHA1DC_FORCE_UNALIGNED_ACCESS > > > for those who want it. Folks who want the undefined behavior have to > > > do something special. > > > > Hmph, I somehow thought that folks who want to stick to the > > standard printed on paper penalizing what practicaly works well in > > the real world would be the one doing extra things. > > Unfortunately, I don't think sha1dc currently supports #defines in that > direction. The only logic is "if we are on intel, do unaligned loads" > and "even if we are not on intel, do it anyway". There is no "even if we > are on intel, do not do unaligned loads". > > I think you'd need something like this: > > diff --git a/Makefile b/Makefile > index 148668368b..705c54dcd8 100644 > --- a/Makefile > +++ b/Makefile > @@ -1194,6 +1194,7 @@ BASIC_CFLAGS += -fsanitize=$(SANITIZE) -fno-sanitize-recover=$(SANITIZE) > BASIC_CFLAGS += -fno-omit-frame-pointer > ifneq ($(filter undefined,$(SANITIZERS)),) > BASIC_CFLAGS += -DNO_UNALIGNED_LOADS > +BASIC_CFLAGS += -DSHA1DC_DISALLOW_UNALIGNED_ACCESS > endif > ifneq ($(filter leak,$(SANITIZERS)),) > BASIC_CFLAGS += -DSUPPRESS_ANNOTATED_LEAKS > diff --git a/sha1dc/sha1.c b/sha1dc/sha1.c > index df0630bc6d..0bdf80d778 100644 > --- a/sha1dc/sha1.c > +++ b/sha1dc/sha1.c > @@ -124,9 +124,11 @@ > #endif > /*ENDIANNESS SELECTION*/ > > +#ifndef SHA1DC_DISALLOW_UNALIGNED_ACCESS > #if defined(SHA1DC_FORCE_UNALIGNED_ACCESS) || defined(SHA1DC_ON_INTEL_LIKE_PROCESSOR) > #define SHA1DC_ALLOW_UNALIGNED_ACCESS > #endif /*UNALIGNMENT DETECTION*/ > +#endif > > > #define rotate_right(x,n) (((x)>>(n))|((x)<<(32-(n)))) > > but of course we cannot touch sha1dc/*, because we might actually be > using the submodule copy instead. And AFAIK there is no good way to > modify the submodule-provided content as part of the build. Why do we > even have the submodule again? ;P > > I guess the same would be true for DC_SHA1_EXTERNAL, too, though. > > So anyway, I think this needs a patch to the upstream sha1dc project. https://github.com/cr-marcstevens/sha1collisiondetection/issues/47 Jeff
