On Tue, Apr 5, 2016 at 4:26 PM, Chad Versace <chad.vers...@intel.com> wrote:
> On 04/04/2016 06:04 PM, Jason Ekstrand wrote: > > It's possible, when doing an x-tiled copy, to end up with a case where > the > > bytes parameter is equal to 16 but the pointer is not actually aligned. > > This causes asserts in debug mode and segfaults in release builds due to > > doing an aligned operation on an unaligned pointer. > > > > Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=93962 > > --- > > src/mesa/drivers/dri/i965/intel_tiled_memcpy.c | 48 > +++++++++++++------------- > > 1 file changed, 24 insertions(+), 24 deletions(-) > > > > diff --git a/src/mesa/drivers/dri/i965/intel_tiled_memcpy.c > b/src/mesa/drivers/dri/i965/intel_tiled_memcpy.c > > index 19079d0..823d8b0 100644 > > --- a/src/mesa/drivers/dri/i965/intel_tiled_memcpy.c > > +++ b/src/mesa/drivers/dri/i965/intel_tiled_memcpy.c > > @@ -85,19 +85,19 @@ rgba8_copy_aligned_dst(void *dst, const void *src, > size_t bytes) > > uint8_t const *s = src; > > > > #ifdef __SSSE3__ > > - if (bytes == 16) { > > - assert(!(((uintptr_t)dst) & 0xf)); > > - rgba8_copy_16_aligned_dst(d+ 0, s+ 0); > > - return dst; > > - } > > + if ((((uintptr_t)dst) & 0xf) == 0) { > > + if (bytes == 16) { > > + rgba8_copy_16_aligned_dst(d+ 0, s+ 0); > > + return dst; > > + } > > [snip] > > I see the bug... Sometimes (dst, src) points into (tiled, linear user ptr) > memory, and > other times into (linear user ptr, tiled) memory. So we can never assume > that either > address is aligned, as it may be a user ptr. > No, that is not correct. We use the aligned_dst version for when dst is tiled and aligned_src for when src is tiled. The problem is that, when copying a 4 pixel wide region from a X-tiled buffer, it can end up getting called with bytes == 16 and an unaligned pointer. > I didn't test it, but it looks correct to me. > > Reviewed-by: Chad Versace <chad.vers...@intel.com> > > (I'm really back from parental leave! I just built Mesa for the first time > in 9 weeks! Of course, I had to install a newer libdrm before it > compiled). > >
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