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mesa/st: Allocate the gl_context with 16-byte alignment.

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The _ModelProjectMatrix matrix embedded inside has members inside of it
marked as 16-byte aligned, and so the context also has to be 16-byte
aligned or access to those members would be invalid.  I believe the
compiler used this to use better 16-byte-aligned load/stores to other
members of the context, breaking when the context's alignment was only 8
(as normal mallocs guarantee).

Fixes: 3175b63a0d ("mesa: don't allocate matrices with malloc")
Tested-by: Rob Clark <robdclark@chromium.org>
Reviewed-by: Rob Clark <robdclark@chromium.org>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/8783>
(cherry picked from commit 55e853d823)
This commit is contained in:
Eric Anholt 2021-01-29 09:59:34 -08:00 • committed by Dylan Baker
parent 4169bef1b6
commit 7bd9982ba1
2 changed files with 6 additions and 4 deletions
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2
.pick_status.json
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@ -517,7 +517,7 @@
"description": "mesa/st: Allocate the gl_context with 16-byte alignment.",
"nominated": true,
"nomination_type": 1,
"resolution": 0,
"resolution": 1,
"master_sha": null,
"because_sha": "3175b63a0dfa290430f9f7eb651387788933a02b"
},

8
src/mesa/state_tracker/st_context.c
View file

@ -1020,12 +1020,14 @@ st_create_context(gl_api api, struct pipe_context *pipe,
if (pipe->set_context_param)
funcs.PinDriverToL3Cache = st_pin_driver_to_l3_cache;
ctx = calloc(1, sizeof(struct gl_context));
/* gl_context must be 16-byte aligned due to the alignment on GLmatrix. */
ctx = align_malloc(sizeof(struct gl_context), 16);
if (!ctx)
return NULL;
memset(ctx, 0, sizeof(*ctx));
if (!_mesa_initialize_context(ctx, api, visual, shareCtx, &funcs)) {
free(ctx);
align_free(ctx);
return NULL;
}
@ -1158,7 +1160,7 @@ st_destroy_context(struct st_context *st)
_mesa_destroy_debug_output(ctx);
free(ctx);
align_free(ctx);
if (save_ctx == ctx) {
/* unbind the context we just deleted */