Message ID | 20240103114819.2913937-1-arnd@kernel.org (mailing list archive) |
---|---|
State | New, archived |
Headers | show |
Series | drm/xe: circumvent bogus stringop-overflow warning | expand |
On Wed, Jan 03, 2024 at 12:48:02PM +0100, Arnd Bergmann wrote: >From: Arnd Bergmann <arnd@arndb.de> > >gcc-13 warns about an array overflow that it sees but that is >prevented by the "asid % NUM_PF_QUEUE" calculation: > >drivers/gpu/drm/xe/xe_gt_pagefault.c: In function 'xe_guc_pagefault_handler': >include/linux/fortify-string.h:57:33: error: writing 16 bytes into a region of size 0 [-Werror=stringop-overflow=] >include/linux/fortify-string.h:689:26: note: in expansion of macro '__fortify_memcpy_chk' > 689 | #define memcpy(p, q, s) __fortify_memcpy_chk(p, q, s, \ > | ^~~~~~~~~~~~~~~~~~~~ >drivers/gpu/drm/xe/xe_gt_pagefault.c:341:17: note: in expansion of macro 'memcpy' > 341 | memcpy(pf_queue->data + pf_queue->tail, msg, len * sizeof(u32)); > | ^~~~~~ ugh... I missed that this was for gcc 13 rather than the broken gcc 11 that we workarounded by excluding gcc 11. >drivers/gpu/drm/xe/xe_gt_types.h:102:25: note: at offset [1144, 265324] into destination object 'tile' of size 8 > >I found that rewriting the assignment using pointer addition rather than the >equivalent array index calculation prevents the warning, so use that instead. > >I sent a bug report against gcc for the false positive warning. > >Fixes: dd08ebf6c352 ("drm/xe: Introduce a new DRM driver for Intel GPUs") >Link: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=113214 >Signed-off-by: Arnd Bergmann <arnd@arndb.de> >--- > drivers/gpu/drm/xe/xe_gt_pagefault.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > >diff --git a/drivers/gpu/drm/xe/xe_gt_pagefault.c b/drivers/gpu/drm/xe/xe_gt_pagefault.c >index 59a70d2e0a7a..78dc08cc2bfe 100644 >--- a/drivers/gpu/drm/xe/xe_gt_pagefault.c >+++ b/drivers/gpu/drm/xe/xe_gt_pagefault.c >@@ -332,7 +332,7 @@ int xe_guc_pagefault_handler(struct xe_guc *guc, u32 *msg, u32 len) > return -EPROTO; > > asid = FIELD_GET(PFD_ASID, msg[1]); >- pf_queue = >->usm.pf_queue[asid % NUM_PF_QUEUE]; >+ pf_queue = gt->usm.pf_queue + (asid % NUM_PF_QUEUE); surprising that it fixed it, but looks fine to get in. Applied to drm-xe-next, thanks. Lucas De Marchi > > spin_lock_irqsave(&pf_queue->lock, flags); > full = pf_queue_full(pf_queue); >-- >2.39.2 >
diff --git a/drivers/gpu/drm/xe/xe_gt_pagefault.c b/drivers/gpu/drm/xe/xe_gt_pagefault.c index 59a70d2e0a7a..78dc08cc2bfe 100644 --- a/drivers/gpu/drm/xe/xe_gt_pagefault.c +++ b/drivers/gpu/drm/xe/xe_gt_pagefault.c @@ -332,7 +332,7 @@ int xe_guc_pagefault_handler(struct xe_guc *guc, u32 *msg, u32 len) return -EPROTO; asid = FIELD_GET(PFD_ASID, msg[1]); - pf_queue = >->usm.pf_queue[asid % NUM_PF_QUEUE]; + pf_queue = gt->usm.pf_queue + (asid % NUM_PF_QUEUE); spin_lock_irqsave(&pf_queue->lock, flags); full = pf_queue_full(pf_queue);