Searched hist:b28cd41f (Results 1 – 1 of 1) sorted by relevance
| /openbmc/linux/drivers/gpu/drm/ |
| H A D | drm_crtc.c | b28cd41f Mon Jan 20 13:09:55 CST 2014 David Herrmann <dh.herrmann@gmail.com> drm/crtc: add sanity checks to create_dumb()
Lets make sure some basic expressions are always true:
bpp != NULL
width != NULL
height != NULL
stride = bpp * width < 2^32
size = stride * height < 2^32
PAGE_ALIGN(size) < 2^32
At least the udl driver doesn't check for multiplication-overflows, so
lets just make sure it will never happen. These checks allow drivers to do
any 32bit math without having to test for mult-overflows themselves.
The two divisions might hurt performance a bit, but dumb_create() is only
used for scanout-buffers, so that should be fine. We could use 64bit math
to avoid the divisions, but that may be slow on 32bit machines.. Or maybe
there should just be a "safe_mult32()" helper, which currently doesn't
exist (I think?).
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: David Herrmann <dh.herrmann@gmail.com>
b28cd41f Mon Jan 20 13:09:55 CST 2014 David Herrmann <dh.herrmann@gmail.com> drm/crtc: add sanity checks to create_dumb()
Lets make sure some basic expressions are always true:
bpp != NULL
width != NULL
height != NULL
stride = bpp * width < 2^32
size = stride * height < 2^32
PAGE_ALIGN(size) < 2^32
At least the udl driver doesn't check for multiplication-overflows, so
lets just make sure it will never happen. These checks allow drivers to do
any 32bit math without having to test for mult-overflows themselves.
The two divisions might hurt performance a bit, but dumb_create() is only
used for scanout-buffers, so that should be fine. We could use 64bit math
to avoid the divisions, but that may be slow on 32bit machines.. Or maybe
there should just be a "safe_mult32()" helper, which currently doesn't
exist (I think?).
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: David Herrmann <dh.herrmann@gmail.com>
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