| Message ID | 20180704172730.GA33562@beast (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On 2018-07-04 07:27 PM, Kees Cook wrote: > As already done treewide, switch from open-coded multiplication to > 2-factor allocation helper. > > Signed-off-by: Kees Cook <keescook@chromium.org> > --- > drivers/gpu/drm/amd/display/modules/color/color_gamma.c | 8 ++++---- > 1 file changed, 4 insertions(+), 4 deletions(-) > > diff --git a/drivers/gpu/drm/amd/display/modules/color/color_gamma.c b/drivers/gpu/drm/amd/display/modules/color/color_gamma.c > index 98edaefa2b47..ee69c949bfbf 100644 > --- a/drivers/gpu/drm/amd/display/modules/color/color_gamma.c > +++ b/drivers/gpu/drm/amd/display/modules/color/color_gamma.c > @@ -1723,8 +1723,8 @@ bool mod_color_calculate_curve(enum dc_transfer_func_predefined trans, > kvfree(rgb_regamma); > } else if (trans == TRANSFER_FUNCTION_HLG || > trans == TRANSFER_FUNCTION_HLG12) { > - rgb_regamma = kvzalloc(sizeof(*rgb_regamma) * > - (MAX_HW_POINTS + _EXTRA_POINTS), > + rgb_regamma = kvcalloc(MAX_HW_POINTS + _EXTRA_POINTS, > + sizeof(*rgb_regamma), > GFP_KERNEL); > if (!rgb_regamma) > goto rgb_regamma_alloc_fail; > @@ -1802,8 +1802,8 @@ bool mod_color_calculate_degamma_curve(enum dc_transfer_func_predefined trans, > kvfree(rgb_degamma); > } else if (trans == TRANSFER_FUNCTION_HLG || > trans == TRANSFER_FUNCTION_HLG12) { > - rgb_degamma = kvzalloc(sizeof(*rgb_degamma) * > - (MAX_HW_POINTS + _EXTRA_POINTS), > + rgb_degamma = kvcalloc(MAX_HW_POINTS + _EXTRA_POINTS, > + sizeof(*rgb_degamma), > GFP_KERNEL); > if (!rgb_degamma) > goto rgb_degamma_alloc_fail; > Since the values are constant, kvcalloc incurs the overflow checking overhead for no gain.
On Thu, Jul 5, 2018 at 6:37 AM, Michel Dänzer <michel@daenzer.net> wrote: > On 2018-07-04 07:27 PM, Kees Cook wrote: >> As already done treewide, switch from open-coded multiplication to >> 2-factor allocation helper. >> >> Signed-off-by: Kees Cook <keescook@chromium.org> >> --- >> drivers/gpu/drm/amd/display/modules/color/color_gamma.c | 8 ++++---- >> 1 file changed, 4 insertions(+), 4 deletions(-) >> >> diff --git a/drivers/gpu/drm/amd/display/modules/color/color_gamma.c b/drivers/gpu/drm/amd/display/modules/color/color_gamma.c >> index 98edaefa2b47..ee69c949bfbf 100644 >> --- a/drivers/gpu/drm/amd/display/modules/color/color_gamma.c >> +++ b/drivers/gpu/drm/amd/display/modules/color/color_gamma.c >> @@ -1723,8 +1723,8 @@ bool mod_color_calculate_curve(enum dc_transfer_func_predefined trans, >> kvfree(rgb_regamma); >> } else if (trans == TRANSFER_FUNCTION_HLG || >> trans == TRANSFER_FUNCTION_HLG12) { >> - rgb_regamma = kvzalloc(sizeof(*rgb_regamma) * >> - (MAX_HW_POINTS + _EXTRA_POINTS), >> + rgb_regamma = kvcalloc(MAX_HW_POINTS + _EXTRA_POINTS, >> + sizeof(*rgb_regamma), >> GFP_KERNEL); >> if (!rgb_regamma) >> goto rgb_regamma_alloc_fail; >> @@ -1802,8 +1802,8 @@ bool mod_color_calculate_degamma_curve(enum dc_transfer_func_predefined trans, >> kvfree(rgb_degamma); >> } else if (trans == TRANSFER_FUNCTION_HLG || >> trans == TRANSFER_FUNCTION_HLG12) { >> - rgb_degamma = kvzalloc(sizeof(*rgb_degamma) * >> - (MAX_HW_POINTS + _EXTRA_POINTS), >> + rgb_degamma = kvcalloc(MAX_HW_POINTS + _EXTRA_POINTS, >> + sizeof(*rgb_degamma), >> GFP_KERNEL); >> if (!rgb_degamma) >> goto rgb_degamma_alloc_fail; >> > > Since the values are constant, kvcalloc incurs the overflow checking > overhead for no gain. The way the macros are designed, they'll get entirely optimized away in that case: http://lkml.kernel.org/r/CAGXu5jLw9kMZRkzL_Q7JdyyprntHF6bdVSE_vjyzect3CenDng@mail.gmail.com Using this patch means if the code ever changes away from constants, it'll still be safe. And static checkers won't yell about the open-coded multiplication here. So it's only up-sides. :) -Kees
diff --git a/drivers/gpu/drm/amd/display/modules/color/color_gamma.c b/drivers/gpu/drm/amd/display/modules/color/color_gamma.c index 98edaefa2b47..ee69c949bfbf 100644 --- a/drivers/gpu/drm/amd/display/modules/color/color_gamma.c +++ b/drivers/gpu/drm/amd/display/modules/color/color_gamma.c @@ -1723,8 +1723,8 @@ bool mod_color_calculate_curve(enum dc_transfer_func_predefined trans, kvfree(rgb_regamma); } else if (trans == TRANSFER_FUNCTION_HLG || trans == TRANSFER_FUNCTION_HLG12) { - rgb_regamma = kvzalloc(sizeof(*rgb_regamma) * - (MAX_HW_POINTS + _EXTRA_POINTS), + rgb_regamma = kvcalloc(MAX_HW_POINTS + _EXTRA_POINTS, + sizeof(*rgb_regamma), GFP_KERNEL); if (!rgb_regamma) goto rgb_regamma_alloc_fail; @@ -1802,8 +1802,8 @@ bool mod_color_calculate_degamma_curve(enum dc_transfer_func_predefined trans, kvfree(rgb_degamma); } else if (trans == TRANSFER_FUNCTION_HLG || trans == TRANSFER_FUNCTION_HLG12) { - rgb_degamma = kvzalloc(sizeof(*rgb_degamma) * - (MAX_HW_POINTS + _EXTRA_POINTS), + rgb_degamma = kvcalloc(MAX_HW_POINTS + _EXTRA_POINTS, + sizeof(*rgb_degamma), GFP_KERNEL); if (!rgb_degamma) goto rgb_degamma_alloc_fail;
As already done treewide, switch from open-coded multiplication to 2-factor allocation helper. Signed-off-by: Kees Cook <keescook@chromium.org> --- drivers/gpu/drm/amd/display/modules/color/color_gamma.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-)