On Fri, Apr 05, 2024 at 11:26:25PM +0300, Jani Nikula wrote:
> Prefer common check_add_overflow() from overflow.h over the locally
> rolled versions of it. While check_add_overflow() does require a
> variable to assign to, unlike add_overflows_t(), it's still better than
> having multiple versions around.
>
> Cc: Kees Cook <keescook@xxxxxxxxxxxx>
> Signed-off-by: Jani Nikula <jani.nikula@xxxxxxxxx>
Reviewed-by: Rodrigo Vivi <rodrigo.vivi@xxxxxxxxx>
> ---
> drivers/gpu/drm/i915/display/intel_fb.c | 6 +++---
> drivers/gpu/drm/i915/i915_utils.h | 14 --------------
> 2 files changed, 3 insertions(+), 17 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/display/intel_fb.c b/drivers/gpu/drm/i915/display/intel_fb.c
> index 3ea6470d6d92..86b443433e8b 100644
> --- a/drivers/gpu/drm/i915/display/intel_fb.c
> +++ b/drivers/gpu/drm/i915/display/intel_fb.c
> @@ -1106,7 +1106,7 @@ static int intel_fb_offset_to_xy(int *x, int *y,
> {
> struct drm_i915_private *i915 = to_i915(fb->dev);
> unsigned int height;
> - u32 alignment;
> + u32 alignment, unused;
>
> if (DISPLAY_VER(i915) >= 12 &&
> !intel_fb_needs_pot_stride_remap(to_intel_framebuffer(fb)) &&
> @@ -1128,8 +1128,8 @@ static int intel_fb_offset_to_xy(int *x, int *y,
> height = ALIGN(height, intel_tile_height(fb, color_plane));
>
> /* Catch potential overflows early */
> - if (add_overflows_t(u32, mul_u32_u32(height, fb->pitches[color_plane]),
> - fb->offsets[color_plane])) {
> + if (check_add_overflow(mul_u32_u32(height, fb->pitches[color_plane]),
> + fb->offsets[color_plane], &unused)) {
> drm_dbg_kms(&i915->drm,
> "Bad offset 0x%08x or pitch %d for color plane %d\n",
> fb->offsets[color_plane], fb->pitches[color_plane],
> diff --git a/drivers/gpu/drm/i915/i915_utils.h b/drivers/gpu/drm/i915/i915_utils.h
> index b45ef0560611..06ec6ceb61d5 100644
> --- a/drivers/gpu/drm/i915/i915_utils.h
> +++ b/drivers/gpu/drm/i915/i915_utils.h
> @@ -73,20 +73,6 @@ bool i915_error_injected(void);
> __i915_printk(i915, i915_error_injected() ? KERN_DEBUG : KERN_ERR, \
> fmt, ##__VA_ARGS__)
>
> -#if defined(GCC_VERSION) && GCC_VERSION >= 70000
> -#define add_overflows_t(T, A, B) \
> - __builtin_add_overflow_p((A), (B), (T)0)
> -#else
> -#define add_overflows_t(T, A, B) ({ \
> - typeof(A) a = (A); \
> - typeof(B) b = (B); \
> - (T)(a + b) < a; \
> -})
> -#endif
> -
> -#define add_overflows(A, B) \
> - add_overflows_t(typeof((A) + (B)), (A), (B))
> -
> #define range_overflows(start, size, max) ({ \
> typeof(start) start__ = (start); \
> typeof(size) size__ = (size); \
> --
> 2.39.2
>
