2023-12-14 12:32:56

by Arnd Bergmann

[permalink] [raw]
Subject: [PATCH] drm/exynos: fix accidental on-stack copy of exynos_drm_plane

From: Arnd Bergmann <[email protected]>

gcc rightfully complains about excessive stack usage in the fimd_win_set_pixfmt()
function:

drivers/gpu/drm/exynos/exynos_drm_fimd.c: In function 'fimd_win_set_pixfmt':
drivers/gpu/drm/exynos/exynos_drm_fimd.c:750:1: error: the frame size of 1032 bytes is larger than 1024 byte
drivers/gpu/drm/exynos/exynos5433_drm_decon.c: In function 'decon_win_set_pixfmt':
drivers/gpu/drm/exynos/exynos5433_drm_decon.c:381:1: error: the frame size of 1032 bytes is larger than 1024 bytes

There is really no reason to copy the large exynos_drm_plane
structure to the stack before using one of its members, so just
use a pointer instead.

Fixes: 6f8ee5c21722 ("drm/exynos: fimd: Make plane alpha configurable")
Signed-off-by: Arnd Bergmann <[email protected]>
---
drivers/gpu/drm/exynos/exynos5433_drm_decon.c | 4 ++--
drivers/gpu/drm/exynos/exynos_drm_fimd.c | 4 ++--
2 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/drivers/gpu/drm/exynos/exynos5433_drm_decon.c b/drivers/gpu/drm/exynos/exynos5433_drm_decon.c
index 4d986077738b..bce027552474 100644
--- a/drivers/gpu/drm/exynos/exynos5433_drm_decon.c
+++ b/drivers/gpu/drm/exynos/exynos5433_drm_decon.c
@@ -319,9 +319,9 @@ static void decon_win_set_bldmod(struct decon_context *ctx, unsigned int win,
static void decon_win_set_pixfmt(struct decon_context *ctx, unsigned int win,
struct drm_framebuffer *fb)
{
- struct exynos_drm_plane plane = ctx->planes[win];
+ struct exynos_drm_plane *plane = &ctx->planes[win];
struct exynos_drm_plane_state *state =
- to_exynos_plane_state(plane.base.state);
+ to_exynos_plane_state(plane->base.state);
unsigned int alpha = state->base.alpha;
unsigned int pixel_alpha;
unsigned long val;
diff --git a/drivers/gpu/drm/exynos/exynos_drm_fimd.c b/drivers/gpu/drm/exynos/exynos_drm_fimd.c
index 8dde7b1e9b35..5bdc246f5fad 100644
--- a/drivers/gpu/drm/exynos/exynos_drm_fimd.c
+++ b/drivers/gpu/drm/exynos/exynos_drm_fimd.c
@@ -661,9 +661,9 @@ static void fimd_win_set_bldmod(struct fimd_context *ctx, unsigned int win,
static void fimd_win_set_pixfmt(struct fimd_context *ctx, unsigned int win,
struct drm_framebuffer *fb, int width)
{
- struct exynos_drm_plane plane = ctx->planes[win];
+ struct exynos_drm_plane *plane = &ctx->planes[win];
struct exynos_drm_plane_state *state =
- to_exynos_plane_state(plane.base.state);
+ to_exynos_plane_state(plane->base.state);
uint32_t pixel_format = fb->format->format;
unsigned int alpha = state->base.alpha;
u32 val = WINCONx_ENWIN;
--
2.39.2


2023-12-14 15:59:34

by Marek Szyprowski

[permalink] [raw]
Subject: Re: [PATCH] drm/exynos: fix accidental on-stack copy of exynos_drm_plane

On 14.12.2023 13:32, Arnd Bergmann wrote:
> From: Arnd Bergmann <[email protected]>
>
> gcc rightfully complains about excessive stack usage in the fimd_win_set_pixfmt()
> function:
>
> drivers/gpu/drm/exynos/exynos_drm_fimd.c: In function 'fimd_win_set_pixfmt':
> drivers/gpu/drm/exynos/exynos_drm_fimd.c:750:1: error: the frame size of 1032 bytes is larger than 1024 byte
> drivers/gpu/drm/exynos/exynos5433_drm_decon.c: In function 'decon_win_set_pixfmt':
> drivers/gpu/drm/exynos/exynos5433_drm_decon.c:381:1: error: the frame size of 1032 bytes is larger than 1024 bytes
>
> There is really no reason to copy the large exynos_drm_plane
> structure to the stack before using one of its members, so just
> use a pointer instead.
>
> Fixes: 6f8ee5c21722 ("drm/exynos: fimd: Make plane alpha configurable")
> Signed-off-by: Arnd Bergmann <[email protected]>


Reviewed-by: Marek Szyprowski <[email protected]>


> ---
> drivers/gpu/drm/exynos/exynos5433_drm_decon.c | 4 ++--
> drivers/gpu/drm/exynos/exynos_drm_fimd.c | 4 ++--
> 2 files changed, 4 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/gpu/drm/exynos/exynos5433_drm_decon.c b/drivers/gpu/drm/exynos/exynos5433_drm_decon.c
> index 4d986077738b..bce027552474 100644
> --- a/drivers/gpu/drm/exynos/exynos5433_drm_decon.c
> +++ b/drivers/gpu/drm/exynos/exynos5433_drm_decon.c
> @@ -319,9 +319,9 @@ static void decon_win_set_bldmod(struct decon_context *ctx, unsigned int win,
> static void decon_win_set_pixfmt(struct decon_context *ctx, unsigned int win,
> struct drm_framebuffer *fb)
> {
> - struct exynos_drm_plane plane = ctx->planes[win];
> + struct exynos_drm_plane *plane = &ctx->planes[win];
> struct exynos_drm_plane_state *state =
> - to_exynos_plane_state(plane.base.state);
> + to_exynos_plane_state(plane->base.state);
> unsigned int alpha = state->base.alpha;
> unsigned int pixel_alpha;
> unsigned long val;
> diff --git a/drivers/gpu/drm/exynos/exynos_drm_fimd.c b/drivers/gpu/drm/exynos/exynos_drm_fimd.c
> index 8dde7b1e9b35..5bdc246f5fad 100644
> --- a/drivers/gpu/drm/exynos/exynos_drm_fimd.c
> +++ b/drivers/gpu/drm/exynos/exynos_drm_fimd.c
> @@ -661,9 +661,9 @@ static void fimd_win_set_bldmod(struct fimd_context *ctx, unsigned int win,
> static void fimd_win_set_pixfmt(struct fimd_context *ctx, unsigned int win,
> struct drm_framebuffer *fb, int width)
> {
> - struct exynos_drm_plane plane = ctx->planes[win];
> + struct exynos_drm_plane *plane = &ctx->planes[win];
> struct exynos_drm_plane_state *state =
> - to_exynos_plane_state(plane.base.state);
> + to_exynos_plane_state(plane->base.state);
> uint32_t pixel_format = fb->format->format;
> unsigned int alpha = state->base.alpha;
> u32 val = WINCONx_ENWIN;

Best regards
--
Marek Szyprowski, PhD
Samsung R&D Institute Poland