linux-kernel - [PATCH] drm/exynos: fix accidental on-stack copy of exynos_drm

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Message-Id: <20231214123237.1727428-1-arnd@kernel.org>
Date:   Thu, 14 Dec 2023 13:32:15 +0100
From:   Arnd Bergmann <arnd@...nel.org>
To:     Inki Dae <inki.dae@...sung.com>,
        Seung-Woo Kim <sw0312.kim@...sung.com>,
        Kyungmin Park <kyungmin.park@...sung.com>,
        David Airlie <airlied@...il.com>,
        Daniel Vetter <daniel@...ll.ch>,
        Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>,
        Christoph Manszewski <c.manszewski@...sung.com>
Cc:     Arnd Bergmann <arnd@...db.de>,
        Alim Akhtar <alim.akhtar@...sung.com>,
        Thierry Reding <treding@...dia.com>,
        Steven Price <steven.price@....com>,
        Rob Herring <robh@...nel.org>, Robert Foss <rfoss@...nel.org>,
        Kieran Bingham <kieran.bingham+renesas@...asonboard.com>,
        Liviu Dudau <liviu.dudau@....com>,
        Sam Ravnborg <sam@...nborg.org>,
        dri-devel@...ts.freedesktop.org,
        linux-arm-kernel@...ts.infradead.org,
        linux-samsung-soc@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH] drm/exynos: fix accidental on-stack copy of exynos_drm_plane

From: Arnd Bergmann <arnd@...db.de>

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 <arnd@...db.de>
---
 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