linux-kernel - [PATCH 1/2] media: verisilicon: fix excessive stack usage

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Message-Id: <20230616144854.3818934-1-arnd@kernel.org>
Date:   Fri, 16 Jun 2023 16:48:47 +0200
From:   Arnd Bergmann <arnd@...nel.org>
To:     Ezequiel Garcia <ezequiel@...guardiasur.com.ar>,
        Philipp Zabel <p.zabel@...gutronix.de>,
        Mauro Carvalho Chehab <mchehab@...nel.org>,
        Hans Verkuil <hverkuil-cisco@...all.nl>,
        Benjamin Gaignard <benjamin.gaignard@...labora.com>,
        Nicolas Dufresne <nicolas.dufresne@...labora.com>
Cc:     Arnd Bergmann <arnd@...db.de>, kernel test robot <lkp@...el.com>,
        Jernej Skrabec <jernej.skrabec@...il.com>,
        linux-media@...r.kernel.org, linux-rockchip@...ts.infradead.org,
        linux-kernel@...r.kernel.org
Subject: [PATCH 1/2] media: verisilicon: fix excessive stack usage

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

In some configurations, gcc decides not to inline the register accessor functions,
which in turn leads to lots of temporary hantro_reg structures on the stack that
cannot be eliminated because they escape into an uninlined function:

drivers/media/platform/verisilicon/rockchip_vpu981_hw_av1_dec.c:1022:1: warning: the frame size of 1112 bytes is larger than 1024 bytes [-Wframe-larger-than=]

Mark all of these as __always_inline so the compiler is able to completely
eliminate the temporary structures instead, which brings the stack usage
back down to just the normal local variables.

Reported-by: kernel test robot <lkp@...el.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202306151506.goHEegOd-lkp@intel.com/
Fixes: 727a400686a2c ("media: verisilicon: Add Rockchip AV1 decoder")
Signed-off-by: Arnd Bergmann <arnd@...db.de>
---
 drivers/media/platform/verisilicon/hantro.h | 22 ++++++++++-----------
 1 file changed, 11 insertions(+), 11 deletions(-)

diff --git a/drivers/media/platform/verisilicon/hantro.h b/drivers/media/platform/verisilicon/hantro.h
index 6523ffb748812..6c5e56ce5b351 100644
--- a/drivers/media/platform/verisilicon/hantro.h
+++ b/drivers/media/platform/verisilicon/hantro.h
@@ -370,26 +370,26 @@ extern int hantro_debug;
 	pr_err("%s:%d: " fmt, __func__, __LINE__, ##args)
 
 /* Structure access helpers. */
-static inline struct hantro_ctx *fh_to_ctx(struct v4l2_fh *fh)
+static __always_inline struct hantro_ctx *fh_to_ctx(struct v4l2_fh *fh)
 {
 	return container_of(fh, struct hantro_ctx, fh);
 }
 
 /* Register accessors. */
-static inline void vepu_write_relaxed(struct hantro_dev *vpu,
+static __always_inline void vepu_write_relaxed(struct hantro_dev *vpu,
 				      u32 val, u32 reg)
 {
 	vpu_debug(6, "0x%04x = 0x%08x\n", reg / 4, val);
 	writel_relaxed(val, vpu->enc_base + reg);
 }
 
-static inline void vepu_write(struct hantro_dev *vpu, u32 val, u32 reg)
+static __always_inline void vepu_write(struct hantro_dev *vpu, u32 val, u32 reg)
 {
 	vpu_debug(6, "0x%04x = 0x%08x\n", reg / 4, val);
 	writel(val, vpu->enc_base + reg);
 }
 
-static inline u32 vepu_read(struct hantro_dev *vpu, u32 reg)
+static __always_inline u32 vepu_read(struct hantro_dev *vpu, u32 reg)
 {
 	u32 val = readl(vpu->enc_base + reg);
 
@@ -397,27 +397,27 @@ static inline u32 vepu_read(struct hantro_dev *vpu, u32 reg)
 	return val;
 }
 
-static inline void vdpu_write_relaxed(struct hantro_dev *vpu,
+static __always_inline void vdpu_write_relaxed(struct hantro_dev *vpu,
 				      u32 val, u32 reg)
 {
 	vpu_debug(6, "0x%04x = 0x%08x\n", reg / 4, val);
 	writel_relaxed(val, vpu->dec_base + reg);
 }
 
-static inline void vdpu_write(struct hantro_dev *vpu, u32 val, u32 reg)
+static __always_inline void vdpu_write(struct hantro_dev *vpu, u32 val, u32 reg)
 {
 	vpu_debug(6, "0x%04x = 0x%08x\n", reg / 4, val);
 	writel(val, vpu->dec_base + reg);
 }
 
-static inline void hantro_write_addr(struct hantro_dev *vpu,
+static __always_inline void hantro_write_addr(struct hantro_dev *vpu,
 				     unsigned long offset,
 				     dma_addr_t addr)
 {
 	vdpu_write(vpu, addr & 0xffffffff, offset);
 }
 
-static inline u32 vdpu_read(struct hantro_dev *vpu, u32 reg)
+static __always_inline u32 vdpu_read(struct hantro_dev *vpu, u32 reg)
 {
 	u32 val = readl(vpu->dec_base + reg);
 
@@ -425,7 +425,7 @@ static inline u32 vdpu_read(struct hantro_dev *vpu, u32 reg)
 	return val;
 }
 
-static inline u32 vdpu_read_mask(struct hantro_dev *vpu,
+static __always_inline u32 vdpu_read_mask(struct hantro_dev *vpu,
 				 const struct hantro_reg *reg,
 				 u32 val)
 {
@@ -437,14 +437,14 @@ static inline u32 vdpu_read_mask(struct hantro_dev *vpu,
 	return v;
 }
 
-static inline void hantro_reg_write(struct hantro_dev *vpu,
+static __always_inline void hantro_reg_write(struct hantro_dev *vpu,
 				    const struct hantro_reg *reg,
 				    u32 val)
 {
 	vdpu_write_relaxed(vpu, vdpu_read_mask(vpu, reg, val), reg->base);
 }
 
-static inline void hantro_reg_write_s(struct hantro_dev *vpu,
+static __always_inline void hantro_reg_write_s(struct hantro_dev *vpu,
 				      const struct hantro_reg *reg,
 				      u32 val)
 {
-- 
2.39.2