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mtdchar: mark bits of ioctl handler noinline

PATCH Applied Arnd Bergmann 4 participants 5 messages Apr 17, 2023 – May 23, 2023 Memory technology devices (MTD)

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Arnd Bergmann

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#0 lore raw

PATCH 1/1 mtdchar: mark bits of ioctl handler noinline

From: Arnd Bergmann <[email protected]>

The addition of the mtdchar_read_ioctl() function caused the stack usage of mtdchar_ioctl() to grow beyond the warning limit on 32-bit architectures with gcc-13:

drivers/mtd/mtdchar.c: In function 'mtdchar_ioctl':
drivers/mtd/mtdchar.c:1229:1: error: the frame size of 1488 bytes is larger than 1024 bytes [-Werror=frame-larger-than=]

Mark both the read and write portions as noinline_for_stack to ensure they don't get inlined and use separate stack slots to reduce the maximum usage, both in the mtdchar_ioctl() and combined with any of its callees.

Fixes 095bb6e44eb1 ("mtdchar: add MEMREAD ioctl")
Signed-off-by Arnd Bergmann <[email protected]>
---
 drivers/mtd/mtdchar.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)
drivers/mtd/mtdchar.c +4 -4
index 01f1c6792df9..8dc4f5c493fc 100644
@@ -590,8 +590,8 @@ static void adjust_oob_length(struct mtd_info *mtd, uint64_t start,
 			    (end_page - start_page + 1) * oob_per_page);
 }
 
-static int mtdchar_write_ioctl(struct mtd_info *mtd,
-		struct mtd_write_req __user *argp)
+static noinline_for_stack int
+mtdchar_write_ioctl(struct mtd_info *mtd, struct mtd_write_req __user *argp)
 {
 	struct mtd_info *master = mtd_get_master(mtd);
 	struct mtd_write_req req;

@@ -688,8 +688,8 @@ static int mtdchar_write_ioctl(struct mtd_info *mtd,
 	return ret;
 }
 
-static int mtdchar_read_ioctl(struct mtd_info *mtd,
-		struct mtd_read_req __user *argp)
+static noinline_for_stack int
+mtdchar_read_ioctl(struct mtd_info *mtd, struct mtd_read_req __user *argp)
 {
 	struct mtd_info *master = mtd_get_master(mtd);
 	struct mtd_read_req req;
Signature · 6 lines
2.39.2


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maintainer Reviewed-by on v1 1/1
#1 lore raw

----- Ursprüngliche Mail -----

Quoted 9 lines

Von: "Arnd Bergmann" <[email protected]>
The addition of the mtdchar_read_ioctl() function caused the stack usage of mtdchar_ioctl() to grow beyond the warning limit on 32-bit architectures with gcc-13:

drivers/mtd/mtdchar.c: In function 'mtdchar_ioctl':
drivers/mtd/mtdchar.c:1229:1: error: the frame size of 1488 bytes is larger than 1024 bytes [-Werror=frame-larger-than=]

Quoted 7 lines

Mark both the read and write portions as noinline_for_stack to ensure they don't get inlined and use separate stack slots to reduce the maximum usage, both in the mtdchar_ioctl() and combined with any of its callees.

Fixes 095bb6e44eb1 ("mtdchar: add MEMREAD ioctl")
Signed-off-by Arnd Bergmann <[email protected]>
Reviewed-by Richard Weinberger <[email protected]>

Thanks,
//richard

maintainer
#2 lore raw
In reply to Arnd Bergmann

Hi Arnd,

[email protected] wrote on Mon, 17 Apr 2023 22:56:50 +0200:

Quoted 9 lines

From: Arnd Bergmann <[email protected]>

The addition of the mtdchar_read_ioctl() function caused the stack usage of mtdchar_ioctl() to grow beyond the warning limit on 32-bit architectures with gcc-13:

drivers/mtd/mtdchar.c: In function 'mtdchar_ioctl':
drivers/mtd/mtdchar.c:1229:1: error: the frame size of 1488 bytes is larger than 1024 bytes [-Werror=frame-larger-than=]

Quoted 7 lines

Mark both the read and write portions as noinline_for_stack to ensure they don't get inlined and use separate stack slots to reduce the maximum usage, both in the mtdchar_ioctl() and combined with any of its callees.

Fixes 095bb6e44eb1 ("mtdchar: add MEMREAD ioctl")
Signed-off-by Arnd Bergmann <[email protected]>

I am about to take this as part of my next fixes PR, should we Cc:
stable? What is the current policy wrt gcc version issues?

Quoted 20 lines
---
 drivers/mtd/mtdchar.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)
drivers/mtd/mtdchar.c +2 -2
index 01f1c6792df9..8dc4f5c493fc 100644
@@ -590,8 +590,8 @@ static void adjust_oob_length(struct mtd_info *mtd, uint64_t start,
 			    (end_page - start_page + 1) * oob_per_page);
 }
 
-static int mtdchar_write_ioctl(struct mtd_info *mtd,
-		struct mtd_write_req __user *argp)
+static noinline_for_stack int
+mtdchar_write_ioctl(struct mtd_info *mtd, struct mtd_write_req __user *argp)
 {
 	struct mtd_info *master = mtd_get_master(mtd);
 	struct mtd_write_req req;

drivers/mtd/mtdchar.c static int mtdchar_write_ioctl(struct mtd_info *mtd, · line 695

Quoted 10 lines
drivers/mtd/mtdchar.c +2 -2
@@ -688,8 +688,8 @@ static int mtdchar_write_ioctl(struct mtd_info *mtd,
 	return ret;
 }
 
-static int mtdchar_read_ioctl(struct mtd_info *mtd,
-		struct mtd_read_req __user *argp)
+static noinline_for_stack int
+mtdchar_read_ioctl(struct mtd_info *mtd, struct mtd_read_req __user *argp)
 {
 	struct mtd_info *master = mtd_get_master(mtd);
 	struct mtd_read_req req;

Thanks,
Miquèl

#3 lore raw
Quoted 3 lines · Miquel Raynal

I am about to take this as part of my next fixes PR, should we Cc:
stable? What is the current policy wrt gcc version issues?

I think in general we do want stable kernels to work with the latest gcc, so please add the Cc:stable annotation.

Arnd

maintainer Applied
#4 lore raw
In reply to Arnd Bergmann
Quoted 9 lines · Arnd Bergmann

From: Arnd Bergmann <[email protected]>

The addition of the mtdchar_read_ioctl() function caused the stack usage of mtdchar_ioctl() to grow beyond the warning limit on 32-bit architectures with gcc-13:

drivers/mtd/mtdchar.c: In function 'mtdchar_ioctl':
drivers/mtd/mtdchar.c:1229:1: error: the frame size of 1488 bytes is larger than 1024 bytes [-Werror=frame-larger-than=]

Quoted 8 lines

Mark both the read and write portions as noinline_for_stack to ensure they don't get inlined and use separate stack slots to reduce the maximum usage, both in the mtdchar_ioctl() and combined with any of its callees.

Fixes 095bb6e44eb1 ("mtdchar: add MEMREAD ioctl")
Signed-off-by Arnd Bergmann <[email protected]>
Reviewed-by Richard Weinberger <[email protected]>

Applied to https://git.kernel.org/pub/scm/linux/kernel/git/mtd/linux.git mtd/fixes, thanks.

Miquel