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| author | Christophe Leroy <christophe.leroy@csgroup.eu> | 2022-03-22 22:47:49 +0100 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2022-03-22 23:57:11 +0100 |
| commit | ad7489d5262d2aa775b5e5a1782793925fa90065 (patch) | |
| tree | 2c54e7ef7021d2244a3428d3f6d1eced13c0b141 | |
| parent | mm: remove usercopy_warn() (diff) | |
| download | linux-ad7489d5262d2aa775b5e5a1782793925fa90065.tar.xz linux-ad7489d5262d2aa775b5e5a1782793925fa90065.zip | |
mm: uninline copy_overflow()
While building a small config with CONFIG_CC_OPTIMISE_FOR_SIZE, I ended
up with more than 50 times the following function in vmlinux because GCC
doesn't honor the 'inline' keyword:
c00243bc <copy_overflow>:
c00243bc: 94 21 ff f0 stwu r1,-16(r1)
c00243c0: 7c 85 23 78 mr r5,r4
c00243c4: 7c 64 1b 78 mr r4,r3
c00243c8: 3c 60 c0 62 lis r3,-16286
c00243cc: 7c 08 02 a6 mflr r0
c00243d0: 38 63 5e e5 addi r3,r3,24293
c00243d4: 90 01 00 14 stw r0,20(r1)
c00243d8: 4b ff 82 45 bl c001c61c <__warn_printk>
c00243dc: 0f e0 00 00 twui r0,0
c00243e0: 80 01 00 14 lwz r0,20(r1)
c00243e4: 38 21 00 10 addi r1,r1,16
c00243e8: 7c 08 03 a6 mtlr r0
c00243ec: 4e 80 00 20 blr
With -Winline, GCC tells:
/include/linux/thread_info.h:212:20: warning: inlining failed in call to 'copy_overflow': call is unlikely and code size would grow [-Winline]
copy_overflow() is a non conditional warning called by check_copy_size()
on an error path.
check_copy_size() have to remain inlined in order to benefit from
constant folding, but copy_overflow() is not worth inlining.
Uninline the warning when CONFIG_BUG is selected.
When CONFIG_BUG is not selected, WARN() does nothing so skip it.
This reduces the size of vmlinux by almost 4kbytes.
Link: https://lkml.kernel.org/r/e1723b9cfa924bcefcd41f69d0025b38e4c9364e.1644819985.git.christophe.leroy@csgroup.eu
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Cc: David Laight <David.Laight@ACULAB.COM>
Cc: Anshuman Khandual <anshuman.khandual@arm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
| -rw-r--r-- | include/linux/thread_info.h | 5 | ||||
| -rw-r--r-- | mm/maccess.c | 6 |
2 files changed, 10 insertions, 1 deletions
diff --git a/include/linux/thread_info.h b/include/linux/thread_info.h index 73a6f34b3847..9f392ec76f2b 100644 --- a/include/linux/thread_info.h +++ b/include/linux/thread_info.h @@ -209,9 +209,12 @@ __bad_copy_from(void); extern void __compiletime_error("copy destination size is too small") __bad_copy_to(void); +void __copy_overflow(int size, unsigned long count); + static inline void copy_overflow(int size, unsigned long count) { - WARN(1, "Buffer overflow detected (%d < %lu)!\n", size, count); + if (IS_ENABLED(CONFIG_BUG)) + __copy_overflow(size, count); } static __always_inline __must_check bool diff --git a/mm/maccess.c b/mm/maccess.c index d3f1a1f0b1c1..3fed2b876539 100644 --- a/mm/maccess.c +++ b/mm/maccess.c @@ -335,3 +335,9 @@ long strnlen_user_nofault(const void __user *unsafe_addr, long count) return ret; } + +void __copy_overflow(int size, unsigned long count) +{ + WARN(1, "Buffer overflow detected (%d < %lu)!\n", size, count); +} +EXPORT_SYMBOL(__copy_overflow); |