| Message ID | 1b19e3168b6bed6b9488d35e50a592f5229a2d45.1644574519.git.christophe.leroy@csgroup.eu (mailing list archive) |
|---|---|
| State | Superseded |
| Headers | show |
| Series | [v2] mm: Uninline copy_overflow() | expand |
From: Christophe Leroy > Sent: 11 February 2022 10:16 ... > 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 it. > > This reduces the size of vmlinux by almost 4kbytes. > > Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu> > --- > v2: Added missing EXPORT_SYMBOL() and enhanced commit message > --- > include/linux/thread_info.h | 5 +---- > mm/maccess.c | 6 ++++++ > 2 files changed, 7 insertions(+), 4 deletions(-) > > diff --git a/include/linux/thread_info.h b/include/linux/thread_info.h > index 73a6f34b3847..1087d1e2be5c 100644 > --- a/include/linux/thread_info.h > +++ b/include/linux/thread_info.h > @@ -209,10 +209,7 @@ __bad_copy_from(void); > extern void __compiletime_error("copy destination size is too small") > __bad_copy_to(void); > > -static inline void copy_overflow(int size, unsigned long count) > -{ > - WARN(1, "Buffer overflow detected (%d < %lu)!\n", size, count); > -} > +void copy_overflow(int size, unsigned long count); > > static __always_inline __must_check bool > check_copy_size(const void *addr, size_t bytes, bool is_source) > diff --git a/mm/maccess.c b/mm/maccess.c > index d3f1a1f0b1c1..6b11a22f4b01 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_GPL(copy_overflow) Can you remove the _GPL ???? I think that basically stops you compiling any non-gpl code if the copy_protection is enabled in the kernel build. I'm guessing that most of the inline wrappers calling this are non-FPL functions. David - Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK Registration No: 1397386 (Wales)
diff --git a/include/linux/thread_info.h b/include/linux/thread_info.h index 73a6f34b3847..1087d1e2be5c 100644 --- a/include/linux/thread_info.h +++ b/include/linux/thread_info.h @@ -209,10 +209,7 @@ __bad_copy_from(void); extern void __compiletime_error("copy destination size is too small") __bad_copy_to(void); -static inline void copy_overflow(int size, unsigned long count) -{ - WARN(1, "Buffer overflow detected (%d < %lu)!\n", size, count); -} +void copy_overflow(int size, unsigned long count); static __always_inline __must_check bool check_copy_size(const void *addr, size_t bytes, bool is_source) diff --git a/mm/maccess.c b/mm/maccess.c index d3f1a1f0b1c1..6b11a22f4b01 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_GPL(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 it. This reduces the size of vmlinux by almost 4kbytes. Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu> --- v2: Added missing EXPORT_SYMBOL() and enhanced commit message --- include/linux/thread_info.h | 5 +---- mm/maccess.c | 6 ++++++ 2 files changed, 7 insertions(+), 4 deletions(-)