@@ -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
@@ -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 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. Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu> --- v4: Make copy_overflow() a no-op when CONFIG_BUG is not selected v3: Added missing ; after EXPORT_SYMBOL() v2: Added missing EXPORT_SYMBOL() and enhanced commit message --- include/linux/thread_info.h | 5 ++++- mm/maccess.c | 6 ++++++ 2 files changed, 10 insertions(+), 1 deletion(-)