The patch titled
Subject: mm: uninline copy_overflow()
has been added to the -mm tree. Its filename is
mm-outline-copy_overflow.patch
This patch should soon appear at
https://ozlabs.org/~akpm/mmots/broken-out/mm-outline-copy_overflow.patch
and later at
https://ozlabs.org/~akpm/mmotm/broken-out/mm-outline-copy_overflow.patch
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------------------------------------------------------
From: Christophe Leroy <christophe.leroy@xxxxxxxxxx>
Subject: 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:
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
That function being a non conditional warning on an error path,
it is not worth inlining.
Outline it.
This reduces the size of vmlinux by almost 4kbytes.
Link: https://lkml.kernel.org/r/b9a31b025e729394e7081257870f0a0e73355a04.1644229010.git.christophe.leroy@xxxxxxxxxx
Signed-off-by: Christophe Leroy <christophe.leroy@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
include/linux/thread_info.h | 5 +----
mm/maccess.c | 5 +++++
2 files changed, 6 insertions(+), 4 deletions(-)
--- a/include/linux/thread_info.h~mm-outline-copy_overflow
+++ a/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)
--- a/mm/maccess.c~mm-outline-copy_overflow
+++ a/mm/maccess.c
@@ -335,3 +335,8 @@ long strnlen_user_nofault(const void __u
return ret;
}
+
+void copy_overflow(int size, unsigned long count)
+{
+ WARN(1, "Buffer overflow detected (%d < %lu)!\n", size, count);
+}
_
Patches currently in -mm which might be from christophe.leroy@xxxxxxxxxx are
mm-remove-usercopy_warn.patch
mm-outline-copy_overflow.patch
ilog2-force-inlining-of-__ilog2_u32-and-__ilog2_u64.patch
