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| author | Rasmus Villemoes <linux@rasmusvillemoes.dk> | 2019-09-13 01:19:27 +0300 |
|---|---|---|
| committer | Miguel Ojeda <miguel.ojeda.sandonis@gmail.com> | 2019-09-15 21:14:15 +0300 |
| commit | 32ee8230b2b06c50f583e14fcd174d7d2edb52f5 (patch) | |
| tree | d93c7870b09acaf7f2e6570f277c6b30217305ce /arch | |
| parent | 40576e5e63ea5eeab814de7af83ad09dd64134ee (diff) | |
| download | linux-32ee8230b2b06c50f583e14fcd174d7d2edb52f5.tar.xz | |
x86: bug.h: use asm_inline in _BUG_FLAGS definitions
This helps preventing a BUG* or WARN* in some static inline from
preventing that (or one of its callers) being inlined, so should allow
gcc to make better informed inlining decisions.
For example, with gcc 9.2, tcp_fastopen_no_cookie() vanishes from
net/ipv4/tcp_fastopen.o. It does not itself have any BUG or WARN, but
it calls dst_metric() which has a WARN_ON_ONCE - and despite that
WARN_ON_ONCE vanishing since the condition is compile-time false,
dst_metric() is apparently sufficiently "large" that when it gets
inlined into tcp_fastopen_no_cookie(), the latter becomes too large
for inlining.
Overall, if one asks size(1), .text decreases a little and .data
increases by about the same amount (x86-64 defconfig)
$ size vmlinux.{before,after}
text data bss dec hex filename
19709726 5202600 1630280 26542606 195020e vmlinux.before
19709330 5203068 1630280 26542678 1950256 vmlinux.after
while bloat-o-meter says
add/remove: 10/28 grow/shrink: 103/51 up/down: 3669/-2854 (815)
...
Total: Before=14783683, After=14784498, chg +0.01%
Acked-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Signed-off-by: Miguel Ojeda <miguel.ojeda.sandonis@gmail.com>
Diffstat (limited to 'arch')
| -rw-r--r-- | arch/x86/include/asm/bug.h | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/arch/x86/include/asm/bug.h b/arch/x86/include/asm/bug.h index 6804d6642767..facba9bc30ca 100644 --- a/arch/x86/include/asm/bug.h +++ b/arch/x86/include/asm/bug.h @@ -32,7 +32,7 @@ #define _BUG_FLAGS(ins, flags) \ do { \ - asm volatile("1:\t" ins "\n" \ + asm_inline volatile("1:\t" ins "\n" \ ".pushsection __bug_table,\"aw\"\n" \ "2:\t" __BUG_REL(1b) "\t# bug_entry::bug_addr\n" \ "\t" __BUG_REL(%c0) "\t# bug_entry::file\n" \ @@ -49,7 +49,7 @@ do { \ #define _BUG_FLAGS(ins, flags) \ do { \ - asm volatile("1:\t" ins "\n" \ + asm_inline volatile("1:\t" ins "\n" \ ".pushsection __bug_table,\"aw\"\n" \ "2:\t" __BUG_REL(1b) "\t# bug_entry::bug_addr\n" \ "\t.word %c0" "\t# bug_entry::flags\n" \ |