From 32ee8230b2b06c50f583e14fcd174d7d2edb52f5 Mon Sep 17 00:00:00 2001 From: Rasmus Villemoes Date: Fri, 13 Sep 2019 00:19:27 +0200 Subject: [PATCH] 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 Signed-off-by: Rasmus Villemoes Signed-off-by: Miguel Ojeda --- arch/x86/include/asm/bug.h | 4 ++-- 1 file 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" \ -- GitLab