summaryrefslogtreecommitdiffstats
path: root/arch/x86/kernel/macros.S
diff options
context:
space:
mode:
authorNadav Amit <namit@vmware.com>2018-10-03 23:30:55 +0200
committerIngo Molnar <mingo@kernel.org>2018-10-04 11:24:59 +0200
commit77f48ec28e4ccff94d2e5f4260a83ac27a7f3099 (patch)
tree71b6fe2f7e4d5dfcf794db78329f60091ddc9123 /arch/x86/kernel/macros.S
parentx86/refcount: Work around GCC inlining bug (diff)
downloadlinux-77f48ec28e4ccff94d2e5f4260a83ac27a7f3099.tar.xz
linux-77f48ec28e4ccff94d2e5f4260a83ac27a7f3099.zip
x86/alternatives: Macrofy lock prefixes to work around GCC inlining bugs
As described in: 77b0bf55bc67: ("kbuild/Makefile: Prepare for using macros in inline assembly code to work around asm() related GCC inlining bugs") GCC's inlining heuristics are broken with common asm() patterns used in kernel code, resulting in the effective disabling of inlining. The workaround is to set an assembly macro and call it from the inline assembly block - i.e. to macrify the affected block. As a result GCC considers the inline assembly block as a single instruction. This patch handles the LOCK prefix, allowing more aggresive inlining: text data bss dec hex filename 18140140 10225284 2957312 31322736 1ddf270 ./vmlinux before 18146889 10225380 2957312 31329581 1de0d2d ./vmlinux after (+6845) This is the reduction in non-inlined functions: Before: 40286 After: 40218 (-68) Tested-by: Kees Cook <keescook@chromium.org> Signed-off-by: Nadav Amit <namit@vmware.com> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Andy Lutomirski <luto@amacapital.net> Cc: Borislav Petkov <bp@alien8.de> Cc: Brian Gerst <brgerst@gmail.com> Cc: Denys Vlasenko <dvlasenk@redhat.com> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Josh Poimboeuf <jpoimboe@redhat.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/20181003213100.189959-6-namit@vmware.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to '')
-rw-r--r--arch/x86/kernel/macros.S1
1 files changed, 1 insertions, 0 deletions
diff --git a/arch/x86/kernel/macros.S b/arch/x86/kernel/macros.S
index f1fe1d570365..852487a9fc56 100644
--- a/arch/x86/kernel/macros.S
+++ b/arch/x86/kernel/macros.S
@@ -8,3 +8,4 @@
#include <linux/compiler.h>
#include <asm/refcount.h>
+#include <asm/alternative-asm.h>