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From: Josh Poimboeuf <jpoimboe@kernel.org>
To: x86@kernel.org
Cc: linux-kernel@vger.kernel.org,
	Linus Torvalds <torvalds@linux-foundation.org>,
	Ingo Molnar <mingo@kernel.org>,
	Peter Zijlstra <peterz@infradead.org>
Subject: [PATCH RFC 3/5] noinstr: Use asm_inline() in instrumentation_{begin,end}()
Date: Tue,  8 Apr 2025 01:21:16 -0700	[thread overview]
Message-ID: <7cb41fe7e87a003fc925164d5cc18efd8e95fcc0.1744098446.git.jpoimboe@kernel.org> (raw)
In-Reply-To: <cover.1744098446.git.jpoimboe@kernel.org>

Use asm_inline() to prevent the compiler from making poor inlining
decisions based on the length of the objtool annotations.

For a defconfig kernel built with GCC 14.2.1, bloat-o-meter reports a
0.18% text size increase:

  add/remove: 88/433 grow/shrink: 967/487 up/down: 87579/-52630 (34949)
  Total: Before=19448407, After=19483356, chg +0.18%

Presumably the text growth is due to increased inlining.  A net total of
345 functions were removed.

Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
---
 include/linux/instrumentation.h | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/include/linux/instrumentation.h b/include/linux/instrumentation.h
index bf675a8aef8a..b1007407d272 100644
--- a/include/linux/instrumentation.h
+++ b/include/linux/instrumentation.h
@@ -9,7 +9,7 @@
 
 /* Begin/end of an instrumentation safe region */
 #define __instrumentation_begin(c) ({					\
-	asm volatile(__stringify(c) ": nop\n\t"				\
+	asm_inline volatile(__stringify(c) ": nop\n\t"			\
 		     ANNOTATE_INSTR_BEGIN(__ASM_BREF(c))		\
 		     : : "i" (c));					\
 })
@@ -47,7 +47,7 @@
  * part of the condition block and does not escape.
  */
 #define __instrumentation_end(c) ({					\
-	asm volatile(__stringify(c) ": nop\n\t"				\
+	asm_inline volatile(__stringify(c) ": nop\n\t"			\
 		     ANNOTATE_INSTR_END(__ASM_BREF(c))			\
 		     : : "i" (c));					\
 })
-- 
2.49.0


  parent reply	other threads:[~2025-04-08  8:21 UTC|newest]

Thread overview: 20+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2025-04-08  8:21 [PATCH RFC 0/5] x86/asm: Improve code generation Josh Poimboeuf
2025-04-08  8:21 ` [PATCH RFC 1/5] objtool: Remove ANNOTATE_IGNORE_ALTERNATIVE from CLAC/STAC Josh Poimboeuf
2025-04-08 18:07   ` Linus Torvalds
2025-04-08 20:45   ` [tip: objtool/urgent] " tip-bot2 for Josh Poimboeuf
2025-04-08  8:21 ` [PATCH RFC 2/5] objtool, x86/hweight: Remove ANNOTATE_IGNORE_ALTERNATIVE Josh Poimboeuf
2025-04-08  8:21 ` Josh Poimboeuf [this message]
2025-04-08  8:30   ` [PATCH RFC 3/5] noinstr: Use asm_inline() in instrumentation_{begin,end}() Ingo Molnar
2025-04-08 11:10     ` Uros Bizjak
2025-04-08 16:46       ` Josh Poimboeuf
2025-04-08  8:21 ` [PATCH RFC 4/5] x86/alternative: Improve code generation readability Josh Poimboeuf
2025-04-09 14:38   ` Peter Zijlstra
2025-04-09 17:41     ` Josh Poimboeuf
2025-04-09 18:02       ` Linus Torvalds
2025-04-09 19:51         ` Josh Poimboeuf
2025-04-09 21:20           ` Linus Torvalds
2025-04-09 21:27             ` Josh Poimboeuf
2025-04-09 21:55               ` Josh Poimboeuf
2025-04-16 23:30         ` Josh Poimboeuf
2025-04-08  8:21 ` [PATCH RFC 5/5] objtool: " Josh Poimboeuf
2025-04-09 14:40   ` Peter Zijlstra

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