linux-kernel - [PATCH v5 4/7] Add markers for text_unlikely and text

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Message-ID: <20241023224409.201771-5-xur@google.com>
Date: Wed, 23 Oct 2024 15:44:03 -0700
From: Rong Xu <xur@...gle.com>
To: Alice Ryhl <aliceryhl@...gle.com>, Andrew Morton <akpm@...ux-foundation.org>, 
	Arnd Bergmann <arnd@...db.de>, Bill Wendling <morbo@...gle.com>, Borislav Petkov <bp@...en8.de>, 
	Breno Leitao <leitao@...ian.org>, Brian Gerst <brgerst@...il.com>, 
	Dave Hansen <dave.hansen@...ux.intel.com>, David Li <davidxl@...gle.com>, 
	Han Shen <shenhan@...gle.com>, Heiko Carstens <hca@...ux.ibm.com>, "H. Peter Anvin" <hpa@...or.com>, 
	Ingo Molnar <mingo@...hat.com>, Jann Horn <jannh@...gle.com>, Jonathan Corbet <corbet@....net>, 
	Josh Poimboeuf <jpoimboe@...nel.org>, Juergen Gross <jgross@...e.com>, 
	Justin Stitt <justinstitt@...gle.com>, Kees Cook <kees@...nel.org>, 
	Masahiro Yamada <masahiroy@...nel.org>, "Mike Rapoport (IBM)" <rppt@...nel.org>, 
	Nathan Chancellor <nathan@...nel.org>, Nick Desaulniers <ndesaulniers@...gle.com>, 
	Nicolas Schier <nicolas@...sle.eu>, "Paul E. McKenney" <paulmck@...nel.org>, 
	Peter Zijlstra <peterz@...radead.org>, Rong Xu <xur@...gle.com>, 
	Sami Tolvanen <samitolvanen@...gle.com>, Thomas Gleixner <tglx@...utronix.de>, 
	Wei Yang <richard.weiyang@...il.com>, workflows@...r.kernel.org, 
	Miguel Ojeda <miguel.ojeda.sandonis@...il.com>, Maksim Panchenko <max4bolt@...il.com>, 
	Yonghong Song <yonghong.song@...ux.dev>, Yabin Cui <yabinc@...gle.com>, 
	Krzysztof Pszeniczny <kpszeniczny@...gle.com>, Sriraman Tallam <tmsriram@...gle.com>, 
	Stephane Eranian <eranian@...gle.com>
Cc: x86@...nel.org, linux-arch@...r.kernel.org, linux-doc@...r.kernel.org, 
	linux-kbuild@...r.kernel.org, linux-kernel@...r.kernel.org, 
	llvm@...ts.linux.dev
Subject: [PATCH v5 4/7] Add markers for text_unlikely and text_hot sections

Add markers like __hot_text_start, __hot_text_end, __unlikely_text_start,
and __unlikely_text_end which will be included in System.map. These markers
indicate how the compiler groups functions, providing valuable information
to developers about the layout and optimization of the code.

Co-developed-by: Han Shen <shenhan@...gle.com>
Signed-off-by: Han Shen <shenhan@...gle.com>
Signed-off-by: Rong Xu <xur@...gle.com>
Suggested-by: Sriraman Tallam <tmsriram@...gle.com>
Tested-by: Yonghong Song <yonghong.song@...ux.dev>
---
 include/asm-generic/vmlinux.lds.h | 14 ++++++++++++--
 1 file changed, 12 insertions(+), 2 deletions(-)

diff --git a/include/asm-generic/vmlinux.lds.h b/include/asm-generic/vmlinux.lds.h
index fd901951549c..e02973f3b418 100644
--- a/include/asm-generic/vmlinux.lds.h
+++ b/include/asm-generic/vmlinux.lds.h
@@ -549,6 +549,16 @@
 		__cpuidle_text_end = .;					\
 		__noinstr_text_end = .;
 
+#define TEXT_UNLIKELY							\
+		__unlikely_text_start = .;				\
+		*(.text.unlikely .text.unlikely.*)			\
+		__unlikely_text_end = .;
+
+#define TEXT_HOT							\
+		__hot_text_start = .;					\
+		*(.text.hot .text.hot.*)				\
+		__hot_text_end = .;
+
 /*
  * .text section. Map to function alignment to avoid address changes
  * during second ld run in second ld pass when generating System.map
@@ -565,9 +575,9 @@
 		ALIGN_FUNCTION();					\
 		*(.text.asan.* .text.tsan.*)				\
 		*(.text.unknown .text.unknown.*)			\
-		*(.text.unlikely .text.unlikely.*)			\
+		TEXT_UNLIKELY						\
 		. = ALIGN(PAGE_SIZE);					\
-		*(.text.hot .text.hot.*)				\
+		TEXT_HOT						\
 		*(TEXT_MAIN .text.fixup)				\
 		NOINSTR_TEXT						\
 		*(.ref.text)
-- 
2.47.0.105.g07ac214952-goog