[PATCH v7 4/7] Add markers for text_unlikely and text_hot sections

[Rong Xu <xur@google.com>]

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@google.com>
Signed-off-by: Han Shen <shenhan@google.com>
Signed-off-by: Rong Xu <xur@google.com>
Suggested-by: Sriraman Tallam <tmsriram@google.com>
Tested-by: Yonghong Song <yonghong.song@linux.dev>
Tested-by: Yabin Cui <yabinc@google.com>
Tested-by: Nathan Chancellor <nathan@kernel.org>
Reviewed-by: Kees Cook <kees@kernel.org>
---
 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 fd901951549c0..e02973f3b4189 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)
-- 
2.47.0.163.g1226f6d8fa-goog