diff mbox series

[v6,4/7] Add markers for text_unlikely and text_hot sections

Message ID 20241026051410.2819338-5-xur@google.com (mailing list archive)
State New
Headers show
Series Add AutoFDO and Propeller support for Clang build | expand

Commit Message

Rong Xu Oct. 26, 2024, 5:14 a.m. UTC 
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>
Change-Id: Ie7688587adf89a14661ceca108680903b546d5d9
---
 include/asm-generic/vmlinux.lds.h | 14 ++++++++++++--
 1 file changed, 12 insertions(+), 2 deletions(-)

Comments

Kees Cook Oct. 28, 2024, 11:56 p.m. UTC | #1 
On Fri, Oct 25, 2024 at 10:14:06PM -0700, Rong Xu wrote:
> 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>

Yup, this is good.

Reviewed-by: Kees Cook <kees@kernel.org>
Kees Cook Oct. 29, 2024, 12:05 a.m. UTC | #2 
On Fri, Oct 25, 2024 at 10:14:06PM -0700, Rong Xu wrote:
> 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>

Reviewed-by: Kees Cook <kees@kernel.org>
diff mbox series

Patch

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)