Enable -ffunction-sections by default for the AutoFDO build. With -ffunction-sections, the compiler places each function in its own section named .text.function_name instead of placing all functions in the .text section. In the AutoFDO build, this allows the linker to utilize profile information to reorganize functions for improved utilization of iCache and iTLB. Co-developed-by: Han Shen <shenhan@xxxxxxxxxx> Signed-off-by: Han Shen <shenhan@xxxxxxxxxx> Signed-off-by: Rong Xu <xur@xxxxxxxxxx> Suggested-by: Sriraman Tallam <tmsriram@xxxxxxxxxx> Tested-by: Yonghong Song <yonghong.song@xxxxxxxxx> Tested-by: Yabin Cui <yabinc@xxxxxxxxxx> Tested-by: Nathan Chancellor <nathan@xxxxxxxxxx> Reviewed-by: Kees Cook <kees@xxxxxxxxxx> --- include/asm-generic/vmlinux.lds.h | 11 +++++++++-- scripts/Makefile.autofdo | 2 +- 2 files changed, 10 insertions(+), 3 deletions(-) diff --git a/include/asm-generic/vmlinux.lds.h b/include/asm-generic/vmlinux.lds.h index e02973f3b4189..bd64fdedabd2f 100644 --- a/include/asm-generic/vmlinux.lds.h +++ b/include/asm-generic/vmlinux.lds.h @@ -95,18 +95,25 @@ * With LTO_CLANG, the linker also splits sections by default, so we need * these macros to combine the sections during the final link. * + * With AUTOFDO_CLANG, by default, the linker splits text sections and + * regroups functions into subsections. + * * RODATA_MAIN is not used because existing code already defines .rodata.x * sections to be brought in with rodata. */ -#if defined(CONFIG_LD_DEAD_CODE_DATA_ELIMINATION) || defined(CONFIG_LTO_CLANG) +#if defined(CONFIG_LD_DEAD_CODE_DATA_ELIMINATION) || defined(CONFIG_LTO_CLANG) || \ +defined(CONFIG_AUTOFDO_CLANG) #define TEXT_MAIN .text .text.[0-9a-zA-Z_]* +#else +#define TEXT_MAIN .text +#endif +#if defined(CONFIG_LD_DEAD_CODE_DATA_ELIMINATION) || defined(CONFIG_LTO_CLANG) #define DATA_MAIN .data .data.[0-9a-zA-Z_]* .data..L* .data..compoundliteral* .data.$__unnamed_* .data.$L* #define SDATA_MAIN .sdata .sdata.[0-9a-zA-Z_]* #define RODATA_MAIN .rodata .rodata.[0-9a-zA-Z_]* .rodata..L* #define BSS_MAIN .bss .bss.[0-9a-zA-Z_]* .bss..L* .bss..compoundliteral* #define SBSS_MAIN .sbss .sbss.[0-9a-zA-Z_]* #else -#define TEXT_MAIN .text #define DATA_MAIN .data #define SDATA_MAIN .sdata #define RODATA_MAIN .rodata diff --git a/scripts/Makefile.autofdo b/scripts/Makefile.autofdo index ff96a63fea7cd..6155d6fc4ca7f 100644 --- a/scripts/Makefile.autofdo +++ b/scripts/Makefile.autofdo @@ -9,7 +9,7 @@ ifndef CONFIG_DEBUG_INFO endif ifdef CLANG_AUTOFDO_PROFILE - CFLAGS_AUTOFDO_CLANG += -fprofile-sample-use=$(CLANG_AUTOFDO_PROFILE) + CFLAGS_AUTOFDO_CLANG += -fprofile-sample-use=$(CLANG_AUTOFDO_PROFILE) -ffunction-sections endif ifdef CONFIG_LTO_CLANG_THIN -- 2.47.0.163.g1226f6d8fa-goog
