When the -ffunction-sections compiler option is enabled, each function is placed in a separate section named .text.function_name rather than putting all functions in a single .text section. However, using -function-sections can cause problems with the linker script. The comments included in include/asm-generic/vmlinux.lds.h note these issues.: “TEXT_MAIN here will match .text.fixup and .text.unlikely if dead code elimination is enabled, so these sections should be converted to use ".." first.” It is unclear whether there is a straightforward method for converting a suffix to "..". This patch modifies the order of subsections within the text output section when the -ffunction-sections flag is enabled. Specifically, it repositions sections with certain fixed patterns (for example .text.unlikely) before TEXT_MAIN, ensuring that they are grouped and matched together. Note that the limitation arises because the linker script employs glob patterns instead of regular expressions for string matching. While there is a method to maintain the current order using complex patterns, this significantly complicates the pattern and increases the likelihood of errors. 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> Suggested-by: Krzysztof Pszeniczny <kpszeniczny@xxxxxxxxxx> --- include/asm-generic/vmlinux.lds.h | 17 +++++++++++++++-- 1 file changed, 15 insertions(+), 2 deletions(-) diff --git a/include/asm-generic/vmlinux.lds.h b/include/asm-generic/vmlinux.lds.h index eeadbaeccf88..5df589c60401 100644 --- a/include/asm-generic/vmlinux.lds.h +++ b/include/asm-generic/vmlinux.lds.h @@ -554,9 +554,21 @@ * during second ld run in second ld pass when generating System.map * * TEXT_MAIN here will match .text.fixup and .text.unlikely if dead - * code elimination is enabled, so these sections should be converted - * to use ".." first. + * code elimination or function-section is enabled. Match these symbols + * first when in these builds. */ +#if defined(CONFIG_LD_DEAD_CODE_DATA_ELIMINATION) || defined(CONFIG_LTO_CLANG) +#define TEXT_TEXT \ + ALIGN_FUNCTION(); \ + *(.text.asan.* .text.tsan.*) \ + *(.text.unknown .text.unknown.*) \ + *(.text.unlikely .text.unlikely.*) \ + . = ALIGN(PAGE_SIZE); \ + *(.text.hot .text.hot.*) \ + *(TEXT_MAIN .text.fixup) \ + NOINSTR_TEXT \ + *(.ref.text) +#else #define TEXT_TEXT \ ALIGN_FUNCTION(); \ *(.text.hot .text.hot.*) \ @@ -566,6 +578,7 @@ NOINSTR_TEXT \ *(.ref.text) \ *(.text.asan.* .text.tsan.*) +#endif /* sched.text is aling to function alignment to secure we have same -- 2.47.0.rc1.288.g06298d1525-goog
