Re: [PATCH v2] codetag: Avoid unused alloc_tags sections/symbols
From: Suren Baghdasaryan <surenb@google.com>
Date: 2025-06-25 16:07:39
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linux-arch, lkml
On Wed, Jun 18, 2025 at 5:50 AM Petr Pavlu [off-list ref] wrote:
With CONFIG_MEM_ALLOC_PROFILING=n, vmlinux and all modules unnecessarily contain the symbols __start_alloc_tags and __stop_alloc_tags, which define an empty range. In the case of modules, the presence of these symbols also forces the linker to create an empty .codetag.alloc_tags section. Update codetag.lds.h to make the data conditional on CONFIG_MEM_ALLOC_PROFILING. Signed-off-by: Petr Pavlu <petr.pavlu@suse.com> Reviewed-by: Kent Overstreet <kent.overstreet@linux.dev> Reviewed-by: Suren Baghdasaryan <surenb@google.com>
Thanks! Acked-by: Suren Baghdasaryan <surenb@google.com>
quoted hunk ↗ jump to hunk
--- Changes since v1 [1]: - Trivially rebased the patch on top of "alloc_tag: remove empty module tag section" [2]. [1] https://lore.kernel.org/all/20250313143002.9118-1-petr.pavlu@suse.com/ (local) [2] https://lore.kernel.org/all/20250610162258.324645-1-cachen@purestorage.com/ (local) include/asm-generic/codetag.lds.h | 10 ++++++++-- 1 file changed, 8 insertions(+), 2 deletions(-)diff --git a/include/asm-generic/codetag.lds.h b/include/asm-generic/codetag.lds.h index a45fe3d141a1..a14f4bdafdda 100644 --- a/include/asm-generic/codetag.lds.h +++ b/include/asm-generic/codetag.lds.h@@ -2,6 +2,12 @@ #ifndef __ASM_GENERIC_CODETAG_LDS_H #define __ASM_GENERIC_CODETAG_LDS_H +#ifdef CONFIG_MEM_ALLOC_PROFILING +#define IF_MEM_ALLOC_PROFILING(...) __VA_ARGS__ +#else +#define IF_MEM_ALLOC_PROFILING(...) +#endif + #define SECTION_WITH_BOUNDARIES(_name) \ . = ALIGN(8); \ __start_##_name = .; \@@ -9,7 +15,7 @@ __stop_##_name = .; #define CODETAG_SECTIONS() \ - SECTION_WITH_BOUNDARIES(alloc_tags) + IF_MEM_ALLOC_PROFILING(SECTION_WITH_BOUNDARIES(alloc_tags)) #define MOD_SEPARATE_CODETAG_SECTION(_name) \ .codetag.##_name : { \@@ -22,6 +28,6 @@ * unload them individually once unused. */ #define MOD_SEPARATE_CODETAG_SECTIONS() \ - MOD_SEPARATE_CODETAG_SECTION(alloc_tags) + IF_MEM_ALLOC_PROFILING(MOD_SEPARATE_CODETAG_SECTION(alloc_tags)) #endif /* __ASM_GENERIC_CODETAG_LDS_H */base-commit: 52da431bf03b5506203bca27fe14a97895c80faf prerequisite-patch-id: acb6e2f6708cd75488806308bfecf682b2367dc9 -- 2.49.0