tjh.dev / kernel
Linux kernel mirror (for testing) git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
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init.h: Disable sanitizer coverage for __init and __head

While __noinstr already contained __no_sanitize_coverage, it needs to
be added to __init and __head section markings to support the Clang
implementation of CONFIG_KSTACK_ERASE. This is to make sure the stack
depth tracking callback is not executed in unsupported contexts.

The other sanitizer coverage options (trace-pc and trace-cmp) aren't
needed in __head nor __init either ("We are interested in code coverage
as a function of a syscall inputs"[1]), so this is fine to disable for
them as well.

Link: https://web.git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/kernel/kcov.c?h=v6.14#n179 [1]
Acked-by: Marco Elver <elver@google.com>
Link: https://lore.kernel.org/r/20250724055029.3623499-3-kees@kernel.org
Signed-off-by: Kees Cook <kees@kernel.org>

Kees Cook 381a38ea 431a380f

+4 -2
+1 -1
arch/x86/include/asm/init.h
··· 5 5 #if defined(CONFIG_CC_IS_CLANG) && CONFIG_CLANG_VERSION < 170000 6 6 #define __head __section(".head.text") __no_sanitize_undefined __no_stack_protector 7 7 #else 8 - #define __head __section(".head.text") __no_sanitize_undefined 8 + #define __head __section(".head.text") __no_sanitize_undefined __no_sanitize_coverage 9 9 #endif 10 10 11 11 struct x86_mapping_info {
+3 -1
include/linux/init.h
··· 49 49 50 50 /* These are for everybody (although not all archs will actually 51 51 discard it in modules) */ 52 - #define __init __section(".init.text") __cold __latent_entropy __noinitretpoline 52 + #define __init __section(".init.text") __cold __latent_entropy \ 53 + __noinitretpoline \ 54 + __no_sanitize_coverage 53 55 #define __initdata __section(".init.data") 54 56 #define __initconst __section(".init.rodata") 55 57 #define __exitdata __section(".exit.data")