[PATCH v2 4/9] compiler_types: Let notrace keep the function prefix NOPs
From: Jose Fernandez (Anthropic) <hidden>
Date: 2026-09-24 22:36:58
Also in:
bpf, linux-efi, linux-kbuild, live-patching, lkml, llvm, rust-for-linux
Subsystem:
the rest · Maintainer:
Linus Torvalds
Let notrace keep the prefix NOPs when the architecture defines CC_USING_PATCHABLE_FUNCTION_PREFIX. kCFI callers check the type hash at a fixed offset before the entry point, so a notrace function needs the same prefix NOPs as any other. Record the entry in a section the linker drops, so ftrace never sees it. Clang 21 takes a section name as a third argument of the attribute. Nothing defines the macro yet, so no functional change. Reviewed-by: Ben Cressey <redacted> Reviewed-by: Florent Revest (Anthropic) <redacted> Assisted-by: LLM Signed-off-by: Jose Fernandez (Anthropic) <redacted> --- include/linux/compiler_types.h | 9 +++++++++ 1 file changed, 9 insertions(+)
diff --git a/include/linux/compiler_types.h b/include/linux/compiler_types.h
index c5921f1390079..43dafaa061942 100644
--- a/include/linux/compiler_types.h
+++ b/include/linux/compiler_types.h@@ -211,6 +211,15 @@ struct ftrace_likely_data { #if defined(CC_USING_HOTPATCH) #define notrace __attribute__((hotpatch(0, 0))) +#elif defined(CC_USING_PATCHABLE_FUNCTION_PREFIX) && !defined(__BINDGEN__) +/* + * Not for bindgen: its libclang may not support the section argument + * (Clang >= 21), and leaving the attribute out does not change the ABI. + */ +#define notrace \ + __attribute__((patchable_function_entry(CC_USING_PATCHABLE_FUNCTION_PREFIX, \ + CC_USING_PATCHABLE_FUNCTION_PREFIX, \ + ".discard.patchable_function_entries"))) #elif defined(CC_USING_PATCHABLE_FUNCTION_ENTRY) #define notrace __attribute__((patchable_function_entry(0, 0))) #else
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2.52.0