Messages in this thread Patch in this message |  | | From | Sumit Garg <> | | Subject | [PATCH v2] arm64: ftrace: use function_nocfi for _mcount as well | | Date | Tue, 5 Oct 2021 18:06:45 +0530 |
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Commit 800618f955a9 ("arm64: ftrace: use function_nocfi for ftrace_call") only fixed address of ftrace_call but address of _mcount needs to be fixed as well. Use function_nocfi() to get the actual address of _mcount function as with CONFIG_CFI_CLANG, the compiler replaces function pointers with jump table addresses which breaks dynamic ftrace as the address of _mcount is replaced with the address of _mcount.cfi_jt.
This problem won't apply where the toolchain implements -fpatchable-function-entry as we'll use that in preference to regular -pg, i.e. this won't show up with recent versions of clang.
Fixes: 9186ad8e66bab6a1 ("arm64: allow CONFIG_CFI_CLANG to be selected") Signed-off-by: Sumit Garg <sumit.garg@linaro.org> Acked-by: Mark Rutland <mark.rutland@arm.com> ---
Changes in v2: - Added fixes tag. - Extended commit description. - Picked up Mark's ack.
arch/arm64/include/asm/ftrace.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/arch/arm64/include/asm/ftrace.h b/arch/arm64/include/asm/ftrace.h index 91fa4baa1a93..347b0cc68f07 100644 --- a/arch/arm64/include/asm/ftrace.h +++ b/arch/arm64/include/asm/ftrace.h @@ -15,7 +15,7 @@ #ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS #define ARCH_SUPPORTS_FTRACE_OPS 1 #else -#define MCOUNT_ADDR ((unsigned long)_mcount) +#define MCOUNT_ADDR ((unsigned long)function_nocfi(_mcount)) #endif /* The BL at the callsite's adjusted rec->ip */ -- 2.17.1
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