| Message ID | 20211011125059.3378646-1-sumit.garg@linaro.org (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [v3] arm64: ftrace: use function_nocfi for _mcount as well | expand |
On Mon, 11 Oct 2021 18:20:59 +0530, Sumit Garg wrote: > 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. > > [...] Applied to arm64 (for-next/misc), thanks! [1/1] arm64: ftrace: use function_nocfi for _mcount as well https://git.kernel.org/arm64/c/de56379f21c7 Cheers,
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 */
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. With mainline, this won't be a problem since by default CONFIG_DYNAMIC_FTRACE_WITH_REGS=y with Clang >= 10 as it supports -fpatchable-function-entry and CFI requires Clang 12 but for consistency we should add function_nocfi() for _mcount as well. Signed-off-by: Sumit Garg <sumit.garg@linaro.org> Acked-by: Mark Rutland <mark.rutland@arm.com> Reviewed-by: Sami Tolvanen <samitolvanen@google.com> --- Changes in v3: - Droped fixes tag as it isn't critical. - Modified commit description in order to make this change for consistency. - Picked up Sami's review tag. 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(-)