From: Sumit Garg <sumit.garg@linaro.org>
To: will@kernel.org, catalin.marinas@arm.com
Cc: linux-arm-kernel@lists.infradead.org, rostedt@goodmis.org,
mingo@redhat.com, samitolvanen@google.com, ben.dai@unisoc.com,
mark.rutland@arm.com, nathan@kernel.org, keescook@chromium.org,
ndesaulniers@google.com, daniel.thompson@linaro.org,
linux-kernel@vger.kernel.org, llvm@lists.linux.dev,
Sumit Garg <sumit.garg@linaro.org>
Subject: [PATCH v3] arm64: ftrace: use function_nocfi for _mcount as well
Date: Mon, 11 Oct 2021 18:20:59 +0530 [thread overview]
Message-ID: <20211011125059.3378646-1-sumit.garg@linaro.org> (raw)
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(-)
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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next reply other threads:[~2021-10-11 12:54 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-10-11 12:50 Sumit Garg [this message]
2021-10-12 8:46 ` [PATCH v3] arm64: ftrace: use function_nocfi for _mcount as well Will Deacon
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