From: Sumit Garg <sumit.garg@linaro.org>
To: linux-arm-kernel@lists.infradead.org
Cc: rostedt@goodmis.org, mingo@redhat.com, catalin.marinas@arm.com,
will@kernel.org, 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 v2] arm64: ftrace: use function_nocfi for _mcount as well
Date: Tue, 5 Oct 2021 18:06:45 +0530 [thread overview]
Message-ID: <20211005123645.2766258-1-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.
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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next reply other threads:[~2021-10-05 12:38 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-10-05 12:36 Sumit Garg [this message]
2021-10-05 15:20 ` [PATCH v2] arm64: ftrace: use function_nocfi for _mcount as well Sami Tolvanen
2021-10-05 15:35 ` Mark Rutland
2021-10-06 5:35 ` Sumit Garg
2021-10-08 8:05 ` Will Deacon
2021-10-11 12:53 ` Sumit Garg
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