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Message-ID: <20221109192831.3057131-1-samitolvanen@google.com>
Date: Wed, 9 Nov 2022 19:28:31 +0000
From: Sami Tolvanen <samitolvanen@...gle.com>
To: Peter Zijlstra <peterz@...radead.org>,
Mark Rutland <mark.rutland@....com>,
Catalin Marinas <catalin.marinas@....com>,
Will Deacon <will@...nel.org>
Cc: Steven Rostedt <rostedt@...dmis.org>,
Masami Hiramatsu <mhiramat@...nel.org>,
Kees Cook <keescook@...omium.org>,
linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
Sami Tolvanen <samitolvanen@...gle.com>
Subject: [PATCH] arm64: ftrace: Define ftrace_stub_graph only with FUNCTION_GRAPH_TRACER
The 0-day bot reports that arm64 builds with CONFIG_CFI_CLANG +
CONFIG_FTRACE are broken when CONFIG_FUNCTION_GRAPH_TRACER is not
enabled:
ld.lld: error: undefined symbol: __kcfi_typeid_ftrace_stub_graph
>>> referenced by entry-ftrace.S:299 (arch/arm64/kernel/entry-ftrace.S:299)
>>> arch/arm64/kernel/entry-ftrace.o:(.text+0x48) in archive vmlinux.a
This is caused by ftrace_stub_graph using SYM_TYPE_FUNC_START when
the address of the function is not taken in any C translation unit.
Fix the build by only defining ftrace_stub_graph when it's actually
needed, i.e. with CONFIG_FUNCTION_GRAPH_TRACER.
Link: https://lore.kernel.org/lkml/202210251659.tRMs78RH-lkp@intel.com/
Fixes: 883bbbffa5a4 ("ftrace,kcfi: Separate ftrace_stub() and ftrace_stub_graph()")
Reported-by: kernel test robot <lkp@...el.com>
Signed-off-by: Sami Tolvanen <samitolvanen@...gle.com>
---
arch/arm64/kernel/entry-ftrace.S | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/arch/arm64/kernel/entry-ftrace.S b/arch/arm64/kernel/entry-ftrace.S
index 795344ab4ec4..322a831f8ede 100644
--- a/arch/arm64/kernel/entry-ftrace.S
+++ b/arch/arm64/kernel/entry-ftrace.S
@@ -299,11 +299,11 @@ SYM_TYPED_FUNC_START(ftrace_stub)
ret
SYM_FUNC_END(ftrace_stub)
+#ifdef CONFIG_FUNCTION_GRAPH_TRACER
SYM_TYPED_FUNC_START(ftrace_stub_graph)
ret
SYM_FUNC_END(ftrace_stub_graph)
-#ifdef CONFIG_FUNCTION_GRAPH_TRACER
/*
* void return_to_handler(void)
*
base-commit: f141df371335645ce29a87d9683a3f79fba7fd67
--
2.38.1.431.g37b22c650d-goog
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