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From: Sami Tolvanen <samitolvanen@google.com>
To: Peter Zijlstra <peterz@infradead.org>,
	Mark Rutland <mark.rutland@arm.com>,
	Catalin Marinas <catalin.marinas@arm.com>,
	Will Deacon <will@kernel.org>
Cc: Steven Rostedt <rostedt@goodmis.org>,
	Masami Hiramatsu <mhiramat@kernel.org>,
	Kees Cook <keescook@chromium.org>,
	linux-arm-kernel@lists.infradead.org,
	linux-kernel@vger.kernel.org,
	Sami Tolvanen <samitolvanen@google.com>
Subject: [PATCH] arm64: ftrace: Define ftrace_stub_graph only with FUNCTION_GRAPH_TRACER
Date: Wed,  9 Nov 2022 19:28:31 +0000	[thread overview]
Message-ID: <20221109192831.3057131-1-samitolvanen@google.com> (raw)

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@intel.com>
Signed-off-by: Sami Tolvanen <samitolvanen@google.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


             reply	other threads:[~2022-11-09 19:28 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-11-09 19:28 Sami Tolvanen [this message]
2022-11-11 13:29 ` Masami Hiramatsu
2022-11-11 16:09 ` Mark Rutland
2022-11-11 18:32 ` Kees Cook
2022-11-14 13:28 ` Catalin Marinas

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