[PATCH] arm64: ftrace: fix ifdeffery

[PATCH] arm64: ftrace: fix ifdeffery

[Mark Rutland]

When I tweaked the ftrace entry assembly in commit:

  3b23e4991fb66f6d ("arm64: implement ftrace with regs")

... my ifdeffery tweaks left ftrace_graph_caller undefined for
CONFIG_DYNAMIC_FTRACE && CONFIG_FUNCTION_GRAPH_TRACER when ftrace is
based on mcount.

The kbuild test robot reported that this issue is detected at link time:

| arch/arm64/kernel/entry-ftrace.o: In function `skip_ftrace_call':
| arch/arm64/kernel/entry-ftrace.S:238: undefined reference to `ftrace_graph_caller'
| arch/arm64/kernel/entry-ftrace.S:238:(.text+0x3c): relocation truncated to fit: R_AARCH64_CONDBR19 against undefined symbol
| `ftrace_graph_caller'
| arch/arm64/kernel/entry-ftrace.S:243: undefined reference to `ftrace_graph_caller'
| arch/arm64/kernel/entry-ftrace.S:243:(.text+0x54): relocation truncated to fit: R_AARCH64_CONDBR19 against undefined symbol
| `ftrace_graph_caller'

This patch fixes the ifdeffery so that the mcount version of
ftrace_graph_caller doesn't depend on CONFIG_DYNAMIC_FTRACE. At the same
time, a redundant #else is removed from the ifdeffery for the
patchable-function-entry version of ftrace_graph_caller.

Fixes: 3b23e4991fb66f6d ("arm64: implement ftrace with regs")
Reported-by: kbuild test robot <lkp@intel.com>
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Cc: Amit Daniel Kachhap <amit.kachhap@arm.com>
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Torsten Duwe <duwe@lst.de>
Cc: Will Deacon <will@kernel.org>
---
 arch/arm64/kernel/entry-ftrace.S | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/arch/arm64/kernel/entry-ftrace.S b/arch/arm64/kernel/entry-ftrace.S
index 4fe1514fcbfd..7d02f9966d34 100644
--- a/arch/arm64/kernel/entry-ftrace.S
+++ b/arch/arm64/kernel/entry-ftrace.S
@@ -133,7 +133,6 @@ ENTRY(ftrace_graph_caller)
 	bl	prepare_ftrace_return
 	b	ftrace_common_return
 ENDPROC(ftrace_graph_caller)
-#else
 #endif
 
 #else /* CONFIG_DYNAMIC_FTRACE_WITH_REGS */
@@ -287,6 +286,7 @@ GLOBAL(ftrace_graph_call)		// ftrace_graph_caller();
 
 	mcount_exit
 ENDPROC(ftrace_caller)
+#endif /* CONFIG_DYNAMIC_FTRACE */
 
 #ifdef CONFIG_FUNCTION_GRAPH_TRACER
 /*
@@ -307,7 +307,6 @@ ENTRY(ftrace_graph_caller)
 	mcount_exit
 ENDPROC(ftrace_graph_caller)
 #endif /* CONFIG_FUNCTION_GRAPH_TRACER */
-#endif /* CONFIG_DYNAMIC_FTRACE */
 #endif /* CONFIG_DYNAMIC_FTRACE_WITH_REGS */
 
 ENTRY(ftrace_stub)
-- 
2.11.0


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Re: [PATCH] arm64: ftrace: fix ifdeffery

[Catalin Marinas]

On Fri, Dec 06, 2019 at 01:01:29PM +0000, Mark Rutland wrote:
> When I tweaked the ftrace entry assembly in commit:
> 
>   3b23e4991fb66f6d ("arm64: implement ftrace with regs")
> 
> ... my ifdeffery tweaks left ftrace_graph_caller undefined for
> CONFIG_DYNAMIC_FTRACE && CONFIG_FUNCTION_GRAPH_TRACER when ftrace is
> based on mcount.
> 
> The kbuild test robot reported that this issue is detected at link time:
> 
> | arch/arm64/kernel/entry-ftrace.o: In function `skip_ftrace_call':
> | arch/arm64/kernel/entry-ftrace.S:238: undefined reference to `ftrace_graph_caller'
> | arch/arm64/kernel/entry-ftrace.S:238:(.text+0x3c): relocation truncated to fit: R_AARCH64_CONDBR19 against undefined symbol
> | `ftrace_graph_caller'
> | arch/arm64/kernel/entry-ftrace.S:243: undefined reference to `ftrace_graph_caller'
> | arch/arm64/kernel/entry-ftrace.S:243:(.text+0x54): relocation truncated to fit: R_AARCH64_CONDBR19 against undefined symbol
> | `ftrace_graph_caller'
> 
> This patch fixes the ifdeffery so that the mcount version of
> ftrace_graph_caller doesn't depend on CONFIG_DYNAMIC_FTRACE. At the same
> time, a redundant #else is removed from the ifdeffery for the
> patchable-function-entry version of ftrace_graph_caller.
> 
> Fixes: 3b23e4991fb66f6d ("arm64: implement ftrace with regs")
> Reported-by: kbuild test robot <lkp@intel.com>
> Signed-off-by: Mark Rutland <mark.rutland@arm.com>
> Cc: Amit Daniel Kachhap <amit.kachhap@arm.com>
> Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
> Cc: Catalin Marinas <catalin.marinas@arm.com>
> Cc: Mark Rutland <mark.rutland@arm.com>
> Cc: Torsten Duwe <duwe@lst.de>
> Cc: Will Deacon <will@kernel.org>

Queued for 5.5-rc1. Thanks.

-- 
Catalin

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