Commit 50362162 authored by Russell King's avatar Russell King
Browse files

ARM: fix function graph tracer and unwinder dependencies 



Naresh Kamboju recently reported that the function-graph tracer crashes
on ARM. The function-graph tracer assumes that the kernel is built with
frame pointers.

We explicitly disabled the function-graph tracer when building Thumb2,
since the Thumb2 ABI doesn't have frame pointers.

We recently changed the way the unwinder method was selected, which
seems to have made it more likely that we can end up with the function-
graph tracer enabled but without the kernel built with frame pointers.

Fix up the function graph tracer dependencies so the option is not
available when we have no possibility of having frame pointers, and
adjust the dependencies on the unwinder option to hide the non-frame
pointer unwinder options if the function-graph tracer is enabled.

Reviewed-by: default avatarMasami Hiramatsu <mhiramat@kernel.org>
Tested-by: default avatarMasami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: default avatarRussell King <rmk+kernel@armlinux.org.uk>
parent 9e98c678

arch/arm/Kconfig

+1 −1
Original line number Diff line number Diff line
@@ -73,7 +73,7 @@ config ARM 
	select HAVE_EFFICIENT_UNALIGNED_ACCESS if (CPU_V6 || CPU_V6K || CPU_V7) && MMU

	select HAVE_EXIT_THREAD

	select HAVE_FTRACE_MCOUNT_RECORD if !XIP_KERNEL

	select HAVE_FUNCTION_GRAPH_TRACER if !THUMB2_KERNEL

	select HAVE_FUNCTION_GRAPH_TRACER if !THUMB2_KERNEL && !CC_IS_CLANG

	select HAVE_FUNCTION_TRACER if !XIP_KERNEL

	select HAVE_GCC_PLUGINS

	select HAVE_HW_BREAKPOINT if PERF_EVENTS && (CPU_V6 || CPU_V6K || CPU_V7)

arch/arm/Kconfig.debug

+3 −3
Original line number Diff line number Diff line
@@ -47,8 +47,8 @@ config DEBUG_WX 


choice

	prompt "Choose kernel unwinder"

	default UNWINDER_ARM if AEABI && !FUNCTION_GRAPH_TRACER

	default UNWINDER_FRAME_POINTER if !AEABI || FUNCTION_GRAPH_TRACER

	default UNWINDER_ARM if AEABI

	default UNWINDER_FRAME_POINTER if !AEABI

	help

	  This determines which method will be used for unwinding kernel stack

	  traces for panics, oopses, bugs, warnings, perf, /proc/<pid>/stack,
@@ -65,7 +65,7 @@ config UNWINDER_FRAME_POINTER 


config UNWINDER_ARM

	bool "ARM EABI stack unwinder"

	depends on AEABI

	depends on AEABI && !FUNCTION_GRAPH_TRACER

	select ARM_UNWIND

	help

	  This option enables stack unwinding support in the kernel

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