Commit f9b58e8c authored by Stefan Agner's avatar Stefan Agner Committed by Russell King
Browse files

ARM: 8800/1: use choice for kernel unwinders 



While in theory multiple unwinders could be compiled in, it does
not make sense in practise. Use a choice to make the unwinder
selection mutually exclusive and mandatory.

Already before this commit it has not been possible to deselect
FRAME_POINTER. Remove the obsolete comment.

Furthermore, to produce a meaningful backtrace with FRAME_POINTER
enabled the kernel needs a specific function prologue:
    mov    ip, sp
    stmfd    sp!, {fp, ip, lr, pc}
    sub    fp, ip, #4

To get to the required prologue gcc uses apcs and no-sched-prolog.
This compiler options are not available on clang, and clang is not
able to generate the required prologue. Make the FRAME_POINTER
config symbol depending on !clang.

Suggested-by: default avatarArnd Bergmann <arnd@arndb.de>
Signed-off-by: default avatarStefan Agner <stefan@agner.ch>
Reviewed-by: default avatarArnd Bergmann <arnd@arndb.de>
Signed-off-by: default avatarRussell King <rmk+kernel@armlinux.org.uk>
parent 3f539501

arch/arm/Kconfig.debug

+28 −16
Original line number Diff line number Diff line
@@ -45,30 +45,42 @@ config DEBUG_WX 


		If in doubt, say "Y".



# RMK wants arm kernels compiled with frame pointers or stack unwinding.

# If you know what you are doing and are willing to live without stack

# traces, you can get a slightly smaller kernel by setting this option to

# n, but then RMK will have to kill you ;).

config FRAME_POINTER

	bool

	depends on !THUMB2_KERNEL

	default y if !ARM_UNWIND || FUNCTION_GRAPH_TRACER

choice

	prompt "Choose kernel unwinder"

	default UNWINDER_ARM if AEABI && !FUNCTION_GRAPH_TRACER

	default UNWINDER_FRAME_POINTER if !AEABI || FUNCTION_GRAPH_TRACER

	help

	  If you say N here, the resulting kernel will be slightly smaller and

	  faster. However, if neither FRAME_POINTER nor ARM_UNWIND are enabled,

	  when a problem occurs with the kernel, the information that is

	  reported is severely limited.

	  This determines which method will be used for unwinding kernel stack

	  traces for panics, oopses, bugs, warnings, perf, /proc/<pid>/stack,

	  livepatch, lockdep, and more.



config ARM_UNWIND

	bool "Enable stack unwinding support (EXPERIMENTAL)"

config UNWINDER_FRAME_POINTER

	bool "Frame pointer unwinder"

	depends on !THUMB2_KERNEL && !CC_IS_CLANG

	select ARCH_WANT_FRAME_POINTERS

	select FRAME_POINTER

	help

	  This option enables the frame pointer unwinder for unwinding

	  kernel stack traces.



config UNWINDER_ARM

	bool "ARM EABI stack unwinder"

	depends on AEABI

	default y

	select ARM_UNWIND

	help

	  This option enables stack unwinding support in the kernel

	  using the information automatically generated by the

	  compiler. The resulting kernel image is slightly bigger but

	  the performance is not affected. Currently, this feature

	  only works with EABI compilers. If unsure say Y.

	  only works with EABI compilers.



endchoice



config ARM_UNWIND

	bool



config FRAME_POINTER

	bool



config DEBUG_USER

	bool "Verbose user fault messages"

lib/Kconfig.debug

+3 −3
Original line number Diff line number Diff line
@@ -1179,7 +1179,7 @@ config LOCKDEP 
	bool

	depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT

	select STACKTRACE

	select FRAME_POINTER if !MIPS && !PPC && !ARM_UNWIND && !S390 && !MICROBLAZE && !ARC && !X86

	select FRAME_POINTER if !MIPS && !PPC && !ARM && !S390 && !MICROBLAZE && !ARC && !X86

	select KALLSYMS

	select KALLSYMS_ALL
@@ -1590,7 +1590,7 @@ config FAULT_INJECTION_STACKTRACE_FILTER 
	depends on FAULT_INJECTION_DEBUG_FS && STACKTRACE_SUPPORT

	depends on !X86_64

	select STACKTRACE

	select FRAME_POINTER if !MIPS && !PPC && !S390 && !MICROBLAZE && !ARM_UNWIND && !ARC && !X86

	select FRAME_POINTER if !MIPS && !PPC && !S390 && !MICROBLAZE && !ARM && !ARC && !X86

	help

	  Provide stacktrace filter for fault-injection capabilities
@@ -1599,7 +1599,7 @@ config LATENCYTOP 
	depends on DEBUG_KERNEL

	depends on STACKTRACE_SUPPORT

	depends on PROC_FS

	select FRAME_POINTER if !MIPS && !PPC && !S390 && !MICROBLAZE && !ARM_UNWIND && !ARC && !X86

	select FRAME_POINTER if !MIPS && !PPC && !S390 && !MICROBLAZE && !ARM && !ARC && !X86

	select KALLSYMS

	select KALLSYMS_ALL

	select STACKTRACE

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