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authorStefan Agner <stefan@agner.ch>2018-10-01 00:02:33 +0200
committerRussell King <rmk+kernel@armlinux.org.uk>2018-10-04 15:48:58 +0200
commitf9b58e8c7d031b0daa5c9a9ee27f5a4028ba53ac (patch)
treeeb472871b0363395c125455e289e5c67e830f9e5 /arch/arm/Kconfig.debug
parentARM: 8798/1: remove unnecessary KBUILD_SRC ifeq conditional (diff)
downloadlinux-f9b58e8c7d031b0daa5c9a9ee27f5a4028ba53ac.tar.xz
linux-f9b58e8c7d031b0daa5c9a9ee27f5a4028ba53ac.zip
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: Arnd Bergmann <arnd@arndb.de> Signed-off-by: Stefan Agner <stefan@agner.ch> Reviewed-by: Arnd Bergmann <arnd@arndb.de> Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
Diffstat (limited to 'arch/arm/Kconfig.debug')
-rw-r--r--arch/arm/Kconfig.debug44
1 files changed, 28 insertions, 16 deletions
diff --git a/arch/arm/Kconfig.debug b/arch/arm/Kconfig.debug
index c155b11e2e87..a810fa8ba404 100644
--- a/arch/arm/Kconfig.debug
+++ b/arch/arm/Kconfig.debug
@@ -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
+ 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 UNWINDER_FRAME_POINTER
+ bool "Frame pointer unwinder"
+ depends on !THUMB2_KERNEL && !CC_IS_CLANG
+ select ARCH_WANT_FRAME_POINTERS
+ select FRAME_POINTER
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 option enables the frame pointer unwinder for unwinding
+ kernel stack traces.
-config ARM_UNWIND
- bool "Enable stack unwinding support (EXPERIMENTAL)"
+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"