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 dependent on GCC.

Suggested-by: Arnd Bergmann <a...@arndb.de>
Signed-off-by: Stefan Agner <ste...@agner.ch>
---
 arch/arm/Kconfig.debug | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/arm/Kconfig.debug b/arch/arm/Kconfig.debug
index 693f84392f1b..cb65cf67dfa2 100644
--- a/arch/arm/Kconfig.debug
+++ b/arch/arm/Kconfig.debug
@@ -54,7 +54,7 @@ config DEBUG_WX
 # n, but then RMK will have to kill you ;).
 config FRAME_POINTER
        bool
-       depends on !THUMB2_KERNEL
+       depends on !THUMB2_KERNEL && CC_IS_GCC
        default y if !ARM_UNWIND || FUNCTION_GRAPH_TRACER
        help
          If you say N here, the resulting kernel will be slightly smaller and
-- 
2.18.0

Reply via email to