powerpc: Work around gcc's -fno-omit-frame-pointer bug

This bug is causing random crashes
(http://bugzilla.kernel.org/show_bug.cgi?id=11414).

-fno-omit-frame-pointer is only needed on powerpc when -pg is also
supplied, and there is a gcc bug that causes incorrect code generation
on 32-bit powerpc when -fno-omit-frame-pointer is used---it uses stack
locations below the stack pointer, which is not allowed by the ABI
because those locations can and sometimes do get corrupted by an
interrupt.

This ensures that CONFIG_FRAME_POINTER is only selected by ftrace.
When CONFIG_FTRACE is enabled we also pass -mno-sched-epilog to work
around the gcc codegen bug.

Patch based on work by:
	Andreas Schwab <schwab@suse.de>
	Segher Boessenkool <segher@kernel.crashing.org>

Signed-off-by: Tony Breeds <tony@bakeyournoodle.com>
Signed-off-by: Paul Mackerras <paulus@samba.org>

1 files changed, 3 insertions, 3 deletions

diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
index 8b5a7d304a5f..0b504814e378 100644
--- a/lib/Kconfig.debug
+++ b/lib/Kconfig.debug
@@ -394,7 +394,7 @@ config LOCKDEP
         bool
         depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
         select STACKTRACE
-        select FRAME_POINTER if !X86 && !MIPS
+        select FRAME_POINTER if !X86 && !MIPS && !PPC
         select KALLSYMS
         select KALLSYMS_ALL
 
@@ -676,13 +676,13 @@ config FAULT_INJECTION_STACKTRACE_FILTER
         depends on FAULT_INJECTION_DEBUG_FS && STACKTRACE_SUPPORT
         depends on !X86_64
         select STACKTRACE
-        select FRAME_POINTER
+        select FRAME_POINTER if !PPC
         help
           Provide stacktrace filter for fault-injection capabilities
 
 config LATENCYTOP
         bool "Latency measuring infrastructure"
-        select FRAME_POINTER if !MIPS
+        select FRAME_POINTER if !MIPS && !PPC
         select KALLSYMS
         select KALLSYMS_ALL
         select STACKTRACE