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>
diff --git a/arch/powerpc/kernel/Makefile b/arch/powerpc/kernel/Makefile
index 64f5948e..946daea 100644
--- a/arch/powerpc/kernel/Makefile
+++ b/arch/powerpc/kernel/Makefile
@@ -14,12 +14,13 @@
ifdef CONFIG_FTRACE
# Do not trace early boot code
-CFLAGS_REMOVE_cputable.o = -pg
-CFLAGS_REMOVE_prom_init.o = -pg
+CFLAGS_REMOVE_cputable.o = -pg -mno-sched-epilog
+CFLAGS_REMOVE_prom_init.o = -pg -mno-sched-epilog
+CFLAGS_REMOVE_btext.o = -pg -mno-sched-epilog
ifdef CONFIG_DYNAMIC_FTRACE
# dynamic ftrace setup.
-CFLAGS_REMOVE_ftrace.o = -pg
+CFLAGS_REMOVE_ftrace.o = -pg -mno-sched-epilog
endif
endif
