Commit 7563dc64 authored by Tony Breeds's avatar Tony Breeds Committed by Paul Mackerras
Browse files

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: default avatarTony Breeds <tony@bakeyournoodle.com>
Signed-off-by: default avatarPaul Mackerras <paulus@samba.org>
parent 303996da

arch/powerpc/Makefile

+5 −0
Original line number Original line Diff line number Diff line
@@ -116,6 +116,11 @@ ifeq ($(CONFIG_6xx),y) 
KBUILD_CFLAGS		+= -mcpu=powerpc

KBUILD_CFLAGS		+= -mcpu=powerpc

endif

endif





# Work around a gcc code-gen bug with -fno-omit-frame-pointer.

ifeq ($(CONFIG_FTRACE),y)

KBUILD_CFLAGS		+= -mno-sched-epilog

endif



cpu-as-$(CONFIG_4xx)		+= -Wa,-m405

cpu-as-$(CONFIG_4xx)		+= -Wa,-m405

cpu-as-$(CONFIG_6xx)		+= -Wa,-maltivec

cpu-as-$(CONFIG_6xx)		+= -Wa,-maltivec

cpu-as-$(CONFIG_POWER4)		+= -Wa,-maltivec

cpu-as-$(CONFIG_POWER4)		+= -Wa,-maltivec

arch/powerpc/kernel/Makefile

+4 −3
Original line number Original line Diff line number Diff line
@@ -14,12 +14,13 @@ endif 




ifdef CONFIG_FTRACE

ifdef CONFIG_FTRACE

# Do not trace early boot code

# Do not trace early boot code

CFLAGS_REMOVE_cputable.o = -pg

CFLAGS_REMOVE_cputable.o = -pg -mno-sched-epilog

CFLAGS_REMOVE_prom_init.o = -pg

CFLAGS_REMOVE_prom_init.o = -pg -mno-sched-epilog

CFLAGS_REMOVE_btext.o = -pg -mno-sched-epilog





ifdef CONFIG_DYNAMIC_FTRACE

ifdef CONFIG_DYNAMIC_FTRACE

# dynamic ftrace setup.

# dynamic ftrace setup.

CFLAGS_REMOVE_ftrace.o = -pg

CFLAGS_REMOVE_ftrace.o = -pg -mno-sched-epilog

endif

endif





endif

endif

arch/powerpc/platforms/powermac/Makefile

+1 −1
Original line number Original line Diff line number Diff line
@@ -2,7 +2,7 @@ CFLAGS_bootx_init.o += -fPIC 




ifdef CONFIG_FTRACE

ifdef CONFIG_FTRACE

# Do not trace early boot code

# Do not trace early boot code

CFLAGS_REMOVE_bootx_init.o = -pg

CFLAGS_REMOVE_bootx_init.o = -pg -mno-sched-epilog

endif

endif





obj-y				+= pic.o setup.o time.o feature.o pci.o \

obj-y				+= pic.o setup.o time.o feature.o pci.o \

lib/Kconfig.debug

+3 −3
Original line number Original line Diff line number Diff line
@@ -394,7 +394,7 @@ config LOCKDEP 
	bool

	bool

	depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT

	depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT

	select STACKTRACE

	select STACKTRACE

	select FRAME_POINTER if !X86 && !MIPS

	select FRAME_POINTER if !X86 && !MIPS && !PPC

	select KALLSYMS

	select KALLSYMS

	select KALLSYMS_ALL

	select KALLSYMS_ALL
@@ -676,13 +676,13 @@ config FAULT_INJECTION_STACKTRACE_FILTER 
	depends on FAULT_INJECTION_DEBUG_FS && STACKTRACE_SUPPORT

	depends on FAULT_INJECTION_DEBUG_FS && STACKTRACE_SUPPORT

	depends on !X86_64

	depends on !X86_64

	select STACKTRACE

	select STACKTRACE

	select FRAME_POINTER

	select FRAME_POINTER if !PPC

	help

	help

	  Provide stacktrace filter for fault-injection capabilities

	  Provide stacktrace filter for fault-injection capabilities





config LATENCYTOP

config LATENCYTOP

	bool "Latency measuring infrastructure"

	bool "Latency measuring infrastructure"

	select FRAME_POINTER if !MIPS

	select FRAME_POINTER if !MIPS && !PPC

	select KALLSYMS

	select KALLSYMS

	select KALLSYMS_ALL

	select KALLSYMS_ALL

	select STACKTRACE

	select STACKTRACE

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