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

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
......@@ -116,6 +116,11 @@ ifeq ($(CONFIG_6xx),y)
KBUILD_CFLAGS += -mcpu=powerpc
endif
# Work around a gcc code-gen bug with -fno-omit-frame-pointer.
ifeq ($(CONFIG_FTRACE),y)
KBUILD_CFLAGS += -mno-sched-epilog
endif
cpu-as-$(CONFIG_4xx) += -Wa,-m405
cpu-as-$(CONFIG_6xx) += -Wa,-maltivec
cpu-as-$(CONFIG_POWER4) += -Wa,-maltivec
......
......@@ -14,12 +14,13 @@ endif
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
......
......@@ -2,7 +2,7 @@ CFLAGS_bootx_init.o += -fPIC
ifdef CONFIG_FTRACE
# Do not trace early boot code
CFLAGS_REMOVE_bootx_init.o = -pg
CFLAGS_REMOVE_bootx_init.o = -pg -mno-sched-epilog
endif
obj-y += pic.o setup.o time.o feature.o pci.o \
......
......@@ -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
......
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