Commit 42b01a55 authored by Vasily Gorbik's avatar Vasily Gorbik
Browse files

s390: always use the packed stack layout 



-mpacked-stack option has been supported by both minimum
gcc and clang versions for a while. With commit e2bc3e91
("scripts/min-tool-version.sh: Raise minimum clang version to 13.0.0
for s390") minimum clang version now also supports a combination
of flags -mpacked-stack -mbackchain -pg -mfentry and fulfills
all requirements to always enable the packed stack layout.

Reviewed-by: default avatarHeiko Carstens <hca@linux.ibm.com>
Signed-off-by: default avatarVasily Gorbik <gor@linux.ibm.com>
parent 9a4f03ad

arch/s390/Kconfig

+1 −15
Original line number Diff line number Diff line
@@ -155,7 +155,7 @@ config S390 
	select HAVE_DYNAMIC_FTRACE_WITH_ARGS

	select HAVE_DYNAMIC_FTRACE_WITH_DIRECT_CALLS

	select HAVE_DYNAMIC_FTRACE_WITH_REGS

	select HAVE_EBPF_JIT if PACK_STACK && HAVE_MARCH_Z196_FEATURES

	select HAVE_EBPF_JIT if HAVE_MARCH_Z196_FEATURES

	select HAVE_EFFICIENT_UNALIGNED_ACCESS

	select HAVE_FAST_GUP

	select HAVE_FENTRY
@@ -656,20 +656,6 @@ config MAX_PHYSMEM_BITS 
	  Increasing the number of bits also increases the kernel image size.

	  By default 46 bits (64TB) are supported.



config PACK_STACK

	def_bool y

	prompt "Pack kernel stack"

	help

	  This option enables the compiler option -mkernel-backchain if it

	  is available. If the option is available the compiler supports

	  the new stack layout which dramatically reduces the minimum stack

	  frame size. With an old compiler a non-leaf function needs a

	  minimum of 96 bytes on 31 bit and 160 bytes on 64 bit. With

	  -mkernel-backchain the minimum size drops to 16 byte on 31 bit

	  and 24 byte on 64 bit.



	  Say Y if you are unsure.



config CHECK_STACK

	def_bool y

	depends on !VMAP_STACK

arch/s390/Makefile

+2 −7
Original line number Diff line number Diff line
@@ -21,7 +21,7 @@ endif 
aflags_dwarf	:= -Wa,-gdwarf-2

KBUILD_AFLAGS_DECOMPRESSOR := $(CLANG_FLAGS) -m64 -D__ASSEMBLY__

KBUILD_AFLAGS_DECOMPRESSOR += $(if $(CONFIG_DEBUG_INFO),$(aflags_dwarf))

KBUILD_CFLAGS_DECOMPRESSOR := $(CLANG_FLAGS) -m64 -O2

KBUILD_CFLAGS_DECOMPRESSOR := $(CLANG_FLAGS) -m64 -O2 -mpacked-stack

KBUILD_CFLAGS_DECOMPRESSOR += -DDISABLE_BRANCH_PROFILING -D__NO_FORTIFY

KBUILD_CFLAGS_DECOMPRESSOR += -fno-delete-null-pointer-checks -msoft-float -mbackchain

KBUILD_CFLAGS_DECOMPRESSOR += -fno-asynchronous-unwind-tables
@@ -68,11 +68,6 @@ cflags-y += -Wa,-I$(srctree)/arch/$(ARCH)/include 
#

cflags-$(CONFIG_FRAME_POINTER) += -fno-optimize-sibling-calls



ifneq ($(call cc-option,-mpacked-stack -mbackchain -msoft-float),)

cflags-$(CONFIG_PACK_STACK)  += -mpacked-stack -D__PACK_STACK

aflags-$(CONFIG_PACK_STACK)  += -D__PACK_STACK

endif



KBUILD_AFLAGS_DECOMPRESSOR += $(aflags-y)

KBUILD_CFLAGS_DECOMPRESSOR += $(cflags-y)
@@ -111,7 +106,7 @@ endif 
# Test CFI features of binutils

cfi := $(call as-instr,.cfi_startproc\n.cfi_val_offset 15$(comma)-160\n.cfi_endproc,-DCONFIG_AS_CFI_VAL_OFFSET=1)



KBUILD_CFLAGS	+= -mbackchain -msoft-float $(cflags-y)

KBUILD_CFLAGS	+= -mpacked-stack -mbackchain -msoft-float $(cflags-y)

KBUILD_CFLAGS	+= -pipe -Wno-sign-compare

KBUILD_CFLAGS	+= -fno-asynchronous-unwind-tables $(cfi)

KBUILD_AFLAGS	+= $(aflags-y) $(cfi)

arch/s390/include/asm/stacktrace.h

+1 −9
Original line number Diff line number Diff line
@@ -36,22 +36,14 @@ static inline bool on_stack(struct stack_info *info, 


/*

 * Stack layout of a C stack frame.

 * Kernel uses the packed stack layout (-mpacked-stack).

 */

#ifndef __PACK_STACK

struct stack_frame {

	unsigned long back_chain;

	unsigned long empty1[5];

	unsigned long gprs[10];

	unsigned int  empty2[8];

};

#else

struct stack_frame {

	unsigned long empty1[5];

	unsigned int  empty2[8];

	unsigned long gprs[10];

	unsigned long back_chain;

};

#endif



/*

 * Unlike current_stack_pointer() which simply returns current value of %r15

arch/s390/kernel/mcount.S

+1 −5
Original line number Diff line number Diff line
@@ -26,12 +26,8 @@ ENDPROC(ftrace_stub) 
#define STACK_PTREGS_PSW	(STACK_PTREGS + __PT_PSW)

#define STACK_PTREGS_ORIG_GPR2	(STACK_PTREGS + __PT_ORIG_GPR2)

#define STACK_PTREGS_FLAGS	(STACK_PTREGS + __PT_FLAGS)

#ifdef __PACK_STACK

/* allocate just enough for r14, r15 and backchain */

/* packed stack: allocate just enough for r14, r15 and backchain */

#define TRACED_FUNC_FRAME_SIZE	24

#else

#define TRACED_FUNC_FRAME_SIZE	STACK_FRAME_OVERHEAD

#endif



	.macro	ftrace_regs_entry, allregs=0

	stg	%r14,(__SF_GPRS+8*8)(%r15)	# save traced function caller

arch/s390/net/bpf_jit_comp.c

+0 −1
Original line number Diff line number Diff line
@@ -7,7 +7,6 @@ 
 *  - HAVE_MARCH_Z196_FEATURES: laal, laalg

 *  - HAVE_MARCH_Z10_FEATURES: msfi, cgrj, clgrj

 *  - HAVE_MARCH_Z9_109_FEATURES: alfi, llilf, clfi, oilf, nilf

 *  - PACK_STACK

 *  - 64BIT

 *

 * Copyright IBM Corp. 2012,2015