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s390: always use the packed stack layout

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-mpacked-stack option has been supported by both minimum
gcc and clang versions for a while. With commit e2bc3e91d9
("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: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
This commit is contained in:
Vasily Gorbik 2022-01-29 00:34:13 +01:00
parent 9a4f03ad6d
commit 42b01a553a
5 changed files with 5 additions and 37 deletions
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16
arch/s390/Kconfig
View File

@ -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

9
arch/s390/Makefile
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@ -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)

10
arch/s390/include/asm/stacktrace.h
View File

@ -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

6
arch/s390/kernel/mcount.S
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@ -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

1
arch/s390/net/bpf_jit_comp.c
View File

@ -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