Files
linux/arch/s390/boot/Makefile
Heiko Carstens f5730d44e0 s390: Add stackprotector support
Stackprotector support was previously unavailable on s390 because by
default compilers generate code which is not suitable for the kernel:
the canary value is accessed via thread local storage, where the address
of thread local storage is within access registers 0 and 1.

Using those registers also for the kernel would come with a significant
performance impact and more complicated kernel entry/exit code, since
access registers contents would have to be exchanged on every kernel entry
and exit.

With the upcoming gcc 16 release new compiler options will become available
which allow to generate code suitable for the kernel. [1]

Compiler option -mstack-protector-guard=global instructs gcc to generate
stackprotector code that refers to a global stackprotector canary value via
symbol __stack_chk_guard. Access to this value is guaranteed to occur via
larl and lgrl instructions.

Furthermore, compiler option -mstack-protector-guard-record generates a
section containing all code addresses that reference the canary value.

To allow for per task canary values the instructions which load the address
of __stack_chk_guard are patched so they access a lowcore field instead: a
per task canary value is available within the task_struct of each task, and
is written to the per-cpu lowcore location on each context switch.

Also add sanity checks and debugging option to be consistent with other
kernel code patching mechanisms.

Full debugging output can be enabled with the following kernel command line
options:

debug_stackprotector
bootdebug
ignore_loglevel
earlyprintk
dyndbg="file stackprotector.c +p"

Example debug output:

stackprot: 0000021e402d4eda: c010005a9ae3 -> c01f00070240

where "<insn address>: <old insn> -> <new insn>".

[1] gcc commit 0cd1f03939d5 ("s390: Support global stack protector")

Reviewed-by: Sven Schnelle <svens@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
2025-11-24 11:45:21 +01:00

131 lines
4.8 KiB
Makefile

# SPDX-License-Identifier: GPL-2.0
#
# Makefile for the linux s390-specific parts of the memory manager.
#
# Tooling runtimes are unavailable and cannot be linked for early boot code
KCOV_INSTRUMENT := n
GCOV_PROFILE := n
UBSAN_SANITIZE := n
KASAN_SANITIZE := n
KCSAN_SANITIZE := n
KMSAN_SANITIZE := n
#
# Use minimum architecture level so it is possible to print an error
# message if the kernel is started on a machine which is too old
#
CC_FLAGS_MARCH_MINIMUM := -march=z10
KBUILD_AFLAGS := $(filter-out $(CC_FLAGS_MARCH),$(KBUILD_AFLAGS_DECOMPRESSOR))
KBUILD_CFLAGS := $(filter-out $(CC_FLAGS_MARCH),$(KBUILD_CFLAGS_DECOMPRESSOR))
KBUILD_AFLAGS += $(CC_FLAGS_MARCH_MINIMUM) -D__DISABLE_EXPORTS
KBUILD_CFLAGS += $(CC_FLAGS_MARCH_MINIMUM) -D__DISABLE_EXPORTS
CFLAGS_sclp_early_core.o += -I$(srctree)/drivers/s390/char
obj-y := head.o als.o startup.o physmem_info.o ipl_parm.o ipl_report.o vmem.o
obj-y += string.o ebcdic.o sclp_early_core.o mem.o ipl_vmparm.o cmdline.o
obj-y += version.o pgm_check.o ctype.o ipl_data.o relocs.o alternative.o
obj-y += uv.o printk.o trampoline.o
obj-$(CONFIG_RANDOMIZE_BASE) += kaslr.o
obj-y += $(if $(CONFIG_KERNEL_UNCOMPRESSED),,decompressor.o) info.o
obj-$(CONFIG_KERNEL_ZSTD) += clz_ctz.o
obj-$(CONFIG_KMSAN) += kmsan.o
obj-$(CONFIG_STACKPROTECTOR) += stackprotector.o
obj-all := $(obj-y) piggy.o syms.o
targets := bzImage section_cmp.boot.data section_cmp.boot.preserved.data $(obj-y)
targets += vmlinux.lds vmlinux vmlinux.bin vmlinux.bin.gz vmlinux.bin.bz2
targets += vmlinux.bin.xz vmlinux.bin.lzma vmlinux.bin.lzo vmlinux.bin.lz4
targets += vmlinux.bin.zst info.bin syms.bin vmlinux.syms $(obj-all)
targets += relocs.S
OBJECTS := $(addprefix $(obj)/,$(obj-y))
OBJECTS_ALL := $(addprefix $(obj)/,$(obj-all))
clean-files += vmlinux.map
quiet_cmd_section_cmp = SECTCMP $*
define cmd_section_cmp
s1=`$(OBJDUMP) -t "$<" | grep "\s$*\s\+" | sort | \
sed -n "/0000000000000000/! s/.*\s$*\s\+//p" | sha256sum`; \
s2=`$(OBJDUMP) -t "$(word 2,$^)" | grep "\s$*\s\+" | sort | \
sed -n "/0000000000000000/! s/.*\s$*\s\+//p" | sha256sum`; \
if [ "$$s1" != "$$s2" ]; then \
echo "error: section $* differs between $< and $(word 2,$^)" >&2; \
exit 1; \
fi; \
touch $@
endef
$(obj)/bzImage: $(obj)/vmlinux $(obj)/section_cmp.boot.data $(obj)/section_cmp.boot.preserved.data FORCE
$(call if_changed,objcopy)
$(obj)/section_cmp%: vmlinux $(obj)/vmlinux FORCE
$(call if_changed,section_cmp)
LDFLAGS_vmlinux-$(CONFIG_LD_ORPHAN_WARN) := --orphan-handling=$(CONFIG_LD_ORPHAN_WARN_LEVEL)
LDFLAGS_vmlinux := $(LDFLAGS_vmlinux-y) --oformat $(LD_BFD) -e startup $(if $(CONFIG_VMLINUX_MAP),-Map=$(obj)/vmlinux.map) --build-id=sha1 -T
$(obj)/vmlinux: $(obj)/vmlinux.lds $(OBJECTS_ALL) FORCE
$(call if_changed,ld)
LDFLAGS_vmlinux.syms := $(LDFLAGS_vmlinux-y) --oformat $(LD_BFD) -e startup -T
$(obj)/vmlinux.syms: $(obj)/vmlinux.lds $(OBJECTS) FORCE
$(call if_changed,ld)
quiet_cmd_dumpsyms = DUMPSYMS $<
define cmd_dumpsyms
$(NM) -n -S --format=bsd "$<" | sed -nE 's/^0*([0-9a-fA-F]+) 0*([0-9a-fA-F]+) [tT] ([^ ]*)$$/\1 \2 \3/p' | tr '\n' '\0' > "$@"
endef
$(obj)/syms.bin: $(obj)/vmlinux.syms FORCE
$(call if_changed,dumpsyms)
OBJCOPYFLAGS_syms.o := -I binary -O elf64-s390 -B s390:64-bit --rename-section .data=.decompressor.syms
$(obj)/syms.o: $(obj)/syms.bin FORCE
$(call if_changed,objcopy)
OBJCOPYFLAGS_info.bin := -O binary --only-section=.vmlinux.info --set-section-flags .vmlinux.info=alloc,load
$(obj)/info.bin: vmlinux FORCE
$(call if_changed,objcopy)
OBJCOPYFLAGS_info.o := -I binary -O elf64-s390 -B s390:64-bit --rename-section .data=.vmlinux.info
$(obj)/info.o: $(obj)/info.bin FORCE
$(call if_changed,objcopy)
OBJCOPYFLAGS_vmlinux.bin := -O binary --remove-section=.comment --remove-section=.vmlinux.info -S
$(obj)/vmlinux.bin: vmlinux FORCE
$(call if_changed,objcopy)
# relocs.S is created by the vmlinux postlink step.
$(obj)/relocs.S: vmlinux
@true
suffix-$(CONFIG_KERNEL_GZIP) := .gz
suffix-$(CONFIG_KERNEL_BZIP2) := .bz2
suffix-$(CONFIG_KERNEL_LZ4) := .lz4
suffix-$(CONFIG_KERNEL_LZMA) := .lzma
suffix-$(CONFIG_KERNEL_LZO) := .lzo
suffix-$(CONFIG_KERNEL_XZ) := .xz
suffix-$(CONFIG_KERNEL_ZSTD) := .zst
$(obj)/vmlinux.bin.gz: $(obj)/vmlinux.bin FORCE
$(call if_changed,gzip)
$(obj)/vmlinux.bin.bz2: $(obj)/vmlinux.bin FORCE
$(call if_changed,bzip2_with_size)
$(obj)/vmlinux.bin.lz4: $(obj)/vmlinux.bin FORCE
$(call if_changed,lz4_with_size)
$(obj)/vmlinux.bin.lzma: $(obj)/vmlinux.bin FORCE
$(call if_changed,lzma_with_size)
$(obj)/vmlinux.bin.lzo: $(obj)/vmlinux.bin FORCE
$(call if_changed,lzo_with_size)
$(obj)/vmlinux.bin.xz: $(obj)/vmlinux.bin FORCE
$(call if_changed,xzkern_with_size)
$(obj)/vmlinux.bin.zst: $(obj)/vmlinux.bin FORCE
$(call if_changed,zstd22_with_size)
OBJCOPYFLAGS_piggy.o := -I binary -O elf64-s390 -B s390:64-bit --rename-section .data=.vmlinux.bin.compressed
$(obj)/piggy.o: $(obj)/vmlinux.bin$(suffix-y) FORCE
$(call if_changed,objcopy)