linux_dsm_epyc7002/arch/s390/kernel/Makefile
Martin Schwidefsky f19fbd5ed6 s390: introduce execute-trampolines for branches
Add CONFIG_EXPOLINE to enable the use of the new -mindirect-branch= and
-mfunction_return= compiler options to create a kernel fortified against
the specte v2 attack.

With CONFIG_EXPOLINE=y all indirect branches will be issued with an
execute type instruction. For z10 or newer the EXRL instruction will
be used, for older machines the EX instruction. The typical indirect
call

	basr	%r14,%r1

is replaced with a PC relative call to a new thunk

	brasl	%r14,__s390x_indirect_jump_r1

The thunk contains the EXRL/EX instruction to the indirect branch

__s390x_indirect_jump_r1:
	exrl	0,0f
	j	.
0:	br	%r1

The detour via the execute type instruction has a performance impact.
To get rid of the detour the new kernel parameter "nospectre_v2" and
"spectre_v2=[on,off,auto]" can be used. If the parameter is specified
the kernel and module code will be patched at runtime.

Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
2018-02-07 15:57:02 +01:00

93 lines
2.7 KiB
Makefile

# SPDX-License-Identifier: GPL-2.0
#
# Makefile for the linux kernel.
#
ifdef CONFIG_FUNCTION_TRACER
# Do not trace tracer code
CFLAGS_REMOVE_ftrace.o = $(CC_FLAGS_FTRACE)
# Do not trace early setup code
CFLAGS_REMOVE_als.o = $(CC_FLAGS_FTRACE)
CFLAGS_REMOVE_early.o = $(CC_FLAGS_FTRACE)
endif
GCOV_PROFILE_als.o := n
GCOV_PROFILE_early.o := n
KCOV_INSTRUMENT_als.o := n
KCOV_INSTRUMENT_early.o := n
UBSAN_SANITIZE_als.o := n
UBSAN_SANITIZE_early.o := n
#
# Use -march=z900 for als.c to be able to print an error
# message if the kernel is started on a machine which is too old
#
ifneq ($(CC_FLAGS_MARCH),-march=z900)
CFLAGS_REMOVE_als.o += $(CC_FLAGS_MARCH)
CFLAGS_REMOVE_als.o += $(CC_FLAGS_EXPOLINE)
CFLAGS_als.o += -march=z900
AFLAGS_REMOVE_head.o += $(CC_FLAGS_MARCH)
AFLAGS_head.o += -march=z900
endif
CFLAGS_als.o += -D__NO_FORTIFY
#
# Passing null pointers is ok for smp code, since we access the lowcore here.
#
CFLAGS_smp.o := -Wno-nonnull
#
# Disable tailcall optimizations for stack / callchain walking functions
# since this might generate broken code when accessing register 15 and
# passing its content to other functions.
#
CFLAGS_stacktrace.o += -fno-optimize-sibling-calls
CFLAGS_dumpstack.o += -fno-optimize-sibling-calls
#
# Pass UTS_MACHINE for user_regset definition
#
CFLAGS_ptrace.o += -DUTS_MACHINE='"$(UTS_MACHINE)"'
obj-y := traps.o time.o process.o base.o early.o setup.o idle.o vtime.o
obj-y += processor.o sys_s390.o ptrace.o signal.o cpcmd.o ebcdic.o nmi.o
obj-y += debug.o irq.o ipl.o dis.o diag.o vdso.o als.o
obj-y += sysinfo.o jump_label.o lgr.o os_info.o machine_kexec.o pgm_check.o
obj-y += runtime_instr.o cache.o fpu.o dumpstack.o guarded_storage.o sthyi.o
obj-y += entry.o reipl.o relocate_kernel.o kdebugfs.o alternative.o
extra-y += head.o head64.o vmlinux.lds
obj-$(CONFIG_EXPOLINE) += nospec-branch.o
CFLAGS_REMOVE_expoline.o += $(CC_FLAGS_EXPOLINE)
obj-$(CONFIG_MODULES) += module.o
obj-$(CONFIG_SMP) += smp.o
obj-$(CONFIG_SCHED_TOPOLOGY) += topology.o
obj-$(CONFIG_HIBERNATION) += suspend.o swsusp.o
obj-$(CONFIG_AUDIT) += audit.o
compat-obj-$(CONFIG_AUDIT) += compat_audit.o
obj-$(CONFIG_COMPAT) += compat_linux.o compat_signal.o
obj-$(CONFIG_COMPAT) += compat_wrapper.o $(compat-obj-y)
obj-$(CONFIG_EARLY_PRINTK) += early_printk.o
obj-$(CONFIG_STACKTRACE) += stacktrace.o
obj-$(CONFIG_KPROBES) += kprobes.o
obj-$(CONFIG_FUNCTION_TRACER) += mcount.o ftrace.o
obj-$(CONFIG_CRASH_DUMP) += crash_dump.o
obj-$(CONFIG_UPROBES) += uprobes.o
obj-$(CONFIG_PERF_EVENTS) += perf_event.o perf_cpum_cf.o perf_cpum_sf.o
obj-$(CONFIG_PERF_EVENTS) += perf_cpum_cf_events.o perf_regs.o
obj-$(CONFIG_TRACEPOINTS) += trace.o
# vdso
obj-y += vdso64/
obj-$(CONFIG_COMPAT) += vdso32/