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Masahiro Yamada 7f7f6f7ad6 Makefile: remove redundant tool coverage variables

Now Kbuild provides reasonable defaults for objtool, sanitizers, and
profilers.

Remove redundant variables.

Note:

This commit changes the coverage for some objects:

  - include arch/mips/vdso/vdso-image.o into UBSAN, GCOV, KCOV
  - include arch/sparc/vdso/vdso-image-*.o into UBSAN
  - include arch/sparc/vdso/vma.o into UBSAN
  - include arch/x86/entry/vdso/extable.o into KASAN, KCSAN, UBSAN, GCOV, KCOV
  - include arch/x86/entry/vdso/vdso-image-*.o into KASAN, KCSAN, UBSAN, GCOV, KCOV
  - include arch/x86/entry/vdso/vdso32-setup.o into KASAN, KCSAN, UBSAN, GCOV, KCOV
  - include arch/x86/entry/vdso/vma.o into GCOV, KCOV
  - include arch/x86/um/vdso/vma.o into KASAN, GCOV, KCOV

I believe these are positive effects because all of them are kernel
space objects.

Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Reviewed-by: Kees Cook <keescook@chromium.org>
Tested-by: Roberto Sassu <roberto.sassu@huawei.com>

2024-05-14 23:35:48 +09:00

4.4 KiB

Raw Blame History

SPDX-License-Identifier: GPL-2.0

Makefile for Kernel-based Virtual Machine module, HYP/nVHE part

asflags-y := -D__KVM_NVHE_HYPERVISOR__ -D__DISABLE_EXPORTS

Tracepoint and MMIO logging symbols should not be visible at nVHE KVM as

there is no way to execute them and any such MMIO access from nVHE KVM

will explode instantly (Words of Marc Zyngier). So introduce a generic flag

DISABLE_TRACE_MMIO to disable MMIO tracing for nVHE KVM.

ccflags-y := -D__KVM_NVHE_HYPERVISOR__ -D__DISABLE_EXPORTS -D__DISABLE_TRACE_MMIO__ ccflags-y += -fno-stack-protector
-DDISABLE_BRANCH_PROFILING
$(DISABLE_STACKLEAK_PLUGIN)

hostprogs := gen-hyprel HOST_EXTRACFLAGS += -I$(objtree)/include

lib-objs := clear_page.o copy_page.o memcpy.o memset.o lib-objs := $(addprefix ../../../lib/, $(lib-objs))

hyp-obj-y := timer-sr.o sysreg-sr.o debug-sr.o switch.o tlb.o hyp-init.o host.o
hyp-main.o hyp-smp.o psci-relay.o early_alloc.o page_alloc.o
cache.o setup.o mm.o mem_protect.o sys_regs.o pkvm.o stacktrace.o ffa.o hyp-obj-y += ../vgic-v3-sr.o ../aarch32.o ../vgic-v2-cpuif-proxy.o ../entry.o
../fpsimd.o ../hyp-entry.o ../exception.o ../pgtable.o hyp-obj-$(CONFIG_LIST_HARDENED) += list_debug.o hyp-obj-y += $(lib-objs)

Build rules for compiling nVHE hyp code

Output of this folder is `kvm_nvhe.o`, a partially linked object

file containing all nVHE hyp code and data.

hyp-obj := $(patsubst %.o,%.nvhe.o,$(hyp-obj-y)) obj-y := kvm_nvhe.o targets += $(hyp-obj) kvm_nvhe.tmp.o kvm_nvhe.rel.o hyp.lds hyp-reloc.S hyp-reloc.o

1) Compile all source files to `.nvhe.o` object files. The file extension

avoids file name clashes for files shared with VHE.

$(obj)/%.nvhe.o: $(src)/%.c FORCE $(call if_changed_rule,cc_o_c) $(obj)/%.nvhe.o: $(src)/%.S FORCE $(call if_changed_rule,as_o_S)

2) Compile linker script.

$(obj)/hyp.lds: $(src)/hyp.lds.S FORCE $(call if_changed_dep,cpp_lds_S)

3) Partially link all '.nvhe.o' files and apply the linker script.

Prefixes names of ELF sections with '.hyp', eg. '.hyp.text'.

Note: The following rule assumes that the 'ld' rule puts LDFLAGS before

the list of dependencies to form '-T $(obj)/hyp.lds'. This is to

keep the dependency on the target while avoiding an error from

GNU ld if the linker script is passed to it twice.

LDFLAGS_kvm_nvhe.tmp.o := -r -T $(obj)/kvm_nvhe.tmp.o: $(obj)/hyp.lds $(addprefix $(obj)/,$(hyp-obj)) FORCE $(call if_changed,ld)

4) Generate list of hyp code/data positions that need to be relocated at

runtime. Because the hypervisor is part of the kernel binary, relocations

produce a kernel VA. We enumerate relocations targeting hyp at build time

and convert the kernel VAs at those positions to hyp VAs.

$(obj)/hyp-reloc.S: $(obj)/kvm_nvhe.tmp.o $(obj)/gen-hyprel FORCE $(call if_changed,hyprel)

5) Compile hyp-reloc.S and link it into the existing partially linked object.

The object file now contains a section with pointers to hyp positions that

will contain kernel VAs at runtime. These pointers have relocations on them

so that they get updated as the hyp object is linked into `vmlinux`.

LDFLAGS_kvm_nvhe.rel.o := -r $(obj)/kvm_nvhe.rel.o: $(obj)/kvm_nvhe.tmp.o $(obj)/hyp-reloc.o FORCE $(call if_changed,ld)

6) Produce the final 'kvm_nvhe.o', ready to be linked into 'vmlinux'.

Prefixes names of ELF symbols with '_kvm_nvhe'.

$(obj)/kvm_nvhe.o: $(obj)/kvm_nvhe.rel.o FORCE $(call if_changed,hypcopy)

The HYPREL command calls `gen-hyprel` to generate an assembly file with

a list of relocations targeting hyp code/data.

quiet_cmd_hyprel = HYPREL $@ cmd_hyprel = $(obj)/gen-hyprel $< > $@

The HYPCOPY command uses `objcopy` to prefix all ELF symbol names

to avoid clashes with VHE code/data.

quiet_cmd_hypcopy = HYPCOPY $@ cmd_hypcopy = $(OBJCOPY) --prefix-symbols=_kvm_nvhe $< $@

Remove ftrace, Shadow Call Stack, and CFI CFLAGS.

This is equivalent to the 'notrace', 'noscs', and 'nocfi' annotations.

KBUILD_CFLAGS := $(filter-out $(CC_FLAGS_FTRACE) $(CC_FLAGS_SCS) $(CC_FLAGS_CFI), $(KBUILD_CFLAGS))

Starting from 13.0.0 llvm emits SHT_REL section '.llvm.call-graph-profile'

when profile optimization is applied. gen-hyprel does not support SHT_REL and

causes a build failure. Remove profile optimization flags.

KBUILD_CFLAGS := $(filter-out -fprofile-sample-use=% -fprofile-use=%, $(KBUILD_CFLAGS)) KBUILD_CFLAGS += -fno-asynchronous-unwind-tables -fno-unwind-tables

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