mirror of
https://git.kernel.org/pub/scm/linux/kernel/git/netdev/net.git/
synced 2026-04-17 22:23:45 -04:00
bea75b3389
Now that all functions are 16 byte aligned, add 16 bytes of NOP padding in front of each function. This prepares things for software call stack tracking and kCFI/FineIBT. This significantly increases kernel .text size, around 5.1% on a x86_64-defconfig-ish build. However, per the random access argument used for alignment, these 16 extra bytes are code that wouldn't be used. Performance measurements back this up by showing no significant performance regressions. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lore.kernel.org/r/20220915111146.950884492@infradead.org
223 lines
7.2 KiB
Makefile
223 lines
7.2 KiB
Makefile
# SPDX-License-Identifier: GPL-2.0
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#
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# Building vDSO images for x86.
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#
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# Absolute relocation type $(ARCH_REL_TYPE_ABS) needs to be defined before
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# the inclusion of generic Makefile.
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ARCH_REL_TYPE_ABS := R_X86_64_JUMP_SLOT|R_X86_64_GLOB_DAT|R_X86_64_RELATIVE|
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ARCH_REL_TYPE_ABS += R_386_GLOB_DAT|R_386_JMP_SLOT|R_386_RELATIVE
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include $(srctree)/lib/vdso/Makefile
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# Sanitizer runtimes are unavailable and cannot be linked here.
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KASAN_SANITIZE := n
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KMSAN_SANITIZE_vclock_gettime.o := n
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KMSAN_SANITIZE_vgetcpu.o := n
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UBSAN_SANITIZE := n
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KCSAN_SANITIZE := n
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OBJECT_FILES_NON_STANDARD := y
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# Prevents link failures: __sanitizer_cov_trace_pc() is not linked in.
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KCOV_INSTRUMENT := n
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VDSO64-$(CONFIG_X86_64) := y
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VDSOX32-$(CONFIG_X86_X32_ABI) := y
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VDSO32-$(CONFIG_X86_32) := y
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VDSO32-$(CONFIG_IA32_EMULATION) := y
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# files to link into the vdso
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vobjs-y := vdso-note.o vclock_gettime.o vgetcpu.o
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vobjs32-y := vdso32/note.o vdso32/system_call.o vdso32/sigreturn.o
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vobjs32-y += vdso32/vclock_gettime.o
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vobjs-$(CONFIG_X86_SGX) += vsgx.o
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# files to link into kernel
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obj-y += vma.o extable.o
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KASAN_SANITIZE_vma.o := y
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UBSAN_SANITIZE_vma.o := y
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KCSAN_SANITIZE_vma.o := y
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OBJECT_FILES_NON_STANDARD_vma.o := n
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OBJECT_FILES_NON_STANDARD_extable.o := n
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# vDSO images to build
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vdso_img-$(VDSO64-y) += 64
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vdso_img-$(VDSOX32-y) += x32
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vdso_img-$(VDSO32-y) += 32
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obj-$(VDSO32-y) += vdso32-setup.o
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vobjs := $(foreach F,$(vobjs-y),$(obj)/$F)
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vobjs32 := $(foreach F,$(vobjs32-y),$(obj)/$F)
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$(obj)/vdso.o: $(obj)/vdso.so
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targets += vdso.lds $(vobjs-y)
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targets += vdso32/vdso32.lds $(vobjs32-y)
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# Build the vDSO image C files and link them in.
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vdso_img_objs := $(vdso_img-y:%=vdso-image-%.o)
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vdso_img_cfiles := $(vdso_img-y:%=vdso-image-%.c)
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vdso_img_sodbg := $(vdso_img-y:%=vdso%.so.dbg)
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obj-y += $(vdso_img_objs)
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targets += $(vdso_img_cfiles)
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targets += $(vdso_img_sodbg) $(vdso_img-y:%=vdso%.so)
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CPPFLAGS_vdso.lds += -P -C
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VDSO_LDFLAGS_vdso.lds = -m elf_x86_64 -soname linux-vdso.so.1 --no-undefined \
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-z max-page-size=4096
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$(obj)/vdso64.so.dbg: $(obj)/vdso.lds $(vobjs) FORCE
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$(call if_changed,vdso_and_check)
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HOST_EXTRACFLAGS += -I$(srctree)/tools/include -I$(srctree)/include/uapi -I$(srctree)/arch/$(SUBARCH)/include/uapi
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hostprogs += vdso2c
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quiet_cmd_vdso2c = VDSO2C $@
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cmd_vdso2c = $(obj)/vdso2c $< $(<:%.dbg=%) $@
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$(obj)/vdso-image-%.c: $(obj)/vdso%.so.dbg $(obj)/vdso%.so $(obj)/vdso2c FORCE
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$(call if_changed,vdso2c)
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#
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# Don't omit frame pointers for ease of userspace debugging, but do
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# optimize sibling calls.
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#
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CFL := $(PROFILING) -mcmodel=small -fPIC -O2 -fasynchronous-unwind-tables -m64 \
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$(filter -g%,$(KBUILD_CFLAGS)) -fno-stack-protector \
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-fno-omit-frame-pointer -foptimize-sibling-calls \
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-DDISABLE_BRANCH_PROFILING -DBUILD_VDSO
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ifdef CONFIG_RETPOLINE
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ifneq ($(RETPOLINE_VDSO_CFLAGS),)
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CFL += $(RETPOLINE_VDSO_CFLAGS)
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endif
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endif
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$(vobjs): KBUILD_CFLAGS := $(filter-out $(PADDING_CFLAGS) $(CC_FLAGS_LTO) $(CC_FLAGS_CFI) $(RANDSTRUCT_CFLAGS) $(GCC_PLUGINS_CFLAGS) $(RETPOLINE_CFLAGS),$(KBUILD_CFLAGS)) $(CFL)
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$(vobjs): KBUILD_AFLAGS += -DBUILD_VDSO
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#
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# vDSO code runs in userspace and -pg doesn't help with profiling anyway.
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#
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CFLAGS_REMOVE_vclock_gettime.o = -pg
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CFLAGS_REMOVE_vdso32/vclock_gettime.o = -pg
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CFLAGS_REMOVE_vgetcpu.o = -pg
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CFLAGS_REMOVE_vsgx.o = -pg
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#
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# X32 processes use x32 vDSO to access 64bit kernel data.
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#
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# Build x32 vDSO image:
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# 1. Compile x32 vDSO as 64bit.
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# 2. Convert object files to x32.
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# 3. Build x32 VDSO image with x32 objects, which contains 64bit codes
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# so that it can reach 64bit address space with 64bit pointers.
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#
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CPPFLAGS_vdsox32.lds = $(CPPFLAGS_vdso.lds)
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VDSO_LDFLAGS_vdsox32.lds = -m elf32_x86_64 -soname linux-vdso.so.1 \
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-z max-page-size=4096
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# x32-rebranded versions
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vobjx32s-y := $(vobjs-y:.o=-x32.o)
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# same thing, but in the output directory
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vobjx32s := $(foreach F,$(vobjx32s-y),$(obj)/$F)
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# Convert 64bit object file to x32 for x32 vDSO.
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quiet_cmd_x32 = X32 $@
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cmd_x32 = $(OBJCOPY) -O elf32-x86-64 $< $@
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$(obj)/%-x32.o: $(obj)/%.o FORCE
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$(call if_changed,x32)
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targets += vdsox32.lds $(vobjx32s-y)
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$(obj)/%.so: OBJCOPYFLAGS := -S --remove-section __ex_table
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$(obj)/%.so: $(obj)/%.so.dbg FORCE
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$(call if_changed,objcopy)
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$(obj)/vdsox32.so.dbg: $(obj)/vdsox32.lds $(vobjx32s) FORCE
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$(call if_changed,vdso_and_check)
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CPPFLAGS_vdso32/vdso32.lds = $(CPPFLAGS_vdso.lds)
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VDSO_LDFLAGS_vdso32.lds = -m elf_i386 -soname linux-gate.so.1
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KBUILD_AFLAGS_32 := $(filter-out -m64,$(KBUILD_AFLAGS)) -DBUILD_VDSO
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$(obj)/vdso32.so.dbg: KBUILD_AFLAGS = $(KBUILD_AFLAGS_32)
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$(obj)/vdso32.so.dbg: asflags-$(CONFIG_X86_64) += -m32
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KBUILD_CFLAGS_32 := $(filter-out -m64,$(KBUILD_CFLAGS))
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KBUILD_CFLAGS_32 := $(filter-out -mcmodel=kernel,$(KBUILD_CFLAGS_32))
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KBUILD_CFLAGS_32 := $(filter-out -fno-pic,$(KBUILD_CFLAGS_32))
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KBUILD_CFLAGS_32 := $(filter-out -mfentry,$(KBUILD_CFLAGS_32))
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KBUILD_CFLAGS_32 := $(filter-out $(RANDSTRUCT_CFLAGS),$(KBUILD_CFLAGS_32))
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KBUILD_CFLAGS_32 := $(filter-out $(GCC_PLUGINS_CFLAGS),$(KBUILD_CFLAGS_32))
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KBUILD_CFLAGS_32 := $(filter-out $(RETPOLINE_CFLAGS),$(KBUILD_CFLAGS_32))
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KBUILD_CFLAGS_32 := $(filter-out $(CC_FLAGS_LTO),$(KBUILD_CFLAGS_32))
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KBUILD_CFLAGS_32 := $(filter-out $(CC_FLAGS_CFI),$(KBUILD_CFLAGS_32))
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KBUILD_CFLAGS_32 := $(filter-out $(PADDING_CFLAGS),$(KBUILD_CFLAGS_32))
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KBUILD_CFLAGS_32 += -m32 -msoft-float -mregparm=0 -fpic
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KBUILD_CFLAGS_32 += -fno-stack-protector
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KBUILD_CFLAGS_32 += $(call cc-option, -foptimize-sibling-calls)
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KBUILD_CFLAGS_32 += -fno-omit-frame-pointer
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KBUILD_CFLAGS_32 += -DDISABLE_BRANCH_PROFILING
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ifdef CONFIG_RETPOLINE
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ifneq ($(RETPOLINE_VDSO_CFLAGS),)
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KBUILD_CFLAGS_32 += $(RETPOLINE_VDSO_CFLAGS)
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endif
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endif
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$(obj)/vdso32.so.dbg: KBUILD_CFLAGS = $(KBUILD_CFLAGS_32)
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$(obj)/vdso32.so.dbg: $(obj)/vdso32/vdso32.lds $(vobjs32) FORCE
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$(call if_changed,vdso_and_check)
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#
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# The DSO images are built using a special linker script.
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#
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quiet_cmd_vdso = VDSO $@
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cmd_vdso = $(LD) -o $@ \
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$(VDSO_LDFLAGS) $(VDSO_LDFLAGS_$(filter %.lds,$(^F))) \
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-T $(filter %.lds,$^) $(filter %.o,$^) && \
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sh $(srctree)/$(src)/checkundef.sh '$(NM)' '$@'
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VDSO_LDFLAGS = -shared --hash-style=both --build-id=sha1 \
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$(call ld-option, --eh-frame-hdr) -Bsymbolic -z noexecstack
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GCOV_PROFILE := n
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quiet_cmd_vdso_and_check = VDSO $@
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cmd_vdso_and_check = $(cmd_vdso); $(cmd_vdso_check)
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#
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# Install the unstripped copies of vdso*.so. If our toolchain supports
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# build-id, install .build-id links as well.
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#
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quiet_cmd_vdso_install = INSTALL $(@:install_%=%)
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define cmd_vdso_install
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cp $< "$(MODLIB)/vdso/$(@:install_%=%)"; \
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if readelf -n $< |grep -q 'Build ID'; then \
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buildid=`readelf -n $< |grep 'Build ID' |sed -e 's/^.*Build ID: \(.*\)$$/\1/'`; \
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first=`echo $$buildid | cut -b-2`; \
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last=`echo $$buildid | cut -b3-`; \
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mkdir -p "$(MODLIB)/vdso/.build-id/$$first"; \
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ln -sf "../../$(@:install_%=%)" "$(MODLIB)/vdso/.build-id/$$first/$$last.debug"; \
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fi
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endef
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vdso_img_insttargets := $(vdso_img_sodbg:%.dbg=install_%)
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$(MODLIB)/vdso: FORCE
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@mkdir -p $(MODLIB)/vdso
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$(vdso_img_insttargets): install_%: $(obj)/%.dbg $(MODLIB)/vdso
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$(call cmd,vdso_install)
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PHONY += vdso_install $(vdso_img_insttargets)
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vdso_install: $(vdso_img_insttargets)
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clean-files := vdso32.so vdso32.so.dbg vdso64* vdso-image-*.c vdsox32.so*
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