Quelle  Makefile

# SPDX-License-Identifier: GPL-2.0
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# Building vDSO images for x86.
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# Include the generic Makefile to check the built vDSO:
include $(srctree)/lib/vdso/Makefile.include

# Files to link into the vDSO:
vobjs-y := vdso-note.o vclock_gettime.o vgetcpu.o vgetrandom.o vgetrandom-chacha.o
vobjs32-y := vdso32/note.o vdso32/system_call.o vdso32/sigreturn.o
vobjs32-y += vdso32/vclock_gettime.o vdso32/vgetcpu.o
vobjs-$(CONFIG_X86_SGX) += vsgx.o

# Files to link into the kernel:
obj-y      += vma.o extable.o

# vDSO images to build:
obj-$(CONFIG_X86_64)    += vdso-image-64.o
obj-$(CONFIG_X86_X32_ABI)   += vdso-image-x32.o
obj-$(CONFIG_COMPAT_32)    += vdso-image-32.o vdso32-setup.o

vobjs := $(addprefix $(obj)/, $(vobjs-y))
vobjs32 := $(addprefix $(obj)/, $(vobjs32-y))

$(obj)/vdso.o: $(obj)/vdso.so

targets += vdso.lds $(vobjs-y)
targets += vdso32/vdso32.lds $(vobjs32-y)

targets += $(foreach x, 64 x32 32, vdso-image-$(x).c vdso$(x).so vdso$(x).so.dbg)

CPPFLAGS_vdso.lds += -P -C

VDSO_LDFLAGS_vdso.lds = -m elf_x86_64 -soname linux-vdso.so.1 \
   -z max-page-size=4096

$(obj)/vdso64.so.dbg: $(obj)/vdso.lds $(vobjs) FORCE
 $(call if_changed,vdso_and_check)

HOST_EXTRACFLAGS += -I$(srctree)/tools/include -I$(srctree)/include/uapi -I$(srctree)/arch/$(SUBARCH)/include/uapi
hostprogs += vdso2c

quiet_cmd_vdso2c = VDSO2C  $@
      cmd_vdso2c = $(obj)/vdso2c $< $(<:%.dbg=%) $@

$(obj)/vdso-image-%.c: $(obj)/vdso%.so.dbg $(obj)/vdso%.so $(obj)/vdso2c FORCE
 $(call if_changed,vdso2c)

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# Don't omit frame pointers for ease of userspace debugging, but do
# optimize sibling calls.
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CFL := $(PROFILING) -mcmodel=small -fPIC -O2 -fasynchronous-unwind-tables -m64 \
       $(filter -g%,$(KBUILD_CFLAGS)) -fno-stack-protector \
       -fno-omit-frame-pointer -foptimize-sibling-calls \
       -DDISABLE_BRANCH_PROFILING -DBUILD_VDSO

ifdef CONFIG_MITIGATION_RETPOLINE
ifneq ($(RETPOLINE_VDSO_CFLAGS),)
  CFL += $(RETPOLINE_VDSO_CFLAGS)
endif
endif

$(vobjs): KBUILD_CFLAGS := $(filter-out $(PADDING_CFLAGS) $(CC_FLAGS_LTO) $(CC_FLAGS_CFI) $(RANDSTRUCT_CFLAGS) $(KSTACK_ERASE_CFLAGS) $(GCC_PLUGINS_CFLAGS) $(RETPOLINE_CFLAGS),$(KBUILD_CFLAGS)) $(CFL)
$(vobjs): KBUILD_AFLAGS += -DBUILD_VDSO

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# vDSO code runs in userspace and -pg doesn't help with profiling anyway.
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CFLAGS_REMOVE_vclock_gettime.o = -pg
CFLAGS_REMOVE_vdso32/vclock_gettime.o = -pg
CFLAGS_REMOVE_vgetcpu.o = -pg
CFLAGS_REMOVE_vdso32/vgetcpu.o = -pg
CFLAGS_REMOVE_vsgx.o = -pg
CFLAGS_REMOVE_vgetrandom.o = -pg

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# X32 processes use x32 vDSO to access 64bit kernel data.
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# Build x32 vDSO image:
# 1. Compile x32 vDSO as 64bit.
# 2. Convert object files to x32.
# 3. Build x32 VDSO image with x32 objects, which contains 64bit codes
# so that it can reach 64bit address space with 64bit pointers.
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CPPFLAGS_vdsox32.lds = $(CPPFLAGS_vdso.lds)
VDSO_LDFLAGS_vdsox32.lds = -m elf32_x86_64 -soname linux-vdso.so.1 \
      -z max-page-size=4096

# x32-rebranded versions
vobjx32s-y := $(vobjs-y:.o=-x32.o)

# same thing, but in the output directory
vobjx32s := $(addprefix $(obj)/, $(vobjx32s-y))

# Convert 64bit object file to x32 for x32 vDSO.
quiet_cmd_x32 = X32     $@
      cmd_x32 = $(OBJCOPY) -O elf32-x86-64 $< $@

$(obj)/%-x32.o: $(obj)/%.o FORCE
 $(call if_changed,x32)

targets += vdsox32.lds $(vobjx32s-y)

$(obj)/%.so: OBJCOPYFLAGS := -S --remove-section __ex_table
$(obj)/%.so: $(obj)/%.so.dbg FORCE
 $(call if_changed,objcopy)

$(obj)/vdsox32.so.dbg: $(obj)/vdsox32.lds $(vobjx32s) FORCE
 $(call if_changed,vdso_and_check)

CPPFLAGS_vdso32/vdso32.lds = $(CPPFLAGS_vdso.lds)
VDSO_LDFLAGS_vdso32.lds = -m elf_i386 -soname linux-gate.so.1

KBUILD_AFLAGS_32 := $(filter-out -m64,$(KBUILD_AFLAGS)) -DBUILD_VDSO
$(obj)/vdso32.so.dbg: KBUILD_AFLAGS = $(KBUILD_AFLAGS_32)
$(obj)/vdso32.so.dbg: asflags-$(CONFIG_X86_64) += -m32

KBUILD_CFLAGS_32 := $(filter-out -m64,$(KBUILD_CFLAGS))
KBUILD_CFLAGS_32 := $(filter-out -mcmodel=kernel,$(KBUILD_CFLAGS_32))
KBUILD_CFLAGS_32 := $(filter-out -fno-pic,$(KBUILD_CFLAGS_32))
KBUILD_CFLAGS_32 := $(filter-out -mfentry,$(KBUILD_CFLAGS_32))
KBUILD_CFLAGS_32 := $(filter-out $(RANDSTRUCT_CFLAGS),$(KBUILD_CFLAGS_32))
KBUILD_CFLAGS_32 := $(filter-out $(KSTACK_ERASE_CFLAGS),$(KBUILD_CFLAGS_32))
KBUILD_CFLAGS_32 := $(filter-out $(GCC_PLUGINS_CFLAGS),$(KBUILD_CFLAGS_32))
KBUILD_CFLAGS_32 := $(filter-out $(RETPOLINE_CFLAGS),$(KBUILD_CFLAGS_32))
KBUILD_CFLAGS_32 := $(filter-out $(CC_FLAGS_LTO),$(KBUILD_CFLAGS_32))
KBUILD_CFLAGS_32 := $(filter-out $(CC_FLAGS_CFI),$(KBUILD_CFLAGS_32))
KBUILD_CFLAGS_32 := $(filter-out $(PADDING_CFLAGS),$(KBUILD_CFLAGS_32))
KBUILD_CFLAGS_32 += -m32 -msoft-float -mregparm=0 -fpic
KBUILD_CFLAGS_32 += -fno-stack-protector
KBUILD_CFLAGS_32 += $(call cc-option, -foptimize-sibling-calls)
KBUILD_CFLAGS_32 += -fno-omit-frame-pointer
KBUILD_CFLAGS_32 += -DDISABLE_BRANCH_PROFILING
KBUILD_CFLAGS_32 += -DBUILD_VDSO

ifdef CONFIG_MITIGATION_RETPOLINE
ifneq ($(RETPOLINE_VDSO_CFLAGS),)
  KBUILD_CFLAGS_32 += $(RETPOLINE_VDSO_CFLAGS)
endif
endif

$(obj)/vdso32.so.dbg: KBUILD_CFLAGS = $(KBUILD_CFLAGS_32)

$(obj)/vdso32.so.dbg: $(obj)/vdso32/vdso32.lds $(vobjs32) FORCE
 $(call if_changed,vdso_and_check)

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# The DSO images are built using a special linker script.
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quiet_cmd_vdso = VDSO    $@
      cmd_vdso = $(LD) -o $@ \
         $(VDSO_LDFLAGS) $(VDSO_LDFLAGS_$(filter %.lds,$(^F))) \
         -T $(filter %.lds,$^) $(filter %.o,$^)

VDSO_LDFLAGS = -shared --hash-style=both --build-id=sha1 --no-undefined \
 $(call ld-option, --eh-frame-hdr) -Bsymbolic -z noexecstack

quiet_cmd_vdso_and_check = VDSO    $@
      cmd_vdso_and_check = $(cmd_vdso); $(cmd_vdso_check)