ebb5e78cc6
Add an initial implementation of a proper (i.e. an ELF shared library)
VDSO. With this commit it does not export any symbols, it only replaces
the current signal return trampoline page. A later commit will add user
implementations of gettimeofday()/clock_gettime().
To support both new toolchains and old ones which don't generate ABI
flags section, we define its content manually and then use a tool
(genvdso) to patch up the section to have the correct name and type.
genvdso also extracts symbol offsets ({,rt_}sigreturn) needed by the
kernel, and generates a C file containing a "struct mips_vdso_image"
containing both the VDSO data and these offsets. This C file is
compiled into the kernel.
On 64-bit kernels we require a different VDSO for each supported ABI,
so we may build up to 3 different VDSOs. The VDSO to use is selected by
the mips_abi structure.
A kernel/user shared data page is created and mapped below the VDSO
image. This is currently empty, but will be used by the user time
function implementations which are added later.
[markos.chandras@imgtec.com:
- Add more comments
- Move abi detection in genvdso.h since it's the get_symbol function
that needs it.
- Add an R6 specific way to calculate the base address of VDSO in order
to avoid the branch instruction which affects performance.
- Do not patch .gnu.attributes since it's not needed for dynamic linking.
- Simplify Makefile a little bit.
- checkpatch fixes
- Restrict VDSO support for binutils < 2.25 for pre-R6
- Include atomic64.h for O32 variant on MIPS64]
Signed-off-by: Alex Smith <alex.smith@imgtec.com>
Signed-off-by: Markos Chandras <markos.chandras@imgtec.com>
Cc: Matthew Fortune <matthew.fortune@imgtec.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/11337/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
160 lines
4.3 KiB
Makefile
160 lines
4.3 KiB
Makefile
# Objects to go into the VDSO.
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obj-vdso-y := elf.o gettimeofday.o sigreturn.o
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# Common compiler flags between ABIs.
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ccflags-vdso := \
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$(filter -I%,$(KBUILD_CFLAGS)) \
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$(filter -E%,$(KBUILD_CFLAGS)) \
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$(filter -march=%,$(KBUILD_CFLAGS))
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cflags-vdso := $(ccflags-vdso) \
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$(filter -W%,$(filter-out -Wa$(comma)%,$(KBUILD_CFLAGS))) \
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-O2 -g -fPIC -fno-common -fno-builtin -G 0 -DDISABLE_BRANCH_PROFILING \
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$(call cc-option, -fno-stack-protector)
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aflags-vdso := $(ccflags-vdso) \
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$(filter -I%,$(KBUILD_CFLAGS)) \
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$(filter -E%,$(KBUILD_CFLAGS)) \
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-D__ASSEMBLY__ -Wa,-gdwarf-2
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#
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# For the pre-R6 code in arch/mips/vdso/vdso.h for locating
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# the base address of VDSO, the linker will emit a R_MIPS_PC32
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# relocation in binutils > 2.25 but it will fail with older versions
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# because that relocation is not supported for that symbol. As a result
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# of which we are forced to disable the VDSO symbols when building
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# with < 2.25 binutils on pre-R6 kernels. For more references on why we
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# can't use other methods to get the base address of VDSO please refer to
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# the comments on that file.
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#
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ifndef CONFIG_CPU_MIPSR6
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ifeq ($(call ld-ifversion, -gt, 22400000, y),)
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$(warning MIPS VDSO requires binutils > 2.24)
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obj-vdso-y := $(filter-out gettimeofday.o, $(obj-vdso-y))
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ccflags-vdso += -DDISABLE_MIPS_VDSO
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endif
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endif
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# VDSO linker flags.
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VDSO_LDFLAGS := \
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-Wl,-Bsymbolic -Wl,--no-undefined -Wl,-soname=linux-vdso.so.1 \
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-nostdlib -shared \
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$(call cc-ldoption, -Wl$(comma)--hash-style=sysv) \
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$(call cc-ldoption, -Wl$(comma)--build-id)
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GCOV_PROFILE := n
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#
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# Shared build commands.
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#
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quiet_cmd_vdsold = VDSO $@
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cmd_vdsold = $(CC) $(c_flags) $(VDSO_LDFLAGS) \
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-Wl,-T $(filter %.lds,$^) $(filter %.o,$^) -o $@
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hostprogs-y := genvdso
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quiet_cmd_genvdso = GENVDSO $@
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define cmd_genvdso
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cp $< $(<:%.dbg=%) && \
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$(OBJCOPY) -S $< $(<:%.dbg=%) && \
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$(obj)/genvdso $< $(<:%.dbg=%) $@ $(VDSO_NAME)
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endef
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#
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# Build native VDSO.
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#
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native-abi := $(filter -mabi=%,$(KBUILD_CFLAGS))
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targets += $(obj-vdso-y)
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targets += vdso.lds vdso.so.dbg vdso.so vdso-image.c
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obj-vdso := $(obj-vdso-y:%.o=$(obj)/%.o)
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$(obj-vdso): KBUILD_CFLAGS := $(cflags-vdso) $(native-abi)
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$(obj-vdso): KBUILD_AFLAGS := $(aflags-vdso) $(native-abi)
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$(obj)/vdso.lds: KBUILD_CPPFLAGS := $(native-abi)
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$(obj)/vdso.so.dbg: $(obj)/vdso.lds $(obj-vdso) FORCE
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$(call if_changed,vdsold)
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$(obj)/vdso-image.c: $(obj)/vdso.so.dbg $(obj)/genvdso FORCE
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$(call if_changed,genvdso)
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obj-y += vdso-image.o
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#
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# Build O32 VDSO.
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#
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# Define these outside the ifdef to ensure they are picked up by clean.
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targets += $(obj-vdso-y:%.o=%-o32.o)
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targets += vdso-o32.lds vdso-o32.so.dbg vdso-o32.so vdso-o32-image.c
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ifdef CONFIG_MIPS32_O32
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obj-vdso-o32 := $(obj-vdso-y:%.o=$(obj)/%-o32.o)
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$(obj-vdso-o32): KBUILD_CFLAGS := $(cflags-vdso) -mabi=32
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$(obj-vdso-o32): KBUILD_AFLAGS := $(aflags-vdso) -mabi=32
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$(obj)/%-o32.o: $(src)/%.S FORCE
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$(call if_changed_dep,as_o_S)
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$(obj)/%-o32.o: $(src)/%.c FORCE
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$(call cmd,force_checksrc)
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$(call if_changed_rule,cc_o_c)
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$(obj)/vdso-o32.lds: KBUILD_CPPFLAGS := -mabi=32
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$(obj)/vdso-o32.lds: $(src)/vdso.lds.S FORCE
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$(call if_changed_dep,cpp_lds_S)
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$(obj)/vdso-o32.so.dbg: $(obj)/vdso-o32.lds $(obj-vdso-o32) FORCE
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$(call if_changed,vdsold)
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$(obj)/vdso-o32-image.c: VDSO_NAME := o32
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$(obj)/vdso-o32-image.c: $(obj)/vdso-o32.so.dbg $(obj)/genvdso FORCE
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$(call if_changed,genvdso)
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obj-y += vdso-o32-image.o
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endif
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#
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# Build N32 VDSO.
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#
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targets += $(obj-vdso-y:%.o=%-n32.o)
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targets += vdso-n32.lds vdso-n32.so.dbg vdso-n32.so vdso-n32-image.c
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ifdef CONFIG_MIPS32_N32
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obj-vdso-n32 := $(obj-vdso-y:%.o=$(obj)/%-n32.o)
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$(obj-vdso-n32): KBUILD_CFLAGS := $(cflags-vdso) -mabi=n32
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$(obj-vdso-n32): KBUILD_AFLAGS := $(aflags-vdso) -mabi=n32
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$(obj)/%-n32.o: $(src)/%.S FORCE
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$(call if_changed_dep,as_o_S)
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$(obj)/%-n32.o: $(src)/%.c FORCE
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$(call cmd,force_checksrc)
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$(call if_changed_rule,cc_o_c)
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$(obj)/vdso-n32.lds: KBUILD_CPPFLAGS := -mabi=n32
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$(obj)/vdso-n32.lds: $(src)/vdso.lds.S FORCE
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$(call if_changed_dep,cpp_lds_S)
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$(obj)/vdso-n32.so.dbg: $(obj)/vdso-n32.lds $(obj-vdso-n32) FORCE
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$(call if_changed,vdsold)
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$(obj)/vdso-n32-image.c: VDSO_NAME := n32
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$(obj)/vdso-n32-image.c: $(obj)/vdso-n32.so.dbg $(obj)/genvdso FORCE
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$(call if_changed,genvdso)
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obj-y += vdso-n32-image.o
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endif
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# FIXME: Need install rule for debug.
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# Needs to deal with dependency for generation of dbg by cmd_genvdso...
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