From ebb5e78cc63417a35254a791de66e1cc84f963cc Mon Sep 17 00:00:00 2001 From: Alex Smith Date: Wed, 21 Oct 2015 09:54:38 +0100 Subject: MIPS: Initial implementation of a VDSO 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 Signed-off-by: Markos Chandras Cc: Matthew Fortune Cc: linux-mips@linux-mips.org Patchwork: https://patchwork.linux-mips.org/patch/11337/ Signed-off-by: Ralf Baechle --- arch/mips/vdso/Makefile | 160 ++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 160 insertions(+) create mode 100644 arch/mips/vdso/Makefile (limited to 'arch/mips/vdso/Makefile') diff --git a/arch/mips/vdso/Makefile b/arch/mips/vdso/Makefile new file mode 100644 index 000000000000..ef5f348f386a --- /dev/null +++ b/arch/mips/vdso/Makefile @@ -0,0 +1,160 @@ +# Objects to go into the VDSO. +obj-vdso-y := elf.o gettimeofday.o sigreturn.o + +# Common compiler flags between ABIs. +ccflags-vdso := \ + $(filter -I%,$(KBUILD_CFLAGS)) \ + $(filter -E%,$(KBUILD_CFLAGS)) \ + $(filter -march=%,$(KBUILD_CFLAGS)) +cflags-vdso := $(ccflags-vdso) \ + $(filter -W%,$(filter-out -Wa$(comma)%,$(KBUILD_CFLAGS))) \ + -O2 -g -fPIC -fno-common -fno-builtin -G 0 -DDISABLE_BRANCH_PROFILING \ + $(call cc-option, -fno-stack-protector) +aflags-vdso := $(ccflags-vdso) \ + $(filter -I%,$(KBUILD_CFLAGS)) \ + $(filter -E%,$(KBUILD_CFLAGS)) \ + -D__ASSEMBLY__ -Wa,-gdwarf-2 + +# +# For the pre-R6 code in arch/mips/vdso/vdso.h for locating +# the base address of VDSO, the linker will emit a R_MIPS_PC32 +# relocation in binutils > 2.25 but it will fail with older versions +# because that relocation is not supported for that symbol. As a result +# of which we are forced to disable the VDSO symbols when building +# with < 2.25 binutils on pre-R6 kernels. For more references on why we +# can't use other methods to get the base address of VDSO please refer to +# the comments on that file. +# +ifndef CONFIG_CPU_MIPSR6 + ifeq ($(call ld-ifversion, -gt, 22400000, y),) + $(warning MIPS VDSO requires binutils > 2.24) + obj-vdso-y := $(filter-out gettimeofday.o, $(obj-vdso-y)) + ccflags-vdso += -DDISABLE_MIPS_VDSO + endif +endif + +# VDSO linker flags. +VDSO_LDFLAGS := \ + -Wl,-Bsymbolic -Wl,--no-undefined -Wl,-soname=linux-vdso.so.1 \ + -nostdlib -shared \ + $(call cc-ldoption, -Wl$(comma)--hash-style=sysv) \ + $(call cc-ldoption, -Wl$(comma)--build-id) + +GCOV_PROFILE := n + +# +# Shared build commands. +# + +quiet_cmd_vdsold = VDSO $@ + cmd_vdsold = $(CC) $(c_flags) $(VDSO_LDFLAGS) \ + -Wl,-T $(filter %.lds,$^) $(filter %.o,$^) -o $@ + +hostprogs-y := genvdso + +quiet_cmd_genvdso = GENVDSO $@ +define cmd_genvdso + cp $< $(<:%.dbg=%) && \ + $(OBJCOPY) -S $< $(<:%.dbg=%) && \ + $(obj)/genvdso $< $(<:%.dbg=%) $@ $(VDSO_NAME) +endef + +# +# Build native VDSO. +# + +native-abi := $(filter -mabi=%,$(KBUILD_CFLAGS)) + +targets += $(obj-vdso-y) +targets += vdso.lds vdso.so.dbg vdso.so vdso-image.c + +obj-vdso := $(obj-vdso-y:%.o=$(obj)/%.o) + +$(obj-vdso): KBUILD_CFLAGS := $(cflags-vdso) $(native-abi) +$(obj-vdso): KBUILD_AFLAGS := $(aflags-vdso) $(native-abi) + +$(obj)/vdso.lds: KBUILD_CPPFLAGS := $(native-abi) + +$(obj)/vdso.so.dbg: $(obj)/vdso.lds $(obj-vdso) FORCE + $(call if_changed,vdsold) + +$(obj)/vdso-image.c: $(obj)/vdso.so.dbg $(obj)/genvdso FORCE + $(call if_changed,genvdso) + +obj-y += vdso-image.o + +# +# Build O32 VDSO. +# + +# Define these outside the ifdef to ensure they are picked up by clean. +targets += $(obj-vdso-y:%.o=%-o32.o) +targets += vdso-o32.lds vdso-o32.so.dbg vdso-o32.so vdso-o32-image.c + +ifdef CONFIG_MIPS32_O32 + +obj-vdso-o32 := $(obj-vdso-y:%.o=$(obj)/%-o32.o) + +$(obj-vdso-o32): KBUILD_CFLAGS := $(cflags-vdso) -mabi=32 +$(obj-vdso-o32): KBUILD_AFLAGS := $(aflags-vdso) -mabi=32 + +$(obj)/%-o32.o: $(src)/%.S FORCE + $(call if_changed_dep,as_o_S) + +$(obj)/%-o32.o: $(src)/%.c FORCE + $(call cmd,force_checksrc) + $(call if_changed_rule,cc_o_c) + +$(obj)/vdso-o32.lds: KBUILD_CPPFLAGS := -mabi=32 +$(obj)/vdso-o32.lds: $(src)/vdso.lds.S FORCE + $(call if_changed_dep,cpp_lds_S) + +$(obj)/vdso-o32.so.dbg: $(obj)/vdso-o32.lds $(obj-vdso-o32) FORCE + $(call if_changed,vdsold) + +$(obj)/vdso-o32-image.c: VDSO_NAME := o32 +$(obj)/vdso-o32-image.c: $(obj)/vdso-o32.so.dbg $(obj)/genvdso FORCE + $(call if_changed,genvdso) + +obj-y += vdso-o32-image.o + +endif + +# +# Build N32 VDSO. +# + +targets += $(obj-vdso-y:%.o=%-n32.o) +targets += vdso-n32.lds vdso-n32.so.dbg vdso-n32.so vdso-n32-image.c + +ifdef CONFIG_MIPS32_N32 + +obj-vdso-n32 := $(obj-vdso-y:%.o=$(obj)/%-n32.o) + +$(obj-vdso-n32): KBUILD_CFLAGS := $(cflags-vdso) -mabi=n32 +$(obj-vdso-n32): KBUILD_AFLAGS := $(aflags-vdso) -mabi=n32 + +$(obj)/%-n32.o: $(src)/%.S FORCE + $(call if_changed_dep,as_o_S) + +$(obj)/%-n32.o: $(src)/%.c FORCE + $(call cmd,force_checksrc) + $(call if_changed_rule,cc_o_c) + +$(obj)/vdso-n32.lds: KBUILD_CPPFLAGS := -mabi=n32 +$(obj)/vdso-n32.lds: $(src)/vdso.lds.S FORCE + $(call if_changed_dep,cpp_lds_S) + +$(obj)/vdso-n32.so.dbg: $(obj)/vdso-n32.lds $(obj-vdso-n32) FORCE + $(call if_changed,vdsold) + +$(obj)/vdso-n32-image.c: VDSO_NAME := n32 +$(obj)/vdso-n32-image.c: $(obj)/vdso-n32.so.dbg $(obj)/genvdso FORCE + $(call if_changed,genvdso) + +obj-y += vdso-n32-image.o + +endif + +# FIXME: Need install rule for debug. +# Needs to deal with dependency for generation of dbg by cmd_genvdso... -- cgit v1.2.3