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712676ea2b
Hook up the generic vDSO implementation to the aarch64 vDSO data page. The _vdso_rng_data required data is placed within the _vdso_data vvar page, by using a offset larger than the vdso_data. The vDSO function requires a ChaCha20 implementation that does not write to the stack, and that can do an entire ChaCha20 permutation. The one provided uses NEON on the permute operation, with a fallback to the syscall for chips that do not support AdvSIMD. This also passes the vdso_test_chacha test along with vdso_test_getrandom. The vdso_test_getrandom bench-single result on Neoverse-N1 shows: vdso: 25000000 times in 0.783884250 seconds libc: 25000000 times in 8.780275399 seconds syscall: 25000000 times in 8.786581518 seconds A small fixup to arch/arm64/include/asm/mman.h was required to avoid pulling kernel code into the vDSO, similar to what's already done in arch/arm64/include/asm/rwonce.h. Signed-off-by: Adhemerval Zanella <adhemerval.zanella@linaro.org> Reviewed-by: Ard Biesheuvel <ardb@kernel.org> Acked-by: Will Deacon <will@kernel.org> Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
82 lines
2.6 KiB
Makefile
82 lines
2.6 KiB
Makefile
# SPDX-License-Identifier: GPL-2.0
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#
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# Building a vDSO image for AArch64.
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#
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# Author: Will Deacon <will.deacon@arm.com>
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# Heavily based on the vDSO Makefiles for other archs.
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#
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# Include the generic Makefile to check the built vdso.
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include $(srctree)/lib/vdso/Makefile
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obj-vdso := vgettimeofday.o note.o sigreturn.o vgetrandom.o vgetrandom-chacha.o
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# Build rules
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targets := $(obj-vdso) vdso.so vdso.so.dbg
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obj-vdso := $(addprefix $(obj)/, $(obj-vdso))
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btildflags-$(CONFIG_ARM64_BTI_KERNEL) += -z force-bti
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# -Bsymbolic has been added for consistency with arm, the compat vDSO and
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# potential future proofing if we end up with internal calls to the exported
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# routines, as x86 does (see 6f121e548f83 ("x86, vdso: Reimplement vdso.so
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# preparation in build-time C")).
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ldflags-y := -shared -soname=linux-vdso.so.1 \
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-Bsymbolic --build-id=sha1 -n $(btildflags-y)
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ifdef CONFIG_LD_ORPHAN_WARN
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ldflags-y += --orphan-handling=$(CONFIG_LD_ORPHAN_WARN_LEVEL)
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endif
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ldflags-y += -T
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ccflags-y := -fno-common -fno-builtin -fno-stack-protector -ffixed-x18
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ccflags-y += -DDISABLE_BRANCH_PROFILING -DBUILD_VDSO
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# -Wmissing-prototypes and -Wmissing-declarations are removed from
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# the CFLAGS to make possible to build the kernel with CONFIG_WERROR enabled.
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CC_FLAGS_REMOVE_VDSO := $(CC_FLAGS_FTRACE) -Os $(CC_FLAGS_SCS) \
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$(RANDSTRUCT_CFLAGS) $(GCC_PLUGINS_CFLAGS) \
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$(CC_FLAGS_LTO) $(CC_FLAGS_CFI) \
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-Wmissing-prototypes -Wmissing-declarations
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CC_FLAGS_ADD_VDSO := -O2 -mcmodel=tiny -fasynchronous-unwind-tables
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CFLAGS_REMOVE_vgettimeofday.o = $(CC_FLAGS_REMOVE_VDSO)
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CFLAGS_REMOVE_vgetrandom.o = $(CC_FLAGS_REMOVE_VDSO)
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CFLAGS_vgettimeofday.o = $(CC_FLAGS_ADD_VDSO)
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CFLAGS_vgetrandom.o = $(CC_FLAGS_ADD_VDSO)
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ifneq ($(c-gettimeofday-y),)
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CFLAGS_vgettimeofday.o += -include $(c-gettimeofday-y)
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endif
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ifneq ($(c-getrandom-y),)
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CFLAGS_vgetrandom.o += -include $(c-getrandom-y)
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endif
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targets += vdso.lds
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CPPFLAGS_vdso.lds += -P -C -U$(ARCH)
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# Link rule for the .so file, .lds has to be first
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$(obj)/vdso.so.dbg: $(obj)/vdso.lds $(obj-vdso) FORCE
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$(call if_changed,vdsold_and_vdso_check)
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# Strip rule for the .so file
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$(obj)/%.so: OBJCOPYFLAGS := -S
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$(obj)/%.so: $(obj)/%.so.dbg FORCE
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$(call if_changed,objcopy)
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# Generate VDSO offsets using helper script
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gen-vdsosym := $(src)/gen_vdso_offsets.sh
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quiet_cmd_vdsosym = VDSOSYM $@
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cmd_vdsosym = $(NM) $< | $(gen-vdsosym) | LC_ALL=C sort > $@
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include/generated/vdso-offsets.h: $(obj)/vdso.so.dbg FORCE
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$(call if_changed,vdsosym)
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# Actual build commands
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quiet_cmd_vdsold_and_vdso_check = LD $@
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cmd_vdsold_and_vdso_check = $(cmd_ld); $(cmd_vdso_check)
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