1578e5d031
On arm64 linux gcc uses -fasynchronous-unwind-tables -funwind-tables
by default since gcc-8, so now the de facto platform ABI is to allow
unwinding from async signal handlers.
However on bare metal targets (aarch64-none-elf), and on old gcc,
async and sync unwind tables are not enabled by default to avoid
runtime memory costs.
This means if linux is built with a baremetal toolchain the vdso.so
may not have unwind tables which breaks the gcc platform ABI guarantee
in userspace.
Add -fasynchronous-unwind-tables explicitly to the vgettimeofday.o
cflags to address the ABI change.
Fixes: 28b1a824a4 ("arm64: vdso: Substitute gettimeofday() with C implementation")
Cc: Will Deacon <will@kernel.org>
Reported-by: Szabolcs Nagy <szabolcs.nagy@arm.com>
Signed-off-by: Vincenzo Frascino <vincenzo.frascino@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
88 lines
2.4 KiB
Makefile
88 lines
2.4 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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# 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_AARCH64_JUMP_SLOT|R_AARCH64_GLOB_DAT|R_AARCH64_ABS64
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include $(srctree)/lib/vdso/Makefile
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obj-vdso := vgettimeofday.o note.o sigreturn.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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ldflags-y := -shared -nostdlib -soname=linux-vdso.so.1 --hash-style=sysv \
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--build-id -n -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
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VDSO_LDFLAGS := -Bsymbolic
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CFLAGS_REMOVE_vgettimeofday.o = $(CC_FLAGS_FTRACE) -Os
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KBUILD_CFLAGS += $(DISABLE_LTO)
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KASAN_SANITIZE := n
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UBSAN_SANITIZE := n
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OBJECT_FILES_NON_STANDARD := y
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KCOV_INSTRUMENT := n
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CFLAGS_vgettimeofday.o = -O2 -mcmodel=tiny -fasynchronous-unwind-tables
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ifneq ($(c-gettimeofday-y),)
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CFLAGS_vgettimeofday.o += -include $(c-gettimeofday-y)
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endif
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# Clang versions less than 8 do not support -mcmodel=tiny
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ifeq ($(CONFIG_CC_IS_CLANG), y)
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ifeq ($(shell test $(CONFIG_CLANG_VERSION) -lt 80000; echo $$?),0)
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CFLAGS_REMOVE_vgettimeofday.o += -mcmodel=tiny
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endif
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endif
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# Disable gcov profiling for VDSO code
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GCOV_PROFILE := n
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obj-y += vdso.o
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extra-y += vdso.lds
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CPPFLAGS_vdso.lds += -P -C -U$(ARCH)
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# Force dependency (incbin is bad)
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$(obj)/vdso.o : $(obj)/vdso.so
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# Link rule for the .so file, .lds has to be first
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$(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 := $(srctree)/$(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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# Install commands for the unstripped file
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quiet_cmd_vdso_install = INSTALL $@
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cmd_vdso_install = cp $(obj)/$@.dbg $(MODLIB)/vdso/$@
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vdso.so: $(obj)/vdso.so.dbg
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@mkdir -p $(MODLIB)/vdso
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$(call cmd,vdso_install)
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vdso_install: vdso.so
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