mirror of
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
synced 2026-08-09 06:14:34 +02:00
Thomas WeißschuhandPaul Walmsley
ad6dcfa023
With LTO enabled the compiler assumes that the vDSO functions are not
used and optimizes them away completely. Currently this happens to
__vdso_clock_getres(), __vdso_clock_gettime(), __vdso_getrandom(),
__vdso_gettimeofday() and __vdso_riscv_hwprobe().
Disable LTO for the vDSO, as these functions are hand-optimized anyways.
Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202606301855.WvkSC4kD-lkp@intel.com/
Fixes: 021d23428b ("RISC-V: build: Allow LTO to be selected")
Cc: stable@vger.kernel.org
Signed-off-by: Thomas Weißschuh <thomas.weissschuh@linutronix.de>
Link: https://patch.msgid.link/20260701-riscv-vdso-lto-v1-1-89db0cd82077@linutronix.de
Signed-off-by: Paul Walmsley <pjw@kernel.org>
106 lines
3.2 KiB
Makefile
106 lines
3.2 KiB
Makefile
# SPDX-License-Identifier: GPL-2.0-only
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# Copied from arch/tile/kernel/vdso/Makefile
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# Include the generic Makefile to check the built vdso.
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include $(srctree)/lib/vdso/Makefile.include
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# Symbols present in the vdso
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vdso-syms = rt_sigreturn
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ifdef CONFIG_64BIT
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vdso-syms += vgettimeofday
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endif
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vdso-syms += getcpu
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vdso-syms += flush_icache
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vdso-syms += hwprobe
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vdso-syms += sys_hwprobe
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ifdef CONFIG_VDSO_GETRANDOM
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vdso-syms += getrandom
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endif
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ifdef VDSO_CFI_BUILD
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CFI_MARCH = _zicfilp_zicfiss
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CFI_FULL = -fcf-protection=full
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CFI_SUFFIX = -cfi
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OFFSET_SUFFIX = _cfi
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ccflags-y += -DVDSO_CFI=1
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asflags-y += -DVDSO_CFI=1
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endif
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# Files to link into the vdso
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obj-vdso = $(patsubst %, %.o, $(vdso-syms)) note.o
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ifdef CONFIG_VDSO_GETRANDOM
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obj-vdso += vgetrandom-chacha.o
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endif
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ccflags-y := -fno-stack-protector
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ccflags-y += -DDISABLE_BRANCH_PROFILING
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ccflags-y += -fno-builtin
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ccflags-y += $(KBUILD_BASE_ISA)$(CFI_MARCH)
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ccflags-y += $(CFI_FULL)
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asflags-y += $(KBUILD_BASE_ISA)$(CFI_MARCH)
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asflags-y += $(CFI_FULL)
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ifneq ($(c-gettimeofday-y),)
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CFLAGS_vgettimeofday.o += -fPIC -include $(c-gettimeofday-y)
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endif
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ifneq ($(c-getrandom-y),)
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CFLAGS_getrandom.o += -fPIC -include $(c-getrandom-y)
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endif
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CFLAGS_hwprobe.o += -fPIC
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# Build rules
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vdso_offsets := vdso$(if $(VDSO_CFI_BUILD),$(CFI_SUFFIX),)-offsets.h
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vdso_o := vdso$(if $(VDSO_CFI_BUILD),$(CFI_SUFFIX),).o
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vdso_so := vdso$(if $(VDSO_CFI_BUILD),$(CFI_SUFFIX),).so
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vdso_so_dbg := vdso$(if $(VDSO_CFI_BUILD),$(CFI_SUFFIX),).so.dbg
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vdso_lds := vdso.lds
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targets := $(obj-vdso) $(vdso_so) $(vdso_so_dbg) $(vdso_lds)
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obj-vdso := $(addprefix $(obj)/, $(obj-vdso))
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obj-y += vdso$(if $(VDSO_CFI_BUILD),$(CFI_SUFFIX),).o
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CPPFLAGS_$(vdso_lds) += -P -C -U$(ARCH)
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ifneq ($(filter vgettimeofday, $(vdso-syms)),)
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CPPFLAGS_$(vdso_lds) += -DHAS_VGETTIMEOFDAY
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endif
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# Disable -pg to prevent insert call site
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CFLAGS_REMOVE_vgettimeofday.o = $(CC_FLAGS_FTRACE) $(CC_FLAGS_SCS) $(CC_FLAGS_LTO)
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CFLAGS_REMOVE_getrandom.o = $(CC_FLAGS_FTRACE) $(CC_FLAGS_SCS) $(CC_FLAGS_LTO)
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CFLAGS_REMOVE_hwprobe.o = $(CC_FLAGS_FTRACE) $(CC_FLAGS_SCS) $(CC_FLAGS_LTO)
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# Force dependency
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$(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_check)
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LDFLAGS_$(vdso_so_dbg) = -shared -soname=linux-vdso.so.1 \
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--build-id=sha1 --eh-frame-hdr
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# strip rule for the .so file
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$(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) $(OFFSET_SUFFIX) | LC_ALL=C sort > $@
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include/generated/$(vdso_offsets): $(obj)/$(vdso_so_dbg) FORCE
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$(call if_changed,vdsosym)
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# actual build commands
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# The DSO images are built using a special linker script
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# Make sure only to export the intended __vdso_xxx symbol offsets.
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quiet_cmd_vdsold_and_check = VDSOLD $@
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cmd_vdsold_and_check = $(LD) $(CFI_FULL) $(ld_flags) -T $(filter-out FORCE,$^) -o $@.tmp && \
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$(OBJCOPY) $(patsubst %, -G __vdso_%, $(vdso-syms)) $@.tmp $@ && \
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rm $@.tmp && \
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$(cmd_vdso_check)
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