ecf78af514
[ Upstream commit50f4dd657a] Even after commit89fd4a1df8("riscv: jump_label: mark arguments as const to satisfy asm constraints"), building with CC_OPTIMIZE_FOR_SIZE + LLVM=1 can reproduce below build error: CC arch/riscv/kernel/vdso/vgettimeofday.o In file included from <built-in>:4: In file included from lib/vdso/gettimeofday.c:5: In file included from include/vdso/datapage.h:17: In file included from include/vdso/processor.h:10: In file included from arch/riscv/include/asm/vdso/processor.h:7: In file included from include/linux/jump_label.h:112: arch/riscv/include/asm/jump_label.h:42:3: error: invalid operand for inline asm constraint 'i' " .option push \n\t" ^ 1 error generated. I think the problem is when "-Os" is passed as CFLAGS, it's removed by "CFLAGS_REMOVE_vgettimeofday.o = $(CC_FLAGS_FTRACE) -Os" which is introduced in commite05d57dcb8("riscv: Fixup __vdso_gettimeofday broke dynamic ftrace"), thus no optimization at all for vgettimeofday.c arm64 does remove "-Os" as well, but it forces "-O2" after removing "-Os". I compared the generated vgettimeofday.o with "-O2" and "-Os", I think no big performance difference. So let's tell the kbuild not to remove "-Os" rather than follow arm64 style. vdso related performance can be improved a lot when building kernel with CC_OPTIMIZE_FOR_SIZE after this commit, ("-Os" VS no optimization) Fixes:e05d57dcb8("riscv: Fixup __vdso_gettimeofday broke dynamic ftrace") Signed-off-by: Jisheng Zhang <jszhang@kernel.org> Tested-by: Conor Dooley <conor.dooley@microchip.com> Link: https://lore.kernel.org/r/20221031182943.2453-1-jszhang@kernel.org Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com> Signed-off-by: Sasha Levin <sashal@kernel.org>
82 lines
2.6 KiB
Makefile
82 lines
2.6 KiB
Makefile
# SPDX-License-Identifier: GPL-2.0-only
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# Copied from arch/tile/kernel/vdso/Makefile
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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_RISCV_32|R_RISCV_64|R_RISCV_JUMP_SLOT
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include $(srctree)/lib/vdso/Makefile
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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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# Files to link into the vdso
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obj-vdso = $(patsubst %, %.o, $(vdso-syms)) note.o
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ccflags-y := -fno-stack-protector
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ifneq ($(c-gettimeofday-y),)
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CFLAGS_vgettimeofday.o += -fPIC -include $(c-gettimeofday-y)
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endif
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# Build rules
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targets := $(obj-vdso) vdso.so vdso.so.dbg vdso.lds vdso-syms.S
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obj-vdso := $(addprefix $(obj)/, $(obj-vdso))
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obj-y += vdso.o vdso-syms.o
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CPPFLAGS_vdso.lds += -P -C -U$(ARCH)
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# Disable -pg to prevent insert call site
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CFLAGS_REMOVE_vgettimeofday.o = $(CC_FLAGS_FTRACE)
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# Disable profiling and instrumentation for VDSO code
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GCOV_PROFILE := n
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KCOV_INSTRUMENT := n
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KASAN_SANITIZE := n
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# Force dependency
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$(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)
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LDFLAGS_vdso.so.dbg = -shared -s -soname=linux-vdso.so.1 \
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--build-id=sha1 --hash-style=both --eh-frame-hdr
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# We also create a special relocatable object that should mirror the symbol
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# table and layout of the linked DSO. With ld --just-symbols we can then
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# refer to these symbols in the kernel code rather than hand-coded addresses.
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$(obj)/vdso-syms.S: $(obj)/vdso.so FORCE
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$(call if_changed,so2s)
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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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# 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 = VDSOLD $@
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cmd_vdsold = $(LD) $(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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# Extracts symbol offsets from the VDSO, converting them into an assembly file
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# that contains the same symbols at the same offsets.
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quiet_cmd_so2s = SO2S $@
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cmd_so2s = $(NM) -D $< | $(srctree)/$(src)/so2s.sh > $@
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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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