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The actual intention is that no dynamic relocation exists in the VDSO. For this the VDSO build validates that the resulting .so file does not have any relocations which are specified via $(ARCH_REL_TYPE_ABS) per architecture, which is fragile as e.g. ARM64 lacks an entry for R_AARCH64_RELATIVE. Aside of that ARCH_REL_TYPE_ABS is a misnomer as it checks for relative relocations too. However, some GNU ld ports produce unneeded R_*_NONE relocation entries. If a port fails to determine the exact .rel[a].dyn size, the trailing zeros become R_*_NONE relocations. E.g. ld's powerpc port recently fixed https://sourceware.org/bugzilla/show_bug.cgi?id=29540). R_*_NONE are generally a no-op in the dynamic loaders. So just ignore them. Remove the ARCH_REL_TYPE_ABS defines and just validate that the resulting .so file does not contain any R_* relocation entries except R_*_NONE. Signed-off-by: Fangrui Song <maskray@google.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Tested-by: Vincenzo Frascino <vincenzo.frascino@arm.com> # for aarch64 Reviewed-by: Christophe Leroy <christophe.leroy@csgroup.eu> Reviewed-by: Vincenzo Frascino <vincenzo.frascino@arm.com> # for vDSO, aarch64 Acked-by: Michael Ellerman <mpe@ellerman.id.au> (powerpc) Link: https://lore.kernel.org/r/20230310190750.3323802-1-maskray@google.com
71 lines
2.1 KiB
Makefile
71 lines
2.1 KiB
Makefile
# SPDX-License-Identifier: GPL-2.0-only
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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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# Symbols present in the vdso
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vdso-syms += rt_sigreturn
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vdso-syms += vgettimeofday
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# Files to link into the vdso
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obj-vdso = $(patsubst %, %.o, $(vdso-syms)) note.o
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ifneq ($(c-gettimeofday-y),)
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CFLAGS_vgettimeofday.o += -include $(c-gettimeofday-y)
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endif
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ccflags-y := -fno-stack-protector -DBUILD_VDSO32
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# Build rules
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targets := $(obj-vdso) vdso.so vdso.so.dbg vdso.lds vdso-dummy.o
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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 gcov profiling for VDSO code
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GCOV_PROFILE := n
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KCOV_INSTRUMENT := n
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# Force dependency
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$(obj)/vdso.o: $(obj)/vdso.so
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SYSCFLAGS_vdso.so.dbg = $(c_flags)
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$(obj)/vdso.so.dbg: $(src)/vdso.lds $(obj-vdso) FORCE
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$(call if_changed,vdsold)
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SYSCFLAGS_vdso.so.dbg = -shared -s -Wl,-soname=linux-vdso.so.1 \
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-Wl,--build-id=sha1 -Wl,--hash-style=both
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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 = $(CC) $(KBUILD_CFLAGS) $(call cc-option, -no-pie) -nostdlib -nostartfiles $(SYSCFLAGS_$(@F)) \
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-Wl,-T,$(filter-out FORCE,$^) -o $@.tmp && \
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$(CROSS_COMPILE)objcopy \
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$(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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