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vdso: Improve cmd_vdso_check to check all dynamic relocations
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 <[email protected]> Signed-off-by: Thomas Gleixner <[email protected]> Tested-by: Vincenzo Frascino <[email protected]> # for aarch64 Reviewed-by: Christophe Leroy <[email protected]> Reviewed-by: Vincenzo Frascino <[email protected]> # for vDSO, aarch64 Acked-by: Michael Ellerman <[email protected]> (powerpc) Link: https://lore.kernel.org/r/[email protected]
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-39
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‎arch/arm/vdso/Makefile

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# SPDX-License-Identifier: GPL-2.0
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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_ARM_JUMP_SLOT|R_ARM_GLOB_DAT|R_ARM_ABS32
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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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hostprogs := vdsomunge

‎arch/arm64/kernel/vdso/Makefile

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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 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

‎arch/arm64/kernel/vdso32/Makefile

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@@ -3,9 +3,6 @@
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# Makefile for vdso32
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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_ARM_JUMP_SLOT|R_ARM_GLOB_DAT|R_ARM_ABS32
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include $(srctree)/lib/vdso/Makefile
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# Same as cc-*option, but using CC_COMPAT instead of CC

‎arch/csky/kernel/vdso/Makefile

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@@ -1,8 +1,6 @@
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# SPDX-License-Identifier: GPL-2.0-only
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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_CKCORE_ADDR32|R_CKCORE_JUMP_SLOT
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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

‎arch/loongarch/vdso/Makefile

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# SPDX-License-Identifier: GPL-2.0
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# Objects to go into the VDSO.
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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_LARCH_32|R_LARCH_64|R_LARCH_MARK_LA|R_LARCH_JUMP_SLOT
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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-y := elf.o vgetcpu.o vgettimeofday.o sigreturn.o

‎arch/mips/vdso/Makefile

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# Sanitizer runtimes are unavailable and cannot be linked here.
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KCSAN_SANITIZE := n
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7-
# 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_MIPS_JUMP_SLOT|R_MIPS_GLOB_DAT
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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-y := elf.o vgettimeofday.o sigreturn.o

‎arch/powerpc/kernel/vdso/Makefile

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# List of files in the vdso, has to be asm only for now
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ARCH_REL_TYPE_ABS := R_PPC_JUMP_SLOT|R_PPC_GLOB_DAT|R_PPC_ADDR32|R_PPC_ADDR24|R_PPC_ADDR16|R_PPC_ADDR16_LO|R_PPC_ADDR16_HI|R_PPC_ADDR16_HA|R_PPC_ADDR14|R_PPC_ADDR14_BRTAKEN|R_PPC_ADDR14_BRNTAKEN|R_PPC_REL24
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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-vdso32 = sigtramp32-32.o gettimeofday-32.o datapage-32.o cacheflush-32.o note-32.o getcpu-32.o

‎arch/riscv/kernel/vdso/Makefile

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# 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 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

‎arch/s390/kernel/vdso32/Makefile

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# List of files in the vdso
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KCOV_INSTRUMENT := n
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ARCH_REL_TYPE_ABS := R_390_COPY|R_390_GLOB_DAT|R_390_JMP_SLOT|R_390_RELATIVE
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ARCH_REL_TYPE_ABS += R_390_GOT|R_390_PLT
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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-vdso32 = vdso_user_wrapper-32.o note-32.o
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‎arch/s390/kernel/vdso64/Makefile

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# List of files in the vdso
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KCOV_INSTRUMENT := n
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ARCH_REL_TYPE_ABS := R_390_COPY|R_390_GLOB_DAT|R_390_JMP_SLOT|R_390_RELATIVE
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ARCH_REL_TYPE_ABS += R_390_GOT|R_390_PLT
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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-vdso64 = vdso_user_wrapper.o note.o
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obj-cvdso64 = vdso64_generic.o getcpu.o

‎arch/x86/entry/vdso/Makefile

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# Building vDSO images for x86.
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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_X86_64_JUMP_SLOT|R_X86_64_GLOB_DAT|R_X86_64_RELATIVE|
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ARCH_REL_TYPE_ABS += R_386_GLOB_DAT|R_386_JMP_SLOT|R_386_RELATIVE
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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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# Sanitizer runtimes are unavailable and cannot be linked here.

‎lib/vdso/Makefile

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@@ -5,18 +5,13 @@ GENERIC_VDSO_DIR := $(dir $(GENERIC_VDSO_MK_PATH))
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c-gettimeofday-$(CONFIG_GENERIC_GETTIMEOFDAY) := $(addprefix $(GENERIC_VDSO_DIR), gettimeofday.c)
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# This cmd checks that the vdso library does not contain absolute relocation
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# This cmd checks that the vdso library does not contain dynamic relocations.
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# It has to be called after the linking of the vdso library and requires it
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# as a parameter.
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#
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# $(ARCH_REL_TYPE_ABS) is defined in the arch specific makefile and corresponds
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# to the absolute relocation types printed by "objdump -R" and accepted by the
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# dynamic linker.
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ifndef ARCH_REL_TYPE_ABS
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$(error ARCH_REL_TYPE_ABS is not set)
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endif
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# As a workaround for some GNU ld ports which produce unneeded R_*_NONE
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# dynamic relocations, ignore R_*_NONE.
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quiet_cmd_vdso_check = VDSOCHK $@
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cmd_vdso_check = if $(OBJDUMP) -R $@ | grep -E -h "$(ARCH_REL_TYPE_ABS)"; \
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cmd_vdso_check = if $(READELF) -rW $@ | grep -v _NONE | grep -q " R_\w*_"; \
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then (echo >&2 "$@: dynamic relocations are not supported"; \
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rm -f $@; /bin/false); fi

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