kernel.git/arch/arm64/kernel/vdso32, branch linux-6.7.y

kbuild: unify vdso_install rules

2023-10-28T12:09:02Z

Currently, there is no standard implementation for vdso_install, leading to various issues: 1. Code duplication Many architectures duplicate similar code just for copying files to the install destination. Some architectures (arm, sparc, x86) create build-id symlinks, introducing more code duplication. 2. Unintended updates of in-tree build artifacts The vdso_install rule depends on the vdso files to install. It may update in-tree build artifacts. This can be problematic, as explained in commit 19514fc665ff ("arm, kbuild: make "make install" not depend on vmlinux"). 3. Broken code in some architectures Makefile code is often copied from one architecture to another without proper adaptation. 'make vdso_install' for parisc does not work. 'make vdso_install' for s390 installs vdso64, but not vdso32. To address these problems, this commit introduces a generic vdso_install rule. Architectures that support vdso_install need to define vdso-install-y in arch/*/Makefile. vdso-install-y lists the files to install. For example, arch/x86/Makefile looks like this: vdso-install-$(CONFIG_X86_64) += arch/x86/entry/vdso/vdso64.so.dbg vdso-install-$(CONFIG_X86_X32_ABI) += arch/x86/entry/vdso/vdsox32.so.dbg vdso-install-$(CONFIG_X86_32) += arch/x86/entry/vdso/vdso32.so.dbg vdso-install-$(CONFIG_IA32_EMULATION) += arch/x86/entry/vdso/vdso32.so.dbg These files will be installed to $(MODLIB)/vdso/ with the .dbg suffix, if exists, stripped away. vdso-install-y can optionally take the second field after the colon separator. This is needed because some architectures install a vdso file as a different base name. The following is a snippet from arch/arm64/Makefile. vdso-install-$(CONFIG_COMPAT_VDSO) += arch/arm64/kernel/vdso32/vdso.so.dbg:vdso32.so This will rename vdso.so.dbg to vdso32.so during installation. If such architectures change their implementation so that the base names match, this workaround will go away. Signed-off-by: Masahiro Yamada Acked-by: Sven Schnelle # s390 Reviewed-by: Nicolas Schier Reviewed-by: Guo Ren Acked-by: Helge Deller # parisc Acked-by: Catalin Marinas Acked-by: Russell King (Oracle)

kbuild: Drop -Wdeclaration-after-statement

2023-06-26T09:14:19Z

With the advent on scope-based resource management it comes really tedious to abide by the contraints of -Wdeclaration-after-statement. It will still be recommeneded to place declarations at the start of a scope where possible, but it will no longer be enforced. Suggested-by: Linus Torvalds Signed-off-by: Peter Zijlstra (Intel) Link: https://lkml.kernel.org/r/CAHk-%3Dwi-RyoUhbChiVaJZoZXheAwnJ7OO%3DGxe85BkPAd93TwDA%40mail.gmail.com

vdso: Improve cmd_vdso_check to check all dynamic relocations

2023-03-21T20:15:34Z

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 Signed-off-by: Thomas Gleixner Tested-by: Vincenzo Frascino # for aarch64 Reviewed-by: Christophe Leroy Reviewed-by: Vincenzo Frascino # for vDSO, aarch64 Acked-by: Michael Ellerman (powerpc) Link: https://lore.kernel.org/r/20230310190750.3323802-1-maskray@google.com

kbuild: upgrade the orphan section warning to an error if CONFIG_WERROR is set

2022-11-01T17:04:52Z

Andrew Cooper suggested upgrading the orphan section warning to a hard link error. However Nathan Chancellor said outright turning the warning into an error with no escape hatch might be too aggressive, as we have had these warnings triggered by new compiler generated sections, and suggested turning orphan sections into an error only if CONFIG_WERROR is set. Kees Cook echoed and emphasized that the mandate from Linus is that we should avoid breaking builds. It wrecks bisection, it causes problems across compiler versions, etc. Thus upgrade the orphan section warning to a hard link error only if CONFIG_WERROR is set. Suggested-by: Andrew Cooper Suggested-by: Nathan Chancellor Signed-off-by: Xin Li Reviewed-by: Nathan Chancellor Tested-by: Nathan Chancellor Signed-off-by: Kees Cook Link: https://lore.kernel.org/r/20221025073023.16137-2-xin3.li@intel.com

arm64: vdso32: Add DWARF_DEBUG

2022-07-01T11:07:43Z

When building the 32-bit vDSO with LLVM 15 and CONFIG_DEBUG_INFO, there are the following orphan section warnings: ld.lld: warning: arch/arm64/kernel/vdso32/note.o:(.debug_abbrev) is being placed in '.debug_abbrev' ld.lld: warning: arch/arm64/kernel/vdso32/note.o:(.debug_info) is being placed in '.debug_info' ld.lld: warning: arch/arm64/kernel/vdso32/note.o:(.debug_str_offsets) is being placed in '.debug_str_offsets' ld.lld: warning: arch/arm64/kernel/vdso32/note.o:(.debug_str) is being placed in '.debug_str' ld.lld: warning: arch/arm64/kernel/vdso32/note.o:(.debug_addr) is being placed in '.debug_addr' ld.lld: warning: arch/arm64/kernel/vdso32/note.o:(.debug_line) is being placed in '.debug_line' ld.lld: warning: arch/arm64/kernel/vdso32/note.o:(.debug_line_str) is being placed in '.debug_line_str' ld.lld: warning: arch/arm64/kernel/vdso32/vgettimeofday.o:(.debug_loclists) is being placed in '.debug_loclists' ld.lld: warning: arch/arm64/kernel/vdso32/vgettimeofday.o:(.debug_abbrev) is being placed in '.debug_abbrev' ld.lld: warning: arch/arm64/kernel/vdso32/vgettimeofday.o:(.debug_info) is being placed in '.debug_info' ld.lld: warning: arch/arm64/kernel/vdso32/vgettimeofday.o:(.debug_rnglists) is being placed in '.debug_rnglists' ld.lld: warning: arch/arm64/kernel/vdso32/vgettimeofday.o:(.debug_str_offsets) is being placed in '.debug_str_offsets' ld.lld: warning: arch/arm64/kernel/vdso32/vgettimeofday.o:(.debug_str) is being placed in '.debug_str' ld.lld: warning: arch/arm64/kernel/vdso32/vgettimeofday.o:(.debug_addr) is being placed in '.debug_addr' ld.lld: warning: arch/arm64/kernel/vdso32/vgettimeofday.o:(.debug_frame) is being placed in '.debug_frame' ld.lld: warning: arch/arm64/kernel/vdso32/vgettimeofday.o:(.debug_line) is being placed in '.debug_line' ld.lld: warning: arch/arm64/kernel/vdso32/vgettimeofday.o:(.debug_line_str) is being placed in '.debug_line_str' These are DWARF5 sections, as that is the implicit default version for clang-14 and newer when just '-g' is used. All DWARF sections are handled by the DWARF_DEBUG macro from include/asm-generic/vmlinux.lds.h so use that macro here to fix the warnings regardless of DWARF version. Fixes: 9d4775b332e1 ("arm64: vdso32: enable orphan handling for VDSO") Signed-off-by: Nathan Chancellor Reviewed-by: Nick Desaulniers Link: https://lore.kernel.org/r/20220630153121.1317045-3-nathan@kernel.org Signed-off-by: Will Deacon

arm64: vdso32: Shuffle .ARM.exidx section above ELF_DETAILS

2022-07-01T11:07:43Z

When building the 32-bit vDSO after commit 5c4fb60816ea ("arm64: vdso32: add ARM.exidx* sections"), ld.lld 11 fails to link: ld.lld: error: could not allocate headers ld.lld: error: unable to place section .text at file offset [0x2A0, 0xBB1]; check your linker script for overflows ld.lld: error: unable to place section .comment at file offset [0xBB2, 0xC8A]; check your linker script for overflows ld.lld: error: unable to place section .symtab at file offset [0xC8C, 0xE0B]; check your linker script for overflows ld.lld: error: unable to place section .strtab at file offset [0xE0C, 0xF1C]; check your linker script for overflows ld.lld: error: unable to place section .shstrtab at file offset [0xF1D, 0xFAA]; check your linker script for overflows ld.lld: error: section .ARM.exidx file range overlaps with .hash >>> .ARM.exidx range is [0x90, 0xCF] >>> .hash range is [0xB4, 0xE3] ld.lld: error: section .hash file range overlaps with .ARM.attributes >>> .hash range is [0xB4, 0xE3] >>> .ARM.attributes range is [0xD0, 0x10B] ld.lld: error: section .ARM.attributes file range overlaps with .dynsym >>> .ARM.attributes range is [0xD0, 0x10B] >>> .dynsym range is [0xE4, 0x133] ld.lld: error: section .ARM.exidx virtual address range overlaps with .hash >>> .ARM.exidx range is [0x90, 0xCF] >>> .hash range is [0xB4, 0xE3] ld.lld: error: section .ARM.exidx load address range overlaps with .hash >>> .ARM.exidx range is [0x90, 0xCF] >>> .hash range is [0xB4, 0xE3] This was fixed in ld.lld 12 with a change to match GNU ld's semantics of placing non-SHF_ALLOC sections after SHF_ALLOC sections. To workaround this issue, move the .ARM.exidx section before the .comment, .symtab, .strtab, and .shstrtab sections (ELF_DETAILS) so that those sections remain contiguous with the .ARM.attributes section. Fixes: 5c4fb60816ea ("arm64: vdso32: add ARM.exidx* sections") Link: https://github.com/llvm/llvm-project/commit/ec29538af2e0886a65f479d6a533956a1c478132 Signed-off-by: Nathan Chancellor Link: https://lore.kernel.org/r/20220630153121.1317045-2-nathan@kernel.org Signed-off-by: Will Deacon

arm64: vdso*: place got/plt sections in .rodata

2022-06-28T16:41:44Z

The vDSO will not contain absolute relocations, so place these sections in .rodata. Signed-off-by: Joey Gouly Link: https://lore.kernel.org/linux-arm-kernel/00abb0c5-6360-0004-353f-e7a88b3bd22c@arm.com/ Cc: Will Deacon Cc: Vincenzo Frascino Link: https://lore.kernel.org/r/20220628151307.35561-3-joey.gouly@arm.com Signed-off-by: Will Deacon

arm64: vdso32: add ARM.exidx* sections

2022-06-28T16:41:44Z

These show up when building with clang+lld. Signed-off-by: Joey Gouly Cc: Will Deacon Cc: Vincenzo Frascino Link: https://lore.kernel.org/r/20220628151307.35561-2-joey.gouly@arm.com Signed-off-by: Will Deacon

arm64: vdso32: enable orphan handling for VDSO

2022-06-23T14:34:59Z

Like vmlinux, enable orphan-handling for the compat VDSO32. This can catch subtle errors that might arise from unexpected sections being included. Signed-off-by: Joey Gouly Cc: Catalin Marinas Cc: Will Deacon Cc: Masahiro Yamada Cc: Vincenzo Frascino Cc: Kees Cook Reviewed-by: Kees Cook Reviewed-by: Vincenzo Frascino Link: https://lore.kernel.org/r/20220510095834.32394-5-joey.gouly@arm.com Signed-off-by: Will Deacon

arm64: vdso32: put ELF related sections in the linker script

2022-06-23T14:34:59Z

Use macros from vmlinux.lds.h to explicitly name sections that are included in the compat VDSO32 output. Signed-off-by: Joey Gouly Cc: Catalin Marinas Cc: Will Deacon Cc: Masahiro Yamada Cc: Vincenzo Frascino Cc: Kees Cook Reviewed-by: Kees Cook Reviewed-by: Vincenzo Frascino Link: https://lore.kernel.org/r/20220510095834.32394-4-joey.gouly@arm.com Signed-off-by: Will Deacon