linux-dev/arch/arm64/kernel/vdso32, branch master

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

arm64: vdso: fix makefile dependency on vdso.so

2022-05-10T11:08:40Z

There is currently no dependency for vdso*-wrap.S on vdso*.so, which means that you can get a build that uses a stale vdso*-wrap.o. In commit a5b8ca97fbf8, the file that includes the vdso.so was moved and renamed from arch/arm64/kernel/vdso/vdso.S to arch/arm64/kernel/vdso-wrap.S, when this happened the Makefile was not updated to force the dependcy on vdso.so. Fixes: a5b8ca97fbf8 ("arm64: do not descend to vdso directories twice") Signed-off-by: Joey Gouly Cc: Masahiro Yamada Cc: Vincenzo Frascino Cc: Catalin Marinas Cc: Will Deacon Link: https://lore.kernel.org/r/20220510102721.50811-1-joey.gouly@arm.com Signed-off-by: Will Deacon

Kbuild: move to -std=gnu11

2022-03-13T08:31:37Z

During a patch discussion, Linus brought up the option of changing the C standard version from gnu89 to gnu99, which allows using variable declaration inside of a for() loop. While the C99, C11 and later standards introduce many other features, most of these are already available in gnu89 as GNU extensions as well. An earlier attempt to do this when gcc-5 started defaulting to -std=gnu11 failed because at the time that caused warnings about designated initializers with older compilers. Now that gcc-5.1 is the minimum compiler version used for building kernels, that is no longer a concern. Similarly, the behavior of 'inline' functions changes between gnu89 using gnu_inline behavior and gnu11 using standard c99+ behavior, but this was taken care of by defining 'inline' to include __attribute__((gnu_inline)) in order to allow building with clang a while ago. Nathan Chancellor reported a new -Wdeclaration-after-statement warning that appears in a system header on arm, this still needs a workaround. The differences between gnu99, gnu11, gnu1x and gnu17 are fairly minimal and mainly impact warnings at the -Wpedantic level that the kernel never enables. Between these, gnu11 is the newest version that is supported by all supported compiler versions, though it is only the default on gcc-5, while all other supported versions of gcc or clang default to gnu1x/gnu17. Link: https://lore.kernel.org/lkml/CAHk-=wiyCH7xeHcmiFJ-YgXUy2Jaj7pnkdKpcovt8fYbVFW3TA@mail.gmail.com/ Link: https://github.com/ClangBuiltLinux/linux/issues/1603 Suggested-by: Linus Torvalds Acked-by: Marco Elver Acked-by: Jani Nikula Acked-by: David Sterba Tested-by: Sedat Dilek Reviewed-by: Alex Shi Reviewed-by: Nick Desaulniers Reviewed-by: Miguel Ojeda Signed-off-by: Arnd Bergmann Reviewed-by: Nathan Chancellor Signed-off-by: Masahiro Yamada

Kbuild: use -Wdeclaration-after-statement

2022-03-13T08:31:10Z

The kernel is moving from using `-std=gnu89` to `-std=gnu11`, permitting the use of additional C11 features such as for-loop initial declarations. One contentious aspect of C99 is that it permits mixed declarations and code, and for now at least, it seems preferable to enforce that declarations must come first. These warnings were already enabled in the kernel itself, but not for KBUILD_USERCFLAGS or the compat VDSO on arch/arm64, which uses a separate set of CFLAGS. This patch fixes an existing violation in modpost.c, which is not reported because of the missing flag in KBUILD_USERCFLAGS: | scripts/mod/modpost.c: In function ‘match’: | scripts/mod/modpost.c:837:3: warning: ISO C90 forbids mixed declarations and code [-Wdeclaration-after-statement] | 837 | const char *endp = p + strlen(p) - 1; | | ^~~~~ Signed-off-by: Mark Rutland [arnd: don't add a duplicate flag to the default set, update changelog] Signed-off-by: Arnd Bergmann Reviewed-by: Nathan Chancellor Reviewed-by: Nick Desaulniers Tested-by: Sedat Dilek # LLVM/Clang v13.0.0 (x86-64) Signed-off-by: Masahiro Yamada

arm64: vdso: remove -nostdlib compiler flag

2021-11-08T10:02:57Z

The -nostdlib option requests the compiler to not use the standard system startup files or libraries when linking. It is effective only when $(CC) is used as a linker driver. Since commit 691efbedc60d ("arm64: vdso: use $(LD) instead of $(CC) to link VDSO"), $(LD) is directly used, hence -nostdlib is unneeded. Signed-off-by: Masahiro Yamada Link: https://lore.kernel.org/r/20211107161802.323125-1-masahiroy@kernel.org Signed-off-by: Will Deacon