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: 9d4775b332 ("arm64: vdso32: enable orphan handling for VDSO")
Signed-off-by: Nathan Chancellor <nathan@kernel.org>
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
Link: https://lore.kernel.org/r/20220630153121.1317045-3-nathan@kernel.org
Signed-off-by: Will Deacon <will@kernel.org>
When building the 32-bit vDSO after commit 5c4fb60816 ("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: 5c4fb60816 ("arm64: vdso32: add ARM.exidx* sections")
Link: ec29538af2
Signed-off-by: Nathan Chancellor <nathan@kernel.org>
Link: https://lore.kernel.org/r/20220630153121.1317045-2-nathan@kernel.org
Signed-off-by: Will Deacon <will@kernel.org>
Allocate the time namespace page among VVAR pages. Provide
__arch_get_timens_vdso_data() helper for VDSO code to get the
code-relative position of VVARs on that special page.
If a task belongs to a time namespace then the VVAR page which contains
the system wide VDSO data is replaced with a namespace specific page
which has the same layout as the VVAR page. That page has vdso_data->seq
set to 1 to enforce the slow path and vdso_data->clock_mode set to
VCLOCK_TIMENS to enforce the time namespace handling path.
The extra check in the case that vdso_data->seq is odd, e.g. a concurrent
update of the VDSO data is in progress, is not really affecting regular
tasks which are not part of a time namespace as the task is spin waiting
for the update to finish and vdso_data->seq to become even again.
If a time namespace task hits that code path, it invokes the corresponding
time getter function which retrieves the real VVAR page, reads host time
and then adds the offset for the requested clock which is stored in the
special VVAR page.
The time-namespace page isn't allocated on !CONFIG_TIME_NAMESPACE, but
vma is the same size, which simplifies criu/vdso migration between
different kernel configs.
Signed-off-by: Andrei Vagin <avagin@gmail.com>
Reviewed-by: Vincenzo Frascino <vincenzo.frascino@arm.com>
Reviewed-by: Dmitry Safonov <dima@arista.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Link: https://lore.kernel.org/r/20200624083321.144975-4-avagin@gmail.com
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
