linux.git/arch/arm64/kernel/vdso, branch v5.10

Merge tag 'arm64-upstream' of git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux

2020-10-23T16:46:16+00:00

Pull more arm64 updates from Will Deacon:
 "A small selection of further arm64 fixes and updates. Most of these
  are fixes that came in during the merge window, with the exception of
  the HAVE_MOVE_PMD mremap() speed-up which we discussed back in 2018
  and somehow forgot to enable upstream.

   - Improve performance of Spectre-v2 mitigation on Falkor CPUs (if
     you're lucky enough to have one)

   - Select HAVE_MOVE_PMD. This has been shown to improve mremap()
     performance, which is used heavily by the Android runtime GC, and
     it seems we forgot to enable this upstream back in 2018.

   - Ensure linker flags are consistent between LLVM and BFD

   - Fix stale comment in Spectre mitigation rework

   - Fix broken copyright header

   - Fix KASLR randomisation of the linear map

   - Prevent arm64-specific prctl()s from compat tasks (return -EINVAL)"

Link: https://lore.kernel.org/kvmarm/20181108181201.88826-3-joelaf@google.com/

* tag 'arm64-upstream' of git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux:
  arm64: proton-pack: Update comment to reflect new function name
  arm64: spectre-v2: Favour CPU-specific mitigation at EL2
  arm64: link with -z norelro regardless of CONFIG_RELOCATABLE
  arm64: Fix a broken copyright header in gen_vdso_offsets.sh
  arm64: mremap speedup - Enable HAVE_MOVE_PMD
  arm64: mm: use single quantity to represent the PA to VA translation
  arm64: reject prctl(PR_PAC_RESET_KEYS) on compat tasks

Merge tag 'kbuild-v5.10' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild

2020-10-22T20:13:57+00:00

Pull Kbuild updates from Masahiro Yamada:

 - Support 'make compile_commands.json' to generate the compilation
   database more easily, avoiding stale entries

 - Support 'make clang-analyzer' and 'make clang-tidy' for static checks
   using clang-tidy

 - Preprocess scripts/modules.lds.S to allow CONFIG options in the
   module linker script

 - Drop cc-option tests from compiler flags supported by our minimal
   GCC/Clang versions

 - Use always 12-digits commit hash for CONFIG_LOCALVERSION_AUTO=y

 - Use sha1 build id for both BFD linker and LLD

 - Improve deb-pkg for reproducible builds and rootless builds

 - Remove stale, useless scripts/namespace.pl

 - Turn -Wreturn-type warning into error

 - Fix build error of deb-pkg when CONFIG_MODULES=n

 - Replace 'hostname' command with more portable 'uname -n'

 - Various Makefile cleanups

* tag 'kbuild-v5.10' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild: (34 commits)
  kbuild: Use uname for LINUX_COMPILE_HOST detection
  kbuild: Only add -fno-var-tracking-assignments for old GCC versions
  kbuild: remove leftover comment for filechk utility
  treewide: remove DISABLE_LTO
  kbuild: deb-pkg: clean up package name variables
  kbuild: deb-pkg: do not build linux-headers package if CONFIG_MODULES=n
  kbuild: enforce -Werror=return-type
  scripts: remove namespace.pl
  builddeb: Add support for all required debian/rules targets
  builddeb: Enable rootless builds
  builddeb: Pass -n to gzip for reproducible packages
  kbuild: split the build log of kallsyms
  kbuild: explicitly specify the build id style
  scripts/setlocalversion: make git describe output more reliable
  kbuild: remove cc-option test of -Werror=date-time
  kbuild: remove cc-option test of -fno-stack-check
  kbuild: remove cc-option test of -fno-strict-overflow
  kbuild: move CFLAGS_{KASAN,UBSAN,KCSAN} exports to relevant Makefiles
  kbuild: remove redundant CONFIG_KASAN check from scripts/Makefile.kasan
  kbuild: do not create built-in objects for external module builds
  ...

treewide: remove DISABLE_LTO

2020-10-20T15:28:53+00:00

This change removes all instances of DISABLE_LTO from
Makefiles, as they are currently unused, and the preferred
method of disabling LTO is to filter out the flags instead.

Note added by Masahiro Yamada:
DISABLE_LTO was added as preparation for GCC LTO, but GCC LTO was
not pulled into the mainline. (https://lkml.org/lkml/2014/4/8/272)

Suggested-by: Kees Cook 
Signed-off-by: Sami Tolvanen 
Reviewed-by: Kees Cook 
Signed-off-by: Masahiro Yamada

arm64: Fix a broken copyright header in gen_vdso_offsets.sh

2020-10-20T11:33:01+00:00

I was going to copy this but I didn't want to chase around the build
system stuff so I did it a different way.

Signed-off-by: Palmer Dabbelt 
Link: https://lore.kernel.org/r/20201017002637.503579-1-palmer@dabbelt.com
Signed-off-by: Will Deacon

Revert "arm64: vdso: Fix compilation with clang older than 8"

2020-10-14T01:38:26+00:00

This reverts commit 3acf4be235280f14d838581a750532219d67facc.

The minimum supported version of clang is clang 10.0.1.

Suggested-by: Nathan Chancellor 
Signed-off-by: Nick Desaulniers 
Signed-off-by: Andrew Morton 
Reviewed-by: Kees Cook 
Reviewed-by: Nathan Chancellor 
Cc: Andrey Konovalov 
Cc: Fangrui Song 
Cc: Marco Elver 
Cc: Miguel Ojeda 
Cc: Sedat Dilek 
Cc: Alexei Starovoitov 
Cc: Daniel Borkmann 
Cc: Masahiro Yamada 
Cc: Vincenzo Frascino 
Cc: Will Deacon 
Link: https://lkml.kernel.org/r/20200902225911.209899-5-ndesaulniers@google.com
Signed-off-by: Linus Torvalds

kbuild: explicitly specify the build id style

2020-10-09T14:57:30+00:00

ld's --build-id defaults to "sha1" style, while lld defaults to "fast".
The build IDs are very different between the two, which may confuse
programs that reference them.

Signed-off-by: Bill Wendling 
Acked-by: David S. Miller 
Signed-off-by: Masahiro Yamada

arch: vdso: add vdso linker script to 'targets' instead of extra-y

2020-09-07T12:41:27+00:00

The vdso linker script is preprocessed on demand.
Adding it to 'targets' is enough to include the .cmd file.

Signed-off-by: Masahiro Yamada 
Acked-by: Catalin Marinas 
Acked-by: Greentime Hu

arm64/vdso: Add time namespace page

2020-07-24T12:15:20+00:00

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 
Reviewed-by: Vincenzo Frascino 
Reviewed-by: Dmitry Safonov 
Cc: Mark Rutland 
Link: https://lore.kernel.org/r/20200624083321.144975-4-avagin@gmail.com
Signed-off-by: Catalin Marinas

arm64: vdso: Don't use gcc plugins for building vgettimeofday.c

2020-06-24T13:04:44+00:00

Don't use gcc plugins for building arch/arm64/kernel/vdso/vgettimeofday.c
to avoid unneeded instrumentation.

Signed-off-by: Alexander Popov 
Link: https://lore.kernel.org/r/20200624123330.83226-4-alex.popov@linux.com
Signed-off-by: Will Deacon

arm64: vdso: Only pass --no-eh-frame-hdr when linker supports it

2020-06-24T12:23:10+00:00

Commit 87676cfca141 ("arm64: vdso: Disable dwarf unwinding through the
sigreturn trampoline") unconditionally passes the '--no-eh-frame-hdr'
option to the linker when building the native vDSO in an attempt to
prevent generation of the .eh_frame_hdr section, the presence of which
has been implicated in segfaults originating from the libgcc unwinder.

Unfortunately, not all versions of binutils support this option, which
has been shown to cause build failures in linux-next:

  |   CALL    scripts/atomic/check-atomics.sh
  |   CALL    scripts/checksyscalls.sh
  |   LD      arch/arm64/kernel/vdso/vdso.so.dbg
  | ld: unrecognized option '--no-eh-frame-hdr'
  | ld: use the --help option for usage information
  | arch/arm64/kernel/vdso/Makefile:64: recipe for target
  | 'arch/arm64/kernel/vdso/vdso.so.dbg' failed
  | make[1]: *** [arch/arm64/kernel/vdso/vdso.so.dbg] Error 1
  | arch/arm64/Makefile:175: recipe for target 'vdso_prepare' failed
  | make: *** [vdso_prepare] Error 2

Only link the vDSO with '--no-eh-frame-hdr' when the linker supports it.
If we end up with the section due to linker defaults, the absence of CFI
information in the sigreturn trampoline will prevent the unwinder from
breaking.

Link: https://lore.kernel.org/r/7a7e31a8-9a7b-2428-ad83-2264f20bdc2d@hisilicon.com
Fixes: 87676cfca141 ("arm64: vdso: Disable dwarf unwinding through the sigreturn trampoline")
Reported-by: Shaokun Zhang 
Tested-by: Jon Hunter 
Signed-off-by: Will Deacon