[v4,0/2] Renovate memcpy_mcsafe with copy_mc_to_{user, kernel}

Message

Dan Williams May 21, 2020, 10:47 p.m. UTC

Changes since v3 [1]:
- Drop extern for new function declarations (Michael)

- Rename memcpy_mcsafe_64.S to copy_mc_64.S instead of copy_mc.S and
  related fixups (Michael)

- Add a new symlink
  (tools/testing/selftests/powerpc/copyloops/copy_mc_64.S) to the new
  copy_mc_64.S to fix selftest build breakage (Michael)

- Drop one instance of copy_safe() that survived from v2 of the patchset
  (Vivek)

- Fix 32-bit x86 build breakage (kbuild robot)

- Kill off rather than rename tools/arch/x86/include/asm/mcsafe_test.h
  since perf is no longer burden with dealing with the copy_mc_generic()
  implementation.

- Build success notification received for revised set (kbuild robot)

[1]: http://lore.kernel.org/r/[e-mail]

---

The primary motivation to go touch memcpy_mcsafe() is that the existing
benefit of doing slow "handle with care" copies is obviated on newer
CPUs. With that concern lifted it also obviates the need to continue to
update the MCA-recovery capability detection code currently gated by
"mcsafe_key". Now the old "mcsafe_key" opt-in to perform the copy with
concerns for recovery fragility can instead be made an opt-out from the
default fast copy implementation (enable_copy_mc_fragile()).

The discussion with Linus on the first iteration of this patch
identified that memcpy_mcsafe() was misnamed relative to its usage. The
new names copy_mc_to_user() and copy_mc_to_kernel() clearly indicate the
intended use case and lets the architecture organize the implementation
accordingly.

For both powerpc and x86 a copy_mc_generic() implementation is added as
the backend for these interfaces.

Patches are relative to tip/master.

---

Dan Williams (2):
      x86, powerpc: Rename memcpy_mcsafe() to copy_mc_to_{user,kernel}()
      x86/copy_mc: Introduce copy_mc_generic()


 arch/powerpc/Kconfig                               |    2 
 arch/powerpc/include/asm/string.h                  |    2 
 arch/powerpc/include/asm/uaccess.h                 |   40 +++--
 arch/powerpc/lib/Makefile                          |    2 
 arch/powerpc/lib/copy_mc_64.S                      |    4 
 arch/x86/Kconfig                                   |    2 
 arch/x86/Kconfig.debug                             |    2 
 arch/x86/include/asm/copy_mc_test.h                |   75 +++++++++
 arch/x86/include/asm/mcsafe_test.h                 |   75 ---------
 arch/x86/include/asm/string_64.h                   |   32 ----
 arch/x86/include/asm/uaccess.h                     |   21 +++
 arch/x86/include/asm/uaccess_64.h                  |   20 --
 arch/x86/kernel/cpu/mce/core.c                     |    8 -
 arch/x86/kernel/quirks.c                           |    9 -
 arch/x86/lib/Makefile                              |    1 
 arch/x86/lib/copy_mc.c                             |   64 ++++++++
 arch/x86/lib/copy_mc_64.S                          |  165 ++++++++++++++++++++
 arch/x86/lib/memcpy_64.S                           |  115 --------------
 arch/x86/lib/usercopy_64.c                         |   21 ---
 drivers/md/dm-writecache.c                         |   15 +-
 drivers/nvdimm/claim.c                             |    2 
 drivers/nvdimm/pmem.c                              |    6 -
 include/linux/string.h                             |    9 -
 include/linux/uaccess.h                            |    9 +
 include/linux/uio.h                                |   10 +
 lib/Kconfig                                        |    7 +
 lib/iov_iter.c                                     |   43 +++--
 tools/arch/x86/include/asm/mcsafe_test.h           |   13 --
 tools/arch/x86/lib/memcpy_64.S                     |  115 --------------
 tools/objtool/check.c                              |    5 -
 tools/perf/bench/Build                             |    1 
 tools/perf/bench/mem-memcpy-x86-64-lib.c           |   24 ---
 tools/testing/nvdimm/test/nfit.c                   |   48 +++---
 .../testing/selftests/powerpc/copyloops/.gitignore |    2 
 tools/testing/selftests/powerpc/copyloops/Makefile |    6 -
 .../selftests/powerpc/copyloops/copy_mc_64.S       |    1 
 .../selftests/powerpc/copyloops/memcpy_mcsafe_64.S |    1 
 37 files changed, 451 insertions(+), 526 deletions(-)
 rename arch/powerpc/lib/{memcpy_mcsafe_64.S => copy_mc_64.S} (98%)
 create mode 100644 arch/x86/include/asm/copy_mc_test.h
 delete mode 100644 arch/x86/include/asm/mcsafe_test.h
 create mode 100644 arch/x86/lib/copy_mc.c
 create mode 100644 arch/x86/lib/copy_mc_64.S
 delete mode 100644 tools/arch/x86/include/asm/mcsafe_test.h
 delete mode 100644 tools/perf/bench/mem-memcpy-x86-64-lib.c
 create mode 120000 tools/testing/selftests/powerpc/copyloops/copy_mc_64.S
 delete mode 120000 tools/testing/selftests/powerpc/copyloops/memcpy_mcsafe_64.S

base-commit: bba413deb1065f1291cb1f366247513f11215520