Changes since v7 [1]: - Rebased on v5.8-rc5 to resolve a conflict with commit eb25de276505 ("tools arch: Update arch/x86/lib/memcpy_64.S copy used in 'perf bench mem memcpy'")
[1]: http://lore.kernel.org/r/159408043801.2272533.17485467640602344900.stgit@dwi...
--- Vishal, since this patch set has experienced unprecedented silence from x86 folks I expect you will need to send it to Linus directly during the merge window. It merges cleanly with recent -next.
Thomas, Ingo, Boris, please chime in to save Vishal from that awkwardness. I am only going to be sporadically online for the next few weeks.
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The primary motivation to go touch memcpy_mcsafe() is that the existing benefit of doing slow and careful copies is obviated on newer CPUs. That fact solves the problem of needing to detect machine-check recovery capability. Now the old "mcsafe_key" opt-in to careful copying can be made an opt-out from the default fast copy implementation.
The discussion with Linus further made clear that this facility had already lost its x86-machine-check specificity starting with commit 2c89130a56a ("x86/asm/memcpy_mcsafe: Add write-protection-fault handling"). The new changes to not require a "careful copy" further de-emphasizes the role that x86-MCA plays in the implementation to just one more source of recoverable trap during the operation.
With the above realizations the name "mcsafe" is no longer accurate and copy_safe() is proposed as its replacement. x86 grows a copy_safe_fast() implementation as a default implementation that is independent of detecting the presence of x86-MCA.
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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: 11ba468877bb23f28956a35e896356252d63c983