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Message-ID: <158823509800.2094061.9683997333958344535.stgit@dwillia2-desk3.amr.corp.intel.com>
Date: Thu, 30 Apr 2020 01:24:58 -0700
From: Dan Williams <dan.j.williams@...el.com>
To: tglx@...utronix.de, mingo@...hat.com
Cc: Tony Luck <tony.luck@...el.com>,
Peter Zijlstra <peterz@...radead.org>,
Linus Torvalds <torvalds@...ux-foundation.org>,
Borislav Petkov <bp@...en8.de>, stable@...r.kernel.org,
x86@...nel.org, "H. Peter Anvin" <hpa@...or.com>,
Paul Mackerras <paulus@...ba.org>,
Benjamin Herrenschmidt <benh@...nel.crashing.org>,
Erwin Tsaur <erwin.tsaur@...el.com>,
Michael Ellerman <mpe@...erman.id.au>,
Arnaldo Carvalho de Melo <acme@...nel.org>,
linux-nvdimm@...ts.01.org, linux-kernel@...r.kernel.org
Subject: [PATCH v2 0/2] Replace and improve "mcsafe" with copy_safe()
Changes since v1:
- Rename memcpy_mcsafe() to copy_safe() since the x86-machine-check
specifics have already been de-emphasized in a previous commit and are
further de-emphasized by these changes. (Linus)
- Move copy_safe() out-of-line since it no longer reverts to plain
memcpy (Linus)
- Move copy_safe() to its own stand-alone compilation unit where it no
longer entangles with arch/x86/lib/memcpy_64.S. This also allows perf
to stop tracking ongoing updates to that file due to copy_safe()
updates. (Linus)
- Move the PowerPC implementation over to the new name.
[1]: http://lore.kernel.org/r/158654083112.1572482.8944305411228188871.stgit@dwillia2-desk3.amr.corp.intel.com
---
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.
---
Dan Williams (2):
copy_safe: Rename memcpy_mcsafe() to copy_safe()
x86/copy_safe: Introduce copy_safe_fast()
arch/powerpc/Kconfig | 2
arch/powerpc/include/asm/string.h | 2
arch/powerpc/include/asm/uaccess.h | 4
arch/powerpc/lib/Makefile | 2
arch/powerpc/lib/copy_safe.S | 4
arch/x86/Kconfig | 2
arch/x86/Kconfig.debug | 2
arch/x86/include/asm/copy_safe.h | 18 ++
arch/x86/include/asm/copy_safe_test.h | 75 +++++++++
arch/x86/include/asm/mcsafe_test.h | 75 ---------
arch/x86/include/asm/string_64.h | 32 ----
arch/x86/include/asm/uaccess_64.h | 21 ---
arch/x86/kernel/cpu/mce/core.c | 9 -
arch/x86/kernel/quirks.c | 10 -
arch/x86/lib/Makefile | 1
arch/x86/lib/copy_safe.c | 66 ++++++++
arch/x86/lib/copy_safe_64.S | 163 ++++++++++++++++++++
arch/x86/lib/memcpy_64.S | 115 --------------
arch/x86/lib/usercopy_64.c | 21 ---
drivers/md/dm-writecache.c | 12 +
drivers/nvdimm/claim.c | 2
drivers/nvdimm/pmem.c | 6 -
include/linux/string.h | 17 +-
include/linux/uio.h | 10 +
lib/Kconfig | 2
lib/iov_iter.c | 36 ++--
tools/arch/x86/include/asm/copy_safe_test.h | 13 ++
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 | 49 +++---
.../testing/selftests/powerpc/copyloops/.gitignore | 2
tools/testing/selftests/powerpc/copyloops/Makefile | 6 -
.../selftests/powerpc/copyloops/copy_safe.S | 0
36 files changed, 429 insertions(+), 508 deletions(-)
rename arch/powerpc/lib/{memcpy_mcsafe_64.S => copy_safe.S} (98%)
create mode 100644 arch/x86/include/asm/copy_safe.h
create mode 100644 arch/x86/include/asm/copy_safe_test.h
delete mode 100644 arch/x86/include/asm/mcsafe_test.h
create mode 100644 arch/x86/lib/copy_safe.c
create mode 100644 arch/x86/lib/copy_safe_64.S
create mode 100644 tools/arch/x86/include/asm/copy_safe_test.h
delete mode 100644 tools/arch/x86/include/asm/mcsafe_test.h
delete mode 100644 tools/perf/bench/mem-memcpy-x86-64-lib.c
rename tools/testing/selftests/powerpc/copyloops/{memcpy_mcsafe_64.S => copy_safe.S} (100%)
base-commit: b8dcd632c06b8706d22934f9bf9bf16a42b1ecc7
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