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Message-ID: <159630255616.3143511.18110575960499749012.stgit@dwillia2-desk3.amr.corp.intel.com>
Date: Sat, 01 Aug 2020 10:22:36 -0700
From: Dan Williams <dan.j.williams@...el.com>
To: tglx@...utronix.de, mingo@...hat.com, vishal.l.verma@...el.com
Cc: Tony Luck <tony.luck@...el.com>, Vivek Goyal <vgoyal@...hat.com>,
Peter Zijlstra <peterz@...radead.org>,
Linus Torvalds <torvalds@...ux-foundation.org>,
Alexander Viro <viro@...iv.linux.org.uk>,
Borislav Petkov <bp@...en8.de>, stable@...r.kernel.org,
x86@...nel.org, "H. Peter Anvin" <hpa@...or.com>,
Andy Lutomirski <luto@...nel.org>,
Paul Mackerras <paulus@...ba.org>,
Benjamin Herrenschmidt <benh@...nel.crashing.org>,
Erwin Tsaur <erwin.tsaur@...el.com>,
Michael Ellerman <mpe@...erman.id.au>,
Mikulas Patocka <mpatocka@...hat.com>,
Arnaldo Carvalho de Melo <acme@...nel.org>,
linux-nvdimm@...ts.01.org, linux-kernel@...r.kernel.org
Subject: [PATCH v8 0/2] Renovate memcpy_mcsafe with copy_mc_to_{user,
kernel}
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@dwillia2-desk3.amr.corp.intel.com
---
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.
---
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):
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
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