From: "Luck, Tony" <tony.luck@intel.com>
To: Balbir Singh <bsingharora@gmail.com>,
Nicholas Piggin <npiggin@gmail.com>
Cc: linux-nvdimm <linux-nvdimm@lists.01.org>,
Michael Ellerman <mpe@ellerman.id.au>,
Matthew Wilcox <mawilcox@microsoft.com>,
linuxppc-dev <linuxppc-dev@lists.ozlabs.org>,
Christoph Hellwig <hch@lst.de>
Subject: RE: [RESEND 2/3] powerpc/memcpy: Add memcpy_mcsafe for pmem
Date: Fri, 6 Apr 2018 15:46:30 +0000 [thread overview]
Message-ID: <3908561D78D1C84285E8C5FCA982C28F7B3C797F@ORSMSX110.amr.corp.intel.com> (raw)
In-Reply-To: <CAKTCnz=LD_uO7bdwFHDHy9KHHJ_dPA1LdxF1Pm7OUFFGr4s_VA@mail.gmail.com>
> I thought the cache-aligned might make sense, since usually we'd expect the
> failure to be at a cache-line level, but our copy_tofrom_user does accurate
> accounting
That's one of the wrinkles in the current x86 memcpy_mcsafe(). It starts by
checking alignment of the source address, and moves a byte at a time until
it is 8-byte aligned. We do this because current x86 implementations do not
gracefully handle an unaligned read that spans from a good cache-line into
a poisoned one.
This is different from copy_tofrom_user which aligns the destination for speed
reasons (unaligned reads have a lower penalty than unaligned writes).
-Tony
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next prev parent reply other threads:[~2018-04-06 15:46 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-04-04 23:19 [RESEND 0/3] Add support for memcpy_mcsafe Balbir Singh
2018-04-04 23:19 ` [RESEND 1/3] powerpc/mce: Bug fixes for MCE handling in kernel space Balbir Singh
2018-04-04 23:49 ` Nicholas Piggin
2018-04-05 1:11 ` Balbir Singh
2018-04-04 23:19 ` [RESEND 2/3] powerpc/memcpy: Add memcpy_mcsafe for pmem Balbir Singh
2018-04-04 23:57 ` Nicholas Piggin
2018-04-05 3:00 ` Dan Williams
2018-04-05 5:04 ` Nicholas Piggin
2018-04-05 5:53 ` Balbir Singh
2018-04-05 6:45 ` Nicholas Piggin
2018-04-05 15:00 ` Dan Williams
2018-05-01 20:57 ` Dan Williams
2018-05-02 12:36 ` Balbir Singh
2018-04-05 20:40 ` Jeff Moyer
2018-04-06 1:26 ` Nicholas Piggin
2018-04-06 9:25 ` Balbir Singh
2018-04-06 15:46 ` Luck, Tony [this message]
2018-04-04 23:19 ` [RESEND 3/3] powerpc/mce: Handle memcpy_mcsafe Balbir Singh
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