From: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
To: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Jason Gunthorpe <jgg@ziepe.ca>,
James Bottomley <James.Bottomley@hansenpartnership.com>,
linux-integrity@vger.kernel.org,
linux-security-module@vger.kernel.org,
Linux List Kernel Mailing <linux-kernel@vger.kernel.org>
Subject: Re: Getting weird TPM error after rebasing my tree to security/next-general
Date: Tue, 29 Jan 2019 15:20:16 +0200 [thread overview]
Message-ID: <20190129132016.GA1602@linux.intel.com> (raw)
In-Reply-To: <CAHk-=whgoJ8aAYH37hnyFjZ8jbYyswyf9wZZ82tTFL5f2he+6g@mail.gmail.com>
On Thu, Jan 24, 2019 at 07:43:30AM +1300, Linus Torvalds wrote:
> On Thu, Jan 24, 2019 at 4:36 AM Jarkko Sakkinen
> <jarkko.sakkinen@linux.intel.com> wrote:
> > >
> > > Is it just that this particular hardware always happened to trigger
> > > the ERMS case (ie "rep movsb")?
> >
> > This is the particular snippet in question:
> >
> > memcpy_fromio(buf, priv->rsp, 6);
> > expected = be32_to_cpup((__be32 *) &buf[2]);
> > if (expected > count || expected < 6)
> > return -EIO;
>
> Ok, strange.
>
> So what *used* to happen is that the memcpy_fromio() would just expand
> as a "memcpy()", and in this case, gcc would then inline the memcpy().
> In fact, gcc does it as a 4-byte access and a two-byte access from
> what I can tell.
I verified, and it is exactly as you stated:
0xffffffff814aaa33 <+51>: mov (%rax),%edx
0xffffffff814aaa35 <+53>: mov %edx,0x0(%rbp)
0xffffffff814aaa38 <+56>: movzwl 0x4(%rax),%eax
0xffffffff814aaa3c <+60>: mov %ax,0x4(%rbp)
And your new version does exactly the same thing to the first six bytes
(with different opcode, but the same memory access pattern).
/Jarkko
next prev parent reply other threads:[~2019-01-29 13:20 UTC|newest]
Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-01-18 14:25 Getting weird TPM error after rebasing my tree to security/next-general Jarkko Sakkinen
2019-01-18 22:09 ` James Bottomley
2019-01-20 16:04 ` Jarkko Sakkinen
2019-01-22 1:02 ` Jarkko Sakkinen
2019-01-22 2:58 ` Jason Gunthorpe
2019-01-22 13:29 ` Jarkko Sakkinen
2019-01-22 18:26 ` Linus Torvalds
2019-01-23 15:36 ` Jarkko Sakkinen
2019-01-23 18:43 ` Linus Torvalds
2019-01-29 13:20 ` Jarkko Sakkinen [this message]
2019-01-31 12:26 ` Jarkko Sakkinen
2019-01-31 16:04 ` Jarkko Sakkinen
2019-01-31 17:06 ` Jarkko Sakkinen
2019-01-31 17:43 ` Linus Torvalds
2019-01-31 18:47 ` Jarkko Sakkinen
2019-01-31 18:35 ` Jarkko Sakkinen
2019-01-31 18:51 ` Linus Torvalds
2019-01-31 18:52 ` Linus Torvalds
2019-01-31 19:10 ` Linus Torvalds
2019-01-31 19:47 ` Winkler, Tomas
2019-02-01 8:12 ` Jarkko Sakkinen
2019-01-31 20:07 ` Winkler, Tomas
2019-01-31 20:47 ` Jarkko Sakkinen
2019-01-31 21:58 ` Linus Torvalds
2019-01-31 23:31 ` Jerry Snitselaar
2019-02-01 11:40 ` Jarkko Sakkinen
2019-01-31 20:45 ` Jarkko Sakkinen
2019-02-01 18:04 ` Linus Torvalds
2019-02-04 11:58 ` Jarkko Sakkinen
2019-01-23 20:11 ` Jarkko Sakkinen
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