From: Borislav Petkov <bp@alien8.de>
To: Dave Hansen <dave@sr71.net>
Cc: linux-kernel@vger.kernel.org, x86@kernel.org, tglx@linutronix.de,
dave.hansen@linux.intel.com, oleg@redhat.com, riel@redhat.com,
sbsiddha@gmail.com, luto@amacapital.net, mingo@redhat.com,
hpa@zytor.com, fenghua.yu@intel.com
Subject: Re: [PATCH 01/16] x86, fpu: wrap get_xsave_addr() to make it safer
Date: Wed, 22 Apr 2015 12:40:47 +0200 [thread overview]
Message-ID: <20150422104047.GA6897@pd.tnic> (raw)
In-Reply-To: <20150401004624.49096AD0@viggo.jf.intel.com>
On Tue, Mar 31, 2015 at 05:46:24PM -0700, Dave Hansen wrote:
> +/*
> + * This wraps up the common operations that need to occur when retrieving
> + * data from an xsave struct. It first ensures that the task was actually
> + * using the FPU and retrieves the data in to a buffer. It then calculates
> + * the offset of the requested field in the buffer.
> + *
> + * This function is safe to call whether the FPU is in use or not.
> + *
> + * Inputs:
> + * @tsk: the task from which we are fetching xsave state
> + * @xsave_field: state which is defined in xsave.h (e.g. XSTATE_FP,
> + * XSTATE_SSE, etc...)
> + * Output:
> + * address of the state in the xsave area.
> + */
> +void *tsk_get_xsave_field(struct task_struct *tsk, int xsave_field)
> +{
> + union thread_xstate *xstate;
> +
> + if (!used_math())
> + return NULL;
Shouldn't this be
if (!tsk_used_math(tsk))
?
Because used_math() is looking at current, maybe even in
preemption-enabled paths - I'm eyeing task_get_bounds_dir() - and
that current might get changed from under us and it might happen that
current != tsk. Yes, no?
> + /*
> + * unlazy_fpu() is poorly named and will actually
> + * save the xstate off in to the memory buffer.
> + */
> + unlazy_fpu(tsk);
> + xstate = tsk->thread.fpu.state;
> +
> + return get_xsave_addr(&xstate->xsave, xsave_field);
And I understand this as "give me the xsave address of @tsk".
Right?
Thanks.
--
Regards/Gruss,
Boris.
ECO tip #101: Trim your mails when you reply.
--
next prev parent reply other threads:[~2015-04-22 10:40 UTC|newest]
Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-04-01 0:46 [PATCH 00/16] x86, mpx updates for 4.1 (take 4) Dave Hansen
2015-04-01 0:46 ` [PATCH 01/16] x86, fpu: wrap get_xsave_addr() to make it safer Dave Hansen
2015-04-22 10:40 ` Borislav Petkov [this message]
2015-04-22 13:16 ` Oleg Nesterov
2015-04-22 13:31 ` Borislav Petkov
2015-04-22 14:56 ` Dave Hansen
2015-04-22 15:17 ` Thomas Gleixner
2015-04-22 15:21 ` Borislav Petkov
2015-04-22 15:26 ` Thomas Gleixner
2015-04-22 16:02 ` Dave Hansen
2015-04-22 15:32 ` Oleg Nesterov
2015-04-22 15:58 ` Borislav Petkov
2015-04-01 0:46 ` [PATCH 02/16] x86, mpx: use new tsk_get_xsave_addr() Dave Hansen
2015-04-01 0:46 ` [PATCH 03/16] x86, mpx: trace #BR exceptions Dave Hansen
2015-04-01 0:46 ` [PATCH 04/16] x86, mpx: trace entry to bounds exception paths Dave Hansen
2015-04-01 0:46 ` [PATCH 05/16] x86, mpx: trace ranged MPX operations Dave Hansen
2015-04-01 0:46 ` [PATCH 06/16] x86, mpx: trace allocation of new bounds tables Dave Hansen
2015-04-01 0:46 ` [PATCH 07/16] x86, mpx: boot-time disable Dave Hansen
2015-04-01 0:46 ` [PATCH 08/16] x86: make is_64bit_mm() widely available Dave Hansen
2015-04-01 0:46 ` [PATCH 09/16] x86: make __VIRTUAL_MASK safe to use on 32 bit Dave Hansen
2015-04-01 0:46 ` [PATCH 10/16] x86, mpx: we do not allocate the bounds directory Dave Hansen
2015-04-01 0:46 ` [PATCH 11/16] x86, mpx: remove redundant MPX_BNDCFG_ADDR_MASK Dave Hansen
2015-04-01 0:46 ` [PATCH 12/16] x86, mpx: Add temporary variable to reduce masking Dave Hansen
2015-04-01 0:46 ` [PATCH 13/16] x86, mpx: new directory entry to addr helper Dave Hansen
2015-04-01 0:46 ` [PATCH 14/16] x86, mpx: do 32-bit-only cmpxchg for 32-bit apps Dave Hansen
2015-04-01 0:46 ` [PATCH 15/16] x86, mpx: support 32-bit binaries on 64-bit kernel Dave Hansen
2015-04-01 0:46 ` [PATCH 16/16] x86, mpx: allow mixed binaries again Dave Hansen
2015-04-21 15:39 ` [PATCH 00/16] x86, mpx updates for 4.1 (take 4) Dave Hansen
2015-04-22 10:49 ` Borislav Petkov
2015-04-22 14:43 ` Dave Hansen
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20150422104047.GA6897@pd.tnic \
--to=bp@alien8.de \
--cc=dave.hansen@linux.intel.com \
--cc=dave@sr71.net \
--cc=fenghua.yu@intel.com \
--cc=hpa@zytor.com \
--cc=linux-kernel@vger.kernel.org \
--cc=luto@amacapital.net \
--cc=mingo@redhat.com \
--cc=oleg@redhat.com \
--cc=riel@redhat.com \
--cc=sbsiddha@gmail.com \
--cc=tglx@linutronix.de \
--cc=x86@kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).