From: Quentin Casasnovas <quentin.casasnovas@oracle.com>
To: Borislav Petkov <bp@suse.de>
Cc: Quentin Casasnovas <quentin.casasnovas@oracle.com>,
Oleg Nesterov <oleg@redhat.com>,
Dave Hansen <dave.hansen@intel.com>,
Ingo Molnar <mingo@kernel.org>,
Andy Lutomirski <luto@amacapital.net>,
Linus Torvalds <torvalds@linux-foundation.org>,
Pekka Riikonen <priikone@iki.fi>, Rik van Riel <riel@redhat.com>,
Suresh Siddha <sbsiddha@gmail.com>,
LKML <linux-kernel@vger.kernel.org>,
"Yu, Fenghua" <fenghua.yu@intel.com>,
"H. Peter Anvin" <hpa@zytor.com>
Subject: Re: [PATCH RFC 0/2] x86/fpu: avoid "xstate_fault" in xsave_user/xrestore_user
Date: Tue, 17 Mar 2015 11:00:46 +0100 [thread overview]
Message-ID: <20150317100046.GA19131@chrystal.uk.oracle.com> (raw)
In-Reply-To: <20150317094750.GD18917@pd.tnic>
On Tue, Mar 17, 2015 at 10:47:50AM +0100, Borislav Petkov wrote:
> On Mon, Mar 16, 2015 at 11:37:44PM +0100, Quentin Casasnovas wrote:
>
> ...
>
> > __user_insn("btl [var2], %0 \n\t",
> > , /* no outputs, no need for dummy arg */
> > SINGLE_ARG("r" (var1), [var2] "r" (var2)), /* two inputs */
> > "cc");
>
> So this becomes pretty unreadable IMO. And we shouldn't go nuts with
> optimizing this and sacrifice readability a lot.
>
> TBH, I'd much prefer:
>
> if (static_cpu_has_safe(X86_FEATURE_XSAVEOPT)) {
> check_insn(XSAVEOPT, ...);
^
> return;
> }
>
> if (static_cpu_has_safe(X86_FEATURE_XSAVES)) {
> check_insn(XSAVES);
> return;
> }
>
> check_insn(XSAVE, ...)
>
> which is pretty clear.
>
Fair point, but AFAIUI we can't do check_insn(XSAVES) alone as of today,
and the "..." in your "check_isns(XSAVEOPT, ...)" code above would still
need to contain the outputs operands.
My suggestion was to rework (check|user)_insn() so it can accept zero to N
inputs, outputs or clobbers to make it generic enough so the snippet of
code you've written becomes valid, and maybe move those macro where they
can be used for other sub-systems?
Am I missing something?
Quentin
next prev parent reply other threads:[~2015-03-17 9:59 UTC|newest]
Thread overview: 126+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-03-04 18:30 Oops with tip/x86/fpu Dave Hansen
2015-03-04 19:06 ` Oleg Nesterov
2015-03-04 19:12 ` Dave Hansen
2015-03-04 20:06 ` Borislav Petkov
2015-03-05 15:14 ` Oleg Nesterov
[not found] ` <20150305182203.GA4203@redhat.com>
2015-03-05 18:34 ` Dave Hansen
2015-03-05 18:46 ` Oleg Nesterov
2015-03-05 18:41 ` Dave Hansen
2015-03-26 22:37 ` Yu, Fenghua
2015-03-26 22:43 ` Dave Hansen
2015-03-26 22:48 ` Yu, Fenghua
2015-03-27 7:30 ` Quentin Casasnovas
2015-03-27 19:06 ` Oleg Nesterov
2015-03-05 8:38 ` Quentin Casasnovas
2015-03-05 15:13 ` Oleg Nesterov
2015-03-05 18:42 ` Borislav Petkov
2015-03-05 22:16 ` Dave Hansen
2015-03-05 19:51 ` [PATCH 0/1] x86/fpu: math_state_restore() should not blindly disable irqs Oleg Nesterov
2015-03-05 19:51 ` [PATCH 1/1] " Oleg Nesterov
2015-03-05 20:11 ` Ingo Molnar
2015-03-05 21:25 ` Oleg Nesterov
2015-03-06 7:58 ` Ingo Molnar
2015-03-06 13:26 ` Oleg Nesterov
2015-03-06 13:39 ` Oleg Nesterov
2015-03-06 13:46 ` Ingo Molnar
2015-03-06 14:01 ` Oleg Nesterov
2015-03-06 14:17 ` Oleg Nesterov
2015-03-06 15:00 ` David Vrabel
2015-03-06 15:36 ` Oleg Nesterov
2015-03-06 16:15 ` David Vrabel
2015-03-06 16:31 ` Oleg Nesterov
2015-03-06 17:33 ` Linus Torvalds
2015-03-06 18:15 ` Oleg Nesterov
2015-03-06 19:23 ` Andy Lutomirski
2015-03-06 22:00 ` Linus Torvalds
2015-03-06 22:28 ` Andy Lutomirski
2015-03-07 10:36 ` Ingo Molnar
2015-03-07 20:11 ` Linus Torvalds
2015-03-08 8:55 ` Ingo Molnar
2015-03-08 11:38 ` Ingo Molnar
2015-03-08 13:59 ` Andy Lutomirski
2015-03-08 14:38 ` Andy Lutomirski
2015-03-07 10:32 ` Ingo Molnar
2015-03-07 15:38 ` [PATCH 0/1] x86/fpu: x86/fpu: avoid math_state_restore() without used_math() in __restore_xstate_sig() Oleg Nesterov
2015-03-07 15:38 ` [PATCH 1/1] " Oleg Nesterov
2015-03-09 14:07 ` Borislav Petkov
2015-03-09 14:34 ` Oleg Nesterov
2015-03-09 15:18 ` Borislav Petkov
2015-03-09 16:24 ` Oleg Nesterov
2015-03-09 16:53 ` Borislav Petkov
2015-03-09 17:05 ` Oleg Nesterov
2015-03-09 17:23 ` Borislav Petkov
2015-03-16 12:07 ` [tip:x86/urgent] x86/fpu: Avoid " tip-bot for Oleg Nesterov
2015-03-05 20:35 ` [PATCH 0/1] x86/fpu: math_state_restore() should not blindly disable irqs Oleg Nesterov
2015-03-09 17:10 ` [PATCH] x86/fpu: drop_fpu() should not assume that tsk == current Oleg Nesterov
2015-03-09 17:36 ` Rik van Riel
2015-03-09 17:48 ` Borislav Petkov
2015-03-09 18:06 ` Oleg Nesterov
2015-03-09 18:10 ` Borislav Petkov
2015-03-16 12:07 ` [tip:x86/urgent] x86/fpu: Drop_fpu() should not assume that tsk equals current tip-bot for Oleg Nesterov
2015-03-11 17:33 ` [PATCH 0/4] x86/fpu: avoid math_state_restore() on kthread exec Oleg Nesterov
2015-03-11 17:34 ` [PATCH 1/4] x86/fpu: document user_fpu_begin() Oleg Nesterov
2015-03-13 9:47 ` Borislav Petkov
2015-03-13 14:34 ` Oleg Nesterov
2015-03-23 12:20 ` [tip:x86/fpu] x86/fpu: Document user_fpu_begin() tip-bot for Oleg Nesterov
2015-03-11 17:34 ` [PATCH 2/4] x86/fpu: introduce restore_init_xstate() Oleg Nesterov
2015-03-13 10:34 ` Borislav Petkov
2015-03-13 14:39 ` Oleg Nesterov
2015-03-13 15:20 ` Borislav Petkov
2015-03-16 19:05 ` Rik van Riel
2015-03-23 12:20 ` [tip:x86/fpu] x86/fpu: Introduce restore_init_xstate() tip-bot for Oleg Nesterov
2015-03-11 17:34 ` [PATCH 3/4] x86/fpu: use restore_init_xstate() instead of math_state_restore() on kthread exec Oleg Nesterov
2015-03-13 10:48 ` Borislav Petkov
2015-03-13 14:45 ` Oleg Nesterov
2015-03-13 15:51 ` Borislav Petkov
2015-03-23 12:21 ` [tip:x86/fpu] x86/fpu: Use " tip-bot for Oleg Nesterov
2015-03-11 17:35 ` [PATCH 4/4] x86/fpu: don't abuse drop_init_fpu() in flush_thread() Oleg Nesterov
2015-03-13 10:52 ` Borislav Petkov
2015-03-13 14:55 ` Oleg Nesterov
2015-03-13 16:19 ` Borislav Petkov
2015-03-13 16:26 ` Oleg Nesterov
2015-03-13 19:27 ` Borislav Petkov
2015-03-14 14:48 ` Oleg Nesterov
2015-03-15 17:36 ` Borislav Petkov
2015-03-15 18:16 ` Oleg Nesterov
2015-03-15 18:50 ` Borislav Petkov
2015-03-15 20:04 ` Oleg Nesterov
2015-03-15 20:38 ` Borislav Petkov
2015-03-16 9:35 ` Borislav Petkov
2015-03-16 10:28 ` Ingo Molnar
2015-03-16 14:39 ` Oleg Nesterov
2015-03-16 15:26 ` Borislav Petkov
2015-03-16 15:34 ` Andy Lutomirski
2015-03-16 15:35 ` Borislav Petkov
2015-03-13 17:30 ` [PATCH v2 " Oleg Nesterov
2015-03-14 10:55 ` Borislav Petkov
2015-03-14 10:57 ` [PATCH] x86/fpu: Fold __drop_fpu() into its sole user Borislav Petkov
2015-03-14 15:15 ` Oleg Nesterov
2015-03-16 10:27 ` Ingo Molnar
2015-03-23 12:21 ` [tip:x86/fpu] x86/fpu: Don't abuse drop_init_fpu() in flush_thread() tip-bot for Oleg Nesterov
2015-03-13 18:26 ` [PATCH 0/1] x86/cpu: don't allocate fpu->state for swapper/0 Oleg Nesterov
2015-03-13 18:27 ` [PATCH 1/1] " Oleg Nesterov
2015-03-16 10:18 ` Borislav Petkov
2015-03-23 12:22 ` [tip:x86/fpu] x86/fpu: Don't " tip-bot for Oleg Nesterov
2015-03-14 11:16 ` [PATCH 0/1] x86/cpu: don't " Borislav Petkov
2015-03-14 15:13 ` [PATCH 0/1] x86/cpu: kill eager_fpu_init_bp() Oleg Nesterov
2015-03-14 15:13 ` [PATCH 1/1] " Oleg Nesterov
2015-03-16 12:44 ` Borislav Petkov
2015-03-23 12:22 ` [tip:x86/fpu] x86/fpu: Kill eager_fpu_init_bp() tip-bot for Oleg Nesterov
2015-03-15 16:49 ` [PATCH RFC 0/2] x86/fpu: avoid "xstate_fault" in xsave_user/xrestore_user Oleg Nesterov
2015-03-15 16:50 ` [PATCH RFC 1/2] x86: introduce __user_insn() and __check_insn() Oleg Nesterov
2015-03-15 16:50 ` [PATCH RFC 2/2] x86/fpu: change xsave_user() and xrestore_user() to use __user_insn() Oleg Nesterov
2015-03-16 22:43 ` Quentin Casasnovas
2015-03-17 9:35 ` Borislav Petkov
2015-03-16 14:36 ` [PATCH RFC 0/2] x86/fpu: avoid "xstate_fault" in xsave_user/xrestore_user Borislav Petkov
2015-03-16 14:57 ` Oleg Nesterov
2015-03-16 17:58 ` Borislav Petkov
2015-03-16 22:37 ` Quentin Casasnovas
2015-03-17 9:47 ` Borislav Petkov
2015-03-17 10:00 ` Quentin Casasnovas [this message]
2015-03-17 11:20 ` Borislav Petkov
2015-03-17 11:36 ` Quentin Casasnovas
2015-03-17 12:07 ` Borislav Petkov
2015-03-18 9:06 ` Quentin Casasnovas
2015-03-18 9:53 ` Borislav Petkov
2015-03-17 10:07 ` Quentin Casasnovas
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