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From: Thomas Gleixner <tglx@linutronix.de>
To: Dave Hansen <dave@sr71.net>
Cc: linux-kernel@vger.kernel.org, x86@kernel.org,
	dave.hansen@linux.intel.com, oleg@redhat.com, bp@alien8.de,
	riel@redhat.com, sbsiddha@gmail.com, luto@amacapital.net,
	mingo@redhat.com, hpa@zytor.com, fenghua.yu@intel.com
Subject: Re: [PATCH 03/19] x86, mpx: Use new get_xsave_field_ptr()
Date: Tue, 19 May 2015 10:16:12 +0200 (CEST)	[thread overview]
Message-ID: <alpine.DEB.2.11.1505191015580.4225@nanos> (raw)
In-Reply-To: <20150519062529.63C78F4E@viggo.jf.intel.com>

On Mon, 18 May 2015, Dave Hansen wrote:
> From: Dave Hansen <dave.hansen@linux.intel.com>
> 
> The MPX registers (bndcsr/bndcfgu/bndstatus) are not directly
> accessible via normal instructions.  They essentially act as
> if they were floating point registers and are saved/restored
> along with those registers.
> 
> There are two main paths in the MPX code where we care about
> the contents of these registers:
> 	1. #BR (bounds) faults
> 	2. the prctl() code where we are setting MPX up
> 
> Both of those paths _might_ be called without the FPU having
> been used.  That means that 'tsk->thread.fpu.state' might
> never be allocated.
> 
> Also, fpu_save_init() is not preempt-safe.  It was a bug to
> call it without disabling preemption.  The new
> get_xsave_addr() calls unlazy_fpu() instead and properly
> disables preemption.
> 
> Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>

Reviewed-by: Thomas Gleixner <tglx@linutronix.de>

  reply	other threads:[~2015-05-19  8:16 UTC|newest]

Thread overview: 33+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-05-19  6:25 [PATCH 00/19] x86, mpx updates for 4.2 (take 7) Dave Hansen
2015-05-19  6:25 ` [PATCH 01/19] x86, mpx, xsave: Fix up bad get_xsave_addr() assumptions Dave Hansen
2015-05-19  6:25 ` [PATCH 02/19] x86, fpu: Wrap get_xsave_addr() to make it safer Dave Hansen
2015-05-19  8:15   ` Thomas Gleixner
2015-05-19  6:25 ` [PATCH 03/19] x86, mpx: Use new get_xsave_field_ptr() Dave Hansen
2015-05-19  8:16   ` Thomas Gleixner [this message]
2015-05-19  6:25 ` [PATCH 04/19] x86, mpx: Cleanup: Do not pass task around when unnecessary Dave Hansen
2015-05-19  8:16   ` Thomas Gleixner
2015-05-19  6:25 ` [PATCH 05/19] x86, mpx: remove redundant MPX_BNDCFG_ADDR_MASK Dave Hansen
2015-05-19  6:25 ` [PATCH 07/19] x86, mpx: boot-time disable Dave Hansen
2015-05-19  6:25 ` [PATCH 06/19] x86, mpx: Restrict mmap size check to bounds tables Dave Hansen
2015-05-19  6:25 ` [PATCH 08/19] x86, mpx: trace #BR exceptions Dave Hansen
2015-05-19  6:25 ` [PATCH 09/19] x86, mpx: trace entry to bounds exception paths Dave Hansen
2015-05-19  8:17   ` Thomas Gleixner
2015-05-19  6:25 ` [PATCH 11/19] x86, mpx: trace allocation of new bounds tables Dave Hansen
2015-05-19  6:25 ` [PATCH 10/19] x86, mpx: Trace the attempts to find " Dave Hansen
2015-05-19  8:17   ` Thomas Gleixner
2015-05-19  6:25 ` [PATCH 13/19] x86, mpx: Add temporary variable to reduce masking Dave Hansen
2015-05-19  6:25 ` [PATCH 12/19] x86: make is_64bit_mm() widely available Dave Hansen
2015-05-19  6:25 ` [PATCH 17/19] x86, mpx: rewrite unmap code Dave Hansen
2015-05-19  6:25 ` [PATCH 15/19] x86, mpx: do 32-bit-only cmpxchg for 32-bit apps Dave Hansen
2015-05-19  8:18   ` Thomas Gleixner
2015-05-19  6:25 ` [PATCH 14/19] x86, mpx: new directory entry to addr helper Dave Hansen
2015-05-19  6:25 ` [PATCH 16/19] x86, mpx: support 32-bit binaries on 64-bit kernel Dave Hansen
2015-05-19  8:21   ` Thomas Gleixner
2015-05-19  6:25 ` [PATCH 18/19] x86, mpx: do not count MPX VMAs as neighbors when unmapping Dave Hansen
2015-05-19  6:25 ` [PATCH 19/19] x86, mpx: allow mixed binaries again Dave Hansen
2015-05-20 10:05 ` [PATCH 00/19] x86, mpx updates for 4.2 (take 7) Ingo Molnar
2015-05-26 16:49   ` Dave Hansen
2015-05-27 12:18     ` Ingo Molnar
2015-05-27 18:36 [PATCH 00/19] x86, mpx updates for 4.2 (take 8) Dave Hansen
2015-05-27 18:36 ` [PATCH 03/19] x86, mpx: Use new get_xsave_field_ptr() Dave Hansen
2015-05-29 22:34 [PATCH 00/19] x86, mpx updates for 4.2 (take 8) Dave Hansen
2015-05-29 22:34 ` [PATCH 03/19] x86, mpx: Use new get_xsave_field_ptr() Dave Hansen
2015-06-07 18:37 [PATCH 00/19] x86, mpx updates for 4.2 (take 9) Dave Hansen
2015-06-07 18:37 ` [PATCH 03/19] x86, mpx: Use new get_xsave_field_ptr() Dave Hansen

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