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
Subject: Re: [PATCH 15/19] x86, mpx: do 32-bit-only cmpxchg for 32-bit apps
Date: Tue, 19 May 2015 10:18:51 +0200 (CEST) [thread overview]
Message-ID: <alpine.DEB.2.11.1505191018380.4225@nanos> (raw)
In-Reply-To: <20150519062534.56F53A63@viggo.jf.intel.com>
On Mon, 18 May 2015, Dave Hansen wrote:
> From: Dave Hansen <dave.hansen@linux.intel.com>
>
> user_atomic_cmpxchg_inatomic() actually looks at sizeof(*ptr) to
> figure out how many bytes to copy. If we run it on a 64-bit
> kernel with a 64-bit pointer, it will copy a 64-bit bounds
> directory entry. That's fine, except when we have 32-bit
> programs with 32-bit bounds directory entries and we only *want*
> 32-bits.
>
> This patch breaks the cmpxchg operation out in to its own
> function and performs the 32-bit type swizzling in there.
>
> Note, the "64-bit" version of this code _would_ work on a
> 32-bit-only kernel. The issue this patch addresses is only for
> when the kernel's 'long' is mismatched from the size of the
> bounds directory entry of the process we are working on.
>
> The new helper modifies 'actual_old_val' or returns an error.
> But gcc doesn't know this, so it warns about 'actual_old_val'
> being unused. Shut it up with an uninitialized_var().
>
> Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
next prev parent reply other threads:[~2015-05-19 8:18 UTC|newest]
Thread overview: 34+ 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
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 [this message]
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
-- strict thread matches above, loose matches on Subject: below --
2015-06-07 18:37 [PATCH 00/19] x86, mpx updates for 4.2 (take 9) Dave Hansen
2015-06-07 18:37 ` [PATCH 15/19] x86, mpx: do 32-bit-only cmpxchg for 32-bit apps Dave Hansen
2015-05-27 18:36 [PATCH 00/19] x86, mpx updates for 4.2 (take 8) Dave Hansen
2015-05-27 18:36 ` [PATCH 15/19] x86, mpx: do 32-bit-only cmpxchg for 32-bit apps Dave Hansen
2015-05-08 18:59 [PATCH 00/19] x86, mpx updates for 4.2 (take 6) Dave Hansen
2015-05-08 18:59 ` [PATCH 15/19] x86, mpx: do 32-bit-only cmpxchg for 32-bit apps Dave Hansen
2015-05-18 21:22 ` Thomas Gleixner
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