From: Ingo Molnar <mingo@kernel.org>
To: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Tony Luck <tony.luck@intel.com>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
Peter Zijlstra <a.p.zijlstra@chello.nl>,
Thomas Gleixner <tglx@linutronix.de>,
"H. Peter Anvin" <hpa@zytor.com>
Subject: Re: [PATCH v11 3/4] x86, mce: Add __mcsafe_copy()
Date: Thu, 18 Feb 2016 19:51:16 +0100 [thread overview]
Message-ID: <20160218185116.GB16753@gmail.com> (raw)
In-Reply-To: <CA+55aFzJ0YR5Q4AyrM2T+yB+BgnTvkVoBuKSbSa5UGdc86BfiA@mail.gmail.com>
* Linus Torvalds <torvalds@linux-foundation.org> wrote:
> On Wed, Feb 17, 2016 at 10:20 AM, Tony Luck <tony.luck@intel.com> wrote:
> >
> > If we faulted during the copy, then 'trapnr' will say which type
> > of trap (X86_TRAP_PF or X86_TRAP_MC) and 'remain' says how many
> > bytes were not copied.
>
> So apart from the naming, a couple of questions:
>
> - I'd like to see the actual *use* case explained, not just what it does.
>
> - why does this use the complex - and slower, on modern machines -
> unrolled manual memory copy, when you might as well just use a single
>
> rep ; movsb
>
> which not only makes it smaller, but makes the exception fixup trivial.
>
> - why not make the "bytes remaining" the same as for a user-space
> copy (ie return it as the return value)?
>
> - at that point, it ends up looking a *lot* like uaccess_try/catch,
> which gets the error code from current_thread_info()->uaccess_err
>
> Hmm?
memcpy_try()/memcpy_catch() definitely has a nice ring to it.
Thanks,
Ingo
next prev parent reply other threads:[~2016-02-18 18:51 UTC|newest]
Thread overview: 53+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-02-17 18:20 [PATCH v11 0/4] Machine check recovery when kernel accesses poison Tony Luck
2016-02-17 18:20 ` [PATCH v11 1/4] x86: Expand exception table to allow new handling options Tony Luck
2016-02-18 10:19 ` [tip:ras/core] x86/mm: Expand the exception table logic " tip-bot for Tony Luck
2016-02-17 18:20 ` [PATCH v11 3/4] x86, mce: Add __mcsafe_copy() Tony Luck
2016-02-18 8:21 ` Ingo Molnar
2016-02-18 9:59 ` Peter Zijlstra
2016-02-18 10:19 ` Ingo Molnar
2016-02-18 10:29 ` Borislav Petkov
2016-02-18 10:35 ` Peter Zijlstra
2016-02-18 14:59 ` Luck, Tony
2016-02-19 7:58 ` Ingo Molnar
2016-02-19 8:43 ` Peter Zijlstra
2016-02-19 9:51 ` Ingo Molnar
2016-02-18 10:29 ` Borislav Petkov
2016-02-18 10:34 ` Ingo Molnar
2016-02-18 10:36 ` Borislav Petkov
2016-02-18 18:48 ` Ingo Molnar
2016-02-18 21:14 ` [PATCH v12] x86, mce: Add memcpy_trap() Luck, Tony
2016-02-19 9:10 ` Ingo Molnar
2016-02-19 17:53 ` [PATCH v13] " Luck, Tony
2016-02-24 17:38 ` Tony Luck
2016-02-24 18:35 ` Linus Torvalds
2016-02-24 19:27 ` Tony Luck
2016-02-24 19:37 ` Linus Torvalds
2016-02-25 8:56 ` Ingo Molnar
2016-02-25 19:33 ` Luck, Tony
2016-02-25 20:39 ` Linus Torvalds
2016-02-25 22:11 ` Andy Lutomirski
2016-02-18 19:47 ` [PATCH v14] x86, mce: Add memcpy_mcsafe() Tony Luck
2016-03-02 20:47 ` Luck, Tony
2016-03-08 17:37 ` [tip:ras/core] x86/mm, x86/mce: " tip-bot for Tony Luck
2016-03-10 19:26 ` [PATCH v14] x86, mce: " Mika Penttilä
2016-03-10 19:37 ` Luck, Tony
2016-03-11 22:10 ` Tony Luck
2016-03-11 22:14 ` Dan Williams
2016-03-12 17:16 ` Ingo Molnar
2016-03-13 1:12 ` Linus Torvalds
2016-03-13 9:25 ` Ingo Molnar
2016-03-14 22:33 ` [PATCH] x86/mm, x86/mce: Fix return type/value for memcpy_mcsafe() Tony Luck
2016-03-16 8:06 ` [tip:x86/urgent] " tip-bot for Tony Luck
2016-02-26 0:58 ` [PATCH v13] x86, mce: Add memcpy_trap() Linus Torvalds
2016-02-26 1:19 ` Andy Lutomirski
2016-02-26 2:38 ` Linus Torvalds
2016-02-18 18:12 ` [PATCH v11 3/4] x86, mce: Add __mcsafe_copy() Linus Torvalds
2016-02-18 18:51 ` Ingo Molnar [this message]
2016-02-18 18:52 ` Luck, Tony
2016-02-18 20:14 ` Ingo Molnar
2016-02-18 21:33 ` Dan Williams
2016-02-17 18:20 ` [PATCH v11 2/4] x86, mce: Check for faults tagged in EXTABLE_CLASS_FAULT exception table entries Tony Luck
2016-02-18 10:19 ` [tip:ras/core] x86/mce: " tip-bot for Tony Luck
2016-02-17 18:20 ` [PATCH v11 4/4] x86: Create a new synthetic cpu capability for machine check recovery Tony Luck
2016-02-18 10:19 ` [tip:x86/asm] x86/cpufeature: " tip-bot for Tony Luck
-- strict thread matches above, loose matches on Subject: below --
2016-02-11 21:34 [PATCH v11 0/4] Machine check recovery when kernel accesses poison Tony Luck
2016-02-11 21:34 ` [PATCH v11 3/4] x86, mce: Add __mcsafe_copy() Tony Luck
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