From: "H. Peter Anvin" <hpa@zytor.com>
To: sbsiddha@gmail.com, Linus Torvalds <torvalds@linux-foundation.org>
Cc: Nate Eldredge <nate@thatsmathematics.com>,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@kernel.org>,
the arch/x86 maintainers <x86@kernel.org>,
stable <stable@vger.kernel.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
Maarten Baert <maarten-baert@hotmail.com>,
Jan Kara <jack@suse.cz>, George Spelvin <linux@horizon.com>,
Pekka Riikonen <priikone@iki.fi>
Subject: Re: [PATCH] Make math_state_restore() save and restore the interrupt flag
Date: Fri, 07 Mar 2014 15:18:39 -0800 [thread overview]
Message-ID: <531A53CF.2000604@zytor.com> (raw)
In-Reply-To: <530FCDD6.3060701@zytor.com>
Hi Suresh,
Any thoughts on this?
-hpa
On 02/27/2014 03:44 PM, H. Peter Anvin wrote:
> So, picking up this thread which got dropped on the floor...
>
> On 02/01/2014 11:19 PM, Suresh Siddha wrote:
>>
>> diff --git a/arch/x86/kernel/i387.c b/arch/x86/kernel/i387.c
>> index e8368c6..4e5f770 100644
>> --- a/arch/x86/kernel/i387.c
>> +++ b/arch/x86/kernel/i387.c
>> @@ -5,6 +5,7 @@
>> * General FPU state handling cleanups
>> * Gareth Hughes <gareth@valinux.com>, May 2000
>> */
>> +#include <linux/bootmem.h>
>> #include <linux/module.h>
>> #include <linux/regset.h>
>> #include <linux/sched.h>
>> @@ -186,6 +187,10 @@ void fpu_init(void)
>> if (xstate_size == 0)
>> init_thread_xstate();
>>
>> + if (!current->thread.fpu.state)
>> + current->thread.fpu.state =
>> + alloc_bootmem_align(xstate_size, __alignof__(struct xsave_struct));
>> +
>> mxcsr_feature_mask_init();
>> xsave_init();
>> eager_fpu_init();
>
> So this bit is giving me a bit of a headache, specifically
> alloc_bootmem_align() is an __init function and fpu_init() obviously isn't.
>
> I am doubly confused because init_thread_xstate() only sets the xstate
> without any XSAVE features, so the memory allocation we get there will
> be insufficient later -- in fact, only a few lines further down the
> function, when xsave_init() is called.
>
> I'm wondering if we could put this somewhere inside
> xstate_enable_boot_cpu() instead, maybe?
>
> I'm assuming the reason you didn't want to in eager_fpu_init_bp()
> anymore is because you want the allocation to happen regardless of if
> eagerfpu is enabled, correct?
>
> -hpa
>
>
next prev parent reply other threads:[~2014-03-07 23:19 UTC|newest]
Thread overview: 41+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-01-30 22:01 [PATCH] Make math_state_restore() save and restore the interrupt flag Nate Eldredge
2014-01-30 22:24 ` Linus Torvalds
2014-01-31 7:33 ` Suresh Siddha
2014-02-01 19:27 ` Linus Torvalds
2014-02-01 19:35 ` H. Peter Anvin
2014-02-01 19:46 ` Linus Torvalds
2014-02-01 20:00 ` H. Peter Anvin
2014-02-01 20:16 ` Linus Torvalds
2014-02-01 20:16 ` H. Peter Anvin
2014-02-01 21:17 ` George Spelvin
2014-02-01 21:36 ` H. Peter Anvin
2014-02-01 23:40 ` H. Peter Anvin
2014-02-02 0:17 ` Linus Torvalds
2014-02-02 1:19 ` George Spelvin
2014-02-02 1:25 ` H. Peter Anvin
2014-02-02 8:45 ` Pekka Riikonen
2014-02-02 1:06 ` Suresh Siddha
2014-02-02 1:26 ` H. Peter Anvin
2014-02-02 1:35 ` Suresh Siddha
2014-02-02 1:38 ` Linus Torvalds
2014-02-02 1:47 ` Suresh Siddha
2014-02-02 1:51 ` Linus Torvalds
2014-02-02 1:57 ` H. Peter Anvin
2014-02-02 2:05 ` Linus Torvalds
2014-02-02 2:12 ` H. Peter Anvin
2014-02-02 1:59 ` Suresh Siddha
2014-02-02 1:43 ` H. Peter Anvin
2014-02-02 1:47 ` Linus Torvalds
2014-02-02 7:19 ` Suresh Siddha
2014-02-02 19:15 ` Linus Torvalds
2014-02-03 6:56 ` Suresh Siddha
2014-02-03 18:20 ` Linus Torvalds
2014-02-04 6:03 ` Suresh Siddha
2014-02-06 5:26 ` Nate Eldredge
2014-02-06 5:34 ` George Spelvin
2014-02-13 15:45 ` Maarten Baert
2014-02-13 20:00 ` George Spelvin
2014-03-11 19:36 ` [tip:x86/urgent] x86, fpu: Check tsk_used_math() in kernel_fpu_end() for eager FPU tip-bot for Suresh Siddha
2014-02-27 23:44 ` [PATCH] Make math_state_restore() save and restore the interrupt flag H. Peter Anvin
2014-03-07 23:18 ` H. Peter Anvin [this message]
2014-03-08 6:18 ` Suresh Siddha
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