From: "Christian König" <christian.koenig@amd.com>
To: Peter Zijlstra <peterz@infradead.org>
Cc: Jann Horn <jannh@google.com>,
Harry Wentland <harry.wentland@amd.com>,
Leo Li <sunpeng.li@amd.com>,
amd-gfx@lists.freedesktop.org,
Alex Deucher <alexander.deucher@amd.com>,
"David (ChunMing) Zhou" <David1.Zhou@amd.com>,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
"H. Peter Anvin" <hpa@zytor.com>,
the arch/x86 maintainers <x86@kernel.org>,
kernel list <linux-kernel@vger.kernel.org>,
Josh Poimboeuf <jpoimboe@redhat.com>,
Andy Lutomirski <luto@kernel.org>,
Arnaldo Carvalho de Melo <acme@kernel.org>,
mhiramat@kernel.org
Subject: Re: AMD DC graphics display code enables -mhard-float, -msse, -msse2 without any visible FPU state protection
Date: Thu, 9 Apr 2020 20:15:57 +0200 [thread overview]
Message-ID: <87a2f2fc-972d-ab9b-a29d-72f02d94e60e@amd.com> (raw)
In-Reply-To: <20200409170916.GR20760@hirez.programming.kicks-ass.net>
Am 09.04.20 um 19:09 schrieb Peter Zijlstra:
> On Thu, Apr 09, 2020 at 05:59:56PM +0200, Peter Zijlstra wrote:
> [SNIP]
>> I'll need another approach, let me consider.
> Christian; it says these files are generated, does that generator know
> which functions are wholly in FPU context and which are not?
Well that "generator" is still a human being :)
It's just that the formulae for the calculation come from the hardware
team and we are not able to easily transcript them to fixed point
calculations.
> My current thinking is that if I annotate all functions that are wholly
> inside kernel_fpu_start() with an __fpu function attribute, then I can
> verify that any call from regular text to fpu text only happens inside
> kernel_fpu_begin()/end(). And I can ensure that all !__fpu annotation
> fuctions only contain !fpu instructions.
Yeah, that sounds like a good idea to me and should be easily doable.
> Can that generator add the __fpu function attribute or is that something
> that would need to be done manually (which seems like it would be
> painful, since it is quite a bit of code) ?
We are currently in the process of moving all the stuff which requires
floating point into a single C file(s) and then make sure that we only
call those within kernel_fpu_begin()/end() blocks.
Annotating those function with __fpu or even saying to gcc that all code
of those files should go into a special text.fpu segment shouldn't be
much of a problem.
Regards,
Christian.
next prev parent reply other threads:[~2020-04-09 18:16 UTC|newest]
Thread overview: 37+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-04-02 2:34 AMD DC graphics display code enables -mhard-float, -msse, -msse2 without any visible FPU state protection Jann Horn
2020-04-02 7:33 ` Christian König
2020-04-02 7:56 ` Jann Horn
2020-04-02 9:36 ` Thomas Gleixner
2020-04-02 14:50 ` Jann Horn
2020-04-02 14:13 ` Peter Zijlstra
2020-04-03 5:28 ` Masami Hiramatsu
2020-04-03 11:21 ` Peter Zijlstra
2020-04-04 3:08 ` Masami Hiramatsu
2020-04-04 3:15 ` Randy Dunlap
2020-04-04 8:32 ` Masami Hiramatsu
2020-04-04 14:32 ` Peter Zijlstra
2020-04-05 3:19 ` Masami Hiramatsu
2020-04-06 10:21 ` Peter Zijlstra
2020-04-07 9:50 ` Masami Hiramatsu
2020-04-07 11:15 ` Peter Zijlstra
2020-04-07 15:41 ` Masami Hiramatsu
2020-04-07 15:43 ` [PATCH] x86: insn: Add insn_is_fpu() Masami Hiramatsu
2020-04-07 15:54 ` AMD DC graphics display code enables -mhard-float, -msse, -msse2 without any visible FPU state protection Peter Zijlstra
2020-04-08 0:31 ` Masami Hiramatsu
2020-04-08 16:09 ` [PATCH v2] x86: insn: Add insn_is_fpu() Masami Hiramatsu
2020-04-09 14:32 ` Peter Zijlstra
2020-04-09 14:45 ` Peter Zijlstra
2020-04-10 0:47 ` Masami Hiramatsu
2020-04-10 1:22 ` [PATCH v3] " Masami Hiramatsu
2020-04-15 8:23 ` Masami Hiramatsu
2020-04-15 8:49 ` [PATCH v4] " Masami Hiramatsu
2020-04-04 14:36 ` AMD DC graphics display code enables -mhard-float, -msse, -msse2 without any visible FPU state protection Peter Zijlstra
2020-04-05 3:37 ` Masami Hiramatsu
2020-04-09 15:59 ` Peter Zijlstra
2020-04-09 17:09 ` Peter Zijlstra
2020-04-09 18:15 ` Christian König [this message]
2020-04-09 20:01 ` Peter Zijlstra
2020-04-10 14:31 ` Christian König
2020-04-15 9:16 ` Peter Zijlstra
2020-04-17 20:27 ` Rodrigo Siqueira
2020-04-17 21:56 ` Peter Zijlstra
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