From: Oleg Nesterov <oleg@redhat.com>
To: Steven Rostedt <rostedt@goodmis.org>
Cc: "Li,Rongqing" <lirongqing@baidu.com>,
Peter Zijlstra <peterz@infradead.org>,
David Laight <david.laight.linux@gmail.com>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"vschneid@redhat.com" <vschneid@redhat.com>,
"mgorman@suse.de" <mgorman@suse.de>,
"bsegall@google.com" <bsegall@google.com>,
"dietmar.eggemann@arm.com" <dietmar.eggemann@arm.com>,
"vincent.guittot@linaro.org" <vincent.guittot@linaro.org>,
"juri.lelli@redhat.com" <juri.lelli@redhat.com>,
"mingo@redhat.com" <mingo@redhat.com>
Subject: Re: [????] Re: [????] Re: divide error in x86 and cputime
Date: Tue, 8 Jul 2025 04:17:04 +0200 [thread overview]
Message-ID: <20250708021703.GD15787@redhat.com> (raw)
In-Reply-To: <20250707220529.19eb2a74@gandalf.local.home>
On 07/07, Steven Rostedt wrote:
>
> On Tue, 8 Jul 2025 01:58:00 +0000
> "Li,Rongqing" <lirongqing@baidu.com> wrote:
>
> > But mul_u64_u64_div_u64() for x86 should not trigger a division error panic,
> maybe should return a ULLONG_MAX on #DE (like non-x86 mul_u64_u64_div_u64(),)
>
> Perhaps.
So do you think
static inline u64 mul_u64_u64_div_u64(u64 a, u64 mul, u64 div)
{
int ok = 0;
u64 q;
asm ("mulq %3; 1: divq %4; movl $1,%1; 2:\n"
_ASM_EXTABLE(1b, 2b)
: "=a" (q), "+r" (ok)
: "a" (a), "rm" (mul), "rm" (div)
: "rdx");
return ok ? q : -1ul;
}
makes sense at least for consistency with the generic implementation
in lib/math/div64.c ?
> But it is still producing garbage.
Agreed. And not a solution to this particular problem.
Oleg.
next prev parent reply other threads:[~2025-07-08 2:18 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-07-07 8:14 divide error in x86 and cputime Li,Rongqing
2025-07-07 15:11 ` Steven Rostedt
2025-07-07 22:09 ` Oleg Nesterov
2025-07-07 22:20 ` Steven Rostedt
2025-07-07 22:33 ` Steven Rostedt
2025-07-07 23:00 ` Oleg Nesterov
2025-07-08 11:00 ` David Laight
2025-07-08 1:40 ` 答复: [????] " Li,Rongqing
2025-07-08 1:53 ` Steven Rostedt
2025-07-08 1:58 ` 答复: [????] " Li,Rongqing
2025-07-08 2:05 ` Steven Rostedt
2025-07-08 2:17 ` Oleg Nesterov [this message]
2025-07-08 9:58 ` David Laight
2025-07-07 22:30 ` Oleg Nesterov
2025-07-07 23:41 ` 答复: [????] " Li,Rongqing
2025-07-07 23:53 ` Steven Rostedt
2025-07-08 0:10 ` 答复: [????] " Li,Rongqing
2025-07-08 0:30 ` Steven Rostedt
2025-07-08 1:17 ` 答复: [????] " Li,Rongqing
2025-07-08 1:41 ` Steven Rostedt
2025-07-08 10:35 ` [????] Re: [????] " David Laight
2025-07-08 11:12 ` 答复: [????] " Li,Rongqing
2025-07-08 0:23 ` 答复: " Li,Rongqing
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