From: Peter Zijlstra <peterz@infradead.org>
To: Andy Lutomirski <luto@amacapital.net>
Cc: Andrew Cooper <andrew.cooper3@citrix.com>,
tglx@linutronix.de, linux-kernel@vger.kernel.org, x86@kernel.org,
Lai Jiangshan <laijs@linux.alibaba.com>,
sean.j.christopherson@intel.com, daniel.thompson@linaro.org
Subject: Re: [PATCH 1/6] x86/entry: Introduce local_db_{save,restore}()
Date: Fri, 29 May 2020 21:02:18 +0200 [thread overview]
Message-ID: <20200529190218.GP706495@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <AC94E789-9EC7-4156-955C-841FF7114176@amacapital.net>
On Fri, May 29, 2020 at 10:28:33AM -0700, Andy Lutomirski wrote:
> > +static __always_inline unsigned long local_db_save(void)
> > +{
> > + unsigned long dr7;
> > +
> > + get_debugreg(&dr7, 7);
> > + dr7 ^= 0x400;
>
> Why xor? This seems extra confusing.
I'll do the normal mask thing ..
next prev parent reply other threads:[~2020-05-29 19:05 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-05-28 20:19 [PATCH 0/6] x86/entry: disallow #DB more Peter Zijlstra
2020-05-28 20:19 ` [PATCH 1/6] x86/entry: Introduce local_db_{save,restore}() Peter Zijlstra
2020-05-28 20:52 ` Andrew Cooper
2020-05-28 21:15 ` Peter Zijlstra
2020-05-28 21:33 ` Peter Zijlstra
2020-05-29 17:28 ` Andy Lutomirski
2020-05-29 19:02 ` Peter Zijlstra [this message]
2020-05-28 21:36 ` Andrew Cooper
2020-05-28 20:19 ` [PATCH 2/6] x86/entry, nmi: Disable #DB Peter Zijlstra
2020-05-28 20:19 ` [PATCH 3/6] x86/entry, mce: Disallow #DB during #MC Peter Zijlstra
2020-05-28 20:19 ` [PATCH 4/6] x86/entry: Optimize local_db_save() for virt Peter Zijlstra
2020-05-29 17:24 ` Sean Christopherson
2020-05-28 20:19 ` [PATCH 5/6] x86/entry: Remove debug IDT frobbing Peter Zijlstra
2020-05-28 20:19 ` [RFC][PATCH 6/6] x86/entry: Remove DBn stacks Peter Zijlstra
2020-05-28 22:35 ` Lai Jiangshan
2020-05-28 22:37 ` Peter Zijlstra
2020-05-28 22:42 ` [PATCH 0/6] x86/entry: disallow #DB more Lai Jiangshan
2020-05-28 22:48 ` Peter Zijlstra
2020-05-28 23:05 ` Lai Jiangshan
2020-05-29 8:00 ` Peter Zijlstra
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