From: Steven Rostedt <rostedt@goodmis.org>
To: Denys Vlasenko <dvlasenk@redhat.com>
Cc: Andy Lutomirski <luto@amacapital.net>,
Linus Torvalds <torvalds@linux-foundation.org>,
Ingo Molnar <mingo@kernel.org>, Borislav Petkov <bp@alien8.de>,
"H. Peter Anvin" <hpa@zytor.com>, Oleg Nesterov <oleg@redhat.com>,
Frederic Weisbecker <fweisbec@gmail.com>,
Alexei Starovoitov <ast@plumgrid.com>,
Will Drewry <wad@chromium.org>, Kees Cook <keescook@chromium.org>,
x86@kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 1/2] x86: stop using PER_CPU_VAR(kernel_stack)
Date: Mon, 23 Mar 2015 13:28:47 -0400 [thread overview]
Message-ID: <20150323132847.79e18ea5@grimm.local.home> (raw)
In-Reply-To: <551048E9.6060800@redhat.com>
On Mon, 23 Mar 2015 18:10:01 +0100
Denys Vlasenko <dvlasenk@redhat.com> wrote:
> On 03/23/2015 03:18 PM, Steven Rostedt wrote:
> > On Sat, 21 Mar 2015 21:44:37 +0100
> > Denys Vlasenko <dvlasenk@redhat.com> wrote:
> >
> >> Instead of PER_CPU_VAR(kernel_stack), 64-bit code
> >> can use PER_CPU_VAR(cpu_tss + TSS_sp0).
> >
> > The change log here is lacking an answer to "why". It only states what
> > it does. What's wrong with using kernel_stack? The change log should
> > explicitly state that. I have no idea why this patch is needed.
>
> Sorry. The reason is:
>
> We want to get rid of kernel_stack, since it is redundant:
> in 64-bits, PER_CPU_VAR(cpu_tss + TSS_sp0) can be used instead,
> in 32-bits, PER_CPU_VAR(cpu_current_top_of_stack) can be used instead.
Can we do a:
#define cpu_current_top_of_stack (cpu_tss + TSS_sp0)
in 64-bit, and make it consistent with i386.
"cpu_tss + TSS_sp0" is rather meaningless. "kernel_stack" or
"top_of_stack" is at least informative.
>
> Patch 2/2 in the same series removes kernel_stack.
Understood, but each commit's change log should be able to stand on its
own.
-- Steve
next prev parent reply other threads:[~2015-03-23 17:28 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-03-21 20:44 Denys Vlasenko
2015-03-21 20:44 ` [PATCH 2/2] x86: remove unused kernel_stack per-cpu variable Denys Vlasenko
2015-03-23 14:18 ` [PATCH 1/2] x86: stop using PER_CPU_VAR(kernel_stack) Steven Rostedt
2015-03-23 17:10 ` Denys Vlasenko
2015-03-23 17:14 ` Borislav Petkov
2015-03-23 17:28 ` Steven Rostedt [this message]
2015-03-23 17:38 ` Denys Vlasenko
2015-03-23 17:45 ` Steven Rostedt
2015-03-23 17:51 ` Denys Vlasenko
2015-03-23 18:27 ` Andy Lutomirski
2015-04-24 15:29 ` Denys Vlasenko
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