From: Frederic Weisbecker <fweisbec@gmail.com>
To: Jan Beulich <JBeulich@novell.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>,
Ingo Molnar <mingo@elte.hu>, Thomas Gleixner <tglx@linutronix.de>,
Arnaldo Carvalho de Melo <acme@redhat.com>,
LKML <linux-kernel@vger.kernel.org>,
"H. Peter Anvin" <hpa@zytor.com>
Subject: Re: [PATCH 5/6] x86: Remove useless unwinder backlink from irq regs saving
Date: Mon, 4 Jul 2011 15:22:23 +0200 [thread overview]
Message-ID: <20110704132158.GA5551@somewhere> (raw)
In-Reply-To: <4E1187E4020000780004BF2C@nat28.tlf.novell.com>
On Mon, Jul 04, 2011 at 08:29:08AM +0100, Jan Beulich wrote:
> >>> On 02.07.11 at 18:29, Frederic Weisbecker <fweisbec@gmail.com> wrote:
> > The unwinder backlink in interrupt entry is very useless.
> > It's actually not part of the stack frame chain and thus is
> > never used.
>
> I very much doubt this - see dump_trace()'s comment in its IRQ-stack
> related code portion (and the corresponding use of irq_stack_end[-1]).
>
> Jan
Good point. I misunderstood that.
But then I believe I accidentally fixed it back in
"x86: Don't use frame pointer to save old stack on irq entry" by
pushing %rsi instead in the new stack. It contains the backlink to
the old stack.
If we keep the macro as-is, I'll add a comment to explain further
what is involved there.
next prev parent reply other threads:[~2011-07-04 13:22 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-07-02 16:29 [RFC GIT PULL] x86 entry / perf stacktrace changes Frederic Weisbecker
2011-07-02 16:29 ` [PATCH 1/6] x86: Save stack pointer in perf live regs savings Frederic Weisbecker
2011-07-02 16:29 ` [PATCH 2/6] x86: Fetch stack from regs when possible in dump_trace() Frederic Weisbecker
2011-07-02 16:29 ` [PATCH 3/6] x86,64: Simplify save_regs() Frederic Weisbecker
2011-07-04 7:20 ` Jan Beulich
2011-07-04 12:57 ` Frederic Weisbecker
2011-07-06 17:34 ` Andi Kleen
2011-07-06 18:20 ` H. Peter Anvin
2011-07-06 20:42 ` Frederic Weisbecker
2011-07-04 12:59 ` Frederic Weisbecker
2011-07-02 16:29 ` [PATCH 4/6] x86,64: Separate arg1 from rbp handling in SAVE_REGS_IRQ Frederic Weisbecker
2011-07-04 7:34 ` Jan Beulich
2011-07-02 16:29 ` [PATCH 5/6] x86: Remove useless unwinder backlink from irq regs saving Frederic Weisbecker
2011-07-04 7:29 ` Jan Beulich
2011-07-04 9:17 ` Ingo Molnar
2011-07-04 13:10 ` Frederic Weisbecker
2011-07-04 13:22 ` Frederic Weisbecker [this message]
2011-07-05 22:21 ` Valdis.Kletnieks
2011-07-02 16:29 ` [PATCH 6/6] x86: Don't use frame pointer to save old stack on irq entry Frederic Weisbecker
2011-07-04 9:13 ` [RFC GIT PULL] x86 entry / perf stacktrace changes Ingo Molnar
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