From: "Jan Beulich" <JBeulich@novell.com>
To: "Frederic Weisbecker" <fweisbec@gmail.com>
Cc: "H. Peter Anvin" <a.p.zijlstra@chello.nl>,
"Ingo Molnar" <mingo@elte.hu>,
"Stephane Eranian" <eranian@google.com>,
"Thomas Gleixner" <tglx@linutronix.de>,
"Arnaldo Carvalho de Melo" <acme@redhat.com>,
"Soeren Sandmann Pedersen" <sandmann@redhat.com>,
"LKML" <linux-kernel@vger.kernel.org>
Subject: Re: [RFC PATCH 1/2] x86: Fix rbp saving in pt_regs on irq entry
Date: Thu, 06 Jan 2011 16:10:55 +0000 [thread overview]
Message-ID: <4D25F79F020000780002AC20@vpn.id2.novell.com> (raw)
In-Reply-To: <20110106154536.GA2308@nowhere>
>>> On 06.01.11 at 16:45, Frederic Weisbecker <fweisbec@gmail.com> wrote:
> Before we had:
>
>
> leaveq
>
> CFI_RESTORE rbp
> CFI_DEF_CFA_REGISTER rsp
> CFI_ADJUST_CFA_OFFSET -8
>
> So CFI_RESTORE means rbp has now the value of the base frame of
> the calling frame (the base frame pointer of the interrupted proc) ?
No - all it means is that %rbp now has its original (caller or
interrupted procedure) value again (i.e. an unwinder should not
try to read it from the stack [or other previously recorded
location] anymore).
> And what follows means that rsp-8 points to the return address?
No - .cfi_def_cfa_register says which register serves as the frame
pointer, and .cfi_adjust_cfa_offset says to adjust the offset from
the frame pointer to the top [or bottom] of frame. At any time
CFA = cfa_register + cfa_offset
with CFA being what all locations on the stack are expressed
relative to.
Jan
next prev parent reply other threads:[~2011-01-06 16:11 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-01-06 14:51 [RFC GIT PULL] perf updates Frederic Weisbecker
2011-01-06 14:51 ` [PATCH 2/2] perf: Build tools with frame pointer Frederic Weisbecker
2011-01-07 15:31 ` [tip:perf/core] perf tools: Build " tip-bot for Frederic Weisbecker
[not found] ` <1294325513-14276-2-git-send-email-fweisbec@gmail.com>
2011-01-06 15:18 ` [RFC PATCH 1/2] x86: Fix rbp saving in pt_regs on irq entry Jan Beulich
2011-01-06 15:45 ` Frederic Weisbecker
2011-01-06 16:10 ` Jan Beulich [this message]
2011-01-06 16:22 ` Frederic Weisbecker
2011-01-06 16:39 ` Jan Beulich
2011-01-06 16:54 ` Frederic Weisbecker
2011-01-06 16:58 ` Jan Beulich
2011-01-06 17:12 ` Frederic Weisbecker
2011-01-06 17:24 ` Frederic Weisbecker
2011-01-07 7:45 ` Jan Beulich
2011-01-07 12:31 ` Ingo Molnar
2011-01-07 16:05 ` Frederic Weisbecker
2011-01-07 16:13 ` Jan Beulich
2011-01-07 16:27 ` Frederic Weisbecker
2011-01-07 16:58 ` Ingo Molnar
2011-01-07 17:17 ` Frederic Weisbecker
2011-01-07 16:33 ` Frederic Weisbecker
2011-01-07 14:26 ` Frederic Weisbecker
2011-01-07 12:23 ` [RFC GIT PULL] perf updates Ingo Molnar
2011-01-07 15:24 ` Frederic Weisbecker
2011-01-07 15:37 ` Ingo Molnar
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