From: Jun Koi <junkoi2004@gmail.com>
To: qemu-devel@nongnu.org
Subject: [Qemu-devel] Question on implementatio of GETPC()
Date: Wed, 28 Apr 2010 13:51:49 +0900 [thread overview]
Message-ID: <t2pfdaac4d51004272151x36aae777wc4f95d1d9ec0de3a@mail.gmail.com> (raw)
Hi,
In x86, GETPC() is implemented as below:
# define GETPC() ((void *)((unsigned long)__builtin_return_address(0) - 1))
As I understand, it gets the returned address on the stack, then
subtract 1 to get back to the above address.
Imagine we have code like this (pseudo asm code):
....
CALL <relative address>
<next-insn>
....
When we call GETPC, we get the address of <next-insn>, and subtract 1.
But the problem is that the CALL insn is more than 1 byte, so how can
GETPC() gives us the address of the CALL insn above?
I guess I must misunderstood something here ....
Many thanks,
Jun
next reply other threads:[~2010-04-28 4:52 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-04-28 4:51 Jun Koi [this message]
2010-04-28 8:12 ` [Qemu-devel] Re: Question on implementatio of GETPC() Jan Kiszka
2010-04-28 8:29 ` Jun Koi
2010-04-28 10:41 ` Jan Kiszka
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=t2pfdaac4d51004272151x36aae777wc4f95d1d9ec0de3a@mail.gmail.com \
--to=junkoi2004@gmail.com \
--cc=qemu-devel@nongnu.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).