From: hpa@zytor.com
To: Josh Poimboeuf <jpoimboe@redhat.com>,
Andy Lutomirski <luto@amacapital.net>
Cc: Linus Torvalds <torvalds@linux-foundation.org>,
Jiri Slaby <jslaby@suse.cz>,
Andrew Morton <akpm@linux-foundation.org>,
live-patching@vger.kernel.org,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>,
the arch/x86 maintainers <x86@kernel.org>,
Andy Lutomirski <luto@kernel.org>, Jiri Kosina <jikos@kernel.org>
Subject: Re: [PATCH 7/7] DWARF: add the config option
Date: Mon, 08 May 2017 11:57:59 -0700 [thread overview]
Message-ID: <5EAB44CD-482B-485F-A0E0-0AE7937FFF2C@zytor.com> (raw)
In-Reply-To: <20170508144049.6x67526a677g2miw@treble>
On May 8, 2017 7:40:49 AM PDT, Josh Poimboeuf <jpoimboe@redhat.com> wrote:
>On Sun, May 07, 2017 at 10:35:28PM -0700, Andy Lutomirski wrote:
>> I think that, if the code were sufficiently robust, it would be handy
>> if the unwinder displayed function arguments. DWARF can do that to a
>> limited extent.
>
>Honestly I get the feeling that displaying function arguments wouldn't
>be realistic (DWARF or no DWARF). On x86-64, arguments are passed in
>registers, so tracking down their values is a lot more involved than
>just looking at the stack.
>
>The DWARF CFI only shows you the callee-saved registers. To figure out
>the other registers you'd have to dive into the other DWARF sections
>and
>examine previous stack frames for clues. I think it's not a
>deterministic process, based on how often I see gdb complain with
>'<value optimized out>'. I'd bet it's a lot harder than a basic stack
>dump.
>
>Also, most kernel functions rely on pointer arguments, which are pretty
>much useless without dumping the contents of the structs they point to.
>But then doing that properly would be a whole new level of difficulty.
At some point you are just reinventing k(g)db...
--
Sent from my Android device with K-9 Mail. Please excuse my brevity.
next prev parent reply other threads:[~2017-05-08 19:04 UTC|newest]
Thread overview: 70+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-05-05 12:21 [PATCH 1/7] DWARF: add option to preserve unwind info Jiri Slaby
2017-05-05 12:21 ` [PATCH 2/7] DWARF: EH-frame based stack unwinding Jiri Slaby
2017-05-05 12:21 ` [PATCH 3/7] vmlinux.lds: preserve eh_frame for DWARF unwinder Jiri Slaby
2017-05-05 12:21 ` [PATCH 4/7] DWARF: initialize structures for kernel and modules Jiri Slaby
2017-05-05 12:21 ` [PATCH 5/7] unwinder: show_stack, check also ret_addr_p's contents Jiri Slaby
2017-05-05 12:21 ` [PATCH 6/7] unwinder: plug in the DWARF unwinder Jiri Slaby
2017-05-05 12:22 ` [PATCH 7/7] DWARF: add the config option Jiri Slaby
2017-05-05 19:57 ` Linus Torvalds
2017-05-06 7:19 ` Ingo Molnar
2017-05-10 7:46 ` Jiri Slaby
2017-05-06 14:24 ` Jiri Kosina
2017-05-07 16:55 ` Josh Poimboeuf
2017-05-07 17:59 ` Ingo Molnar
2017-05-07 18:08 ` hpa
2017-05-07 21:48 ` Josh Poimboeuf
2017-05-08 7:50 ` Vojtech Pavlik
2017-05-08 13:14 ` Josh Poimboeuf
2017-05-08 5:35 ` Andy Lutomirski
2017-05-08 6:15 ` Ingo Molnar
2017-05-08 14:40 ` Josh Poimboeuf
2017-05-08 18:57 ` hpa [this message]
2017-05-09 0:21 ` Andy Lutomirski
2017-05-09 1:38 ` Josh Poimboeuf
2017-05-09 2:31 ` Andy Lutomirski
2017-05-09 3:38 ` Josh Poimboeuf
2017-05-09 10:00 ` hpa
2017-05-09 14:58 ` Josh Poimboeuf
2017-05-09 16:46 ` H.J. Lu
2017-05-10 8:15 ` Jiri Slaby
2017-05-10 13:09 ` Josh Poimboeuf
2017-05-10 16:23 ` H.J. Lu
2017-05-09 18:47 ` Jiri Kosina
2017-05-09 19:22 ` Josh Poimboeuf
2017-05-10 8:32 ` Jiri Slaby
2017-05-10 13:13 ` Josh Poimboeuf
2017-05-23 7:07 ` Peter Zijlstra
2017-05-23 7:27 ` Ingo Molnar
2017-05-19 20:53 ` Josh Poimboeuf
2017-05-19 20:57 ` H. Peter Anvin
2017-05-19 20:59 ` H. Peter Anvin
2017-05-19 21:29 ` Josh Poimboeuf
2017-05-19 21:35 ` Josh Poimboeuf
2017-05-20 5:23 ` Andy Lutomirski
2017-05-20 16:20 ` Josh Poimboeuf
2017-05-20 17:19 ` Josh Poimboeuf
2017-05-20 20:01 ` H.J. Lu
2017-05-20 21:58 ` Andy Lutomirski
2017-05-20 22:20 ` H.J. Lu
2017-05-22 11:34 ` Jiri Kosina
2017-05-22 14:39 ` H.J. Lu
2017-05-22 21:07 ` H. Peter Anvin
2017-05-22 21:37 ` H. Peter Anvin
2017-05-22 22:11 ` Josh Poimboeuf
2017-05-20 20:16 ` Linus Torvalds
2017-05-20 21:56 ` Andy Lutomirski
2017-05-20 23:00 ` Linus Torvalds
2017-05-20 23:29 ` Linus Torvalds
2017-05-26 6:54 ` Jiri Slaby
2017-05-26 11:29 ` Jiri Slaby
2017-05-26 12:14 ` Josh Poimboeuf
2017-05-22 11:12 ` Ingo Molnar
2017-05-22 21:16 ` H. Peter Anvin
2017-05-22 23:23 ` Jiri Kosina
2017-05-23 5:49 ` Ingo Molnar
2017-05-26 19:16 ` hpa
2017-05-28 9:12 ` Ingo Molnar
2017-05-10 7:39 ` Jiri Slaby
2017-05-10 12:42 ` Josh Poimboeuf
2017-05-10 12:47 ` Jiri Slaby
2017-05-10 18:11 ` Linus Torvalds
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=5EAB44CD-482B-485F-A0E0-0AE7937FFF2C@zytor.com \
--to=hpa@zytor.com \
--cc=akpm@linux-foundation.org \
--cc=jikos@kernel.org \
--cc=jpoimboe@redhat.com \
--cc=jslaby@suse.cz \
--cc=linux-kernel@vger.kernel.org \
--cc=live-patching@vger.kernel.org \
--cc=luto@amacapital.net \
--cc=luto@kernel.org \
--cc=mingo@redhat.com \
--cc=tglx@linutronix.de \
--cc=torvalds@linux-foundation.org \
--cc=x86@kernel.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).