From mboxrd@z Thu Jan  1 00:00:00 1970
Content-Type: multipart/mixed; boundary="===============2722927340228211309=="
MIME-Version: 1.0
From: Mark Wielaard <mjw@redhat.com>
To: elfutils-devel@lists.fedorahosted.org
Subject: Re: [patch] Fix resolving ELF symbols for live PIDs with deleted files
Date: Fri, 29 Aug 2014 11:55:32 +0200
Message-ID: <1409306132.4981.13.camel@bordewijk.wildebeest.org>
In-Reply-To: 20140828201216.GA2549@host2.jankratochvil.net

--===============2722927340228211309==
Content-Type: text/plain; charset="utf-8"
MIME-Version: 1.0
Content-Transfer-Encoding: quoted-printable

On Thu, 2014-08-28 at 22:12 +0200, Jan Kratochvil wrote:
> Formerly shared libraries did not get resolved properly:
> 	#2  0x00007fc4d86c56d6
> 	#3  0x0000000000400938 main
> =

> Fixed elfutils produce:
> 	#2  0x00007f61094876d6 libfunc
> 	#3  0x0000000000400938 main
> =

> Signed-off-by: Jan Kratochvil <jan.kratochvil@redhat.com>

Nice, thanks. I would add the why to the commit message. "For deleted
shared library files the offsets to the symbol table were calculated
wrongly from the phdrs because the main_bias wasn't taken into account."

+2014-08-28  Jan Kratochvil  <jan.kratochvil@redhat.com>
> +
> +	* dwfl_module_getdwarf.c (find_offsets): Add parameter main_bias, use
> +	it.
> +	(find_dynsym): Pass the new parameter main_bias.
> =

Looks good.

+# Older Linux (such as 2.6.32) required PTRACE_ATTACH to read /proc/PID/me=
m.
> +sleep 60 & p=3D$!; sleep 0.1
> +addr=3D0x$(cat /proc/$p/maps|sed -n 's#^\([0-9a-f]*\)-[0-9a-f]* r[^ ]* 0=
0* .*/sleep$#\1#p'|head -n1)
> +supported=3D$[$(dd if=3D/proc/$p/mem bs=3D1 skip=3D$[$addr] count=3D1|wc=
 -c)]
> +kill -9 $p
> +if [ $supported -eq 0 ]; then
> +  exit 77
> +fi
 =

I don't think this check is needed. eu-stack needs to be attached to get
the register values and dwfl_linux_proc_find_elf makes sure the process
is attached before calling elf_from_remote_memory.

Cheers,

Mark

--===============2722927340228211309==--