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Re: vdso handling
- From: Pedro Alves <palves at redhat dot com>
- To: "Metzger, Markus T" <markus dot t dot metzger at intel dot com>, Pedro Alves <palves at redhat dot com>, Mark Wielaard <mjw at redhat dot com>, Cary Coutant <ccoutant at google dot com>, Doug Evans <dje at google dot com>, "gdb at sourceware dot org" <gdb at sourceware dot org>, "binutils at sourceware dot org" <binutils at sourceware dot org>
- Date: Fri, 21 Mar 2014 15:54:50 +0000
- Subject: Re: vdso handling
- Authentication-results: sourceware.org; auth=none
- References: <20140313010147 dot GZ26922 at bubble dot grove dot modra dot org> <1394704336 dot 11818 dot 115 dot camel at bordewijk dot wildebeest dot org> <20140313130322 dot GA3384 at bubble dot grove dot modra dot org> <5321C7C8 dot 6000707 at redhat dot com> <5321C8FA dot 40708 at gmail dot com> <5321CE1A dot 20509 at redhat dot com> <20140313235347 dot GD3384 at bubble dot grove dot modra dot org> <A78C989F6D9628469189715575E55B230AAB6B17 at IRSMSX103 dot ger dot corp dot intel dot com> <20140318230939 dot GA9145 at bubble dot grove dot modra dot org> <A78C989F6D9628469189715575E55B230AAB701F at IRSMSX103 dot ger dot corp dot intel dot com> <20140320015950 dot GB13347 at bubble dot grove dot modra dot org>
On 03/20/2014 01:59 AM, Alan Modra wrote:
> On Wed, Mar 19, 2014 at 08:29:47AM +0000, Metzger, Markus T wrote:
>> Shouldn't the ehdr indicate that there are no sections in this case?
> Nope. See my other email to Pedro.
>> If we can't trust the image to contain everything that the ELF header
>> describes, would it be safer to generate fake sections based on the
>> program header? We already assume that the program header is
>> contained in the image.
> Yes, you're correct that it is wrong to assume program headers are
> loaded. Even worse, the in-memory image doesn't even need to contain
> the ELF file header.
Yeah, and I was just assuming it didn't, hence my "just trust the
headers" push before.
I'm now thinking that we'll need pseudo-sections from program
headers anyway, so I'd suggest going in that direction, leaving
the add-symbol-file-from-memory command's intention generic,
and leave revisiting how gdb retrieves the vdso itself off of
memory for another day.