Messages in this thread | | | Date | Fri, 10 Nov 2006 09:50:52 +0900 | From | Horms <> | Subject | Re: [PATCH 02/02] Elf: Align elf notes properly |
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On Thu, Nov 09, 2006 at 07:00:22AM -0700, Eric W. Biederman wrote: > Magnus Damm <magnus@valinux.co.jp> writes: > > > elf: Align elf notes properly > > > > The kernel currently contains several elf note aligment implementations. Most > > implementations follow the spec on 32-bit platforms, but none current aligns > > the notes correctly on 64-bit platforms. This patch tries to fix this by > > interpreting the 64-bit and 32-bit elf specs as the following: > > > > offset bytes name > > 0 4 n_namesz -+ -+ > > 4 4 n_descsz | elf note header | > > 8 4 n_type -+ | elf note entry size - N4 > > 12 N1 name | > > N2 N3 desc -+ > > > > WS = word size in bytes (4 for 32 bit, 8 for 64 bit) > > N1 = roundup(n_namesz + sizeof(elf note header), WS) - sizeof(elf note header) > > N2 = sizeof(elf note header) + N1 > > N3 = roundup(n_descsz, WS) > > N4 = sizeof(elf note header) + N1 + N2 > > > > The elf note header contains three 32-bit values on 32-bit and 64-bit systems. > > The header is followed by name and desc data together with padding. The > > alignment and padding varies depending on the word size. > > I see your point and I disagree. The notes in a kernel generated > core dump do not vary in size. Find me some implementation evidence that > anyone ever added the extra 4 bytes of alignment to the description and the > padding fields and I will be ready to consider this. Currently this > just appears to be reading a draft spec that doesn't match reality.
Or perhaps a spec that hasn't been implemented correctly. I guess that the real question is, what padding is correct?
-- Horms H: http://www.vergenet.net/~horms/ W: http://www.valinux.co.jp/en/
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