Messages in this thread | | | From | (Eric W. Biederman) | Subject | Re: [PATCH 02/02] Elf: Align elf notes properly | Date | Thu, 09 Nov 2006 07:00:22 -0700 |
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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.
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