Re: [Xen-devel] Booting signed xen.efi through shim

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 13.09.17 at 07:27, <tamas@xxxxxxxxxxxxx> wrote:
>Sections:
>Idx Name          Size      VMA               LMA               File off  Algn
>  0 .text         0017a1ba  ffff82d080200000  ffff82d080200000  00001000  2**12
>                  CONTENTS, ALLOC, LOAD, CODE
>  1 .rodata       000826a0  ffff82d080400000  ffff82d080400000  0017c000  2**5
>                  CONTENTS, ALLOC, LOAD, DATA
>  2 .buildid      00000035  ffff82d0804826a0  ffff82d0804826a0  001fe6a0  2**2
>                  CONTENTS, ALLOC, LOAD, READONLY, DATA
>  3 .init         00077df0  ffff82d080600000  ffff82d080600000  001ff000  2**12
>                  CONTENTS, ALLOC, LOAD, CODE, DATA
>  4 .data.re      0000aa40  ffff82d080800000  ffff82d080800000  00277000  2**7
>                  CONTENTS, ALLOC, LOAD, DATA
>  5 .data         000105a8  ffff82d08080b000  ffff82d08080b000  00282000  2**12
>                  CONTENTS, ALLOC, LOAD, DATA
>  6 .bss          00143280  ffff82d080820000  ffff82d080820000  00000000  2**4
>                  ALLOC, RELOC

Objdump is apparently ignoring a section attribute bit here - my
own utility properly prints "bss" in addition to "read" (which presumably
matches "ALLOC" above, albeit that's a bogus translation apparently
applying ELF semantics to COFF). You'll want to check that bit 7 in the
section attributes is set. I'm also puzzled by "RELOC", but I do see a
matching bit dumped here; not sure why that's being set.

It is certainly the case that .bss style sections are expected to have a
zero file offset, as there's no data for such sections inside the file (note
the missing "CONTENTS" above. So I would conclude that, unless the
bss flag really got lost, it's a shim loader bug. Since other people can
load xen.efi with the shim, that might be a problem with the particular
version you're using.

>  7 .reloc        000016b0  ffff82d080a00000  ffff82d080a00000  00293000  2**2
>                  CONTENTS, ALLOC, LOAD, READONLY, DATA
>  8 .pad          00400000  ffff82d080c00000  ffff82d080c00000  00000000  2**2
>                  ALLOC

Mostly the same for this section.

Jan


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