Re: [PATCH v2 2/3] libelf: Expand ELF note printing

[Jason Andryuk <jason.andryuk@xxxxxxx>]

On 2024-03-14 09:16, Jan Beulich wrote:
> On 13.03.2024 20:30, Jason Andryuk wrote:
> > @@ -217,6 +225,15 @@ elf_errorstatus elf_xen_parse_note(struct elf_binary *elf,
> >       case XEN_ELFNOTE_PHYS32_ENTRY:
> >           parms->phys_entry = val;
> >           break;
> > +
> > +    case XEN_ELFNOTE_L1_MFN_VALID:
> > +        if ( elf_uval(elf, note, descsz) != 2 * sizeof(uint64_t) )
> > +            return -1;
> elf_note_numeric() use sites don't have such a check. Why would we need
> one here, and even more so causing a error to be raised when in reality
> the supplied values (still) aren't consumed? Furthermore the documentation
> says "pairs" (plural) for a reason. Finally maddr_t-sized only happens to
> mean uint64_t on all architectures we presently support.
I failed to pay attention to the definition stating plural pairs.  I saw 
Linux stored two 64bit values and printed them.
I added the size check to avoid going out of bounds.  elf_note_numeric() 
handles 1, 2, 4 or 8 bytes and returns 0 otherwise, so it won't overrun 
boundaries.  That's why it was getting printed as "ELF: note: 
L1_MFN_VALID = 0"
What motivated this was seeing "PVH_RELOCATION = 0".  That confusingly 
looks like relocation is disabled.
I'm fine dropping this attempt at printing the L1_MFN_VALID note. 
maddr_t is not defined, and it looks the note values were 32bit in 
non-PAE kernels.  It could just be printed as "ELF: note: L1_MFN_VALID" 
with no details.
Regards,
Jason

> > +        elf_msg(elf, "mask: %#"PRIx64" val: %#"PRIx64"\n",
> > +                elf_note_numeric_array(elf, note, 8, 0),
> > +                elf_note_numeric_array(elf, note, 8, 1));
> > +        break;
> >       }
> >       return 0;
> >   }