[PATCH v7] MIPS: Sync elf.h from binutils

[Maciej W. Rozycki]

On Mon, 21 Aug 2023, Ying Huang wrote:

> Can you help commit  these two patchs?

 To move forward you need to put the findings from the discussion in the 
change description, especially given the difficulty to figure out what the 
correct naming convention for the ELF file header flags is supposed to be.  
This is so that the next time this information is needed it is readily 
available rather than requiring chasing in the archives and/or depending 
on the presence of people who may still remember it as on this occasion.

 I think it will help if you split the glibc patch into self-contained 
functional subsets:

1. File header flags -- need documentation, as noted above.

2. SHT_MIPS_ABIFLAGS section type -- obviously correct, no need to
   elaborate on it.

3. Relocation types -- obviously correct, no need to elaborate on it.

4. GNU attribute stuff -- technically Tag_GNU_MIPS_ABI_FP along with the 
   enumeration it comes with is a bug fix for commit 0bd956720c45 ("Add 
   support for MIPS O32 FPXX and .MIPS.abiflags") which, conservatively, 
   only added definitions actually used by the dynamic loader itself, 
   despite that the header is a part of our public API for the MIPS psABI.  
   I think that either said definitions ought to have been provided 
   internally only or the whole of the API should have been exported at 
   once (this applies to #2 above too).

   Then the MSA stuff and Val_GNU_MIPS_ABI_FP_NAN2008 as later additions 
   are distinct changes each.  I think it is worth mentioning in the 
   inline comment that the latter attribute value has been superseded by 
   EF_MIPS_NAN2008.

   I'd be tempted to say these would best be three distint changes then, 
   but maybe other people would consider it overly pedantic.

 Then the binutils change needs to document the switch from E_* to EF_* 
definitions accordingly.

  Maciej