Re: [PATCH] x86/speculation, objtool: Use absolute relocations for annotations

[Peter Zijlstra]

On Thu, Sep 21, 2023 at 09:22:53PM +0200, Peter Zijlstra wrote:
> On Thu, Sep 21, 2023 at 10:36:27AM -0700, Fangrui Song wrote:
> 
> > Well, only if the clever assembler doesn't support 32-bit absolute
> > relocation for a 64-bit architecture.
> > I don't know such an architecture. In addition, as long as the
> > architecture intends to support DWARF32, it has to support 32-bit
> > absolute relocations for a 64-bit architecture.
> 
> Ooh... my bad. For some reason I thought that absolute meant native word
> size. But you already mentioned R_X86_64_32 (and I failed to check) and
> that is indeed an absolute (S+A) relocation of 32bit (dword) size.
> 
> And apparently we also have R_X64_64_16 and R_X86_64_8, which would even
> allow something like:

Hurm, just checked PPC/PPC64 and ARM64 and they only do 16bit (and up)
absolute relocations, not the single byte form.

So if I want to keep this portable, I suppose I shouldn't go smaller.