Messages in this thread | | | Date | Thu, 21 Sep 2023 21:31:01 +0200 | From | Peter Zijlstra <> | Subject | Re: [PATCH] x86/speculation, objtool: Use absolute relocations for annotations |
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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.
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