On Sun, Jan 15, 2023 at 11:49:49PM +0800, Jisheng Zhang wrote: > Instead of using absolute addresses for both the old instrucions and > the alternative instructions, use offsets relative to the alt_entry > values. So this not only cuts the size of the alternative entry, but > also meets the prerequisite for patching alternatives in the vDSO, > since absolute alternative entries are subject to dynamic relocation, > which is incompatible with the vDSO building. > > Signed-off-by: Jisheng Zhang <jszhang@xxxxxxxxxx> > Reviewed-by: Andrew Jones <ajones@xxxxxxxxxxxxxxxx> > +/* add the relative offset to the address of the offset to get the absolute address */ > +#define __ALT_PTR(a, f) ((void *)&(a)->f + (a)->f) > +#define ALT_OLD_PTR(a) __ALT_PTR(a, old_offset) > +#define ALT_ALT_PTR(a) __ALT_PTR(a, alt_offset) LGTM, thanks for doing that! Certainly makes things more understandable. Reviewed-by: Conor Dooley <conor.dooley@xxxxxxxxxxxxx> > + oldptr = ALT_OLD_PTR(alt); > + altptr = ALT_ALT_PTR(alt); > if (!__riscv_isa_extension_available(NULL, alt->errata_id)) > continue; > One minor nit, the oldptr/altptr assignments could go down here, below the if/continue, right? Obviously don't respin for that though! > - patch_text_nosync(alt->old_ptr, alt->alt_ptr, alt->alt_len); > - riscv_alternative_fix_offsets(alt->old_ptr, alt->alt_len, > - alt->old_ptr - alt->alt_ptr); > + patch_text_nosync(oldptr, altptr, alt->alt_len); > + riscv_alternative_fix_offsets(oldptr, alt->alt_len, oldptr - altptr); > } > } > #endif
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