Messages in this thread | | | Date | Wed, 24 Nov 2021 11:30:37 -0800 | From | Josh Poimboeuf <> | Subject | Re: [RFC][PATCH 6/6] objtool: Add IBT validation / fixups |
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On Mon, Nov 22, 2021 at 06:03:07PM +0100, Peter Zijlstra wrote: > +static int validate_ibt_reloc(struct objtool_file *file, struct reloc *reloc, char **name) > +{ > + struct instruction *dest; > + struct section *sec; > + unsigned long off; > + > + sec = reloc->sym->sec; > + off = reloc->sym->offset + reloc->addend; > + > + dest = find_insn(file, sec, off); > + if (!dest) > + return 0; > + > + if (name && dest->func) > + *name = dest->func->name;
I think these checks can be further narrowed down by only looking for X86_64_64 relocs.
> + list_for_each_entry(insn, &file->endbr_list, call_node) { > + if (ibt_seal) { > + elf_write_insn(file->elf, insn->sec, > + insn->offset, insn->len, > + arch_nop_insn(insn->len)); > + }
Like the retpoline rewriting, I'd much rather have objtool create annotations which the kernel can then read and patch itself.
e.g. have '.ibt.direct_call_sites' and '.ibt.unused_endbr_insns' sections.
-- Josh
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