Messages in this thread | | | Date | Tue, 14 Nov 2023 16:06:27 +0100 | From | Borislav Petkov <> | Subject | Re: [PATCH v4 2/5] x86/alternative: add indirect call patching |
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On Mon, Oct 30, 2023 at 03:25:05PM +0100, Juergen Gross wrote: > +#ifdef CONFIG_X86_64 > + /* ff 15 00 00 00 00 call *0x0(%rip) */ > + target = *(void **)(instr + a->instrlen + *(s32 *)(instr + 2)); > +#else > + /* ff 15 00 00 00 00 call *0x0 */ > + target = *(void **)(*(s32 *)(instr + 2));
Yeah, let's document those a bit better. Either with comments above or as Peter suggests:
/* Add 2 to skip opcode and ModRM byte: */ disp32 = *(s32 *)(instr + 2);
rip_rela_ptr = (void **)(instr + a->instrlen + disp32); target = *rip_rela_ptr;
so that it is crystal clear what we're doing here.
Thx.
-- Regards/Gruss, Boris.
https://people.kernel.org/tglx/notes-about-netiquette
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