Messages in this thread Patch in this message | | | Date | Mon, 15 Mar 2021 17:23:03 +0100 | From | Peter Zijlstra <> | Subject | Re: [RFC][PATCH] x86/alternatives: Optimize optimize_nops() |
| |
On Mon, Mar 15, 2021 at 04:45:24PM +0100, Peter Zijlstra wrote: > --- a/arch/x86/kernel/alternative.c > +++ b/arch/x86/kernel/alternative.c > @@ -345,19 +345,39 @@ recompute_jump(struct alt_instr *a, u8 * > static void __init_or_module noinline optimize_nops(struct alt_instr *a, u8 *instr) > { > unsigned long flags; > + int nops = 0, i = 0; > + struct insn insn; > + u8 *nop = NULL; > + > + do { > + kernel_insn_init(&insn, &instr[i], MAX_INSN_SIZE); > + insn_get_length(&insn); > +
I suppose you'd like to see that replaced with something like this, rite?
--- a/arch/x86/kernel/alternative.c +++ b/arch/x86/kernel/alternative.c @@ -350,8 +350,8 @@ static void __init_or_module noinline op u8 *nop = NULL; do { - kernel_insn_init(&insn, &instr[i], MAX_INSN_SIZE); - insn_get_length(&insn); + if (insn_decode(&insn, &instr[i], MAX_INSN_SIZE, INSN_MODE_KERN)) + return; if (insn.length == 1 && insn.opcode.bytes[0] == 0x90) { if (!nop) {
| |