Eduard Zingerman eddyz87@gmail.com writes:
On Thu, 2025-03-13 at 18:21 +0100, Luis Gerhorst wrote:
err = do_check_insn(env, insn, pop_log, &do_print_state, regs, state,&prev_insn_idx);
- `regs` remains declared in do_check(), while nothing prevents pushing its declaration to do_check_insn().
- `state` is `env->cur_state`, so I'd avoid passing it as a parameter (just to reduce count);
- `prev_insn_idx` is unused by `do_check_insn`;
- `pop_log` is not used by `do_check_insn`;
Changed for v2, thank you very much.
- given that `insn` is presumed to correspond to `env->insn_idx` in many places down the stack not sure about this parameter.
I don't have a strong opinion on this either. Unless someone objects I will keep it as it matches the other check_*() functions like this.
if (err < 0) {return err;} else if (err == INSN_IDX_MODIFIED) {Also, I'd get rid of `INSN_IDX_MODIFIED` and move `env->insn_idx++` into `do_check_insn()`. This would save a few mental cycles when looking at the code with full patch-set applied:
} else if (err == INSN_IDX_MODIFIED) { continue; } else if (err == PROCESS_BPF_EXIT) { goto process_bpf_exit; } WARN_ON_ONCE(err); if (state->speculative && cur_aux(env)->nospec_result) { ... bunch of actions ... } env->insn_idx++;One needs to stop for a moment and think why "bunch of actions" is performed for regular index increment, but not for INSN_IDX_MODIFIED.
That certainly makes it more readable. I changed it for v2.
If we have an instruction that does not simply do `insn_idx++` but jumps, the `nospec_result` check should never trigger. Otherwise, the patched nospec might be skipped. Currently, this is satisfied because `nospec_result` is only used for store-instructions. I will add a comment and WARN_ON_ONCE to document that for v2.