RE: [patch v2 1/2] x86,module: Detect VMX modules and disable Split-Lock-Detect

[David Laight]

From: Peter Zijlstra
> Sent: 02 April 2020 16:24
> 
> I picked VMXOFF (which also appears in vmmon.ko) instead of VMXON
> because that latter takes an argument is therefore more difficult to
> decode.
...
> +	while (text < text_end) {
> +		kernel_insn_init(&insn, text, text_end - text);
> +		insn_get_length(&insn);
> +
> +		if (WARN_ON_ONCE(!insn_complete(&insn)))
> +			break;
> +
> +		if (insn.length == 3 &&
> +		    (!memcmp(text, vmlaunch, sizeof(vmlaunch)) ||
> +		     !memcmp(text, vmxoff, sizeof(vmxoff))))
> +				goto bad_module;
> +
> +		text += insn.length;
> +	}

How long is that going to take on a module with (say) 400k of text?

	David

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