Re: [RESEND][PATCH v3 09/17] x86/static_call: Add out-of-line static call implementation

[Borislav Petkov]

On Tue, Mar 24, 2020 at 02:56:12PM +0100, Peter Zijlstra wrote:
> +static void __static_call_transform(void *insn, u8 opcode, void *func)
> +{
> +	const void *code = text_gen_insn(opcode, (long)insn, (long)func);
> +
> +	if (WARN_ONCE(*(u8 *)insn != opcode,
> +		      "unexpected static call insn opcode 0x%x at %pS\n",
> +		      opcode, insn))
> +		return;
> +
> +	if (memcmp(insn, code, CALL_INSN_SIZE) == 0)
> +		return;
> +
> +	text_poke_bp(insn, code, CALL_INSN_SIZE, NULL);

Right, this is working with CALL_INSN_SIZE but ...

> +}
> +
> +void arch_static_call_transform(void *site, void *tramp, void *func)
> +{
> +	mutex_lock(&text_mutex);
> +
> +	if (tramp)
> +		__static_call_transform(tramp, JMP32_INSN_OPCODE, func);

... it gets called with JMP32_INSN_OPCODE too. I mean, both lengths are
equal and all - it is just a bit confusing at a first glance. Maybe slap
a small comment that it is ok.

Thx.

-- 
Regards/Gruss,
    Boris.

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