Re: [tip: core/kprobes] arm/ftrace: Use __patch_text()

[Dmitry Osipenko]

07.02.2020 14:27, Peter Zijlstra ÐÐÑÐÑ:
>> NVIDIA Tegra20/30 are not booting with CONFIG_FTRACE=y, but even with
>> CONFIG_FTRACE=n things are not working well.
> 
> Ooh, I think I see. Can you try this:
> 
> diff --git a/arch/arm/kernel/ftrace.c b/arch/arm/kernel/ftrace.c
> index 2a5ff69c28e6..10499d44964a 100644
> --- a/arch/arm/kernel/ftrace.c
> +++ b/arch/arm/kernel/ftrace.c
> @@ -78,13 +78,10 @@ static int ftrace_modify_code(unsigned long pc, unsigned long old,
>  {
>  	unsigned long replaced;
>  
> -	if (IS_ENABLED(CONFIG_THUMB2_KERNEL)) {
> +	if (IS_ENABLED(CONFIG_THUMB2_KERNEL))
>  		old = __opcode_to_mem_thumb32(old);
> -		new = __opcode_to_mem_thumb32(new);
> -	} else {
> +	else
>  		old = __opcode_to_mem_arm(old);
> -		new = __opcode_to_mem_arm(new);
> -	}
>  
>  	if (validate) {
>  		if (probe_kernel_read(&replaced, (void *)pc, MCOUNT_INSN_SIZE))
> 

Hello Peter,

It fixes the problem, at least kernel is booting fine now and I can't
notice any problems. Thank you very much! :)

Tested-by: Dmitry Osipenko <digetx@xxxxxxxxx>