Re: [for-next][PATCH 12/16] kprobes: Initialize kprobes at postcore_initcall

[Catalin Marinas <catalin.marinas@arm.com>]

On Wed, Jul 03, 2019 at 10:02:05AM -0400, Steven Rostedt wrote:
> > On arm64 kprobes depends on the BRK handler we register in
> > debug_traps_init(), which is an arch_initcall.
> > 
> > As of this change, init_krprobes() calls init_test_probes() before
> > that's registered, so we end up hitting a BRK before we can handle it.
> 
> Would something like this help?
> 
> -- Steve
> 
> diff --git a/kernel/kprobes.c b/kernel/kprobes.c
> index 5471efbeb937..0ca6f53c8505 100644
> --- a/kernel/kprobes.c
> +++ b/kernel/kprobes.c
> @@ -2235,6 +2235,8 @@ static struct notifier_block kprobe_module_nb = {
>  extern unsigned long __start_kprobe_blacklist[];
>  extern unsigned long __stop_kprobe_blacklist[];
>  
> +static bool run_kprobe_tests __initdata;
> +
>  static int __init init_kprobes(void)
>  {
>  	int i, err = 0;
> @@ -2286,11 +2288,18 @@ static int __init init_kprobes(void)
>  	kprobes_initialized = (err == 0);
>  
>  	if (!err)
> -		init_test_probes();
> +		run_kprobe_tests = true;
>  	return err;
>  }
>  subsys_initcall(init_kprobes);
>  
> +static int __init run_init_test_probes(void)
> +{
> +	if (run_kprobe_tests)
> +		init_test_probes();

A return 0 here.

> +}
> +module_init(run_init_test_probes);

This does the trick. I prefer your fix as it leaves the arch code
unchanged. In case you need it:

Tested-by: Catalin Marinas <catalin.marinas@arm.com>

Thanks.

-- 
Catalin