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Date: Tue, 4 Jun 2019 08:54:01 +0200
From: Peter Zijlstra <peterz@infradead.org>
Subject: Re: [RFC V2] mm: Generalize notify_page_fault()
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To: Anshuman Khandual <anshuman.khandual@arm.com>
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On Tue, Jun 04, 2019 at 12:04:06PM +0530, Anshuman Khandual wrote:
> diff --git a/mm/memory.c b/mm/memory.c
> index ddf20bd..b6bae8f 100644
> --- a/mm/memory.c
> +++ b/mm/memory.c
> @@ -52,6 +52,7 @@
>  #include <linux/pagemap.h>
>  #include <linux/memremap.h>
>  #include <linux/ksm.h>
> +#include <linux/kprobes.h>
>  #include <linux/rmap.h>
>  #include <linux/export.h>
>  #include <linux/delayacct.h>
> @@ -141,6 +142,21 @@ static int __init init_zero_pfn(void)
>  core_initcall(init_zero_pfn);
>  
>  
> +int __kprobes notify_page_fault(struct pt_regs *regs, unsigned int trap)
> +{
> +	int ret = 0;
> +
> +	/*
> +	 * To be potentially processing a kprobe fault and to be allowed
> +	 * to call kprobe_running(), we have to be non-preemptible.
> +	 */
> +	if (kprobes_built_in() && !preemptible() && !user_mode(regs)) {
> +		if (kprobe_running() && kprobe_fault_handler(regs, trap))
> +			ret = 1;
> +	}
> +	return ret;
> +}

That thing should be called kprobe_page_fault() or something,
notify_page_fault() is a horribly crap name for this function.