Re: [PATCH v4 2/8] riscv/kprobe: Allocate detour buffer from module area

[liaochang (A)]

在 2022/11/17 9:25, Steven Rostedt 写道:
> On Sun,  6 Nov 2022 18:03:10 +0800
> Chen Guokai <chenguokai17@xxxxxxxxxxxxxxxx> wrote:
> 
>> @@ -84,6 +85,30 @@ int __kprobes arch_prepare_kprobe(struct kprobe *p)
>>  }
>>  
>>  #ifdef CONFIG_MMU
>> +#if defined(CONFIG_OPTPROBES) && defined(CONFIG_64BIT)
>> +void *alloc_optinsn_page(void)
>> +{
>> +	void *page;
>> +
>> +	page = __vmalloc_node_range(PAGE_SIZE, 1, MODULES_VADDR,
>> +				    MODULES_END, GFP_KERNEL,
>> +				    PAGE_KERNEL, 0, NUMA_NO_NODE,
>> +				    __builtin_return_address(0));
>> +	if (!page)
>> +		return NULL;
>> +
>> +	set_vm_flush_reset_perms(page);
>> +	/*
>> +	 * First make the page read-only, and only then make it executable to
>> +	 * prevent it from being W+X in between.
>> +	 */
>> +	set_memory_ro((unsigned long)page, 1);
>> +	set_memory_x((unsigned long)page, 1);
> 
> FYI, the above combination is going to be going away:
> 
>   https://lore.kernel.org/all/Y10OyLCLAAS6rsZv@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx/

Thanks for reminding, i will use this API in next revision.
> -- Steve
> 
> 
>> +
>> +	return page;
>> +}
>> +#endif
>> +
> 

-- 
BR,
Liao, Chang