linux-kernel - Re: [PATCH v1 2/4] x86/xen: add basic KASAN support for PV kernel

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Date:   Fri, 10 Jan 2020 11:46:45 +0000
From:   Sergey Dyasli <sergey.dyasli@...rix.com>
To:     Boris Ostrovsky <boris.ostrovsky@...cle.com>,
        <xen-devel@...ts.xen.org>, <kasan-dev@...glegroups.com>,
        <linux-mm@...ck.org>, <linux-kernel@...r.kernel.org>
CC:     Andrey Ryabinin <aryabinin@...tuozzo.com>,
        Alexander Potapenko <glider@...gle.com>,
        Dmitry Vyukov <dvyukov@...gle.com>,
        Juergen Gross <jgross@...e.com>,
        Stefano Stabellini <sstabellini@...nel.org>,
        George Dunlap <george.dunlap@...rix.com>,
        Ross Lagerwall <ross.lagerwall@...rix.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        "sergey.dyasli@...rix.com >> Sergey Dyasli" 
        <sergey.dyasli@...rix.com>
Subject: Re: [PATCH v1 2/4] x86/xen: add basic KASAN support for PV kernel

On 09/01/2020 23:27, Boris Ostrovsky wrote:
> 
> 
> On 1/8/20 10:20 AM, Sergey Dyasli wrote:
>> @@ -1943,6 +1973,15 @@ void __init xen_setup_kernel_pagetable(pgd_t *pgd, unsigned long max_pfn)
>>       if (i && i < pgd_index(__START_KERNEL_map))
>>           init_top_pgt[i] = ((pgd_t *)xen_start_info->pt_base)[i];
>>   +#ifdef CONFIG_KASAN
>> +    /*
>> +     * Copy KASAN mappings
>> +     * ffffec0000000000 - fffffbffffffffff (=44 bits) kasan shadow memory (16TB)
>> +     */
>> +    for (i = 0xec0 >> 3; i < 0xfc0 >> 3; i++)
> 
> Are you referring here to  KASAN_SHADOW_START and KASAN_SHADOW_END? If so, can you use them instead?

Indeed, the following macros make the code neater:

#ifdef CONFIG_KASAN
	/* Copy KASAN mappings */
	for (i = pgd_index(KASAN_SHADOW_START);
	     i < pgd_index(KASAN_SHADOW_END);
	     i++)
		init_top_pgt[i] = ((pgd_t *)xen_start_info->pt_base)[i];
#endif /* ifdef CONFIG_KASAN */

--
Thanks,
Sergey