Re: [PATCH 1/2] ARM: ioremap: Flush PGDs for VMALLOC shadow

["Russell King (Oracle)" <linux@armlinux.org.uk>]

On Tue, Oct 15, 2024 at 11:37:14PM +0200, Linus Walleij wrote:
> @@ -125,6 +126,12 @@ void __check_vmalloc_seq(struct mm_struct *mm)
>  		       pgd_offset_k(VMALLOC_START),
>  		       sizeof(pgd_t) * (pgd_index(VMALLOC_END) -
>  					pgd_index(VMALLOC_START)));
> +		if (IS_ENABLED(CONFIG_KASAN_VMALLOC)) {
> +			memcpy(pgd_offset(mm, (unsigned long)kasan_mem_to_shadow((void *)VMALLOC_START)),
> +			       pgd_offset_k((unsigned long)kasan_mem_to_shadow((void *)VMALLOC_START)),
> +			       sizeof(pgd_t) * (pgd_index((unsigned long)kasan_mem_to_shadow((void *)VMALLOC_END)) -
> +						pgd_index((unsigned long)kasan_mem_to_shadow((void *)VMALLOC_START))));

Maybe the following would be more readable:

static unsigned long arm_kasan_mem_to_shadow(unsigned long addr)
{
	return (unsigned long)kasan_mem_to_shadow((void *)addr);
}

static void memcpy_pgd(struct mm_struct *mm, unsigned long start,
		       unsigned long end)
{
	memcpy(pgd_offset(mm, start), pgd_offset_k(start),
	       sizeof(pgd_t) * (pgd_index(end) - pgd_index(start)));
}

		seq = ...;
		memcpy_pgd(mm, VMALLOC_START, VMALLOC_END);

		if (IS_ENABLED(CONFIG_KASAN_VMALLOC)) {
			unsigned long start =
				arm_kasan_mem_to_shadow(VMALLOC_START);
			unsigned long end =
				arm_kasan_mem_to_shadow(VMALLOC_END);

			memcpy_pgd(mm, start, end);
> +		}

?

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