Re: [PATCH v7 9/9] sparc64: Add support for ADI (Application Data Integrity)

[David Miller <davem@davemloft.net>]

From: Khalid Aziz <khalid.aziz@oracle.com>
Date: Wed,  9 Aug 2017 15:26:02 -0600

> +void adi_restore_tags(struct mm_struct *mm, struct vm_area_struct *vma,
> +		      unsigned long addr, pte_t pte)
> +{
 ...
> +	tag = tag_start(addr, tag_desc);
> +	paddr = pte_val(pte) & _PAGE_PADDR_4V;
> +	for (tmp = paddr; tmp < (paddr+PAGE_SIZE); tmp += adi_blksize()) {
> +		version1 = (*tag) >> 4;
> +		version2 = (*tag) & 0x0f;
> +		*tag++ = 0;
> +		asm volatile("stxa %0, [%1] %2\n\t"
> +			:
> +			: "r" (version1), "r" (tmp),
> +			  "i" (ASI_MCD_REAL));
> +		tmp += adi_blksize();
> +		asm volatile("stxa %0, [%1] %2\n\t"
> +			:
> +			: "r" (version2), "r" (tmp),
> +			  "i" (ASI_MCD_REAL));
> +	}
> +	asm volatile("membar #Sync\n\t");

You do a membar here.

> +		for (i = pfrom; i < (pfrom + PAGE_SIZE); i += adi_blksize()) {
> +			asm volatile("ldxa [%1] %2, %0\n\t"
> +					: "=r" (adi_tag)
> +					:  "r" (i), "i" (ASI_MCD_REAL));
> +			asm volatile("stxa %0, [%1] %2\n\t"
> +					:
> +					: "r" (adi_tag), "r" (pto),
> +					  "i" (ASI_MCD_REAL));

But not here.

Is this OK?  I suspect you need to add a membar this this second piece
of MCD tag storing code.