arch/powerpc/mm/book3s64/hash_64k.c

Source file repositories/reference/linux-study-clean/arch/powerpc/mm/book3s64/hash_64k.c

File Facts

System
Linux kernel
Corpus path
arch/powerpc/mm/book3s64/hash_64k.c
Extension
.c
Size
9380 bytes
Lines
344
Domain
Architecture Layer
Bucket
arch/powerpc
Inferred role
Architecture Layer: implementation source
Status
source implementation candidate

Why This File Exists

CPU and platform-specific kernel glue: boot entry, traps, syscall entry, interrupts, page tables, context switch, and low-level barriers.

Dependency Surface

Detected Declarations

Annotated Snippet

if (unlikely(soft_invalid)) {
			/*
			 * We got a valid slot from a hardware point of view.
			 * but we cannot use it, because we use this special
			 * value; as defined by hpte_soft_invalid(), to track
			 * invalid slots. We cannot use it. So invalidate it.
			 */
			gslot = slot & _PTEIDX_GROUP_IX;
			mmu_hash_ops.hpte_invalidate(hpte_group + gslot, vpn,
						     MMU_PAGE_4K, MMU_PAGE_4K,
						     ssize, 0);
		}

		if (unlikely(slot == -1 || soft_invalid)) {
			/*
			 * For soft invalid slot, let's ensure that we release a
			 * slot from the primary, with the hope that we will
			 * acquire that slot next time we try. This will ensure
			 * that we do not get the same soft-invalid slot.
			 */
			if (soft_invalid || (mftb() & 0x1))
				hpte_group = (hash & htab_hash_mask) * HPTES_PER_GROUP;

			mmu_hash_ops.hpte_remove(hpte_group);
			/*
			 * FIXME!! Should be try the group from which we removed ?
			 */
			goto repeat;
		}
	}
	/*
	 * Hypervisor failure. Restore old pte and return -1
	 * similar to __hash_page_*
	 */
	if (unlikely(slot == -2)) {
		*ptep = __pte(old_pte);
		hash_failure_debug(ea, access, vsid, trap, ssize,
				   MMU_PAGE_4K, MMU_PAGE_4K, old_pte);
		return -1;
	}

	new_pte |= pte_set_hidx(ptep, rpte, subpg_index, slot, PTRS_PER_PTE);
	new_pte |= H_PAGE_HASHPTE;

	if (stress_hpt())
		hpt_do_stress(ea, hpte_group);

	*ptep = __pte(new_pte & ~H_PAGE_BUSY);
	return 0;
}

int __hash_page_64K(unsigned long ea, unsigned long access,
		    unsigned long vsid, pte_t *ptep, unsigned long trap,
		    unsigned long flags, int ssize)
{
	real_pte_t rpte;
	unsigned long hpte_group;
	unsigned long rflags, pa;
	unsigned long old_pte, new_pte;
	unsigned long vpn, hash, slot;
	unsigned long shift = mmu_psize_defs[MMU_PAGE_64K].shift;

	/*
	 * atomically mark the linux large page PTE busy and dirty
	 */
	do {
		pte_t pte = READ_ONCE(*ptep);

		old_pte = pte_val(pte);
		/* If PTE busy, retry the access */
		if (unlikely(old_pte & H_PAGE_BUSY))
			return 0;
		/* If PTE permissions don't match, take page fault */
		if (unlikely(!check_pte_access(access, old_pte)))
			return 1;
		/*
		 * Check if PTE has the cache-inhibit bit set
		 * If so, bail out and refault as a 4k page
		 */
		if (!mmu_has_feature(MMU_FTR_CI_LARGE_PAGE) &&
		    unlikely(pte_ci(pte)))
			return 0;
		/*
		 * Try to lock the PTE, add ACCESSED and DIRTY if it was
		 * a write access.
		 */
		new_pte = old_pte | H_PAGE_BUSY | _PAGE_ACCESSED;
		if (access & _PAGE_WRITE)
			new_pte |= _PAGE_DIRTY;
	} while (!pte_xchg(ptep, __pte(old_pte), __pte(new_pte)));

Annotation

Implementation Notes