sparc64: Handle hugepage TSB being NULL.

[linux-2.6-block.git] / arch / sparc / mm / tlb.c

/* arch/sparc64/mm/tlb.c
 *
 * Copyright (C) 2004 David S. Miller <davem@redhat.com>
 */

#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/percpu.h>
#include <linux/mm.h>
#include <linux/swap.h>
#include <linux/preempt.h>

#include <asm/pgtable.h>
#include <asm/pgalloc.h>
#include <asm/tlbflush.h>
#include <asm/cacheflush.h>
#include <asm/mmu_context.h>
#include <asm/tlb.h>

/* Heavily inspired by the ppc64 code.  */

static DEFINE_PER_CPU(struct tlb_batch, tlb_batch);

void flush_tlb_pending(void)
{
	struct tlb_batch *tb = &get_cpu_var(tlb_batch);

	if (tb->tlb_nr) {
		flush_tsb_user(tb);

		if (CTX_VALID(tb->mm->context)) {
#ifdef CONFIG_SMP
			smp_flush_tlb_pending(tb->mm, tb->tlb_nr,
					      &tb->vaddrs[0]);
#else
			__flush_tlb_pending(CTX_HWBITS(tb->mm->context),
					    tb->tlb_nr, &tb->vaddrs[0]);
#endif
		}
		tb->tlb_nr = 0;
	}

	put_cpu_var(tlb_batch);
}

static void tlb_batch_add_one(struct mm_struct *mm, unsigned long vaddr,
			      bool exec)
{
	struct tlb_batch *tb = &get_cpu_var(tlb_batch);
	unsigned long nr;

	vaddr &= PAGE_MASK;
	if (exec)
		vaddr |= 0x1UL;

	nr = tb->tlb_nr;

	if (unlikely(nr != 0 && mm != tb->mm)) {
		flush_tlb_pending();
		nr = 0;
	}

	if (nr == 0)
		tb->mm = mm;

	tb->vaddrs[nr] = vaddr;
	tb->tlb_nr = ++nr;
	if (nr >= TLB_BATCH_NR)
		flush_tlb_pending();

	put_cpu_var(tlb_batch);
}

void tlb_batch_add(struct mm_struct *mm, unsigned long vaddr,
		   pte_t *ptep, pte_t orig, int fullmm)
{
	if (tlb_type != hypervisor &&
	    pte_dirty(orig)) {
		unsigned long paddr, pfn = pte_pfn(orig);
		struct address_space *mapping;
		struct page *page;

		if (!pfn_valid(pfn))
			goto no_cache_flush;

		page = pfn_to_page(pfn);
		if (PageReserved(page))
			goto no_cache_flush;

		/* A real file page? */
		mapping = page_mapping(page);
		if (!mapping)
			goto no_cache_flush;

		paddr = (unsigned long) page_address(page);
		if ((paddr ^ vaddr) & (1 << 13))
			flush_dcache_page_all(mm, page);
	}

no_cache_flush:
	if (!fullmm)
		tlb_batch_add_one(mm, vaddr, pte_exec(orig));
}

#ifdef CONFIG_TRANSPARENT_HUGEPAGE
static void tlb_batch_pmd_scan(struct mm_struct *mm, unsigned long vaddr,
			       pmd_t pmd, bool exec)
{
	unsigned long end;
	pte_t *pte;

	pte = pte_offset_map(&pmd, vaddr);
	end = vaddr + HPAGE_SIZE;
	while (vaddr < end) {
		if (pte_val(*pte) & _PAGE_VALID)
			tlb_batch_add_one(mm, vaddr, exec);
		pte++;
		vaddr += PAGE_SIZE;
	}
	pte_unmap(pte);
}

void set_pmd_at(struct mm_struct *mm, unsigned long addr,
		pmd_t *pmdp, pmd_t pmd)
{
	pmd_t orig = *pmdp;

	*pmdp = pmd;

	if (mm == &init_mm)
		return;

	if ((pmd_val(pmd) ^ pmd_val(orig)) & PMD_ISHUGE) {
		if (pmd_val(pmd) & PMD_ISHUGE)
			mm->context.huge_pte_count++;
		else
			mm->context.huge_pte_count--;
		if (mm->context.huge_pte_count == 1)
			hugetlb_setup(mm);
	}

	if (!pmd_none(orig)) {
		bool exec = ((pmd_val(orig) & PMD_HUGE_EXEC) != 0);

		addr &= HPAGE_MASK;
		if (pmd_val(orig) & PMD_ISHUGE)
			tlb_batch_add_one(mm, addr, exec);
		else
			tlb_batch_pmd_scan(mm, addr, orig, exec);
	}
}

void pgtable_trans_huge_deposit(struct mm_struct *mm, pgtable_t pgtable)
{
	struct list_head *lh = (struct list_head *) pgtable;

	assert_spin_locked(&mm->page_table_lock);

	/* FIFO */
	if (!mm->pmd_huge_pte)
		INIT_LIST_HEAD(lh);
	else
		list_add(lh, (struct list_head *) mm->pmd_huge_pte);
	mm->pmd_huge_pte = pgtable;
}

pgtable_t pgtable_trans_huge_withdraw(struct mm_struct *mm)
{
	struct list_head *lh;
	pgtable_t pgtable;

	assert_spin_locked(&mm->page_table_lock);

	/* FIFO */
	pgtable = mm->pmd_huge_pte;
	lh = (struct list_head *) pgtable;
	if (list_empty(lh))
		mm->pmd_huge_pte = NULL;
	else {
		mm->pmd_huge_pte = (pgtable_t) lh->next;
		list_del(lh);
	}
	pte_val(pgtable[0]) = 0;
	pte_val(pgtable[1]) = 0;

	return pgtable;
}
#endif /* CONFIG_TRANSPARENT_HUGEPAGE */