From: Keir Fraser <keir@xensource.com>
Date: Sat, 31 Mar 2007 11:42:02 +0000 (+0100)
Subject: linux: Add a hook before a page table entry is cleared, for use with
X-Git-Tag: archive/raspbian/4.8.0-1+rpi1~1^2~15270^2~24
X-Git-Url: https://dgit.raspbian.org/%22http:/www.example.com/cgi/%22https://%22%22/%22http:/www.example.com/cgi/%22https:/%22%22?a=commitdiff_plain;h=7fd0f937ba5af29fb1cfe7622ff4aea6b4133639;p=xen.git

linux: Add a hook before a page table entry is cleared, for use with
the grant-table device.

Signed-off-by: Derek Murray <Derek.Murray@cl.cam.ac.uk>
---

diff --git a/linux-2.6-xen-sparse/include/linux/mm.h b/linux-2.6-xen-sparse/include/linux/mm.h
index 1368b8450a..19654229cc 100644
--- a/linux-2.6-xen-sparse/include/linux/mm.h
+++ b/linux-2.6-xen-sparse/include/linux/mm.h
@@ -205,6 +205,11 @@ struct vm_operations_struct {
 	/* notification that a previously read-only page is about to become
 	 * writable, if an error is returned it will cause a SIGBUS */
 	int (*page_mkwrite)(struct vm_area_struct *vma, struct page *page);
+	/* Area-specific function for clearing the PTE at @ptep. Returns the
+	 * original value of @ptep. */
+	pte_t (*ptep_get_and_clear_full)(struct vm_area_struct *vma, 
+					 unsigned long addr, pte_t *ptep, 
+					 int is_fullmm);
 #ifdef CONFIG_NUMA
 	int (*set_policy)(struct vm_area_struct *vma, struct mempolicy *new);
 	struct mempolicy *(*get_policy)(struct vm_area_struct *vma,
diff --git a/linux-2.6-xen-sparse/mm/memory.c b/linux-2.6-xen-sparse/mm/memory.c
index f55ed7dedc..4af5beccaa 100644
--- a/linux-2.6-xen-sparse/mm/memory.c
+++ b/linux-2.6-xen-sparse/mm/memory.c
@@ -659,8 +659,15 @@ static unsigned long zap_pte_range(struct mmu_gather *tlb,
 				     page->index > details->last_index))
 					continue;
 			}
-			ptent = ptep_get_and_clear_full(mm, addr, pte,
-							tlb->fullmm);
+			if (unlikely(vma->vm_ops && 
+				     vma->vm_ops->ptep_get_and_clear_full))
+				ptent = vma->vm_ops->
+					ptep_get_and_clear_full(vma, addr,
+								pte,
+								tlb->fullmm);
+			else
+				ptent = ptep_get_and_clear_full(mm, addr, pte,
+								tlb->fullmm);
 			tlb_remove_tlb_entry(tlb, pte, addr);
 			if (unlikely(!page))
 				continue;
@@ -755,6 +762,7 @@ static unsigned long unmap_page_range(struct mmu_gather *tlb,
 		details = NULL;
 
 	BUG_ON(addr >= end);
+
 	tlb_start_vma(tlb, vma);
 	pgd = pgd_offset(vma->vm_mm, addr);
 	do {