[patch 3/7] x86 PAT: hooks in generic vm code to help archs to track pfnmap regions - v3

venkatesh.pallipadi
2008-12-18T20:02:54Z

[-- Attachment #1: generic_pfn_range_tracking.patch --]
[-- Type: text/plain, Size: 4946 bytes --]

Introduce generic hooks in remap_pfn_range and vm_insert_pfn and
corresponding copy and free routines with reserve and free tracking.

Signed-off-by: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>
Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com>

---
include/linux/mm.h | 6 ++++
mm/memory.c | 76 ++++++++++++++++++++++++++++++++++++++++++++++++++++-
2 files changed, 81 insertions(+), 1 deletion(-)

Index: linux-2.6/mm/memory.c
===================================================================
--- linux-2.6.orig/mm/memory.c 2008-12-18 10:10:50.000000000 -0800
+++ linux-2.6/mm/memory.c 2008-12-18 10:11:23.000000000 -0800
@@ -99,6 +99,50 @@ int randomize_va_space __read_mostly =
2;
#endif

+#ifndef track_pfn_vma_new
+/*
+ * Interface that can be used by architecture code to keep track of
+ * memory type of pfn mappings (remap_pfn_range, vm_insert_pfn)
+ *
+ * track_pfn_vma_new is called when a _new_ pfn mapping is being established
+ * for physical range indicated by pfn and size.
+ */
+int track_pfn_vma_new(struct vm_area_struct *vma, pgprot_t prot,
+ unsigned long pfn, unsigned long size)
+{
+ return 0;
+}
+#endif
+
+#ifndef track_pfn_vma_copy
+/*
+ * Interface that can be used by architecture code to keep track of
+ * memory type of pfn mappings (remap_pfn_range, vm_insert_pfn)
+ *
+ * track_pfn_vma_copy is called when vma that is covering the pfnmap gets
+ * copied through copy_page_range().
+ */
+int track_pfn_vma_copy(struct vm_area_struct *vma)
+{
+ return 0;
+}
+#endif
+
+#ifndef untrack_pfn_vma
+/*
+ * Interface that can be used by architecture code to keep track of
+ * memory type of pfn mappings (remap_pfn_range, vm_insert_pfn)
+ *
+ * untrack_pfn_vma is called while unmapping a pfnmap for a region.
+ * untrack can be called for a specific region indicated by pfn and size or
+ * can be for the entire vma (in which case size can be zero).
+ */
+void untrack_pfn_vma(struct vm_area_struct *vma, unsigned long pfn,
+ unsigned long size)
+{
+}
+#endif
+
static int __init disable_randmaps(char *s)
{
randomize_va_space = 0;
@@ -669,6 +713,16 @@ int copy_page_range(struct mm_struct *ds
if (is_vm_hugetlb_page(vma))
return copy_hugetlb_page_range(dst_mm, src_mm, vma);

+ if (is_pfn_mapping(vma)) {
+ /*
+ * We do not free on error cases below as remove_vma
+ * gets called on error from higher level routine
+ */
+ ret = track_pfn_vma_copy(vma);
+ if (ret)
+ return ret;
+ }
+
/*
* We need to invalidate the secondary MMU mappings only when
* there could be a permission downgrade on the ptes of the
@@ -915,6 +969,9 @@ unsigned long unmap_vmas(struct mmu_gath
if (vma->vm_flags & VM_ACCOUNT)
*nr_accounted += (end - start) >> PAGE_SHIFT;

+ if (is_pfn_mapping(vma))
+ untrack_pfn_vma(vma, 0, 0);
+
while (start != end) {
if (!tlb_start_valid) {
tlb_start = start;
@@ -1473,6 +1530,7 @@ out:
int vm_insert_pfn(struct vm_area_struct *vma, unsigned long addr,
unsigned long pfn)
{
+ int ret;
/*
* Technically, architectures with pte_special can avoid all these
* restrictions (same for remap_pfn_range). However we would like
@@ -1487,7 +1545,15 @@ int vm_insert_pfn(struct vm_area_struct

if (addr < vma->vm_start || addr >= vma->vm_end)
return -EFAULT;
- return insert_pfn(vma, addr, pfn, vma->vm_page_prot);
+ if (track_pfn_vma_new(vma, vma->vm_page_prot, pfn, PAGE_SIZE))
+ return -EINVAL;
+
+ ret = insert_pfn(vma, addr, pfn, vma->vm_page_prot);
+
+ if (ret)
+ untrack_pfn_vma(vma, pfn, PAGE_SIZE);
+
+ return ret;
}
EXPORT_SYMBOL(vm_insert_pfn);

@@ -1625,6 +1691,10 @@ int remap_pfn_range(struct vm_area_struc

vma->vm_flags |= VM_IO | VM_RESERVED | VM_PFNMAP;

+ err = track_pfn_vma_new(vma, prot, pfn, PAGE_ALIGN(size));
+ if (err)
+ return -EINVAL;
+
BUG_ON(addr >= end);
pfn -= addr >> PAGE_SHIFT;
pgd = pgd_offset(mm, addr);
@@ -1636,6 +1706,10 @@ int remap_pfn_range(struct vm_area_struc
if (err)
break;
} while (pgd++, addr = next, addr != end);
+
+ if (err)
+ untrack_pfn_vma(vma, pfn, PAGE_ALIGN(size));
+
return err;
}
EXPORT_SYMBOL(remap_pfn_range);
Index: linux-2.6/include/linux/mm.h
===================================================================
--- linux-2.6.orig/include/linux/mm.h 2008-12-18 10:10:50.000000000 -0800
+++ linux-2.6/include/linux/mm.h 2008-12-18 10:11:23.000000000 -0800
@@ -155,6 +155,12 @@ static inline int is_pfn_mapping(struct
return (vma->vm_flags & VM_PFNMAP);
}

+extern int track_pfn_vma_new(struct vm_area_struct *vma, pgprot_t prot,
+ unsigned long pfn, unsigned long size);
+extern int track_pfn_vma_copy(struct vm_area_struct *vma);
+extern void untrack_pfn_vma(struct vm_area_struct *vma, unsigned long pfn,
+ unsigned long size);
+
/*
* vm_fault is filled by the the pagefault handler and passed to the vma's
* ->fault function. The vma's ->fault is responsible for returning a bitmask

--