[patch 2/5] x86 PAT: Modify follow_phys to return phys_addr prot and return value

venkatesh.pallipadi
2008-12-19T21:50:42Z

[-- Attachment #1: modify_follow_phys.patch --]
[-- Type: text/plain, Size: 3570 bytes --]

follow_phys does similar things as follow_pfnmap_pte. Make a minor change
to follow_phys so that it can be used in place of follow_pfnmap_pte.
Physical address return value with 0 as error return does not work in
follow_phys as the actual physical address 0 mapping may exist in pte.

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

---
include/linux/mm.h | 2 ++
mm/memory.c | 31 ++++++++++++++-----------------
2 files changed, 16 insertions(+), 17 deletions(-)

Index: linux-2.6/include/linux/mm.h
===================================================================
--- linux-2.6.orig/include/linux/mm.h 2008-12-19 09:56:02.000000000 -0800
+++ linux-2.6/include/linux/mm.h 2008-12-19 11:04:32.000000000 -0800
@@ -804,6 +804,8 @@ int copy_page_range(struct mm_struct *ds
struct vm_area_struct *vma);
void unmap_mapping_range(struct address_space *mapping,
loff_t const holebegin, loff_t const holelen, int even_cows);
+int follow_phys(struct vm_area_struct *vma, unsigned long address,
+ unsigned int flags, unsigned long *prot, resource_size_t *phys);
int generic_access_phys(struct vm_area_struct *vma, unsigned long addr,
void *buf, int len, int write);

Index: linux-2.6/mm/memory.c
===================================================================
--- linux-2.6.orig/mm/memory.c 2008-12-19 09:55:29.000000000 -0800
+++ linux-2.6/mm/memory.c 2008-12-19 11:05:40.000000000 -0800
@@ -2981,9 +2981,9 @@ int in_gate_area_no_task(unsigned long a
#endif /* __HAVE_ARCH_GATE_AREA */

#ifdef CONFIG_HAVE_IOREMAP_PROT
-static resource_size_t follow_phys(struct vm_area_struct *vma,
- unsigned long address, unsigned int flags,
- unsigned long *prot)
+int follow_phys(struct vm_area_struct *vma,
+ unsigned long address, unsigned int flags,
+ unsigned long *prot, resource_size_t *phys)
{
pgd_t *pgd;
pud_t *pud;
@@ -2992,24 +2992,26 @@ static resource_size_t follow_phys(struc
spinlock_t *ptl;
resource_size_t phys_addr = 0;
struct mm_struct *mm = vma->vm_mm;
+ int ret = -EINVAL;

- VM_BUG_ON(!(vma->vm_flags & (VM_IO | VM_PFNMAP)));
+ if (!(vma->vm_flags & (VM_IO | VM_PFNMAP)))
+ goto out;

pgd = pgd_offset(mm, address);
if (pgd_none(*pgd) || unlikely(pgd_bad(*pgd)))
- goto no_page_table;
+ goto out;

pud = pud_offset(pgd, address);
if (pud_none(*pud) || unlikely(pud_bad(*pud)))
- goto no_page_table;
+ goto out;

pmd = pmd_offset(pud, address);
if (pmd_none(*pmd) || unlikely(pmd_bad(*pmd)))
- goto no_page_table;
+ goto out;

/* We cannot handle huge page PFN maps. Luckily they don't exist. */
if (pmd_huge(*pmd))
- goto no_page_table;
+ goto out;

ptep = pte_offset_map_lock(mm, pmd, address, &ptl);
if (!ptep)
@@ -3024,13 +3026,13 @@ static resource_size_t follow_phys(struc
phys_addr <<= PAGE_SHIFT; /* Shift here to avoid overflow on PAE */

*prot = pgprot_val(pte_pgprot(pte));
+ *phys = phys_addr;
+ ret = 0;

unlock:
pte_unmap_unlock(ptep, ptl);
out:
- return phys_addr;
-no_page_table:
- return 0;
+ return ret;
}

int generic_access_phys(struct vm_area_struct *vma, unsigned long addr,
@@ -3041,12 +3043,7 @@ int generic_access_phys(struct vm_area_s
void *maddr;
int offset = addr & (PAGE_SIZE-1);

- if (!(vma->vm_flags & (VM_IO | VM_PFNMAP)))
- return -EINVAL;
-
- phys_addr = follow_phys(vma, addr, write, &prot);
-
- if (!phys_addr)
+ if (follow_phys(vma, addr, write, &prot, &phys_addr))
return -EINVAL;

maddr = ioremap_prot(phys_addr, PAGE_SIZE, prot);

--