Re: nommu: Add new vmalloc_user() and remap_vmalloc_range() interfaces.

From: Greg Ungerer
Date: Thu Nov 29 2007 - 01:18:11 EST




Paul Mundt wrote:
This builds on top of the earlier vmalloc_32_user() work introduced by
b50731732f926d6c49fd0724616a7344c31cd5cf, as we now have places in the
nommu allmodconfig that hit up against these missing APIs.

As vmalloc_32_user() is already implemented, this is moved over to
vmalloc_user() and simply made a wrapper. As all current nommu platforms
are 32-bit addressable, there's no special casing we have to do for
ZONE_DMA and things of that nature as per GFP_VMALLOC32.

remap_vmalloc_range() needs to check VM_USERMAP in order to figure out
whether we permit the remap or not, which means that we also have to
rework the vmalloc_user() code to grovel for the VMA and set the flag.

Signed-off-by: Paul Mundt <lethal@xxxxxxxxxxxx>

Acked-by: Greg Ungerer <gerg@xxxxxxxxxxxx>


mm/nommu.c | 45 ++++++++++++++++++++++++++++++++++++++++++++-
1 file changed, 44 insertions(+), 1 deletion(-)

diff --git a/mm/nommu.c b/mm/nommu.c
index 35622c5..c4768d0 100644
--- a/mm/nommu.c
+++ b/mm/nommu.c
@@ -10,6 +10,7 @@
* Copyright (c) 2000-2003 David McCullough <davidm@xxxxxxxxxxxx>
* Copyright (c) 2000-2001 D Jeff Dionne <jeff@xxxxxxxxxxx>
* Copyright (c) 2002 Greg Ungerer <gerg@xxxxxxxxxxxx>
+ * Copyright (c) 2007 Paul Mundt <lethal@xxxxxxxxxxxx>
*/
#include <linux/module.h>
@@ -183,6 +184,26 @@ void *__vmalloc(unsigned long size, gfp_t gfp_mask, pgprot_t prot)
}
EXPORT_SYMBOL(__vmalloc);
+void *vmalloc_user(unsigned long size)
+{
+ void *ret;
+
+ ret = __vmalloc(size, GFP_KERNEL | __GFP_HIGHMEM | __GFP_ZERO,
+ PAGE_KERNEL);
+ if (ret) {
+ struct vm_area_struct *vma;
+
+ down_write(&current->mm->mmap_sem);
+ vma = find_vma(current->mm, (unsigned long)ret);
+ if (vma)
+ vma->vm_flags |= VM_USERMAP;
+ up_write(&current->mm->mmap_sem);
+ }
+
+ return ret;
+}
+EXPORT_SYMBOL(vmalloc_user);
+
struct page * vmalloc_to_page(void *addr)
{
return virt_to_page(addr);
@@ -253,10 +274,17 @@ EXPORT_SYMBOL(vmalloc_32);
*
* The resulting memory area is 32bit addressable and zeroed so it can be
* mapped to userspace without leaking data.
+ *
+ * VM_USERMAP is set on the corresponding VMA so that subsequent calls to
+ * remap_vmalloc_range() are permissible.
*/
void *vmalloc_32_user(unsigned long size)
{
- return __vmalloc(size, GFP_KERNEL | __GFP_ZERO, PAGE_KERNEL);
+ /*
+ * We'll have to sort out the ZONE_DMA bits for 64-bit,
+ * but for now this can simply use vmalloc_user() directly.
+ */
+ return vmalloc_user(size);
}
EXPORT_SYMBOL(vmalloc_32_user);
@@ -1213,6 +1241,21 @@ int remap_pfn_range(struct vm_area_struct *vma, unsigned long from,
}
EXPORT_SYMBOL(remap_pfn_range);
+int remap_vmalloc_range(struct vm_area_struct *vma, void *addr,
+ unsigned long pgoff)
+{
+ unsigned int size = vma->vm_end - vma->vm_start;
+
+ if (!(vma->vm_flags & VM_USERMAP))
+ return -EINVAL;
+
+ vma->vm_start = (unsigned long)(addr + (pgoff << PAGE_SHIFT));
+ vma->vm_end = vma->vm_start + size;
+
+ return 0;
+}
+EXPORT_SYMBOL(remap_vmalloc_range);
+
void swap_unplug_io_fn(struct backing_dev_info *bdi, struct page *page)
{
}


--
------------------------------------------------------------------------
Greg Ungerer -- Chief Software Dude EMAIL: gerg@xxxxxxxxxxxx
Secure Computing Corporation PHONE: +61 7 3435 2888
825 Stanley St, FAX: +61 7 3891 3630
Woolloongabba, QLD, 4102, Australia WEB: http://www.SnapGear.com
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/