[RFC][PATCH 1/3] xip: no struct pages -- get_xip_mem
Convert XIP to support non-struct page backed memory.
The get_xip_page API is changed from a page based to an address/pfn based one.
(Eventually needs Nicks SOB)
Signed-off-by: Jared Hulbert <jaredeh@xxxxxxxxx>
---
fs/open.c | 2
include/linux/fs.h | 4 -
mm/fadvise.c | 2
mm/filemap_xip.c | 204 ++++++++++++++++++++++++-----------------------------
mm/madvise.c | 2
5 files changed, 101 insertions(+), 113 deletions(-)
---
diff --git a/fs/open.c b/fs/open.c
index 5419853..9a2d5f6 100644
--- a/fs/open.c
+++ b/fs/open.c
@@ -774,7 +774,7 @@ static struct file *__dentry_open(struct dentry
*dentry, struct vfsmount *mnt,
if (f->f_flags & O_DIRECT) {
if (!f->f_mapping->a_ops ||
((!f->f_mapping->a_ops->direct_IO) &&
- (!f->f_mapping->a_ops->get_xip_page))) {
+ (!f->f_mapping->a_ops->get_xip_mem))) {
fput(f);
f = ERR_PTR(-EINVAL);
}
diff --git a/include/linux/fs.h b/include/linux/fs.h
index b84b848..ac671bc 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -475,8 +475,8 @@ struct address_space_operations {
int (*releasepage) (struct page *, gfp_t);
ssize_t (*direct_IO)(int, struct kiocb *, const struct iovec *iov,
loff_t offset, unsigned long nr_segs);
- struct page* (*get_xip_page)(struct address_space *, sector_t,
- int);
+ int (*get_xip_mem)(struct address_space *, pgoff_t, int, void **,
+ unsigned long *);
/* migrate the contents of a page to the specified target */
int (*migratepage) (struct address_space *,
struct page *, struct page *);
diff --git a/mm/fadvise.c b/mm/fadvise.c
index 3c0f1e9..343cfdf 100644
--- a/mm/fadvise.c
+++ b/mm/fadvise.c
@@ -49,7 +49,7 @@ asmlinkage long sys_fadvise64_64(int fd, loff_t
offset, loff_t len, int advice)
goto out;
}
- if (mapping->a_ops->get_xip_page) {
+ if (mapping->a_ops->get_xip_mem) {
switch (advice) {
case POSIX_FADV_NORMAL:
case POSIX_FADV_RANDOM:
diff --git a/mm/filemap_xip.c b/mm/filemap_xip.c
index 5e598c4..2cd8ad0 100644
--- a/mm/filemap_xip.c
+++ b/mm/filemap_xip.c
@@ -15,6 +15,7 @@
#include <linux/rmap.h>
#include <linux/sched.h>
#include <asm/tlbflush.h>
+#include <asm/io.h>
/*
* We do use our own empty page to avoid interference with other users
@@ -42,25 +43,26 @@ static struct page *xip_sparse_page(void)
/*
* This is a file read routine for execute in place files, and uses
- * the mapping->a_ops->get_xip_page() function for the actual low-level
+ * the mapping->a_ops->get_xip_mem() function for the actual low-level
* stuff.
*
* Note the struct file* is not used at all. It may be NULL.
*/
-static void
+static ssize_t
do_xip_mapping_read(struct address_space *mapping,
struct file_ra_state *_ra,
struct file *filp,
loff_t *ppos,
- read_descriptor_t *desc,
- read_actor_t actor)
+ char __user *buf,
+ size_t len)
{
struct inode *inode = mapping->host;
pgoff_t index, end_index;
unsigned long offset;
loff_t isize;
+ size_t copied = 0, error = 0;
- BUG_ON(!mapping->a_ops->get_xip_page);
+ BUG_ON(!mapping->a_ops->get_xip_mem);
index = *ppos >> PAGE_CACHE_SHIFT;
offset = *ppos & ~PAGE_CACHE_MASK;
@@ -70,10 +72,10 @@ do_xip_mapping_read(struct address_space *mapping,
goto out;
end_index = (isize - 1) >> PAGE_CACHE_SHIFT;
- for (;;) {
- struct page *page;
- unsigned long nr, ret;
-
+ do {
+ unsigned long nr, left, pfn;
+ void *kaddr;
+ int zero = 0;
/* nr is the maximum number of bytes to copy from this page */
nr = PAGE_CACHE_SIZE;
if (index >= end_index) {
@@ -85,19 +87,16 @@ do_xip_mapping_read(struct address_space *mapping,
}
}
nr = nr - offset;
+ if (nr > len)
+ nr = len;
- page = mapping->a_ops->get_xip_page(mapping,
- index*(PAGE_SIZE/512), 0);
- if (!page)
- goto no_xip_page;
- if (unlikely(IS_ERR(page))) {
- if (PTR_ERR(page) == -ENODATA) {
- /* sparse */
- page = ZERO_PAGE(0);
- } else {
- desc->error = PTR_ERR(page);
+ error = mapping->a_ops->get_xip_mem(mapping, index, 0, &kaddr,
+ &pfn);
+ if (error) {
+ if (error != -ENODATA)
goto out;
- }
+ /* sparse */
+ zero = 1;
}
/* If users can be writing to this page using arbitrary
@@ -105,10 +104,10 @@ do_xip_mapping_read(struct address_space *mapping,
* before reading the page on the kernel side.
*/
if (mapping_writably_mapped(mapping))
- flush_dcache_page(page);
+ /* address based flush */ ;
/*
- * Ok, we have the page, so now we can copy it to user space...
+ * Ok, we have the mem, so now we can copy it to user space...
*
* The actor routine returns how many bytes were actually used..
* NOTE! This may not be the same as how much of a user buffer
@@ -116,47 +115,38 @@ do_xip_mapping_read(struct address_space *mapping,
* "pos" here (the actor routine has to update the user buffer
* pointers and the remaining count).
*/
- ret = actor(desc, page, offset, nr);
- offset += ret;
- index += offset >> PAGE_CACHE_SHIFT;
- offset &= ~PAGE_CACHE_MASK;
+ if (!zero)
+ left = __copy_to_user(buf + copied, kaddr + offset, nr);
+ else
+ left = __clear_user(buf + copied, nr);
- if (ret == nr && desc->count)
- continue;
- goto out;
+ if (left) {
+ error = -EFAULT;
+ goto out;
+ }
-no_xip_page:
- /* Did not get the page. Report it */
- desc->error = -EIO;
- goto out;
- }
+ copied += (nr - left);
+ offset += (nr - left);
+ index += offset >> PAGE_CACHE_SHIFT;
+ offset &= ~PAGE_CACHE_MASK;
+ } while (copied < len);
out:
- *ppos = ((loff_t) index << PAGE_CACHE_SHIFT) + offset;
+ *ppos += copied;
if (filp)
file_accessed(filp);
+
+ return (copied ? copied : error);
}
ssize_t
xip_file_read(struct file *filp, char __user *buf, size_t len, loff_t *ppos)
{
- read_descriptor_t desc;
-
if (!access_ok(VERIFY_WRITE, buf, len))
return -EFAULT;
- desc.written = 0;
- desc.arg.buf = buf;
- desc.count = len;
- desc.error = 0;
-
- do_xip_mapping_read(filp->f_mapping, &filp->f_ra, filp,
- ppos, &desc, file_read_actor);
-
- if (desc.written)
- return desc.written;
- else
- return desc.error;
+ return do_xip_mapping_read(filp->f_mapping, &filp->f_ra, filp,
+ ppos, buf, len);
}
EXPORT_SYMBOL_GPL(xip_file_read);
@@ -211,13 +201,16 @@ __xip_unmap (struct address_space * mapping,
*
* This function is derived from filemap_fault, but used for execute in place
*/
-static int xip_file_fault(struct vm_area_struct *area, struct vm_fault *vmf)
+static int xip_file_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
{
- struct file *file = area->vm_file;
+ struct file *file = vma->vm_file;
struct address_space *mapping = file->f_mapping;
struct inode *inode = mapping->host;
struct page *page;
pgoff_t size;
+ void *kaddr;
+ unsigned long pfn;
+ int err;
/* XXX: are VM_FAULT_ codes OK? */
@@ -225,35 +218,39 @@ static int xip_file_fault(struct vm_area_struct
*area, struct vm_fault *vmf)
if (vmf->pgoff >= size)
return VM_FAULT_SIGBUS;
- page = mapping->a_ops->get_xip_page(mapping,
- vmf->pgoff*(PAGE_SIZE/512), 0);
- if (!IS_ERR(page))
- goto out;
- if (PTR_ERR(page) != -ENODATA)
+ err = mapping->a_ops->get_xip_mem(mapping, vmf->pgoff, 0, &kaddr, &pfn);
+ if (!err)
+ goto found;
+
+ if (err != -ENODATA)
return VM_FAULT_OOM;
- /* sparse block */
- if ((area->vm_flags & (VM_WRITE | VM_MAYWRITE)) &&
- (area->vm_flags & (VM_SHARED| VM_MAYSHARE)) &&
- (!(mapping->host->i_sb->s_flags & MS_RDONLY))) {
- /* maybe shared writable, allocate new block */
- page = mapping->a_ops->get_xip_page(mapping,
- vmf->pgoff*(PAGE_SIZE/512), 1);
- if (IS_ERR(page))
- return VM_FAULT_SIGBUS;
- /* unmap page at pgoff from all other vmas */
- __xip_unmap(mapping, vmf->pgoff);
- } else {
+ if ((!(vma->vm_flags & (VM_WRITE | VM_MAYWRITE))) &&
+ (!(vma->vm_flags & (VM_SHARED| VM_MAYSHARE))) &&
+ (mapping->host->i_sb->s_flags & MS_RDONLY)) {
/* not shared and writable, use xip_sparse_page() */
page = xip_sparse_page();
if (!page)
return VM_FAULT_OOM;
+
+ page_cache_get(page);
+ vmf->page = page;
+ return 0;
}
-out:
- page_cache_get(page);
- vmf->page = page;
- return 0;
+ /* maybe shared writable, allocate new block */
+ err = mapping->a_ops->get_xip_mem(mapping,vmf->pgoff, 1, &kaddr, &pfn);
+ if (err)
+ return VM_FAULT_SIGBUS;
+ /* unmap sparse mappings at pgoff from all other vmas */
+ __xip_unmap(mapping, vmf->pgoff);
+
+ found:
+ err = vm_insert_mixed(vma, (unsigned long)vmf->virtual_address, pfn);
+ if (err == -ENOMEM)
+ return VM_FAULT_OOM;
+ BUG_ON(err);
+ return VM_FAULT_NOPAGE;
}
static struct vm_operations_struct xip_file_vm_ops = {
@@ -262,11 +259,11 @@ static struct vm_operations_struct xip_file_vm_ops = {
int xip_file_mmap(struct file * file, struct vm_area_struct * vma)
{
- BUG_ON(!file->f_mapping->a_ops->get_xip_page);
+ BUG_ON(!file->f_mapping->a_ops->get_xip_mem);
file_accessed(file);
vma->vm_ops = &xip_file_vm_ops;
- vma->vm_flags |= VM_CAN_NONLINEAR;
+ vma->vm_flags |= VM_CAN_NONLINEAR | VM_MIXEDMAP;
return 0;
}
EXPORT_SYMBOL_GPL(xip_file_mmap);
@@ -279,17 +276,16 @@ __xip_file_write(struct file *filp, const char
__user *buf,
const struct address_space_operations *a_ops = mapping->a_ops;
struct inode *inode = mapping->host;
long status = 0;
- struct page *page;
size_t bytes;
ssize_t written = 0;
- BUG_ON(!mapping->a_ops->get_xip_page);
+ BUG_ON(!mapping->a_ops->get_xip_mem);
do {
- unsigned long index;
- unsigned long offset;
+ unsigned long index, offset, pfn;
size_t copied;
- char *kaddr;
+ void *kaddr;
+ int err;
offset = (pos & (PAGE_CACHE_SIZE -1)); /* Within page */
index = pos >> PAGE_CACHE_SHIFT;
@@ -297,28 +293,23 @@ __xip_file_write(struct file *filp, const char
__user *buf,
if (bytes > count)
bytes = count;
- page = a_ops->get_xip_page(mapping,
- index*(PAGE_SIZE/512), 0);
- if (IS_ERR(page) && (PTR_ERR(page) == -ENODATA)) {
+ err = a_ops->get_xip_mem(mapping, index, 0, &kaddr, &pfn);
+ if (err && (err == -ENODATA)) {
/* we allocate a new page unmap it */
- page = a_ops->get_xip_page(mapping,
- index*(PAGE_SIZE/512), 1);
- if (!IS_ERR(page))
+ err = a_ops->get_xip_mem(mapping, index, 1, &kaddr,
+ &pfn);
+ if (!err)
/* unmap page at pgoff from all other vmas */
__xip_unmap(mapping, index);
}
- if (IS_ERR(page)) {
- status = PTR_ERR(page);
+ if (err) {
+ status = err;
break;
}
- fault_in_pages_readable(buf, bytes);
- kaddr = kmap_atomic(page, KM_USER0);
- copied = bytes -
- __copy_from_user_inatomic_nocache(kaddr + offset, buf, bytes);
- kunmap_atomic(kaddr, KM_USER0);
- flush_dcache_page(page);
+ copied = bytes;
+ copied -= __copy_from_user_nocache(kaddr + offset, buf, bytes);
if (likely(copied > 0)) {
status = copied;
@@ -398,7 +389,7 @@ EXPORT_SYMBOL_GPL(xip_file_write);
/*
* truncate a page used for execute in place
- * functionality is analog to block_truncate_page but does use get_xip_page
+ * functionality is analog to block_truncate_page but does use get_xip_mem
* to get the page instead of page cache
*/
int
@@ -408,9 +399,11 @@ xip_truncate_page(struct address_space *mapping,
loff_t from)
unsigned offset = from & (PAGE_CACHE_SIZE-1);
unsigned blocksize;
unsigned length;
- struct page *page;
+ void *kaddr;
+ unsigned long pfn;
+ int err;
- BUG_ON(!mapping->a_ops->get_xip_page);
+ BUG_ON(!mapping->a_ops->get_xip_mem);
blocksize = 1 << mapping->host->i_blkbits;
length = offset & (blocksize - 1);
@@ -421,18 +414,13 @@ xip_truncate_page(struct address_space *mapping,
loff_t from)
length = blocksize - length;
- page = mapping->a_ops->get_xip_page(mapping,
- index*(PAGE_SIZE/512), 0);
- if (!page)
- return -ENOMEM;
- if (unlikely(IS_ERR(page))) {
- if (PTR_ERR(page) == -ENODATA)
- /* Hole? No need to truncate */
- return 0;
- else
- return PTR_ERR(page);
+ err = mapping->a_ops->get_xip_mem(mapping, index, 0, &kaddr, &pfn);
+ if (!err) {
+ memset(kaddr + offset, 0, length);
+ } else if (err == -ENODATA) {
+ /* Hole? No need to truncate */
+ return 0;
}
- zero_user(page, offset, length);
- return 0;
+ return err;
}
EXPORT_SYMBOL_GPL(xip_truncate_page);
diff --git a/mm/madvise.c b/mm/madvise.c
index 93ee375..23a0ec3 100644
--- a/mm/madvise.c
+++ b/mm/madvise.c
@@ -112,7 +112,7 @@ static long madvise_willneed(struct vm_area_struct * vma,
if (!file)
return -EBADF;
- if (file->f_mapping->a_ops->get_xip_page) {
+ if (file->f_mapping->a_ops->get_xip_mem) {
/* no bad return value, but ignore advice */
return 0;
}
--
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