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Subject[PATCH 4/6] Add new base function _install_special_mapping() to mmap.c
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From: Stefani Seibold <stefani@seibold.net>

The _install_special_mapping() is the new base function for
install_special_mapping(). This function will return a pointer to the vma
which was created or a error code in an ERR_PTR()

The install_special_mapping() will unscramble this to the old behaviour,
returning an int.

This new function will be needed by the X86_64/IA32_EMULATION to map the
hpet into the 32 bit address space. This will be done with
io_remap_pfn_range() which requieres a vm_area_struct.

Signed-off-by: Stefani Seibold <stefani@seibold.net>
---
include/linux/mm.h | 3 +++
mm/mmap.c | 20 ++++++++++++++++----
2 files changed, 19 insertions(+), 4 deletions(-)

diff --git a/include/linux/mm.h b/include/linux/mm.h
index bcaab4e..82a992b 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -1435,6 +1435,9 @@ extern void set_mm_exe_file(struct mm_struct *mm, struct file *new_exe_file);
extern struct file *get_mm_exe_file(struct mm_struct *mm);

extern int may_expand_vm(struct mm_struct *mm, unsigned long npages);
+extern struct vm_area_struct *_install_special_mapping(struct mm_struct *mm,
+ unsigned long addr, unsigned long len,
+ unsigned long flags, struct page **pages);
extern int install_special_mapping(struct mm_struct *mm,
unsigned long addr, unsigned long len,
unsigned long flags, struct page **pages);
diff --git a/mm/mmap.c b/mm/mmap.c
index 9a796c4..dd85d21 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -2515,7 +2515,7 @@ static const struct vm_operations_struct special_mapping_vmops = {
* The array pointer and the pages it points to are assumed to stay alive
* for as long as this mapping might exist.
*/
-int install_special_mapping(struct mm_struct *mm,
+struct vm_area_struct *_install_special_mapping(struct mm_struct *mm,
unsigned long addr, unsigned long len,
unsigned long vm_flags, struct page **pages)
{
@@ -2524,7 +2524,7 @@ int install_special_mapping(struct mm_struct *mm,

vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL);
if (unlikely(vma == NULL))
- return -ENOMEM;
+ return ERR_PTR(-ENOMEM);

INIT_LIST_HEAD(&vma->anon_vma_chain);
vma->vm_mm = mm;
@@ -2545,11 +2545,23 @@ int install_special_mapping(struct mm_struct *mm,

perf_event_mmap(vma);

- return 0;
+ return vma;

out:
kmem_cache_free(vm_area_cachep, vma);
- return ret;
+ return ERR_PTR(ret);
+}
+
+int install_special_mapping(struct mm_struct *mm,
+ unsigned long addr, unsigned long len,
+ unsigned long vm_flags, struct page **pages)
+{
+ struct vm_area_struct *vma = _install_special_mapping(mm,
+ addr, len, vm_flags, pages);
+
+ if (IS_ERR(vma))
+ return PTR_ERR(vma);
+ return 0;
}

static DEFINE_MUTEX(mm_all_locks_mutex);
--
1.8.0


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