We want to allocate ELF note segment buffer on the 2nd kernel in
vmalloc space and remap it to user-space in order to reduce the risk
that memory allocation fails on system with huge number of CPUs and so
with huge ELF note segment that exceeds 11-order block size.
Although there's already remap_vmalloc_range for the purpose of
remapping vmalloc memory to user-space, we need to specify user-space
range via vma. Mmap on /proc/vmcore needs to remap range across
multiple objects, so the interface that requires vma to cover full
range is problematic.
This patch introduces remap_vmalloc_range_partial that receives
user-space range as a pair of base address and size and can be used
for mmap on /proc/vmcore case.
remap_vmalloc_range is rewritten using remap_vmalloc_range_partial.
Signed-off-by: HATAYAMA Daisuke <d.hatayama@xxxxxxxxxxxxxx>
---
include/linux/vmalloc.h | 4 +++
mm/vmalloc.c | 63 +++++++++++++++++++++++++++++++++--------------
2 files changed, 48 insertions(+), 19 deletions(-)
diff --git a/include/linux/vmalloc.h b/include/linux/vmalloc.h
index 7d5773a..dd0a2c8 100644
--- a/include/linux/vmalloc.h
+++ b/include/linux/vmalloc.h
@@ -82,6 +82,10 @@ extern void *vmap(struct page **pages, unsigned int count,
unsigned long flags, pgprot_t prot);
extern void vunmap(const void *addr);
+extern int remap_vmalloc_range_partial(struct vm_area_struct *vma,
+ unsigned long uaddr, void *kaddr,
+ unsigned long size);
+
extern int remap_vmalloc_range(struct vm_area_struct *vma, void *addr,
unsigned long pgoff);
void vmalloc_sync_all(void);
diff --git a/mm/vmalloc.c b/mm/vmalloc.c
index 3875fa2..d9a9f4f6 100644
--- a/mm/vmalloc.c
+++ b/mm/vmalloc.c
@@ -2148,42 +2148,44 @@ finished:
}
/**
- * remap_vmalloc_range - map vmalloc pages to userspace
- * @vma: vma to cover (map full range of vma)
- * @addr: vmalloc memory
- * @pgoff: number of pages into addr before first page to map
+ * remap_vmalloc_range_partial - map vmalloc pages to userspace
+ * @vma: vma to cover
+ * @uaddr: target user address to start at
+ * @kaddr: virtual address of vmalloc kernel memory
+ * @size: size of map area
*
* Returns: 0 for success, -Exxx on failure
*
- * This function checks that addr is a valid vmalloc'ed area, and
- * that it is big enough to cover the vma. Will return failure if
- * that criteria isn't met.
+ * This function checks that @kaddr is a valid vmalloc'ed area,
+ * and that it is big enough to cover the range starting at
+ * @uaddr in @vma. Will return failure if that criteria isn't
+ * met.
*
* Similar to remap_pfn_range() (see mm/memory.c)
*/
-int remap_vmalloc_range(struct vm_area_struct *vma, void *addr,
- unsigned long pgoff)
+int remap_vmalloc_range_partial(struct vm_area_struct *vma, unsigned long uaddr,
+ void *kaddr, unsigned long size)
{
struct vm_struct *area;
- unsigned long uaddr = vma->vm_start;
- unsigned long usize = vma->vm_end - vma->vm_start;
- if ((PAGE_SIZE-1) & (unsigned long)addr)
+ size = PAGE_ALIGN(size);
+
+ if (((PAGE_SIZE-1) & (unsigned long)uaddr) ||
+ ((PAGE_SIZE-1) & (unsigned long)kaddr))
return -EINVAL;
- area = find_vm_area(addr);
+ area = find_vm_area(kaddr);
if (!area)
return -EINVAL;
if (!(area->flags & VM_USERMAP))
return -EINVAL;
- if (usize + (pgoff << PAGE_SHIFT) > area->size - PAGE_SIZE)
+ if (kaddr + size > area->addr + area->size)
return -EINVAL;
- addr += pgoff << PAGE_SHIFT;
do {
- struct page *page = vmalloc_to_page(addr);
+ struct page *page = vmalloc_to_page(kaddr);
int ret;
ret = vm_insert_page(vma, uaddr, page);
@@ -2191,14 +2193,37 @@ int remap_vmalloc_range(struct vm_area_struct *vma, void *addr,
return ret;
uaddr += PAGE_SIZE;
- addr += PAGE_SIZE;
- usize -= PAGE_SIZE;
- } while (usize > 0);
+ kaddr += PAGE_SIZE;
+ size -= PAGE_SIZE;
+ } while (size > 0);
vma->vm_flags |= VM_DONTEXPAND | VM_DONTDUMP;
return 0;
}
+EXPORT_SYMBOL(remap_vmalloc_range_partial);
+
+/**
+ * remap_vmalloc_range - map vmalloc pages to userspace
+ * @vma: vma to cover (map full range of vma)
+ * @addr: vmalloc memory
+ * @pgoff: number of pages into addr before first page to map
+ *
+ * Returns: 0 for success, -Exxx on failure
+ *
+ * This function checks that addr is a valid vmalloc'ed area, and
+ * that it is big enough to cover the vma. Will return failure if
+ * that criteria isn't met.
+ *
+ * Similar to remap_pfn_range() (see mm/memory.c)
+ */
+int remap_vmalloc_range(struct vm_area_struct *vma, void *addr,
+ unsigned long pgoff)
+{
+ return remap_vmalloc_range_partial(vma, vma->vm_start,
+ addr + (pgoff << PAGE_SHIFT),
+ vma->vm_end - vma->vm_start);
+}
EXPORT_SYMBOL(remap_vmalloc_range);
/*
--
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