This patch introduces mmap_vmcore().
If flag MEM_TYPE_CURRENT_KERNEL is set, map buffer on the 2nd
kernel. If not set, map some area in old memory.
Neither writable nor executable mapping is permitted even with
mprotect(). Non-writable mapping is also requirement of
remap_pfn_range() when mapping linear pages on non-consequtive
physical pages; see is_cow_mapping().
On x86-32 PAE kernels, mmap() supports at most 16TB memory only. This
limitation comes from the fact that the third argument of
remap_pfn_range(), pfn, is of 32-bit length on x86-32: unsigned long.
Signed-off-by: HATAYAMA Daisuke <d.hatayama at jp.fujitsu.com>
---
fs/proc/vmcore.c | 68 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
1 files changed, 68 insertions(+), 0 deletions(-)
diff --git a/fs/proc/vmcore.c b/fs/proc/vmcore.c
index cd0f9d9..aecdc72 100644
--- a/fs/proc/vmcore.c
+++ b/fs/proc/vmcore.c
@@ -176,9 +176,77 @@ static ssize_t read_vmcore(struct file *file, char __user *buffer,
return acc;
}
+static int mmap_vmcore(struct file *file, struct vm_area_struct *vma)
+{
+ size_t size = vma->vm_end - vma->vm_start;
+ u64 start, end, len, tsz;
+ struct vmcore *m;
+
+ start = (u64)vma->vm_pgoff << PAGE_SHIFT;
+ end = start + size;
+
+ if (size > vmcore_size || end > vmcore_size)
+ return -EINVAL;
+
+ if (vma->vm_flags & (VM_WRITE | VM_EXEC))
+ return -EPERM;
+
+ vma->vm_flags &= ~(VM_MAYWRITE | VM_MAYEXEC);
+
+ len = 0;
+
+ if (start < elfcorebuf_sz) {
+ u64 pfn;
+
+ tsz = elfcorebuf_sz - start;
+ if (size < tsz)
+ tsz = size;
+ pfn = __pa(elfcorebuf + start) >> PAGE_SHIFT;
+ if (remap_pfn_range(vma, vma->vm_start, pfn, tsz,
+ vma->vm_page_prot))
+ return -EAGAIN;
+ size -= tsz;
+ start += tsz;
+ len += tsz;
+
+ if (size == 0)
+ return 0;
+ }
+
+ list_for_each_entry(m, &vmcore_list, list) {
+ if (start < m->offset + m->size) {
+ u64 paddr = 0;
+
+ tsz = m->offset + m->size - start;
+ if (size < tsz)
+ tsz = size;
+ if (m->flag & MEM_TYPE_CURRENT_KERNEL) {
+ paddr = __pa(m->buf + start - m->offset);
+ } else {
+ paddr = m->paddr + start - m->offset;
+ }
+ if (remap_pfn_range(vma, vma->vm_start + len,
+ paddr >> PAGE_SHIFT, tsz,
+ vma->vm_page_prot)) {
+ do_munmap(vma->vm_mm, vma->vm_start, len);
+ return -EAGAIN;
+ }
+ size -= tsz;
+ start += tsz;
+ len += tsz;
+
+ if (size == 0)
+ return 0;
+ }
+ }
+
+ return 0;
+}
+
static const struct file_operations proc_vmcore_operations = {
.read = read_vmcore,
.llseek = default_llseek,
+ .mmap = mmap_vmcore,
};
static struct vmcore* __init get_new_element(void)
