s390/vmcore: implement remap_oldmem_pfn_range for s390

Introduce the s390 specific way to map pages from oldmem.  The memory area
below OLDMEM_SIZE is mapped with offset OLDMEM_BASE.  The other old memory
is mapped directly.

Signed-off-by: Jan Willeke <willeke@de.ibm.com>
Signed-off-by: Michael Holzheu <holzheu@linux.vnet.ibm.com>
Cc: HATAYAMA Daisuke <d.hatayama@jp.fujitsu.com>
Cc: Vivek Goyal <vgoyal@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 26 insertions, 0 deletions

diff --git a/arch/s390/kernel/crash_dump.c b/arch/s390/kernel/crash_dump.c
index 0c9a897a1fb5..3e776158b330 100644
--- a/arch/s390/kernel/crash_dump.c
+++ b/arch/s390/kernel/crash_dump.c
@@ -99,6 +99,32 @@ ssize_t copy_oldmem_page(unsigned long pfn, char *buf,
 }
 
 /*
+ * Remap "oldmem"
+ *
+ * For the kdump reserved memory this functions performs a swap operation:
+ * [0 - OLDMEM_SIZE] is mapped to [OLDMEM_BASE - OLDMEM_BASE + OLDMEM_SIZE]
+ */
+int remap_oldmem_pfn_range(struct vm_area_struct *vma, unsigned long from,
+                           unsigned long pfn, unsigned long size, pgprot_t prot)
+{
+        unsigned long size_old;
+        int rc;
+
+        if (pfn < OLDMEM_SIZE >> PAGE_SHIFT) {
+                size_old = min(size, OLDMEM_SIZE - (pfn << PAGE_SHIFT));
+                rc = remap_pfn_range(vma, from,
+                                     pfn + (OLDMEM_BASE >> PAGE_SHIFT),
+                                     size_old, prot);
+                if (rc || size == size_old)
+                        return rc;
+                size -= size_old;
+                from += size_old;
+                pfn += size_old >> PAGE_SHIFT;
+        }
+        return remap_pfn_range(vma, from, pfn, size, prot);
+}
+
+/*
  * Copy memory from old kernel
  */
 int copy_from_oldmem(void *dest, void *src, size_t count)