3 files changed, 57 insertions, 7 deletions

diff --git a/arch/powerpc/mm/mem.c b/arch/powerpc/mm/mem.c
index d9e37f365b54..f67e118116fa 100644
--- a/arch/powerpc/mm/mem.c
+++ b/arch/powerpc/mm/mem.c
@@ -154,19 +154,35 @@ out:
 
 /*
  * walk_memory_resource() needs to make sure there is no holes in a given
- * memory range. On PPC64, since this range comes from /sysfs, the range
- * is guaranteed to be valid, non-overlapping and can not contain any
- * holes. By the time we get here (memory add or remove), /proc/device-tree
- * is updated and correct. Only reason we need to check against device-tree
- * would be if we allow user-land to specify a memory range through a
- * system call/ioctl etc. instead of doing offline/online through /sysfs.
+ * memory range.  PPC64 does not maintain the memory layout in /proc/iomem.
+ * Instead it maintains it in lmb.memory structures.  Walk through the
+ * memory regions, find holes and callback for contiguous regions.
  */
 int
 walk_memory_resource(unsigned long start_pfn, unsigned long nr_pages, void *arg,
                         int (*func)(unsigned long, unsigned long, void *))
 {
-        return  (*func)(start_pfn, nr_pages, arg);
+        struct lmb_property res;
+        unsigned long pfn, len;
+        u64 end;
+        int ret = -1;
+
+        res.base = (u64) start_pfn << PAGE_SHIFT;
+        res.size = (u64) nr_pages << PAGE_SHIFT;
+
+        end = res.base + res.size - 1;
+        while ((res.base < end) && (lmb_find(&res) >= 0)) {
+                pfn = (unsigned long)(res.base >> PAGE_SHIFT);
+                len = (unsigned long)(res.size >> PAGE_SHIFT);
+                ret = (*func)(pfn, len, arg);
+                if (ret)
+                        break;
+                res.base += (res.size + 1);
+                res.size = (end - res.base + 1);
+        }
+        return ret;
 }
+EXPORT_SYMBOL_GPL(walk_memory_resource);
 
 #endif /* CONFIG_MEMORY_HOTPLUG */
 
diff --git a/include/linux/lmb.h b/include/linux/lmb.h
index 55d4b261a9e8..c46c89505dac 100644
--- a/include/linux/lmb.h
+++ b/include/linux/lmb.h
@@ -54,6 +54,7 @@ extern u64 __init lmb_phys_mem_size(void);
 extern u64 __init lmb_end_of_DRAM(void);
 extern void __init lmb_enforce_memory_limit(u64 memory_limit);
 extern int __init lmb_is_reserved(u64 addr);
+extern int lmb_find(struct lmb_property *res);
 
 extern void lmb_dump_all(void);
 
diff --git a/lib/lmb.c b/lib/lmb.c
index 5b2a739bc3d5..83287d3869a3 100644
--- a/lib/lmb.c
+++ b/lib/lmb.c
@@ -474,3 +474,36 @@ int __init lmb_is_reserved(u64 addr)
         }
         return 0;
 }
+
+/*
+ * Given a <base, len>, find which memory regions belong to this range.
+ * Adjust the request and return a contiguous chunk.
+ */
+int lmb_find(struct lmb_property *res)
+{
+        int i;
+        u64 rstart, rend;
+
+        rstart = res->base;
+        rend = rstart + res->size - 1;
+
+        for (i = 0; i < lmb.memory.cnt; i++) {
+                u64 start = lmb.memory.region[i].base;
+                u64 end = start + lmb.memory.region[i].size - 1;
+
+                if (start > rend)
+                        return -1;
+
+                if ((end >= rstart) && (start < rend)) {
+                        /* adjust the request */
+                        if (rstart < start)
+                                rstart = start;
+                        if (rend > end)
+                                rend = end;
+                        res->base = rstart;
+                        res->size = rend - rstart + 1;
+                        return 0;
+                }
+        }
+        return -1;
+}