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-rw-r--r--kernel/resource.c36
1 files changed, 36 insertions, 0 deletions
diff --git a/kernel/resource.c b/kernel/resource.c
index 46322019ab7d..0bcebffc4e77 100644
--- a/kernel/resource.c
+++ b/kernel/resource.c
@@ -491,6 +491,42 @@ int __weak page_is_ram(unsigned long pfn)
}
EXPORT_SYMBOL_GPL(page_is_ram);
+/*
+ * Search for a resouce entry that fully contains the specified region.
+ * If found, return 1 if it is RAM, 0 if not.
+ * If not found, or region is not fully contained, return -1
+ *
+ * Used by the ioremap functions to ensure the user is not remapping RAM and is
+ * a vast speed up over walking through the resource table page by page.
+ */
+int region_is_ram(resource_size_t start, unsigned long size)
+{
+ struct resource *p;
+ resource_size_t end = start + size - 1;
+ int flags = IORESOURCE_MEM | IORESOURCE_BUSY;
+ const char *name = "System RAM";
+ int ret = -1;
+
+ read_lock(&resource_lock);
+ for (p = iomem_resource.child; p ; p = p->sibling) {
+ if (end < p->start)
+ continue;
+
+ if (p->start <= start && end <= p->end) {
+ /* resource fully contains region */
+ if ((p->flags != flags) || strcmp(p->name, name))
+ ret = 0;
+ else
+ ret = 1;
+ break;
+ }
+ if (p->end < start)
+ break; /* not found */
+ }
+ read_unlock(&resource_lock);
+ return ret;
+}
+
void __weak arch_remove_reservations(struct resource *avail)
{
}