1 files changed, 37 insertions, 1 deletions

diff --git a/arch/x86/kernel/resource.c b/arch/x86/kernel/resource.c
index 407a900da9df..89638af2ff19 100644
--- a/arch/x86/kernel/resource.c
+++ b/arch/x86/kernel/resource.c
@@ -1,11 +1,47 @@
 #include <linux/ioport.h>
 #include <asm/e820.h>
 
+static void resource_clip(struct resource *res, resource_size_t start,
+                          resource_size_t end)
+{
+        resource_size_t low = 0, high = 0;
+
+        if (res->end < start || res->start > end)
+                return;         /* no conflict */
+
+        if (res->start < start)
+                low = start - res->start;
+
+        if (res->end > end)
+                high = res->end - end;
+
+        /* Keep the area above or below the conflict, whichever is larger */
+        if (low > high)
+                res->end = start - 1;
+        else
+                res->start = end + 1;
+}
+
+static void remove_e820_regions(struct resource *avail)
+{
+        int i;
+        struct e820entry *entry;
+
+        for (i = 0; i < e820.nr_map; i++) {
+                entry = &e820.map[i];
+
+                resource_clip(avail, entry->addr,
+                              entry->addr + entry->size - 1);
+        }
+}
+
 void arch_remove_reservations(struct resource *avail)
 {
-        /* Trim out BIOS area (low 1MB) */
+        /* Trim out BIOS area (low 1MB) and E820 regions */
         if (avail->flags & IORESOURCE_MEM) {
                 if (avail->start < BIOS_END)
                         avail->start = BIOS_END;
+
+                remove_e820_regions(avail);
         }
 }