ARM: ignore memory below PHYS_OFFSET

If the kernel is loaded higher in physical memory than normal, and we
calculate PHYS_OFFSET higher than the start of RAM, this leads to
boot problems as we attempt to map part of this RAM into userspace.
Rather than struggle with this, just truncate the mapping.

Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

1 files changed, 14 insertions, 0 deletions

diff --git a/arch/arm/kernel/setup.c b/arch/arm/kernel/setup.c
index 7a2dd4689a75..061cea820e3f 100644
--- a/arch/arm/kernel/setup.c
+++ b/arch/arm/kernel/setup.c
@@ -660,6 +660,20 @@ int __init arm_add_memory(u64 start, u64 size)
         }
 #endif
 
+        if (aligned_start < PHYS_OFFSET) {
+                if (aligned_start + size <= PHYS_OFFSET) {
+                        pr_info("Ignoring memory below PHYS_OFFSET: 0x%08llx-0x%08llx\n",
+                                aligned_start, aligned_start + size);
+                        return -EINVAL;
+                }
+
+                pr_info("Ignoring memory below PHYS_OFFSET: 0x%08llx-0x%08llx\n",
+                        aligned_start, (u64)PHYS_OFFSET);
+
+                size -= PHYS_OFFSET - aligned_start;
+                aligned_start = PHYS_OFFSET;
+        }
+
         bank->start = aligned_start;
         bank->size = size & ~(phys_addr_t)(PAGE_SIZE - 1);