[PATCH 3.11 106/144] ARM: ignore memory below PHYS_OFFSET

[Luis Henriques]

3.11.10.7 -stable review patch.  If anyone has any objections, please let me know.

------------------

From: Russell King <rmk+kernel at arm.linux.org.uk>

commit 571b14375019c3a66ef70d4d4a7083f4238aca30 upstream.

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 at arm.linux.org.uk>
Cc: Wang Nan <wangnan0 at huawei.com>
Signed-off-by: Luis Henriques <luis.henriques at canonical.com>
---
 arch/arm/kernel/setup.c | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

diff --git a/arch/arm/kernel/setup.c b/arch/arm/kernel/setup.c
index f58f646..37ea994 100644
--- a/arch/arm/kernel/setup.c
+++ b/arch/arm/kernel/setup.c
@@ -656,6 +656,20 @@ int __init arm_add_memory(phys_addr_t start, phys_addr_t 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);
 
-- 
1.9.1