From: Russell King <rmk+kernel@arm.linux.org.uk>
Date: Sat, 11 Jan 2014 11:22:18 +0000 (+0000)
Subject: ARM: ignore memory below PHYS_OFFSET
X-Git-Url: http://git.mmlx.us/?a=commitdiff_plain;h=22fc72288f35219585f11fd40e663c0d3a30a28a;p=linux-edison.git

ARM: ignore memory below PHYS_OFFSET

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@arm.linux.org.uk>
Cc: Wang Nan <wangnan0@huawei.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---

diff --git a/arch/arm/kernel/setup.c b/arch/arm/kernel/setup.c
index 3ba573cb716..eb83bcc70ec 100644
--- a/arch/arm/kernel/setup.c
+++ b/arch/arm/kernel/setup.c
@@ -564,6 +564,20 @@ 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);