[3.11.y.z extended stable] Patch "ARM: ignore memory below PHYS_OFFSET" has been added to staging queue

[Luis Henriques]

This is a note to let you know that I have just added a patch titled

    ARM: ignore memory below PHYS_OFFSET

to the linux-3.11.y-queue branch of the 3.11.y.z extended stable tree 
which can be found at:

 http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.11.y-queue

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.11.y.z tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Luis

------

>From 16dd5aed65a79946ad14d3c14ef967e9e49ef931 Mon Sep 17 00:00:00 2001
From: Russell King <rmk+kernel at arm.linux.org.uk>
Date: Sat, 11 Jan 2014 11:22:18 +0000
Subject: 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 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