ARM: 7628/1: head.S: map one extra section for the ATAG/DTB area

We currently use a temporary 1MB section aligned to a 1MB boundary for
mapping the provided device tree until the final page table is created.
However, if the device tree happens to cross that 1MB boundary, the end
of it remains unmapped and the kernel crashes when it attempts to access
it.  Given no restriction on the location of that DTB, it could end up
with only a few bytes mapped at the end of a section.

Solve this issue by mapping two consecutive sections.

Signed-off-by: Nicolas Pitre <nico@linaro.org>
Tested-by: Sascha Hauer <s.hauer@pengutronix.de>
Tested-by: Tomasz Figa <t.figa@samsung.com>
Cc: stable@vger.kernel.org
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

1 files changed, 3 insertions, 0 deletions

diff --git a/arch/arm/kernel/head.S b/arch/arm/kernel/head.S
index 4eee351f4668..61fcb18c7e5b 100644
--- a/arch/arm/kernel/head.S
+++ b/arch/arm/kernel/head.S
@@ -246,6 +246,7 @@ __create_page_tables:
 
         /*
          * Then map boot params address in r2 if specified.
+         * We map 2 sections in case the ATAGs/DTB crosses a section boundary.
          */
         mov     r0, r2, lsr #SECTION_SHIFT
         movs    r0, r0, lsl #SECTION_SHIFT
@@ -253,6 +254,8 @@ __create_page_tables:
         addne   r3, r3, #PAGE_OFFSET
         addne   r3, r4, r3, lsr #(SECTION_SHIFT - PMD_ORDER)
         orrne   r6, r7, r0
+        strne   r6, [r3], #1 << PMD_ORDER
+        addne   r6, r6, #1 << SECTION_SHIFT
         strne   r6, [r3]
 
 #ifdef CONFIG_DEBUG_LL