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

commit 6f16f4998f98e42e3f2dedf663cfb691ff0324af upstream.

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>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
[bwh: Backported to 3.2:
 - Adjust context
 - The mapping is not conditional; drop the 'ne' suffixes]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

diff --git a/arch/arm/kernel/head.S b/arch/arm/kernel/head.S
index 08c82fd844a8683533216048b54ff2f210729fb6..3606e85cf8cc12abc1f314798f7295c1c20cca67 100644 (file)
--- a/arch/arm/kernel/head.S
+++ b/arch/arm/kernel/head.S
@@ -221,6 +221,7 @@ __create_page_tables:
        /*
         * Then map boot params address in r2 or
         * the first 1MB of ram if boot params address is not 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
@@ -229,6 +230,8 @@ __create_page_tables:
        add     r3, r3, #PAGE_OFFSET
        add     r3, r4, r3, lsr #(SECTION_SHIFT - PMD_ORDER)
        orr     r6, r7, r0
+       str     r6, [r3], #1 << PMD_ORDER
+       add     r6, r6, #1 << SECTION_SHIFT
        str     r6, [r3]
 
 #ifdef CONFIG_DEBUG_LL