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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/arch/arm/kernel/head.S b/arch/arm/kernel/head.S
index 4eee351f4668e2bbee54c3771a5389ce8900c10c..61fcb18c7e5b54015ecafa1b3ed5a777d1149d4b 100644 (file)
--- 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