From: Ard Biesheuvel ardb@kernel.org
commit 10fce53c0ef8f6e79115c3d9e0d7ea1338c3fa37 upstream
The early ATAGS/DT mapping code uses SECTION_SHIFT to mask low order bits of R2, and decides that no ATAGS/DTB were provided if the resulting value is 0x0.
This means that on systems where DRAM starts at 0x0 (such as Raspberry Pi), no explicit mapping of the DT will be created if R2 points into the first 1 MB section of memory. This was not a problem before, because the decompressed kernel is loaded at the base of DRAM and mapped using sections as well, and so as long as the DT is referenced via a virtual address that uses the same translation (the linear map, in this case), things work fine.
However, commit 7a1be318f579 ("9012/1: move device tree mapping out of linear region") changes this, and now the DT is referenced via a virtual address that is disjoint from the linear mapping of DRAM, and so we need the early code to create the DT mapping unconditionally.
So let's create the early DT mapping for any value of R2 != 0x0.
Reported-by: "kernelci.org bot" bot@kernelci.org Reviewed-by: Linus Walleij linus.walleij@linaro.org Signed-off-by: Ard Biesheuvel ardb@kernel.org Signed-off-by: Russell King rmk+kernel@armlinux.org.uk Signed-off-by: Florian Fainelli f.fainelli@gmail.com --- arch/arm/kernel/head.S | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/arch/arm/kernel/head.S b/arch/arm/kernel/head.S index 4f49e8c71ef1..5ceed4d9ee03 100644 --- a/arch/arm/kernel/head.S +++ b/arch/arm/kernel/head.S @@ -274,10 +274,10 @@ __create_page_tables: * 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 + cmp r2, #0 ldrne r3, =FDT_FIXED_BASE >> (SECTION_SHIFT - PMD_ORDER) addne r3, r3, r4 - orrne r6, r7, r0 + orrne r6, r7, r0, lsl #SECTION_SHIFT strne r6, [r3], #1 << PMD_ORDER addne r6, r6, #1 << SECTION_SHIFT strne r6, [r3]