From 4473a153a5fdf0360a98fe22139ba32322205d29 Mon Sep 17 00:00:00 2001 From: Ard Biesheuvel Date: Tue, 17 Nov 2020 08:41:01 +0100 Subject: [PATCH] ARM: 9027/1: head.S: explicitly map DT even if it lives in the first physical section 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 0a4f71f38b1b ("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" Reviewed-by: Linus Walleij Signed-off-by: Ard Biesheuvel Signed-off-by: Russell King --- 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 9b18d8c661295..26ffd462a9755 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] -- 2.39.5