Patch "ARM: 9027/1: head.S: explicitly map DT even if it lives in the first physical section" has been added to the 5.4-stable tree

[gregkh at linuxfoundation.org]

This is a note to let you know that I've just added the patch titled

    ARM: 9027/1: head.S: explicitly map DT even if it lives in the first physical section

to the 5.4-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     arm-9027-1-head.s-explicitly-map-dt-even-if-it-lives-in-the-first-physical-section.patch
and it can be found in the queue-5.4 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable at vger.kernel.org> know about it.


>From foo at baz Mon May 17 01:36:09 PM CEST 2021
From: Florian Fainelli <f.fainelli at gmail.com>
Date: Mon, 10 May 2021 06:33:21 -0700
Subject: ARM: 9027/1: head.S: explicitly map DT even if it lives in the first physical section
To: stable at vger.kernel.org
Cc: Ard Biesheuvel <ardb at kernel.org>, "kernelci.org bot" <bot at kernelci.org>, Linus Walleij <linus.walleij at linaro.org>, Russell King <rmk+kernel at armlinux.org.uk>, Florian Fainelli <f.fainelli at gmail.com>, Jonathan Corbet <corbet at lwn.net>, Russell King <linux at armlinux.org.uk>, Nicolas Pitre <nico at fluxnic.net>, Sasha Levin <sashal at kernel.org>, linux-doc at vger.kernel.org (open list:DOCUMENTATION), linux-kernel at vger.kernel.org (open list), linux-arm-kernel at lists.infradead.org (moderated list:ARM PORT), Greg Kroah-Hartman <gregkh at linuxfoundation.org>
Message-ID: <20210510133321.1790243-5-f.fainelli at gmail.com>

From: Ard Biesheuvel <ardb at 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 at kernelci.org>
Reviewed-by: Linus Walleij <linus.walleij at linaro.org>
Signed-off-by: Ard Biesheuvel <ardb at kernel.org>
Signed-off-by: Russell King <rmk+kernel at armlinux.org.uk>
Signed-off-by: Florian Fainelli <f.fainelli at gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh at linuxfoundation.org>
---
 arch/arm/kernel/head.S |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

--- 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]


Patches currently in stable-queue which might be from f.fainelli at gmail.com are

queue-5.4/arm-9020-1-mm-use-correct-section-size-macro-to-describe-the-fdt-virtual-address.patch
queue-5.4/arm-9011-1-centralize-phys-to-virt-conversion-of-dt-atags-address.patch
queue-5.4/arm-9027-1-head.s-explicitly-map-dt-even-if-it-lives-in-the-first-physical-section.patch
queue-5.4/arm-9012-1-move-device-tree-mapping-out-of-linear-region.patch