Patch "arm64: kernel: avoid literal load of virtual address with MMU off" has been added to the 4.7-stable tree

Patch "arm64: kernel: avoid literal load of virtual address with MMU off" has been added to the 4.7-stable tree

[gregkh]

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

    arm64: kernel: avoid literal load of virtual address with MMU off

to the 4.7-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:
     arm64-kernel-avoid-literal-load-of-virtual-address-with-mmu-off.patch
and it can be found in the queue-4.7 subdirectory.

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


>From bc9f3d7788a88d080a30599bde68f383daf8f8a5 Mon Sep 17 00:00:00 2001
From: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Date: Wed, 17 Aug 2016 17:54:41 +0200
Subject: arm64: kernel: avoid literal load of virtual address with MMU off

From: Ard Biesheuvel <ard.biesheuvel@linaro.org>

commit bc9f3d7788a88d080a30599bde68f383daf8f8a5 upstream.

Literal loads of virtual addresses are subject to runtime relocation when
CONFIG_RELOCATABLE=y, and given that the relocation routines run with the
MMU and caches enabled, literal loads of relocated values performed with
the MMU off are not guaranteed to return the latest value unless the
memory covering the literal is cleaned to the PoC explicitly.

So defer the literal load until after the MMU has been enabled, just like
we do for primary_switch() and secondary_switch() in head.S.

Fixes: 1e48ef7fcc37 ("arm64: add support for building vmlinux as a relocatable PIE binary")
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Acked-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 arch/arm64/kernel/sleep.S |   10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

--- a/arch/arm64/kernel/sleep.S
+++ b/arch/arm64/kernel/sleep.S
@@ -101,12 +101,20 @@ ENTRY(cpu_resume)
 	bl	el2_setup		// if in EL2 drop to EL1 cleanly
 	/* enable the MMU early - so we can access sleep_save_stash by va */
 	adr_l	lr, __enable_mmu	/* __cpu_setup will return here */
-	ldr	x27, =_cpu_resume	/* __enable_mmu will branch here */
+	adr_l	x27, _resume_switched	/* __enable_mmu will branch here */
 	adrp	x25, idmap_pg_dir
 	adrp	x26, swapper_pg_dir
 	b	__cpu_setup
 ENDPROC(cpu_resume)
 
+	.pushsection	".idmap.text", "ax"
+_resume_switched:
+	ldr	x8, =_cpu_resume
+	br	x8
+ENDPROC(_resume_switched)
+	.ltorg
+	.popsection
+
 ENTRY(_cpu_resume)
 	mrs	x1, mpidr_el1
 	adrp	x8, mpidr_hash


Patches currently in stable-queue which might be from ard.biesheuvel@linaro.org are

queue-4.7/arm64-kernel-avoid-literal-load-of-virtual-address-with-mmu-off.patch
queue-4.7/x86-platform-uv-skip-uv-runtime-services-mapping-in-the-efi_runtime_disabled-case.patch
queue-4.7/arm64-avoid-tlb-conflict-with-config_randomize_base.patch
queue-4.7/efi-capsule-allocate-whole-capsule-into-virtual-memory.patch