This is a note to let you know that I've just added the patch titled
arm64: mm: use correct mapping granularity under DEBUG_RODATA
to the 4.3-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-mm-use-correct-mapping-granularity-under-debug_rodata.patch
and it can be found in the queue-4.3 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 4fee9f364b9b99f76732f2a6fd6df679a237fa74 Mon Sep 17 00:00:00 2001
From: Ard Biesheuvel <ard.biesheuvel@xxxxxxxxxx>
Date: Mon, 16 Nov 2015 11:18:14 +0100
Subject: arm64: mm: use correct mapping granularity under DEBUG_RODATA
From: Ard Biesheuvel <ard.biesheuvel@xxxxxxxxxx>
commit 4fee9f364b9b99f76732f2a6fd6df679a237fa74 upstream.
When booting a 64k pages kernel that is built with CONFIG_DEBUG_RODATA
and resides at an offset that is not a multiple of 512 MB, the rounding
that occurs in __map_memblock() and fixup_executable() results in
incorrect regions being mapped.
The following snippet from /sys/kernel/debug/kernel_page_tables shows
how, when the kernel is loaded 2 MB above the base of DRAM at 0x40000000,
the first 2 MB of memory (which may be inaccessible from non-secure EL1
or just reserved by the firmware) is inadvertently mapped into the end of
the module region.
---[ Modules start ]---
0xfffffdffffe00000-0xfffffe0000000000 2M RW NX ... UXN MEM/NORMAL
---[ Modules end ]---
---[ Kernel Mapping ]---
0xfffffe0000000000-0xfffffe0000090000 576K RW NX ... UXN MEM/NORMAL
0xfffffe0000090000-0xfffffe0000200000 1472K ro x ... UXN MEM/NORMAL
0xfffffe0000200000-0xfffffe0000800000 6M ro x ... UXN MEM/NORMAL
0xfffffe0000800000-0xfffffe0000810000 64K ro x ... UXN MEM/NORMAL
0xfffffe0000810000-0xfffffe0000a00000 1984K RW NX ... UXN MEM/NORMAL
0xfffffe0000a00000-0xfffffe00ffe00000 4084M RW NX ... UXN MEM/NORMAL
The same issue is likely to occur on 16k pages kernels whose load
address is not a multiple of 32 MB (i.e., SECTION_SIZE). So round to
SWAPPER_BLOCK_SIZE instead of SECTION_SIZE.
Fixes: da141706aea5 ("arm64: add better page protections to arm64")
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@xxxxxxxxxx>
Acked-by: Mark Rutland <mark.rutland@xxxxxxx>
Acked-by: Laura Abbott <labbott@xxxxxxxxxx>
Signed-off-by: Catalin Marinas <catalin.marinas@xxxxxxx>
[ard.biesheuvel: add #define of SWAPPER_BLOCK_SIZE for -stable version]
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
arch/arm64/mm/mmu.c | 13 +++++++------
1 file changed, 7 insertions(+), 6 deletions(-)
--- a/arch/arm64/mm/mmu.c
+++ b/arch/arm64/mm/mmu.c
@@ -301,6 +301,7 @@ static void create_mapping_late(phys_add
}
#ifdef CONFIG_DEBUG_RODATA
+#define SWAPPER_BLOCK_SIZE (PAGE_SHIFT == 12 ? SECTION_SIZE : PAGE_SIZE)
static void __init __map_memblock(phys_addr_t start, phys_addr_t end)
{
/*
@@ -308,8 +309,8 @@ static void __init __map_memblock(phys_a
* for now. This will get more fine grained later once all memory
* is mapped
*/
- unsigned long kernel_x_start = round_down(__pa(_stext), SECTION_SIZE);
- unsigned long kernel_x_end = round_up(__pa(__init_end), SECTION_SIZE);
+ unsigned long kernel_x_start = round_down(__pa(_stext), SWAPPER_BLOCK_SIZE);
+ unsigned long kernel_x_end = round_up(__pa(__init_end), SWAPPER_BLOCK_SIZE);
if (end < kernel_x_start) {
create_mapping(start, __phys_to_virt(start),
@@ -397,18 +398,18 @@ void __init fixup_executable(void)
{
#ifdef CONFIG_DEBUG_RODATA
/* now that we are actually fully mapped, make the start/end more fine grained */
- if (!IS_ALIGNED((unsigned long)_stext, SECTION_SIZE)) {
+ if (!IS_ALIGNED((unsigned long)_stext, SWAPPER_BLOCK_SIZE)) {
unsigned long aligned_start = round_down(__pa(_stext),
- SECTION_SIZE);
+ SWAPPER_BLOCK_SIZE);
create_mapping(aligned_start, __phys_to_virt(aligned_start),
__pa(_stext) - aligned_start,
PAGE_KERNEL);
}
- if (!IS_ALIGNED((unsigned long)__init_end, SECTION_SIZE)) {
+ if (!IS_ALIGNED((unsigned long)__init_end, SWAPPER_BLOCK_SIZE)) {
unsigned long aligned_end = round_up(__pa(__init_end),
- SECTION_SIZE);
+ SWAPPER_BLOCK_SIZE);
create_mapping(__pa(__init_end), (unsigned long)__init_end,
aligned_end - __pa(__init_end),
PAGE_KERNEL);
Patches currently in stable-queue which might be from ard.biesheuvel@xxxxxxxxxx are
queue-4.3/arm64-mm-use-correct-mapping-granularity-under-debug_rodata.patch
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