Re: Patch "arm64: mm: use correct mapping granularity under DEBUG_RODATA" has been added to the 4.1-stable tree
From: Ard Biesheuvel <hidden>
Date: 2016-01-28 08:18:27
On 27 January 2016 at 07:54, [off-list ref] wrote:
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 4.1-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-4.1 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let [off-list ref] know about it.Apologies for the late notice: as mentioned in the other thread, this will fail to build due to a missing #define of SWAPPER_BLOCK_SIZE. I will submit a new version specific to -stable (which just adds the #define locally) Thanks, Ard.
quoted hunk ↗ jump to hunk
From 4fee9f364b9b99f76732f2a6fd6df679a237fa74 Mon Sep 17 00:00:00 2001 From: Ard Biesheuvel <redacted> Date: Mon, 16 Nov 2015 11:18:14 +0100 Subject: arm64: mm: use correct mapping granularity under DEBUG_RODATA From: Ard Biesheuvel <redacted> 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 <redacted> Acked-by: Mark Rutland <mark.rutland@arm.com> Acked-by: Laura Abbott <redacted> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> --- arch/arm64/mm/mmu.c | 12 ++++++------ 1 file changed, 6 insertions(+), 6 deletions(-)--- a/arch/arm64/mm/mmu.c +++ b/arch/arm64/mm/mmu.c@@ -307,8 +307,8 @@ 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),@@ -396,18 +396,18 @@ 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@linaro.org are queue-4.1/arm-arm64-kvm-test-properly-for-a-pte-s-uncachedness.patch queue-4.1/arm64-mm-use-correct-mapping-granularity-under-debug_rodata.patch queue-4.1/arm-arm64-kvm-correct-pte-uncachedness-check.patch