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authorLinus Torvalds <torvalds@linux-foundation.org>2014-08-04 12:31:53 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2014-08-04 12:31:53 -0700
commit5167d09ffad5b16b574d35ce3047ed34caf1e837 (patch)
treefc45dd9cbd578f5010e7b8208ecdfc6534547989 /Documentation
parent8533ce72718871fb528d853391746f36243273af (diff)
parentea1719672f59eeb85829073b567495c4f472ac9f (diff)
Merge tag 'arm64-upstream' of git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux
Pull arm64 updates from Will Deacon: "Once again, Catalin's off on holiday and I'm looking after the arm64 tree. Please can you pull the following arm64 updates for 3.17? Note that this branch also includes the new GICv3 driver (merged via a stable tag from Jason's irqchip tree), since there is a fix for older binutils on top. Changes include: - context tracking support (NO_HZ_FULL) which narrowly missed 3.16 - vDSO layout rework following Andy's work on x86 - TEXT_OFFSET fuzzing for bootloader testing - /proc/cpuinfo tidy-up - preliminary work to support 48-bit virtual addresses, but this is currently disabled until KVM has been ported to use it (the patches do, however, bring some nice clean-up) - boot-time CPU sanity checks (especially useful on heterogenous systems) - support for syscall auditing - support for CC_STACKPROTECTOR - defconfig updates" * tag 'arm64-upstream' of git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux: (55 commits) arm64: add newline to I-cache policy string Revert "arm64: dmi: Add SMBIOS/DMI support" arm64: fpsimd: fix a typo in fpsimd_save_partial_state ENDPROC arm64: don't call break hooks for BRK exceptions from EL0 arm64: defconfig: enable devtmpfs mount option arm64: vdso: fix build error when switching from LE to BE arm64: defconfig: add virtio support for running as a kvm guest arm64: gicv3: Allow GICv3 compilation with older binutils arm64: fix soft lockup due to large tlb flush range arm64/crypto: fix makefile rule for aes-glue-%.o arm64: Do not invoke audit_syscall_* functions if !CONFIG_AUDIT_SYSCALL arm64: Fix barriers used for page table modifications arm64: Add support for 48-bit VA space with 64KB page configuration arm64: asm/pgtable.h pmd/pud definitions clean-up arm64: Determine the vmalloc/vmemmap space at build time based on VA_BITS arm64: Clean up the initial page table creation in head.S arm64: Remove asm/pgtable-*level-types.h files arm64: Remove asm/pgtable-*level-hwdef.h files arm64: Convert bool ARM64_x_LEVELS to int ARM64_PGTABLE_LEVELS arm64: mm: Implement 4 levels of translation tables ...
Diffstat (limited to 'Documentation')
-rw-r--r--Documentation/arm64/booting.txt43
-rw-r--r--Documentation/arm64/memory.txt69
2 files changed, 61 insertions, 51 deletions
diff --git a/Documentation/arm64/booting.txt b/Documentation/arm64/booting.txt
index 37fc4f632176..85af34d55cee 100644
--- a/Documentation/arm64/booting.txt
+++ b/Documentation/arm64/booting.txt
@@ -72,27 +72,54 @@ The decompressed kernel image contains a 64-byte header as follows:
u32 code0; /* Executable code */
u32 code1; /* Executable code */
- u64 text_offset; /* Image load offset */
- u64 res0 = 0; /* reserved */
- u64 res1 = 0; /* reserved */
+ u64 text_offset; /* Image load offset, little endian */
+ u64 image_size; /* Effective Image size, little endian */
+ u64 flags; /* kernel flags, little endian */
u64 res2 = 0; /* reserved */
u64 res3 = 0; /* reserved */
u64 res4 = 0; /* reserved */
u32 magic = 0x644d5241; /* Magic number, little endian, "ARM\x64" */
- u32 res5 = 0; /* reserved */
+ u32 res5; /* reserved (used for PE COFF offset) */
Header notes:
+- As of v3.17, all fields are little endian unless stated otherwise.
+
- code0/code1 are responsible for branching to stext.
+
- when booting through EFI, code0/code1 are initially skipped.
res5 is an offset to the PE header and the PE header has the EFI
- entry point (efi_stub_entry). When the stub has done its work, it
+ entry point (efi_stub_entry). When the stub has done its work, it
jumps to code0 to resume the normal boot process.
-The image must be placed at the specified offset (currently 0x80000)
-from the start of the system RAM and called there. The start of the
-system RAM must be aligned to 2MB.
+- Prior to v3.17, the endianness of text_offset was not specified. In
+ these cases image_size is zero and text_offset is 0x80000 in the
+ endianness of the kernel. Where image_size is non-zero image_size is
+ little-endian and must be respected. Where image_size is zero,
+ text_offset can be assumed to be 0x80000.
+
+- The flags field (introduced in v3.17) is a little-endian 64-bit field
+ composed as follows:
+ Bit 0: Kernel endianness. 1 if BE, 0 if LE.
+ Bits 1-63: Reserved.
+
+- When image_size is zero, a bootloader should attempt to keep as much
+ memory as possible free for use by the kernel immediately after the
+ end of the kernel image. The amount of space required will vary
+ depending on selected features, and is effectively unbound.
+
+The Image must be placed text_offset bytes from a 2MB aligned base
+address near the start of usable system RAM and called there. Memory
+below that base address is currently unusable by Linux, and therefore it
+is strongly recommended that this location is the start of system RAM.
+At least image_size bytes from the start of the image must be free for
+use by the kernel.
+
+Any memory described to the kernel (even that below the 2MB aligned base
+address) which is not marked as reserved from the kernel e.g. with a
+memreserve region in the device tree) will be considered as available to
+the kernel.
Before jumping into the kernel, the following conditions must be met:
diff --git a/Documentation/arm64/memory.txt b/Documentation/arm64/memory.txt
index d50fa618371b..344e85cc7323 100644
--- a/Documentation/arm64/memory.txt
+++ b/Documentation/arm64/memory.txt
@@ -2,18 +2,18 @@
==============================
Author: Catalin Marinas <catalin.marinas@arm.com>
-Date : 20 February 2012
This document describes the virtual memory layout used by the AArch64
Linux kernel. The architecture allows up to 4 levels of translation
tables with a 4KB page size and up to 3 levels with a 64KB page size.
-AArch64 Linux uses 3 levels of translation tables with the 4KB page
-configuration, allowing 39-bit (512GB) virtual addresses for both user
-and kernel. With 64KB pages, only 2 levels of translation tables are
-used but the memory layout is the same.
+AArch64 Linux uses either 3 levels or 4 levels of translation tables
+with the 4KB page configuration, allowing 39-bit (512GB) or 48-bit
+(256TB) virtual addresses, respectively, for both user and kernel. With
+64KB pages, only 2 levels of translation tables, allowing 42-bit (4TB)
+virtual address, are used but the memory layout is the same.
-User addresses have bits 63:39 set to 0 while the kernel addresses have
+User addresses have bits 63:48 set to 0 while the kernel addresses have
the same bits set to 1. TTBRx selection is given by bit 63 of the
virtual address. The swapper_pg_dir contains only kernel (global)
mappings while the user pgd contains only user (non-global) mappings.
@@ -21,58 +21,40 @@ The swapper_pgd_dir address is written to TTBR1 and never written to
TTBR0.
-AArch64 Linux memory layout with 4KB pages:
+AArch64 Linux memory layout with 4KB pages + 3 levels:
Start End Size Use
-----------------------------------------------------------------------
0000000000000000 0000007fffffffff 512GB user
+ffffff8000000000 ffffffffffffffff 512GB kernel
-ffffff8000000000 ffffffbbfffeffff ~240GB vmalloc
-ffffffbbffff0000 ffffffbbffffffff 64KB [guard page]
+AArch64 Linux memory layout with 4KB pages + 4 levels:
-ffffffbc00000000 ffffffbdffffffff 8GB vmemmap
-
-ffffffbe00000000 ffffffbffbbfffff ~8GB [guard, future vmmemap]
-
-ffffffbffa000000 ffffffbffaffffff 16MB PCI I/O space
-
-ffffffbffb000000 ffffffbffbbfffff 12MB [guard]
-
-ffffffbffbc00000 ffffffbffbdfffff 2MB fixed mappings
-
-ffffffbffbe00000 ffffffbffbffffff 2MB [guard]
-
-ffffffbffc000000 ffffffbfffffffff 64MB modules
-
-ffffffc000000000 ffffffffffffffff 256GB kernel logical memory map
+Start End Size Use
+-----------------------------------------------------------------------
+0000000000000000 0000ffffffffffff 256TB user
+ffff000000000000 ffffffffffffffff 256TB kernel
-AArch64 Linux memory layout with 64KB pages:
+AArch64 Linux memory layout with 64KB pages + 2 levels:
Start End Size Use
-----------------------------------------------------------------------
0000000000000000 000003ffffffffff 4TB user
+fffffc0000000000 ffffffffffffffff 4TB kernel
-fffffc0000000000 fffffdfbfffeffff ~2TB vmalloc
-fffffdfbffff0000 fffffdfbffffffff 64KB [guard page]
+AArch64 Linux memory layout with 64KB pages + 3 levels:
-fffffdfc00000000 fffffdfdffffffff 8GB vmemmap
-
-fffffdfe00000000 fffffdfffbbfffff ~8GB [guard, future vmmemap]
-
-fffffdfffa000000 fffffdfffaffffff 16MB PCI I/O space
-
-fffffdfffb000000 fffffdfffbbfffff 12MB [guard]
-
-fffffdfffbc00000 fffffdfffbdfffff 2MB fixed mappings
-
-fffffdfffbe00000 fffffdfffbffffff 2MB [guard]
+Start End Size Use
+-----------------------------------------------------------------------
+0000000000000000 0000ffffffffffff 256TB user
+ffff000000000000 ffffffffffffffff 256TB kernel
-fffffdfffc000000 fffffdffffffffff 64MB modules
-fffffe0000000000 ffffffffffffffff 2TB kernel logical memory map
+For details of the virtual kernel memory layout please see the kernel
+booting log.
Translation table lookup with 4KB pages:
@@ -86,7 +68,7 @@ Translation table lookup with 4KB pages:
| | | | +-> [20:12] L3 index
| | | +-----------> [29:21] L2 index
| | +---------------------> [38:30] L1 index
- | +-------------------------------> [47:39] L0 index (not used)
+ | +-------------------------------> [47:39] L0 index
+-------------------------------------------------> [63] TTBR0/1
@@ -99,10 +81,11 @@ Translation table lookup with 64KB pages:
| | | | v
| | | | [15:0] in-page offset
| | | +----------> [28:16] L3 index
- | | +--------------------------> [41:29] L2 index (only 38:29 used)
- | +-------------------------------> [47:42] L1 index (not used)
+ | | +--------------------------> [41:29] L2 index
+ | +-------------------------------> [47:42] L1 index
+-------------------------------------------------> [63] TTBR0/1
+
When using KVM, the hypervisor maps kernel pages in EL2, at a fixed
offset from the kernel VA (top 24bits of the kernel VA set to zero):