- Initial page table creation reworked to avoid breaking large block
mappings (huge pages) into smaller ones. The ARM architecture requires
break-before-make in such cases to avoid TLB conflicts but that's not
always possible on live page tables
- Kernel virtual memory layout: the kernel image is no longer linked to
the bottom of the linear mapping (PAGE_OFFSET) but at the bottom of
the vmalloc space, allowing the kernel to be loaded (nearly) anywhere
in physical RAM
- Kernel ASLR: position independent kernel Image and modules being
randomly mapped in the vmalloc space with the randomness is provided
by UEFI (efi_get_random_bytes() patches merged via the arm64 tree,
acked by Matt Fleming)
- Implement relative exception tables for arm64, required by KASLR
(initial code for ARCH_HAS_RELATIVE_EXTABLE added to lib/extable.c but
actual x86 conversion to deferred to 4.7 because of the merge
dependencies)
- Support for the User Access Override feature of ARMv8.2: this allows
uaccess functions (get_user etc.) to be implemented using LDTR/STTR
instructions. Such instructions, when run by the kernel, perform
unprivileged accesses adding an extra level of protection. The
set_fs() macro is used to "upgrade" such instruction to privileged
accesses via the UAO bit
- Half-precision floating point support (part of ARMv8.2)
- Optimisations for CPUs with or without a hardware prefetcher (using
run-time code patching)
- copy_page performance improvement to deal with 128 bytes at a time
- Sanity checks on the CPU capabilities (via CPUID) to prevent
incompatible secondary CPUs from being brought up (e.g. weird
big.LITTLE configurations)
- valid_user_regs() reworked for better sanity check of the sigcontext
information (restored pstate information)
- ACPI parking protocol implementation
- CONFIG_DEBUG_RODATA enabled by default
- VDSO code marked as read-only
- DEBUG_PAGEALLOC support
- ARCH_HAS_UBSAN_SANITIZE_ALL enabled
- Erratum workaround Cavium ThunderX SoC
- set_pte_at() fix for PROT_NONE mappings
- Code clean-ups
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Merge tag 'arm64-upstream' of git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux
Pull arm64 updates from Catalin Marinas:
"Here are the main arm64 updates for 4.6. There are some relatively
intrusive changes to support KASLR, the reworking of the kernel
virtual memory layout and initial page table creation.
Summary:
- Initial page table creation reworked to avoid breaking large block
mappings (huge pages) into smaller ones. The ARM architecture
requires break-before-make in such cases to avoid TLB conflicts but
that's not always possible on live page tables
- Kernel virtual memory layout: the kernel image is no longer linked
to the bottom of the linear mapping (PAGE_OFFSET) but at the bottom
of the vmalloc space, allowing the kernel to be loaded (nearly)
anywhere in physical RAM
- Kernel ASLR: position independent kernel Image and modules being
randomly mapped in the vmalloc space with the randomness is
provided by UEFI (efi_get_random_bytes() patches merged via the
arm64 tree, acked by Matt Fleming)
- Implement relative exception tables for arm64, required by KASLR
(initial code for ARCH_HAS_RELATIVE_EXTABLE added to lib/extable.c
but actual x86 conversion to deferred to 4.7 because of the merge
dependencies)
- Support for the User Access Override feature of ARMv8.2: this
allows uaccess functions (get_user etc.) to be implemented using
LDTR/STTR instructions. Such instructions, when run by the kernel,
perform unprivileged accesses adding an extra level of protection.
The set_fs() macro is used to "upgrade" such instruction to
privileged accesses via the UAO bit
- Half-precision floating point support (part of ARMv8.2)
- Optimisations for CPUs with or without a hardware prefetcher (using
run-time code patching)
- copy_page performance improvement to deal with 128 bytes at a time
- Sanity checks on the CPU capabilities (via CPUID) to prevent
incompatible secondary CPUs from being brought up (e.g. weird
big.LITTLE configurations)
- valid_user_regs() reworked for better sanity check of the
sigcontext information (restored pstate information)
- ACPI parking protocol implementation
- CONFIG_DEBUG_RODATA enabled by default
- VDSO code marked as read-only
- DEBUG_PAGEALLOC support
- ARCH_HAS_UBSAN_SANITIZE_ALL enabled
- Erratum workaround Cavium ThunderX SoC
- set_pte_at() fix for PROT_NONE mappings
- Code clean-ups"
* tag 'arm64-upstream' of git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux: (99 commits)
arm64: kasan: Fix zero shadow mapping overriding kernel image shadow
arm64: kasan: Use actual memory node when populating the kernel image shadow
arm64: Update PTE_RDONLY in set_pte_at() for PROT_NONE permission
arm64: Fix misspellings in comments.
arm64: efi: add missing frame pointer assignment
arm64: make mrs_s prefixing implicit in read_cpuid
arm64: enable CONFIG_DEBUG_RODATA by default
arm64: Rework valid_user_regs
arm64: mm: check at build time that PAGE_OFFSET divides the VA space evenly
arm64: KVM: Move kvm_call_hyp back to its original localtion
arm64: mm: treat memstart_addr as a signed quantity
arm64: mm: list kernel sections in order
arm64: lse: deal with clobbered IP registers after branch via PLT
arm64: mm: dump: Use VA_START directly instead of private LOWEST_ADDR
arm64: kconfig: add submenu for 8.2 architectural features
arm64: kernel: acpi: fix ioremap in ACPI parking protocol cpu_postboot
arm64: Add support for Half precision floating point
arm64: Remove fixmap include fragility
arm64: Add workaround for Cavium erratum 27456
arm64: mm: Mark .rodata as RO
...
Linus Torvalds
588ab3f9af