linux.git/arch/arm64/kernel/image.h, branch v4.18

arm64/efi: Make strrchr() available to the EFI namespace

2018-03-05T19:45:38+00:00

libfdt gained a new dependency on strrchr, so make it available to the
EFI namespace before we update libfdt.

Thanks to Ard for providing this fix.

Cc: Catalin Marinas 
Acked-by: Ard Biesheuvel 
Acked-by: Will Deacon 
Signed-off-by: Rob Herring

Merge tag 'arm64-upstream' of git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux

2016-05-17T00:17:24+00:00

Pull arm64 updates from Will Deacon:

 - virt_to_page/page_address optimisations

 - support for NUMA systems described using device-tree

 - support for hibernate/suspend-to-disk

 - proper support for maxcpus= command line parameter

 - detection and graceful handling of AArch64-only CPUs

 - miscellaneous cleanups and non-critical fixes

* tag 'arm64-upstream' of git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux: (92 commits)
  arm64: do not enforce strict 16 byte alignment to stack pointer
  arm64: kernel: Fix incorrect brk randomization
  arm64: cpuinfo: Missing NULL terminator in compat_hwcap_str
  arm64: secondary_start_kernel: Remove unnecessary barrier
  arm64: Ensure pmd_present() returns false after pmd_mknotpresent()
  arm64: Replace hard-coded values in the pmd/pud_bad() macros
  arm64: Implement pmdp_set_access_flags() for hardware AF/DBM
  arm64: Fix typo in the pmdp_huge_get_and_clear() definition
  arm64: mm: remove unnecessary EXPORT_SYMBOL_GPL
  arm64: always use STRICT_MM_TYPECHECKS
  arm64: kvm: Fix kvm teardown for systems using the extended idmap
  arm64: kaslr: increase randomization granularity
  arm64: kconfig: drop CONFIG_RTC_LIB dependency
  arm64: make ARCH_SUPPORTS_DEBUG_PAGEALLOC depend on !HIBERNATION
  arm64: hibernate: Refuse to hibernate if the boot cpu is offline
  arm64: kernel: Add support for hibernate/suspend-to-disk
  PM / Hibernate: Call flush_icache_range() on pages restored in-place
  arm64: Add new asm macro copy_page
  arm64: Promote KERNEL_START/KERNEL_END definitions to a header file
  arm64: kernel: Include _AC definition in page.h
  ...

arm64/efi/libstub: Make screen_info accessible to the UEFI stub

2016-04-28T09:33:59+00:00

Unlike on 32-bit ARM, where we need to pass the stub's version of struct
screen_info to the kernel proper via a configuration table, on 64-bit ARM
it simply involves making the core kernel's copy of struct screen_info
visible to the stub by exposing an __efistub_ alias for it.

Signed-off-by: Ard Biesheuvel 
Signed-off-by: Matt Fleming 
Acked-by: Will Deacon 
Cc: Borislav Petkov 
Cc: David Herrmann 
Cc: Mark Rutland 
Cc: Peter Jones 
Cc: Peter Zijlstra 
Cc: Thomas Gleixner 
Cc: linux-efi@vger.kernel.org
Link: http://lkml.kernel.org/r/1461614832-17633-21-git-send-email-matt@codeblueprint.co.uk
Signed-off-by: Ingo Molnar

arm64: don't map TEXT_OFFSET bytes below the kernel if we can avoid it

2016-04-26T11:23:25+00:00

For historical reasons, the kernel Image must be loaded into physical
memory at a 512 KB offset above a 2 MB aligned base address. The region
between the base address and the start of the kernel Image has no
significance to the kernel itself, but it is currently mapped explicitly
into the early kernel VMA range for all translation granules.

In some cases (i.e., 4 KB granule), this is unavoidable, due to the 2 MB
granularity of the early kernel mappings. However, in other cases, e.g.,
when running with larger page sizes, or in the future, with more granular
KASLR, there is no reason to map it explicitly like we do currently.

So update the logic so that the region is mapped only if that happens as
a side effect of rounding the start address of the kernel to swapper block
size, and leave it unmapped otherwise.

Since the symbol kernel_img_size now simply resolves to the memory
footprint of the kernel Image, we can drop its definition from image.h
and opencode its calculation.

Acked-by: Catalin Marinas 
Signed-off-by: Ard Biesheuvel 
Signed-off-by: Will Deacon

arm64: move early boot code to the .init segment

2016-04-14T17:11:30+00:00

Apart from the arm64/linux and EFI header data structures, there is nothing
in the .head.text section that must reside at the beginning of the Image.
So let's move it to the .init section where it belongs.

Note that this involves some minor tweaking of the EFI header, primarily
because the address of 'stext' no longer coincides with the start of the
.text section. It also requires a couple of relocated symbol references
to be slightly rewritten or their definition moved to the linker script.

Signed-off-by: Ard Biesheuvel 
Signed-off-by: Will Deacon

Merge tag 'arm64-upstream' of git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux

2016-03-18T03:03:47+00:00

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
  ...

arm64: avoid R_AARCH64_ABS64 relocations for Image header fields

2016-02-24T14:57:25+00:00

Unfortunately, the current way of using the linker to emit build time
constants into the Image header will no longer work once we switch to
the use of PIE executables. The reason is that such constants are emitted
into the binary using R_AARCH64_ABS64 relocations, which are resolved at
runtime, not at build time, and the places targeted by those relocations
will contain zeroes before that.

So refactor the endian swapping linker script constant generation code so
that it emits the upper and lower 32-bit words separately.

Signed-off-by: Ard Biesheuvel 
Signed-off-by: Catalin Marinas

arm64: allow kernel Image to be loaded anywhere in physical memory

2016-02-18T18:16:53+00:00

This relaxes the kernel Image placement requirements, so that it
may be placed at any 2 MB aligned offset in physical memory.

This is accomplished by ignoring PHYS_OFFSET when installing
memblocks, and accounting for the apparent virtual offset of
the kernel Image. As a result, virtual address references
below PAGE_OFFSET are correctly mapped onto physical references
into the kernel Image regardless of where it sits in memory.

Special care needs to be taken for dealing with memory limits passed
via mem=, since the generic implementation clips memory top down, which
may clip the kernel image itself if it is loaded high up in memory. To
deal with this case, we simply add back the memory covering the kernel
image, which may result in more memory to be retained than was passed
as a mem= parameter.

Since mem= should not be considered a production feature, a panic notifier
handler is installed that dumps the memory limit at panic time if one was
set.

Signed-off-by: Ard Biesheuvel 
Signed-off-by: Catalin Marinas

arm64/efi: Make strnlen() available to the EFI namespace

2016-02-16T10:32:10+00:00

Changes introduced in the upstream version of libfdt pulled in by commit
91feabc2e224 ("scripts/dtc: Update to upstream commit b06e55c88b9b") use
the strnlen() function, which isn't currently available to the EFI name-
space. Add it to the EFI namespace to avoid a linker error.

Cc: Catalin Marinas 
Cc: Rob Herring 
Reviewed-by: Ard Biesheuvel 
Signed-off-by: Thierry Reding 
Signed-off-by: Will Deacon

arm64: hide __efistub_ aliases from kallsyms

2016-01-25T11:09:04+00:00

Commit e8f3010f7326 ("arm64/efi: isolate EFI stub from the kernel
proper") isolated the EFI stub code from the kernel proper by prefixing
all of its symbols with __efistub_, and selectively allowing access to
core kernel symbols from the stub by emitting __efistub_ aliases for
functions and variables that the stub can access legally.

As an unintended side effect, these aliases are emitted into the
kallsyms symbol table, which means they may turn up in backtraces,
e.g.,

  ...
  PC is at __efistub_memset+0x108/0x200
  LR is at fixup_init+0x3c/0x48
  ...
  [] __efistub_memset+0x108/0x200
  [] free_initmem+0x2c/0x40
  [] kernel_init+0x20/0xe0
  [] ret_from_fork+0x10/0x40

The backtrace in question has nothing to do with the EFI stub, but
simply returns one of the several aliases of memset() that have been
recorded in the kallsyms table. This is undesirable, since it may
suggest to people who are not aware of this that the issue they are
seeing is somehow EFI related.

So hide the __efistub_ aliases from kallsyms, by emitting them as
absolute linker symbols explicitly. The distinction between those
and section relative symbols is completely irrelevant to these
definitions, and to the final link we are performing when these
definitions are being taken into account (the distinction is only
relevant to symbols defined inside a section definition when performing
a partial link), and so the resulting values are identical to the
original ones. Since absolute symbols are ignored by kallsyms, this
will result in these values to be omitted from its symbol table.

After this patch, the backtrace generated from the same address looks
like this:
  ...
  PC is at __memset+0x108/0x200
  LR is at fixup_init+0x3c/0x48
  ...
  [] __memset+0x108/0x200
  [] free_initmem+0x2c/0x40
  [] kernel_init+0x20/0xe0
  [] ret_from_fork+0x10/0x40

Signed-off-by: Ard Biesheuvel 
Signed-off-by: Will Deacon