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

Pull arm64 festive updates from Will Deacon:
 "In the end, we ended up with quite a lot more than I expected:

   - Support for ARMv8.3 Pointer Authentication in userspace (CRIU and
     kernel-side support to come later)

   - Support for per-thread stack canaries, pending an update to GCC
     that is currently undergoing review

   - Support for kexec_file_load(), which permits secure boot of a kexec
     payload but also happens to improve the performance of kexec
     dramatically because we can avoid the sucky purgatory code from
     userspace. Kdump will come later (requires updates to libfdt).

   - Optimisation of our dynamic CPU feature framework, so that all
     detected features are enabled via a single stop_machine()
     invocation

   - KPTI whitelisting of Cortex-A CPUs unaffected by Meltdown, so that
     they can benefit from global TLB entries when KASLR is not in use

   - 52-bit virtual addressing for userspace (kernel remains 48-bit)

   - Patch in LSE atomics for per-cpu atomic operations

   - Custom preempt.h implementation to avoid unconditional calls to
     preempt_schedule() from preempt_enable()

   - Support for the new 'SB' Speculation Barrier instruction

   - Vectorised implementation of XOR checksumming and CRC32
     optimisations

   - Workaround for Cortex-A76 erratum #1165522

   - Improved compatibility with Clang/LLD

   - Support for TX2 system PMUS for profiling the L3 cache and DMC

   - Reflect read-only permissions in the linear map by default

   - Ensure MMIO reads are ordered with subsequent calls to Xdelay()

   - Initial support for memory hotplug

   - Tweak the threshold when we invalidate the TLB by-ASID, so that
     mremap() performance is improved for ranges spanning multiple PMDs.

   - Minor refactoring and cleanups"

* tag 'arm64-upstream' of git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux: (125 commits)
  arm64: kaslr: print PHYS_OFFSET in dump_kernel_offset()
  arm64: sysreg: Use _BITUL() when defining register bits
  arm64: cpufeature: Rework ptr auth hwcaps using multi_entry_cap_matches
  arm64: cpufeature: Reduce number of pointer auth CPU caps from 6 to 4
  arm64: docs: document pointer authentication
  arm64: ptr auth: Move per-thread keys from thread_info to thread_struct
  arm64: enable pointer authentication
  arm64: add prctl control for resetting ptrauth keys
  arm64: perf: strip PAC when unwinding userspace
  arm64: expose user PAC bit positions via ptrace
  arm64: add basic pointer authentication support
  arm64/cpufeature: detect pointer authentication
  arm64: Don't trap host pointer auth use to EL2
  arm64/kvm: hide ptrauth from guests
  arm64/kvm: consistently handle host HCR_EL2 flags
  arm64: add pointer authentication register bits
  arm64: add comments about EC exception levels
  arm64: perf: Treat EXCLUDE_EL* bit definitions as unsigned
  arm64: kpti: Whitelist Cortex-A CPUs that don't implement the CSV3 field
  arm64: enable per-task stack canaries
  ...

5 files changed, 117 insertions, 0 deletions

diff --git a/Documentation/arm64/booting.txt b/Documentation/arm64/booting.txt
index 8d0df62c3fe0..8df9f4658d6f 100644
--- a/Documentation/arm64/booting.txt
+++ b/Documentation/arm64/booting.txt
@@ -205,6 +205,14 @@ Before jumping into the kernel, the following conditions must be met:
     ICC_SRE_EL2.SRE (bit 0) must be initialised to 0b0.
   - The DT or ACPI tables must describe a GICv2 interrupt controller.
 
+  For CPUs with pointer authentication functionality:
+  - If EL3 is present:
+    SCR_EL3.APK (bit 16) must be initialised to 0b1
+    SCR_EL3.API (bit 17) must be initialised to 0b1
+  - If the kernel is entered at EL1:
+    HCR_EL2.APK (bit 40) must be initialised to 0b1
+    HCR_EL2.API (bit 41) must be initialised to 0b1
+
 The requirements described above for CPU mode, caches, MMUs, architected
 timers, coherency and system registers apply to all CPUs.  All CPUs must
 enter the kernel in the same exception level.
diff --git a/Documentation/arm64/cpu-feature-registers.txt b/Documentation/arm64/cpu-feature-registers.txt
index 7964f03846b1..d4b4dd1fe786 100644
--- a/Documentation/arm64/cpu-feature-registers.txt
+++ b/Documentation/arm64/cpu-feature-registers.txt
@@ -184,12 +184,20 @@ infrastructure:
      x--------------------------------------------------x
      | Name                         |  bits   | visible |
      |--------------------------------------------------|
+     | GPI                          | [31-28] |    y    |
+     |--------------------------------------------------|
+     | GPA                          | [27-24] |    y    |
+     |--------------------------------------------------|
      | LRCPC                        | [23-20] |    y    |
      |--------------------------------------------------|
      | FCMA                         | [19-16] |    y    |
      |--------------------------------------------------|
      | JSCVT                        | [15-12] |    y    |
      |--------------------------------------------------|
+     | API                          | [11-8]  |    y    |
+     |--------------------------------------------------|
+     | APA                          | [7-4]   |    y    |
+     |--------------------------------------------------|
      | DPB                          | [3-0]   |    y    |
      x--------------------------------------------------x
 
diff --git a/Documentation/arm64/elf_hwcaps.txt b/Documentation/arm64/elf_hwcaps.txt
index ea819ae024dd..13d6691b37be 100644
--- a/Documentation/arm64/elf_hwcaps.txt
+++ b/Documentation/arm64/elf_hwcaps.txt
@@ -182,3 +182,15 @@ HWCAP_FLAGM
 HWCAP_SSBS
 
     Functionality implied by ID_AA64PFR1_EL1.SSBS == 0b0010.
+
+HWCAP_PACA
+
+    Functionality implied by ID_AA64ISAR1_EL1.APA == 0b0001 or
+    ID_AA64ISAR1_EL1.API == 0b0001, as described by
+    Documentation/arm64/pointer-authentication.txt.
+
+HWCAP_PACG
+
+    Functionality implied by ID_AA64ISAR1_EL1.GPA == 0b0001 or
+    ID_AA64ISAR1_EL1.GPI == 0b0001, as described by
+    Documentation/arm64/pointer-authentication.txt.
diff --git a/Documentation/arm64/pointer-authentication.txt b/Documentation/arm64/pointer-authentication.txt
new file mode 100644
index 000000000000..a25cd21290e9
--- /dev/null
+++ b/Documentation/arm64/pointer-authentication.txt
@@ -0,0 +1,88 @@
+Pointer authentication in AArch64 Linux
+=======================================
+
+Author: Mark Rutland <mark.rutland@arm.com>
+Date: 2017-07-19
+
+This document briefly describes the provision of pointer authentication
+functionality in AArch64 Linux.
+
+
+Architecture overview
+---------------------
+
+The ARMv8.3 Pointer Authentication extension adds primitives that can be
+used to mitigate certain classes of attack where an attacker can corrupt
+the contents of some memory (e.g. the stack).
+
+The extension uses a Pointer Authentication Code (PAC) to determine
+whether pointers have been modified unexpectedly. A PAC is derived from
+a pointer, another value (such as the stack pointer), and a secret key
+held in system registers.
+
+The extension adds instructions to insert a valid PAC into a pointer,
+and to verify/remove the PAC from a pointer. The PAC occupies a number
+of high-order bits of the pointer, which varies dependent on the
+configured virtual address size and whether pointer tagging is in use.
+
+A subset of these instructions have been allocated from the HINT
+encoding space. In the absence of the extension (or when disabled),
+these instructions behave as NOPs. Applications and libraries using
+these instructions operate correctly regardless of the presence of the
+extension.
+
+The extension provides five separate keys to generate PACs - two for
+instruction addresses (APIAKey, APIBKey), two for data addresses
+(APDAKey, APDBKey), and one for generic authentication (APGAKey).
+
+
+Basic support
+-------------
+
+When CONFIG_ARM64_PTR_AUTH is selected, and relevant HW support is
+present, the kernel will assign random key values to each process at
+exec*() time. The keys are shared by all threads within the process, and
+are preserved across fork().
+
+Presence of address authentication functionality is advertised via
+HWCAP_PACA, and generic authentication functionality via HWCAP_PACG.
+
+The number of bits that the PAC occupies in a pointer is 55 minus the
+virtual address size configured by the kernel. For example, with a
+virtual address size of 48, the PAC is 7 bits wide.
+
+Recent versions of GCC can compile code with APIAKey-based return
+address protection when passed the -msign-return-address option. This
+uses instructions in the HINT space (unless -march=armv8.3-a or higher
+is also passed), and such code can run on systems without the pointer
+authentication extension.
+
+In addition to exec(), keys can also be reinitialized to random values
+using the PR_PAC_RESET_KEYS prctl. A bitmask of PR_PAC_APIAKEY,
+PR_PAC_APIBKEY, PR_PAC_APDAKEY, PR_PAC_APDBKEY and PR_PAC_APGAKEY
+specifies which keys are to be reinitialized; specifying 0 means "all
+keys".
+
+
+Debugging
+---------
+
+When CONFIG_ARM64_PTR_AUTH is selected, and HW support for address
+authentication is present, the kernel will expose the position of TTBR0
+PAC bits in the NT_ARM_PAC_MASK regset (struct user_pac_mask), which
+userspace can acquire via PTRACE_GETREGSET.
+
+The regset is exposed only when HWCAP_PACA is set. Separate masks are
+exposed for data pointers and instruction pointers, as the set of PAC
+bits can vary between the two. Note that the masks apply to TTBR0
+addresses, and are not valid to apply to TTBR1 addresses (e.g. kernel
+pointers).
+
+
+Virtualization
+--------------
+
+Pointer authentication is not currently supported in KVM guests. KVM
+will mask the feature bits from ID_AA64ISAR1_EL1, and attempted use of
+the feature will result in an UNDEFINED exception being injected into
+the guest.
diff --git a/Documentation/arm64/silicon-errata.txt b/Documentation/arm64/silicon-errata.txt
index 8f9577621144..1f09d043d086 100644
--- a/Documentation/arm64/silicon-errata.txt
+++ b/Documentation/arm64/silicon-errata.txt
@@ -57,6 +57,7 @@ stable kernels.
 | ARM            | Cortex-A73      | #858921         | ARM64_ERRATUM_858921        |
 | ARM            | Cortex-A55      | #1024718        | ARM64_ERRATUM_1024718       |
 | ARM            | Cortex-A76      | #1188873        | ARM64_ERRATUM_1188873       |
+| ARM            | Cortex-A76      | #1165522        | ARM64_ERRATUM_1165522       |
 | ARM            | Cortex-A76      | #1286807        | ARM64_ERRATUM_1286807       |
 | ARM            | MMU-500         | #841119,#826419 | N/A                         |
 |                |                 |                 |                             |