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

Pull arm64 updates from Catalin Marinas:
 "The bulk is in-kernel pointer authentication, activity monitors and
  lots of asm symbol annotations. I also queued the sys_mremap() patch
  commenting the asymmetry in the address untagging.

  Summary:

   - In-kernel Pointer Authentication support (previously only offered
     to user space).

   - ARM Activity Monitors (AMU) extension support allowing better CPU
     utilisation numbers for the scheduler (frequency invariance).

   - Memory hot-remove support for arm64.

   - Lots of asm annotations (SYM_*) in preparation for the in-kernel
     Branch Target Identification (BTI) support.

   - arm64 perf updates: ARMv8.5-PMU 64-bit counters, refactoring the
     PMU init callbacks, support for new DT compatibles.

   - IPv6 header checksum optimisation.

   - Fixes: SDEI (software delegated exception interface) double-lock on
     hibernate with shared events.

   - Minor clean-ups and refactoring: cpu_ops accessor,
     cpu_do_switch_mm() converted to C, cpufeature finalisation helper.

   - sys_mremap() comment explaining the asymmetric address untagging
     behaviour"

* tag 'arm64-upstream' of git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux: (81 commits)
  mm/mremap: Add comment explaining the untagging behaviour of mremap()
  arm64: head: Convert install_el2_stub to SYM_INNER_LABEL
  arm64: Introduce get_cpu_ops() helper function
  arm64: Rename cpu_read_ops() to init_cpu_ops()
  arm64: Declare ACPI parking protocol CPU operation if needed
  arm64: move kimage_vaddr to .rodata
  arm64: use mov_q instead of literal ldr
  arm64: Kconfig: verify binutils support for ARM64_PTR_AUTH
  lkdtm: arm64: test kernel pointer authentication
  arm64: compile the kernel with ptrauth return address signing
  kconfig: Add support for 'as-option'
  arm64: suspend: restore the kernel ptrauth keys
  arm64: __show_regs: strip PAC from lr in printk
  arm64: unwind: strip PAC from kernel addresses
  arm64: mask PAC bits of __builtin_return_address
  arm64: initialize ptrauth keys for kernel booting task
  arm64: initialize and switch ptrauth kernel keys
  arm64: enable ptrauth earlier
  arm64: cpufeature: handle conflicts based on capability
  arm64: cpufeature: Move cpu capability helpers inside C file
  ...

1 files changed, 6 insertions, 0 deletions

diff --git a/scripts/Kconfig.include b/scripts/Kconfig.include
index 496d11c92c97..8074f14d9d0d 100644
--- a/scripts/Kconfig.include
+++ b/scripts/Kconfig.include
@@ -31,6 +31,12 @@ cc-option = $(success,$(CC) -Werror $(CLANG_FLAGS) $(1) -S -x c /dev/null -o /de
 # Return y if the linker supports <flag>, n otherwise
 ld-option = $(success,$(LD) -v $(1))
 
+# $(as-option,<flag>)
+# /dev/zero is used as output instead of /dev/null as some assembler cribs when
+# both input and output are same. Also both of them have same write behaviour so
+# can be easily substituted.
+as-option = $(success, $(CC) $(CLANG_FLAGS) $(1) -c -x assembler /dev/null -o /dev/zero)
+
 # $(as-instr,<instr>)
 # Return y if the assembler supports <instr>, n otherwise
 as-instr = $(success,printf "%b\n" "$(1)" | $(CC) $(CLANG_FLAGS) -c -x assembler -o /dev/null -)