Pull arm64 fixes from Will Deacon:
 "A batch of arm64 fixes.

  Although the diffstat is a bit larger than we'd usually have at this
  stage, a decent amount of it is the addition of comments describing
  our syscall tracing behaviour, and also a sweep across all the modular
  arm64 PMU drivers to make them rebust against unloading and unbinding.

  There are a couple of minor things kicking around at the moment (CPU
  errata and module PLTs for very large modules), but I'm not expecting
  any significant changes now for us in 5.8.

   - Fix kernel text addresses for relocatable images booting using EFI
     and with KASLR disabled so that they match the vmlinux ELF binary.

   - Fix unloading and unbinding of PMU driver modules.

   - Fix generic mmiowb() when writeX() is called from preemptible
     context (reported by the riscv folks).

   - Fix ptrace hardware single-step interactions with signal handlers,
     system calls and reverse debugging.

   - Fix reporting of 64-bit x0 register for 32-bit tasks via
     'perf_regs'.

   - Add comments describing syscall entry/exit tracing ABI"

* tag 'arm64-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux:
  drivers/perf: Prevent forced unbinding of PMU drivers
  asm-generic/mmiowb: Allow mmiowb_set_pending() when preemptible()
  arm64: Use test_tsk_thread_flag() for checking TIF_SINGLESTEP
  arm64: ptrace: Use NO_SYSCALL instead of -1 in syscall_trace_enter()
  arm64: syscall: Expand the comment about ptrace and syscall(-1)
  arm64: ptrace: Add a comment describing our syscall entry/exit trap ABI
  arm64: compat: Ensure upper 32 bits of x0 are zero on syscall return
  arm64: ptrace: Override SPSR.SS when single-stepping is enabled
  arm64: ptrace: Consistently use pseudo-singlestep exceptions
  drivers/perf: Fix kernel panic when rmmod PMU modules during perf sampling
  efi/libstub/arm64: Retain 2MB kernel Image alignment if !KASLR