riscv: improve percpu helpers and PIO mapping

Changes in v5:
- Keep the PIO helper fix local to RISC-V: drop the generic
  HAS_IOPORT_MAP dependency change and the generic ioport_map() change
  from v4.
- Add the missing linux/bits.h include for GENMASK and BITS_PER_BYTE.
- Fix the 8/16-bit LR/SC fallback to mask subword results before writing
  them back.
- Use early-clobber constraints in the 8/16-bit add_return LR/SC fallback.
- Fix this_cpu_and_4/8 to pass the intended operand to RISC-V amoand.
- Initialize the secondary idle task pcpu_offset before starting the CPU.

Yunhui Cui (3):
  riscv: io: avoid null-pointer arithmetic in PIO helpers
  riscv: introduce percpu.h into include/asm
  riscv: store percpu offset into thread_info

 arch/riscv/include/asm/asm.h         |   6 +-
 arch/riscv/include/asm/io.h          |  26 ++-
 arch/riscv/include/asm/percpu.h      | 287 +++++++++++++++++++++++++++
 arch/riscv/include/asm/switch_to.h   |   8 +
 arch/riscv/include/asm/thread_info.h |   3 +-
 arch/riscv/kernel/asm-offsets.c      |   1 +
 arch/riscv/kernel/smpboot.c          |   8 +
 arch/riscv/net/bpf_jit_comp64.c      |   9 +-
 8 files changed, 326 insertions(+), 22 deletions(-)
 create mode 100644 arch/riscv/include/asm/percpu.h

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2.39.5