riscv: Add GENERIC_ENTRY support

From: Guo Ren <guoren@linux.alibaba.com>

The patches convert riscv to use the generic entry infrastructure from
kernel/entry/*. Some optimization for entry.S with new .macro and merge
ret_from_kernel_thread into ret_from_fork.

The 1,2 are the preparation of generic entry. 3~7 are the main part
of generic entry.

All tested with rv64, rv32, rv64 + 32rootfs, all are passed.

You can directly try it with:
[1] https://github.com/guoren83/linux/tree/generic_entry_v11

Any reviews and tests are helpful.

v11:
 - Rebase on newest for-next-20221211
 - Remove stack optimization patch series
 - Optimize comments
 - Replace ENTRY with SYM_CODE/FUNC_START in entry.S

v10:
https://lore.kernel.org/linux-riscv/20221208025816.138712...
 - Rebase on palmer/for-next branch (20221208)
 - Remove unrelated patches from the series (Suggested-by: Bjorn)
 - Fixup Typos. 

v9:
https://lore.kernel.org/linux-riscv/20221130034059.826599...
 - Fixup NR_syscalls check (by Ben Hutchings)
 - Add Tested-by: Jisheng Zhang

v8:
https://lore.kernel.org/linux-riscv/20221103075047.163492...
 - Rebase on palmer/for-next branch (20221102)
 - Add save/restore_from_x5_to_x31 .macro (JishengZhang)
 - Consolidate ret_from_kernel_thread into ret_from_fork (JishengZhang)
 - Optimize __noinstr_section comment (JiangshanLai)

v7:
https://lore.kernel.org/linux-riscv/20221015114702.348998...
 - Fixup regs_irqs_disabled with SR_PIE
 - Optimize stackleak_erase -> stackleak_erase_on_task_stack (Thx Mark
   Rutland)
 - Add BUG_ON(!irqs_disabled()) in trap handlers
 - Using regs_irqs_disabled in __do_page_fault
 - Remove unnecessary irq disable in ret_from_exception and add comment

v6:
https://lore.kernel.org/linux-riscv/20221002012451.235112...
 - Use THEAD_SIZE_ORDER for thread size adjustment in kconfig (Thx Arnd)
 - Move call_on_stack to inline style (Thx Peter Zijlstra)
 - Fixup fp chain broken (Thx Chen Zhongjin)
 - Remove common entry modification, and fixup page_fault entry (Thx
   Peter Zijlstra)
 - Treat some traps as nmi entry (Thx Peter Zijlstra)

v5:
https://lore.kernel.org/linux-riscv/20220918155246.120329...
 - Add riscv own stackleak patch instead of generic entry modification
   (by Mark Rutland)
 - Add EXPERT dependency for THREAD_SIZE (by Arnd)
 - Add EXPERT dependency for IRQ_STACK (by Sebastian, David Laight)
 - Corrected __trap_section (by Peter Zijlstra)
 - Add Tested-by (Yipeng Zou)
 - Use CONFIG_SOFTIRQ_ON_OWN_STACK replace "#ifndef CONFIG_PREEMPT_RT"
 - Fixup systrace_enter compile error
 - Fixup exit_to_user_mode_prepare preempt_disable warning

V4:
https://lore.kernel.org/linux-riscv/20220908022506.127579...
 - Fixup entry.S with "la" bug (by Conor.Dooley)
 - Fixup missing noinstr bug (by Peter Zijlstra)

V3:
https://lore.kernel.org/linux-riscv/20220906035423.634617...
 - Fixup CONFIG_COMPAT=n compile error
 - Add THREAD_SIZE_ORDER config
 - Optimize elf_kexec.c warning fixup
 - Add static to irq_stack_ptr definition

V2:
https://lore.kernel.org/linux-riscv/20220904072637.8619-1...
 - Fixup compile error by include "riscv: ptrace: Remove duplicate
   operation"
 - Fixup compile warning
   Reported-by: kernel test robot <lkp@intel.com>
 - Add test repo link in cover letter

V1:
https://lore.kernel.org/linux-riscv/20220903163808.195413...

Guo Ren (3):
  riscv: ptrace: Remove duplicate operation
  riscv: entry: Add noinstr to prevent instrumentation inserted
  riscv: entry: Convert to generic entry

Jisheng Zhang (3):
  riscv: entry: Remove extra level wrappers of trace_hardirqs_{on,off}
  riscv: entry: Consolidate ret_from_kernel_thread into ret_from_fork
  riscv: entry: Consolidate general regs saving/restoring

Lai Jiangshan (1):
  compiler_types.h: Add __noinstr_section() for noinstr

 arch/riscv/Kconfig                    |   1 +
 arch/riscv/include/asm/asm.h          |  63 +++++
 arch/riscv/include/asm/csr.h          |   1 -
 arch/riscv/include/asm/entry-common.h |   8 +
 arch/riscv/include/asm/ptrace.h       |  10 +-
 arch/riscv/include/asm/stacktrace.h   |   5 +
 arch/riscv/include/asm/syscall.h      |   6 +
 arch/riscv/include/asm/thread_info.h  |  13 +-
 arch/riscv/kernel/Makefile            |   2 -
 arch/riscv/kernel/entry.S             | 334 +++-----------------------
 arch/riscv/kernel/irq.c               |  15 ++
 arch/riscv/kernel/mcount-dyn.S        |  56 +----
 arch/riscv/kernel/process.c           |   5 +-
 arch/riscv/kernel/ptrace.c            |  44 ----
 arch/riscv/kernel/signal.c            |  29 +--
 arch/riscv/kernel/sys_riscv.c         |  31 +++
 arch/riscv/kernel/trace_irq.c         |  27 ---
 arch/riscv/kernel/trace_irq.h         |  11 -
 arch/riscv/kernel/traps.c             |  86 +++++--
 arch/riscv/mm/fault.c                 |  16 +-
 include/linux/compiler_types.h        |  15 +-
 21 files changed, 279 insertions(+), 499 deletions(-)
 create mode 100644 arch/riscv/include/asm/entry-common.h
 delete mode 100644 arch/riscv/kernel/trace_irq.c
 delete mode 100644 arch/riscv/kernel/trace_irq.h

-- 
2.36.1