[v2,00/14] RISCV basic exception handling implementation

Message

Oleksii Kurochko Jan. 27, 2023, 1:59 p.m. UTC

The patch series is based on another one [Basic early_printk and smoke
test implementation] which hasn't been commited yet.

The patch series provides a basic implementation of exception handling.
It can do only basic things such as decode a cause of an exception,
save/restore registers and execute "wfi" instruction if an exception
can not be handled.

To verify that exception handling works well it was implemented macros
from <asm/bug.h> such as BUG/WARN/run_in_exception/assert_failed.
The implementation of macros is used "ebreak" instruction and set up bug
frame tables for each type of macros.
Also it was implemented register save/restore to return and continue work
after WARN/run_in_exception.
Not all functionality of the macros was implemented as some of them
require hard-panic the system which is not available now. Instead of
hard-panic 'wfi' instruction is used but it should be definitely changed
in the neareset future.
It wasn't implemented show_execution_state() and stack trace discovering
as it's not necessary now.

---
Changes in V2:
  - take the latest riscv_encoding.h from OpenSBI, update it with Xen
    related changes, and update the commit message with "Origin:"
    tag and the commit message itself.
  - add "Origin:" tag to the commit messag of the patch
    [xen/riscv: add <asm/csr.h> header].
  - Remove the patch [xen/riscv: add early_printk_hnum() function] as the
    functionality provided by the patch isn't used now.
  - Refactor prcoess.h: move structure offset defines to asm-offsets.c,
    change register_t to unsigned long.
  - Refactor entry.S to use offsets defined in asm-offsets.C
  - Rename {__,}handle_exception to handle_trap() and do_trap() to be more
    consistent with RISC-V spec.
  - Merge the pathc which introduces do_unexpected_trap() with the patch
    [xen/riscv: introduce exception handlers implementation].
  - Rename setup_trap_handler() to trap_init() and update correspondingly
    the patches in the patch series.
  - Refactor bug.h, remove bug_instr_t type from it.
  - Refactor decode_trap_cause() function to be more optimization-friendly.
  - Add two new empty headers: <cache.h> and <string.h> as they are needed to
    include <xen/lib.h> which provides ARRAY_SIZE and other macros.
  - Code style fixes.
---

Oleksii Kurochko (14):
  xen/riscv: add _zicsr to CFLAGS
  xen/riscv: add <asm/asm.h> header
  xen/riscv: add <asm/riscv_encoding.h header
  xen/riscv: add <asm/csr.h> header
  xen/riscv: introduce empty <asm/string.h>
  xen/riscv: introduce empty <asm/cache.h>
  xen/riscv: introduce exception context
  xen/riscv: introduce exception handlers implementation
  xen/riscv: introduce decode_cause() stuff
  xen/riscv: mask all interrupts
  xen/riscv: introduce trap_init()
  xen/riscv: introduce an implementation of macros from <asm/bug.h>
  xen/riscv: test basic handling stuff
  automation: add smoke test to verify macros from bug.h

 automation/scripts/qemu-smoke-riscv64.sh    |   2 +-
 xen/arch/riscv/Makefile                     |   2 +
 xen/arch/riscv/arch.mk                      |   2 +-
 xen/arch/riscv/entry.S                      |  94 ++
 xen/arch/riscv/include/asm/asm.h            |  54 ++
 xen/arch/riscv/include/asm/bug.h            | 118 +++
 xen/arch/riscv/include/asm/cache.h          |   6 +
 xen/arch/riscv/include/asm/csr.h            |  84 ++
 xen/arch/riscv/include/asm/processor.h      |  82 ++
 xen/arch/riscv/include/asm/riscv_encoding.h | 927 ++++++++++++++++++++
 xen/arch/riscv/include/asm/string.h         |   6 +
 xen/arch/riscv/include/asm/traps.h          |  14 +
 xen/arch/riscv/riscv64/asm-offsets.c        |  53 ++
 xen/arch/riscv/riscv64/head.S               |   5 +
 xen/arch/riscv/setup.c                      |  21 +
 xen/arch/riscv/traps.c                      | 231 +++++
 xen/arch/riscv/xen.lds.S                    |  10 +
 17 files changed, 1709 insertions(+), 2 deletions(-)
 create mode 100644 xen/arch/riscv/entry.S
 create mode 100644 xen/arch/riscv/include/asm/asm.h
 create mode 100644 xen/arch/riscv/include/asm/bug.h
 create mode 100644 xen/arch/riscv/include/asm/cache.h
 create mode 100644 xen/arch/riscv/include/asm/csr.h
 create mode 100644 xen/arch/riscv/include/asm/processor.h
 create mode 100644 xen/arch/riscv/include/asm/riscv_encoding.h
 create mode 100644 xen/arch/riscv/include/asm/string.h
 create mode 100644 xen/arch/riscv/include/asm/traps.h
 create mode 100644 xen/arch/riscv/traps.c