[V5,0/6] riscv: Add KGDB and KDB support

Message

Vincent Chen June 1, 2020, 3:39 a.m. UTC

This patch set implements required ports to enable RISC-V kernel to support
KGDB and KDB features. Because there is no immediate value in the RISC-V
trap instruction, the kernel cannot identify the purpose of each trap
exception through the opcode. This makes the existing identification
schemes in other architecture unsuitable for the RISC-V kernel. In order
to solve this problem, this patch adds the kgdb_has_hit_break() to kgdb.c
to help the RISC-V kernel identify the KGDB trap exception. In addition,
the XML target description was introduced in this patch set to enable KGDB
to report the contents of the $status, $cause and $badaddr registers.

This patchset has passed the kgdbts test suite provided by Linux kernel on
HiFive unleashed board and QEMU.

Changes since v4:
1. Fix some compile warnings reported by linux kbuild test
2. Select ARCH_OPTIONAL_KERNEL_RWX to enable the kconfig prompt of
   CONFIG_STRICT_KERNEL_RWX

Changes since v3:
1. remove duplicate macro defition
2. Rename CONFIG_ARCH_SUPPORTS_GDB_XML to CONFIG_HAVE_ARCH_KGDB_QXFER_PKT
   in the description of patch 03/05.

Changes since v2:
1. Fix typos
2. Rename CONFIG_ARCH_SUPPORTS_GDB_XML to CONFIG_HAVE_ARCH_KGDB_QXFER_PKT
3. Add the prefix kgdb_ to the handler functions and arrays that handle 
   "qxfer" packets

Changes since v1:
1. Replace the magic number with macro when filling the gdb_regs[].
2. Only support GDB XML packet instead of all query packets.
3. Move the macros used to parse instructions to parse_asm.h



Vincent Chen (6):
  kgdb: Add kgdb_has_hit_break function
  riscv: Add KGDB support
  kgdb: enable arch to support XML packet support.
  riscv: enable the Kconfig prompt of STRICT_KERNEL_RWX
  riscv: Use the XML target descriptions to report 3 system registers
  riscv: Add SW single-step support for KDB

 arch/riscv/Kconfig                 |   3 +
 arch/riscv/include/asm/gdb_xml.h   | 116 +++++++++++
 arch/riscv/include/asm/kdebug.h    |  12 ++
 arch/riscv/include/asm/kgdb.h      | 113 +++++++++++
 arch/riscv/include/asm/parse_asm.h | 219 +++++++++++++++++++++
 arch/riscv/kernel/Makefile         |   1 +
 arch/riscv/kernel/kgdb.c           | 392 +++++++++++++++++++++++++++++++++++++
 arch/riscv/kernel/traps.c          |   5 +
 include/linux/kgdb.h               |  12 ++
 kernel/debug/debug_core.c          |  12 ++
 kernel/debug/gdbstub.c             |  13 ++
 lib/Kconfig.kgdb                   |   5 +
 12 files changed, 903 insertions(+)
 create mode 100644 arch/riscv/include/asm/gdb_xml.h
 create mode 100644 arch/riscv/include/asm/kdebug.h
 create mode 100644 arch/riscv/include/asm/kgdb.h
 create mode 100644 arch/riscv/include/asm/parse_asm.h
 create mode 100644 arch/riscv/kernel/kgdb.c