[PATCH 0/2] gdb, opcodes: Add non-enum disassembler options

Tsukasa OI research_trasio@irq.a4lg.com
Wed Aug 31 02:15:30 GMT 2022


Hello,

This is a part of my work: implement `arch' disassembler option in RISC-V.
However, it requires technical changes also affecting opcodes:ARC and MIPS
and GDB.  It will take some time because we have to wait many Binutils
prerequisites but this technical change can be discussed now (due to it
affects both Binutils and GDB).

PATCH 1/2: Binutils changes
PATCH 2/2: GDB changes

Independently applying Binutils/GDB changes is completely safe because we
haven't implemented any actual non-enum options.


[Example: Implement `arch' disassembler option]

$ objdump -b binary -m riscv:rv32 -M arch=rv32i_zfinx -D sample.bin
(... analyze a binary file with 'RV32I_Zfinx' ISA)

You can try my modified version at:
<https://github.com/a4lg/binutils-gdb/wiki/riscv_dis_arch_priv_spec>
<https://github.com/a4lg/binutils-gdb/tree/riscv-dis-arch-priv-spec>


[Technical Changes]

There is a portable mechanism for disassembler options and used on some
architectures:

-   ARC
-   Arm
-   MIPS
-   PowerPC
-   RISC-V
-   S/390

However, it only supports following forms:

-   [NAME]
-   [NAME]=[ENUM_VALUE]

Valid values for [ENUM_VALUE] must be predefined in
`disasm_option_arg_t.values'.  For instance, for -M cpu=[CPU] in ARC
architecture, opcodes/arc-dis.c builds valid CPU model list from
include/elf/arc-cpu.def.

This patchset adds following third format:

-   [NAME]=[ARBITRARY_VALUE] (cannot contain "," though)

This is identified by `NULL' value of `disasm_option_arg_t.values'
(normally, this is a non-NULL pointer to a NULL-terminated list).

Note that this patch modifies following architectures (that use
similar code to print disassembler help message) for consistency:

-   ARC
-   MIPS
-   RISC-V

In the future, adding "verify" function to disasm_option_arg_t (or some)
might be an option as it may provide flexible argument validation.

Thanks,
Tsukasa




Tsukasa OI (2):
  opcodes: Add non-enum disassembler options
  gdb: Add non-enum disassembler options

 gdb/disasm.c        | 4 ++++
 include/dis-asm.h   | 3 ++-
 opcodes/arc-dis.c   | 2 ++
 opcodes/mips-dis.c  | 2 ++
 opcodes/riscv-dis.c | 2 ++
 5 files changed, 12 insertions(+), 1 deletion(-)


base-commit: 803584b96d97e1f6ea50b0a0064d2a03ab0baa60
-- 
2.34.1



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