Re: [PATCH 00/10] RISC-V: Refactor instructions

[Andrew Jones]

On Thu, Aug 03, 2023 at 07:10:25PM -0700, Charlie Jenkins wrote:
> There are numerous systems in the kernel that rely on directly
> modifying, creating, and reading instructions. Many of these systems
> have rewritten code to do this. This patch will delegate all instruction
> handling into insn.h and reg.h. All of the compressed instructions, RVI,
> Zicsr, M, A instructions are included, as well as a subset of the F,D,Q
> extensions.
> 
> ---
> This is modifying code that https://lore.kernel.org/lkml/20230731183925.152145-1-namcaov@xxxxxxxxx/
> is also touching.
> 
> ---
> Testing:
> 
> There are a lot of subsystems touched and I have not tested every
> individual instruction. I did a lot of copy-pasting from the RISC-V spec
> so opcodes and such should be correct

How about we create macros which generate each of the functions an
instruction needs, e.g. riscv_insn_is_*(), etc. based on the output of
[1]. I know basically nothing about that project, but it looks like it
creates most the defines this series is creating from what we [hope] to
be an authoritative source. I also assume that if we don't like the
current output format, then we could probably post patches to the project
to get the format we want. For example, we could maybe propose an "lc"
format for "Linux C".

I'd also recommend only importing the generated defines and generating
the functions that will actually have immediate consumers or are part of
a set of defines that have immediate consumers. Each consumer of new
instructions will be responsible for generating and importing the defines
and adding the respective macro invocations to generate the functions.
This series can also take that approach, i.e. convert one set of
instructions at a time, each in a separate patch.

[1] https://github.com/riscv/riscv-opcodes

Thanks,
drew


> , but the construction of every
> instruction is not fully tested.
> 
> vector: Compiled and booted
> 
> jump_label: Ensured static keys function as expected.
> 
> kgdb: Attempted to run the provided tests but they failed even without
> my changes
> 
> module: Loaded and unloaded modules
> 
> patch.c: Ensured kernel booted
> 
> kprobes: Used a kprobing module to probe jalr, auipc, and branch
> instructions
> 
> nommu misaligned addresses: Kernel boots
> 
> kvm: Ran KVM selftests
> 
> bpf: Kernel boots. Most of the instructions are exclusively used by BPF
> but I am unsure of the best way of testing BPF.
> 
> Signed-off-by: Charlie Jenkins <charlie@xxxxxxxxxxxx>
> 
> ---
> Charlie Jenkins (10):
>       RISC-V: Expand instruction definitions
>       RISC-V: vector: Refactor instructions
>       RISC-V: Refactor jump label instructions
>       RISC-V: KGDB: Refactor instructions
>       RISC-V: module: Refactor instructions
>       RISC-V: Refactor patch instructions
>       RISC-V: nommu: Refactor instructions
>       RISC-V: kvm: Refactor instructions
>       RISC-V: bpf: Refactor instructions
>       RISC-V: Refactor bug and traps instructions
> 
>  arch/riscv/include/asm/bug.h             |   18 +-
>  arch/riscv/include/asm/insn.h            | 2744 +++++++++++++++++++++++++++---
>  arch/riscv/include/asm/reg.h             |   88 +
>  arch/riscv/kernel/jump_label.c           |   13 +-
>  arch/riscv/kernel/kgdb.c                 |   13 +-
>  arch/riscv/kernel/module.c               |   80 +-
>  arch/riscv/kernel/patch.c                |    3 +-
>  arch/riscv/kernel/probes/kprobes.c       |   13 +-
>  arch/riscv/kernel/probes/simulate-insn.c |  100 +-
>  arch/riscv/kernel/probes/uprobes.c       |    5 +-
>  arch/riscv/kernel/traps.c                |    9 +-
>  arch/riscv/kernel/traps_misaligned.c     |  218 +--
>  arch/riscv/kernel/vector.c               |    5 +-
>  arch/riscv/kvm/vcpu_insn.c               |  281 +--
>  arch/riscv/net/bpf_jit.h                 |  707 +-------
>  15 files changed, 2825 insertions(+), 1472 deletions(-)
> ---
> base-commit: 5d0c230f1de8c7515b6567d9afba1f196fb4e2f4
> change-id: 20230801-master-refactor-instructions-v4-433aa040da03
> -- 
> - Charlie
> 
> 
> -- 
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