Re: [PATCH v4 02/17] bsd-user: Add RISC-V CPU execution loop and syscall handling

[Alistair Francis <alistair23@gmail.com>]

On Wed, Aug 28, 2024 at 7:53 PM Ajeet Singh <itachis6234@gmail.com> wrote:
>
> From: Mark Corbin <mark@dibsco.co.uk>
>
> Implemented the RISC-V CPU execution loop, including handling various
> exceptions and system calls. The loop continuously executes CPU
> instructions,processes exceptions, and handles system calls by invoking
> FreeBSD syscall handlers.
>
> Signed-off-by: Mark Corbin <mark@dibsco.co.uk>
> Signed-off-by: Ajeet Singh <itachis@FreeBSD.org>
> Co-authored-by: Jessica Clarke <jrtc27@jrtc27.com>
> Co-authored-by: Kyle Evans <kevans@FreeBSD.org>
> Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
> ---
>  bsd-user/riscv/target_arch_cpu.h | 94 ++++++++++++++++++++++++++++++++
>  1 file changed, 94 insertions(+)
>
> diff --git a/bsd-user/riscv/target_arch_cpu.h b/bsd-user/riscv/target_arch_cpu.h
> index e17c910ae9..ba589909e2 100644
> --- a/bsd-user/riscv/target_arch_cpu.h
> +++ b/bsd-user/riscv/target_arch_cpu.h
> @@ -36,4 +36,98 @@ static inline void target_cpu_init(CPURISCVState *env,
>      env->pc = regs->sepc;
>  }
>
> +static inline void target_cpu_loop(CPURISCVState *env)
> +{
> +    CPUState *cs = env_cpu(env);
> +    int trapnr;
> +    abi_long ret;
> +    unsigned int syscall_num;
> +    int32_t signo, code;
> +
> +    for (;;) {
> +        cpu_exec_start(cs);
> +        trapnr = cpu_exec(cs);
> +        cpu_exec_end(cs);
> +        process_queued_cpu_work(cs);
> +
> +        signo = 0;
> +
> +        switch (trapnr) {
> +        case EXCP_INTERRUPT:
> +            /* just indicate that signals should be handled asap */
> +            break;
> +        case EXCP_ATOMIC:
> +            cpu_exec_step_atomic(cs);
> +            break;
> +        case RISCV_EXCP_U_ECALL:
> +            syscall_num = env->gpr[xT0];
> +            env->pc += TARGET_INSN_SIZE;
> +            /* Compare to cpu_fetch_syscall_args() in riscv/riscv/trap.c */
> +            if (TARGET_FREEBSD_NR___syscall == syscall_num ||
> +                TARGET_FREEBSD_NR_syscall == syscall_num) {
> +                ret = do_freebsd_syscall(env,
> +                                         env->gpr[xA0],
> +                                         env->gpr[xA1],
> +                                         env->gpr[xA2],
> +                                         env->gpr[xA3],
> +                                         env->gpr[xA4],
> +                                         env->gpr[xA5],
> +                                         env->gpr[xA6],
> +                                         env->gpr[xA7],
> +                                         0);
> +            } else {
> +                ret = do_freebsd_syscall(env,
> +                                         syscall_num,
> +                                         env->gpr[xA0],
> +                                         env->gpr[xA1],
> +                                         env->gpr[xA2],
> +                                         env->gpr[xA3],
> +                                         env->gpr[xA4],
> +                                         env->gpr[xA5],
> +                                         env->gpr[xA6],
> +                                         env->gpr[xA7]

There is trailing white space on these lines and in a few other
patches in this series.

Can you run ./scripts/checkpatch.pl against the changes and then send
a v5 with the issues addressed

Alistair

> +                    );
> +            }
> +
> +            /*
> +             * Compare to cpu_set_syscall_retval() in
> +             * riscv/riscv/vm_machdep.c
> +             */
> +            if (ret >= 0) {
> +                env->gpr[xA0] = ret;
> +                env->gpr[xT0] = 0;
> +            } else if (ret == -TARGET_ERESTART) {
> +                env->pc -= TARGET_INSN_SIZE;
> +            } else if (ret != -TARGET_EJUSTRETURN) {
> +                env->gpr[xA0] = -ret;
> +                env->gpr[xT0] = 1;
> +            }
> +            break;
> +        case RISCV_EXCP_ILLEGAL_INST:
> +            signo = TARGET_SIGILL;
> +            code = TARGET_ILL_ILLOPC;
> +            break;
> +        case RISCV_EXCP_BREAKPOINT:
> +            signo = TARGET_SIGTRAP;
> +            code = TARGET_TRAP_BRKPT;
> +            break;
> +        case EXCP_DEBUG:
> +            signo = TARGET_SIGTRAP;
> +            code = TARGET_TRAP_BRKPT;
> +            break;
> +        default:
> +            fprintf(stderr, "qemu: unhandled CPU exception "
> +                "0x%x - aborting\n", trapnr);
> +            cpu_dump_state(cs, stderr, 0);
> +            abort();
> +        }
> +
> +        if (signo) {
> +            force_sig_fault(signo, code, env->pc);
> +        }
> +
> +        process_pending_signals(env);
> +    }
> +}
> +
>  #endif /* TARGET_ARCH_CPU_H */
> --
> 2.34.1
>
>