Re: [PATCH 09/24] bsd-user/arm/target_arch_cpu.h: Implement system call dispatch

[Kyle Evans <kevans@freebsd.org>]

On Tue, Oct 19, 2021 at 11:45 AM Warner Losh <imp@bsdimp.com> wrote:
>
> Implement the system call dispatch. This implements all three kinds of
> system call: direct and the two indirect variants. It handles all the
> special cases for thumb as well.
>
> Signed-off-by: Stacey Son <sson@FreeBSD.org>
> Signed-off-by: Klye Evans <kevans@FreeBSD.org>
> Signed-off-by: Warner Losh <imp@bsdimp.com>

s/Klye/Kyle/

> ---
>  bsd-user/arm/target_arch_cpu.h | 95 ++++++++++++++++++++++++++++++++++
>  1 file changed, 95 insertions(+)
>
> diff --git a/bsd-user/arm/target_arch_cpu.h b/bsd-user/arm/target_arch_cpu.h
> index 62d6ee89b6..bc2eb05cfe 100644
> --- a/bsd-user/arm/target_arch_cpu.h
> +++ b/bsd-user/arm/target_arch_cpu.h
> @@ -39,6 +39,7 @@ static inline void target_cpu_loop(CPUARMState *env)
>  {
>      int trapnr;
>      target_siginfo_t info;
> +    unsigned int n;
>      CPUState *cs = env_cpu(env);
>
>      for (;;) {
> @@ -57,6 +58,100 @@ static inline void target_cpu_loop(CPUARMState *env)
>                  queue_signal(env, info.si_signo, &info);
>              }
>              break;
> +        case EXCP_SWI:
> +        case EXCP_BKPT:
> +            {
> +                env->eabi = 1; /* FreeBSD is eabi only now */
> +                /*
> +                 * system call
> +                 * See arm/arm/trap.c cpu_fetch_syscall_args()
> +                 */
> +                if (trapnr == EXCP_BKPT) {
> +                    if (env->thumb) {
> +                        env->regs[15] += 2;
> +                    } else {
> +                        env->regs[15] += 4;
> +                    }
> +                }
> +                n = env->regs[7];
> +                if (bsd_type == target_freebsd) {
> +                    int ret;
> +                    abi_ulong params = get_sp_from_cpustate(env);
> +                    int32_t syscall_nr = n;
> +                    int32_t arg1, arg2, arg3, arg4, arg5, arg6, arg7, arg8;
> +
> +                    /* See arm/arm/trap.c cpu_fetch_syscall_args() */
> +                    if (syscall_nr == TARGET_FREEBSD_NR_syscall) {
> +                        syscall_nr = env->regs[0];
> +                        arg1 = env->regs[1];
> +                        arg2 = env->regs[2];
> +                        arg3 = env->regs[3];
> +                        get_user_s32(arg4, params);
> +                        params += sizeof(int32_t);
> +                        get_user_s32(arg5, params);
> +                        params += sizeof(int32_t);
> +                        get_user_s32(arg6, params);
> +                        params += sizeof(int32_t);
> +                        get_user_s32(arg7, params);
> +                        arg8 = 0;
> +                    } else if (syscall_nr == TARGET_FREEBSD_NR___syscall) {
> +                        syscall_nr = env->regs[0];
> +                        arg1 = env->regs[2];
> +                        arg2 = env->regs[3];
> +                        get_user_s32(arg3, params);
> +                        params += sizeof(int32_t);
> +                        get_user_s32(arg4, params);
> +                        params += sizeof(int32_t);
> +                        get_user_s32(arg5, params);
> +                        params += sizeof(int32_t);
> +                        get_user_s32(arg6, params);
> +                        arg7 = 0;
> +                        arg8 = 0;
> +                    } else {
> +                        arg1 = env->regs[0];
> +                        arg2 = env->regs[1];
> +                        arg3 = env->regs[2];
> +                        arg4 = env->regs[3];
> +                        get_user_s32(arg5, params);
> +                        params += sizeof(int32_t);
> +                        get_user_s32(arg6, params);
> +                        params += sizeof(int32_t);
> +                        get_user_s32(arg7, params);
> +                        params += sizeof(int32_t);
> +                        get_user_s32(arg8, params);
> +                    }
> +                    ret = do_freebsd_syscall(env, syscall_nr, arg1, arg2, arg3,
> +                            arg4, arg5, arg6, arg7, arg8);
> +                    /*
> +                     * Compare to arm/arm/vm_machdep.c
> +                     * cpu_set_syscall_retval()
> +                     */
> +                    if (-TARGET_EJUSTRETURN == ret) {
> +                        /*
> +                         * Returning from a successful sigreturn syscall.
> +                         * Avoid clobbering register state.
> +                         */
> +                        break;
> +                    }
> +                    if (-TARGET_ERESTART == ret) {
> +                        env->regs[15] -= env->thumb ? 2 : 4;
> +                        break;
> +                    }
> +                    if ((unsigned int)ret >= (unsigned int)(-515)) {
> +                        ret = -ret;
> +                        cpsr_write(env, CPSR_C, CPSR_C, CPSRWriteByInstr);
> +                        env->regs[0] = ret;
> +                    } else {
> +                        cpsr_write(env, 0, CPSR_C, CPSRWriteByInstr);
> +                        env->regs[0] = ret; /* XXX need to handle lseek()? */
> +                        /* env->regs[1] = 0; */
> +                    }
> +                } else {
> +                    fprintf(stderr, "qemu: bsd_type (= %d) syscall "
> +                            "not supported\n", bsd_type);
> +                }
> +            }
> +            break;
>          case EXCP_INTERRUPT:
>              /* just indicate that signals should be handled asap */
>              break;
> --
> 2.32.0
>

Modulo typo:

Reviewed-by: Kyle Evans <kevans@FreeBSD.org>