Re: [Qemu-devel] [PATCH v6 1/8] linux-user: Add support for semtimedop() syscall

[Laurent Vivier <laurent@vivier.eu>]

Le 04/09/2019 à 14:59, Aleksandar Markovic a écrit :
> From: Aleksandar Rikalo <arikalo@wavecomp.com>
> 
> Add support for semtimedop() emulation. It is based on invocation
> of safe_semtimedop().
> 
> Conversion is left out of safe_semtimedop(), since other safe_xxx()
> usually don't contain similar conversions.
> 
> Signed-off-by: Aleksandar Rikalo <arikalo@wavecomp.com>
> Signed-off-by: Aleksandar Markovic <amarkovic@wavecomp.com>
> ---
>  linux-user/syscall.c | 40 ++++++++++++++++++++++++++++++++++++++++
>  1 file changed, 40 insertions(+)
> 
> diff --git a/linux-user/syscall.c b/linux-user/syscall.c
> index 8367cb1..b5bc6e4 100644
> --- a/linux-user/syscall.c
> +++ b/linux-user/syscall.c
> @@ -6649,7 +6649,43 @@ static inline abi_long host_to_target_statx(struct target_statx *host_stx,
>      return 0;
>  }
>  #endif
> +#ifdef TARGET_NR_semtimedop
> +static inline abi_long do_semtimedop(int semid, abi_long ptr, unsigned nsops,
> +                                     abi_long timeout)
> +{
> +    struct sembuf *sops;
> +    struct timespec ts, *pts;
> +    abi_long ret;
> +
> +    if (timeout) {
> +        pts = &ts;
> +        if (target_to_host_timespec(pts, timeout)) {
> +            return -TARGET_EFAULT;
> +        }
> +    } else {
> +        pts = NULL;
> +    }
>  
> +    sops = g_malloc(sizeof(struct sembuf) * nsops);
> +    if (sops == NULL) {
> +        return -TARGET_EFAULT;
> +    }
> +
> +    if (target_to_host_sembuf(sops, ptr, nsops)) {
> +        g_free(sops);
> +        return -TARGET_EFAULT;
> +    }
> +
> +#ifdef __NR_semtimedop
> +    ret = get_errno(safe_semtimedop(semid, sops, nsops, pts));
> +#else
> +    ret = -TARGET_ENOSYS;
> +#endif

You can do like in do_semop():

    ret = -TARGET_ENOSYS;
#ifdef __NR_semtimedop
    ret = get_errno(safe_semtimedop(semid, sops, nsops, pts));
#endif
#ifdef __NR_ipc
    if (ret == -TARGET_ENOSYS) {
        ret = get_errno(safe_ipc(IPCOP_semtimedop, semid, nsops, 0, sops, pts));
    }
#endif

> +    g_free(sops);
> +
> +    return ret;
> +}
> +#endif

The you can remove do_semop() and replace it:

    case IPCOP_semop:
        ret = do_semtimedop(first, ptr, second, NULL);
        break;

and

#ifdef TARGET_NR_semop
    case TARGET_NR_semop:
        return do_semtimedop(arg1, arg2, arg3, NULL);
#endif

you can also add in do_ipc():

    case IPCOP_semtimedop
        ret = do_semtimedop( ... );
        break;

>  
>  /* ??? Using host futex calls even when target atomic operations
>     are not really atomic probably breaks things.  However implementing
> @@ -9193,6 +9229,10 @@ static abi_long do_syscall1(void *cpu_env, int num, abi_long arg1,
>      case TARGET_NR_semop:
>          return do_semop(arg1, arg2, arg3);
>  #endif
> +#ifdef TARGET_NR_semtimedop
> +    case TARGET_NR_semtimedop:
> +        return do_semtimedop(arg1, arg2, arg3, arg4);
> +#endif
>  #ifdef TARGET_NR_semctl
>      case TARGET_NR_semctl:
>          return do_semctl(arg1, arg2, arg3, arg4);
> 

Thanks,
Laurent