Re: [Qemu-devel] [PATCH 2/3] linux-user: Fix NR_fadvise64 and NR_fadvise64_64 for 32-bit guests

[Laurent Vivier]

Le 31/05/2016 à 16:45, Peter Maydell a écrit :
> Fix errors in the implementation of NR_fadvise64 and NR_fadvise64_64
> for 32-bit guests, which pass their off_t values in register pairs.
> We can't use the 64-bit code path for this, so split out the 32-bit
> cases, so that we can correctly handle the "only offset is 64-bit"
> and "both offset and length are 64-bit" syscall flavours, and
> "uses aligned register pairs" and "does not" flavours of target.
> 
> Signed-off-by: Peter Maydell <address@hidden>
Reviewed-by: Laurent Vivier <address@hidden>

> ---
>  linux-user/syscall.c | 40 ++++++++++++++++++++++++++++++++++++++++
>  1 file changed, 40 insertions(+)
> 
> diff --git a/linux-user/syscall.c b/linux-user/syscall.c
> index 4894919..638b455 100644
> --- a/linux-user/syscall.c
> +++ b/linux-user/syscall.c
> @@ -9340,6 +9340,44 @@ abi_long do_syscall(void *cpu_env, int num, abi_long 
> arg1,
>          ret = -host_to_target_errno(ret);
>          break;
>  #endif
> +
> +#if TARGET_ABI_BITS == 32
> +
> +#ifdef TARGET_NR_fadvise64_64
> +    case TARGET_NR_fadvise64_64:
> +        /* 6 args: fd, offset (high, low), len (high, low), advice */
> +        if (regpairs_aligned(cpu_env)) {
> +            /* offset is in (3,4), len in (5,6) and advice in 7 */
> +            arg2 = arg3;
> +            arg3 = arg4;
> +            arg4 = arg5;
> +            arg5 = arg6;
> +            arg6 = arg7;
> +        }
> +        ret = -host_to_target_errno(posix_fadvise(arg1,
> +                                                  target_offset64(arg2, 
> arg3),
> +                                                  target_offset64(arg4, 
> arg5),
> +                                                  arg6));
> +        break;
> +#endif
> +
> +#ifdef TARGET_NR_fadvise64
> +    case TARGET_NR_fadvise64:
> +        /* 5 args: fd, offset (high, low), len, advice */
> +        if (regpairs_aligned(cpu_env)) {
> +            /* offset is in (3,4), len in 5 and advice in 6 */
> +            arg2 = arg3;
> +            arg3 = arg4;
> +            arg4 = arg5;
> +            arg5 = arg6;
> +        }
> +        ret = -host_to_target_errno(posix_fadvise(arg1,
> +                                                  target_offset64(arg2, 
> arg3),
> +                                                  arg4, arg5));
> +        break;
> +#endif
> +
> +#else /* not a 32-bit ABI */
>  #if defined(TARGET_NR_fadvise64_64) || defined(TARGET_NR_fadvise64)
>  #ifdef TARGET_NR_fadvise64_64
>      case TARGET_NR_fadvise64_64:
> @@ -9359,6 +9397,8 @@ abi_long do_syscall(void *cpu_env, int num, abi_long 
> arg1,
>          ret = -posix_fadvise(arg1, arg2, arg3, arg4);
>       break;
>  #endif
> +#endif /* end of 64-bit ABI fadvise handling */
> +
>  #ifdef TARGET_NR_madvise
>      case TARGET_NR_madvise:
>          /* A straight passthrough may not be safe because qemu sometimes
>