Re: [Qemu-devel] [PATCH] linux-user: rlimit conversion between host and target.

[Richard Henderson <rth@twiddle.net>]

On 04/11/2010 12:07 PM, takasi-y@ops.dti.ne.jp wrote:
> rlim_t conversion between host and target added.
> Otherwise there are some incorrect case like
> - RLIM_INFINITY on 32bit target -> 64bit host. 
> - RLIM_INFINITY on 64bit host -> mips and sparc target ?
> - Big value(for 32bit target) on 64bit host -> 32bit target.
> 
> One is added into getrlimit, setrlimit, and ugetrlimit. It converts both
> RLIM_INFINITY and value bigger than target can hold(>31bit) to RLIM_INFINITY.
> 
> Another one is added to guest_stack_size calculation introduced by
> 703e0e89. The rule is mostly same except the result on the case is keeping
> the value of guest_stack_size.
> 
> Slightly tested for SH4, and x86_64 -linux-user on x86_64-pc-linux host.
> 
> Signed-off-by: Takashi YOSHII <takasi-y@ops.dti.ne.jp>

Acked-by: Richard Henderson <rth@twiddle.net>


> ---
>  linux-user/main.c         |    3 ++-
>  linux-user/syscall.c      |   30 ++++++++++++++++++++++--------
>  linux-user/syscall_defs.h |    8 ++++++++
>  3 files changed, 32 insertions(+), 9 deletions(-)
> 
> diff --git a/linux-user/main.c b/linux-user/main.c
> index b394c00..60eea3a 100644
> --- a/linux-user/main.c
> +++ b/linux-user/main.c
> @@ -2645,7 +2645,8 @@ int main(int argc, char **argv, char **envp)
>      {
>          struct rlimit lim;
>          if (getrlimit(RLIMIT_STACK, &lim) == 0
> -            && lim.rlim_cur != RLIM_INFINITY) {
> +            && lim.rlim_cur != RLIM_INFINITY
> +            && lim.rlim_cur == (target_long)lim.rlim_cur) {
>              guest_stack_size = lim.rlim_cur;
>          }
>      }
> diff --git a/linux-user/syscall.c b/linux-user/syscall.c
> index a03e432..cfc91d1 100644
> --- a/linux-user/syscall.c
> +++ b/linux-user/syscall.c
> @@ -831,6 +831,22 @@ static inline abi_long host_to_target_rusage(abi_ulong target_addr,
>      return 0;
>  }
>  
> +static inline rlim_t target_to_host_rlim(target_ulong target_rlim)
> +{
> +    if (target_rlim == TARGET_RLIM_INFINITY)
> +        return RLIM_INFINITY;
> +    else
> +        return tswapl(target_rlim);
> +}
> +
> +static inline target_ulong host_to_target_rlim(rlim_t rlim)
> +{
> +    if (rlim == RLIM_INFINITY || rlim != (target_long)rlim)
> +        return TARGET_RLIM_INFINITY;
> +    else
> +        return tswapl(rlim);
> +}
> +
>  static inline abi_long copy_from_user_timeval(struct timeval *tv,
>                                                abi_ulong target_tv_addr)
>  {
> @@ -5124,21 +5140,19 @@ abi_long do_syscall(void *cpu_env, int num, abi_long arg1,
>          break;
>      case TARGET_NR_setrlimit:
>          {
> -            /* XXX: convert resource ? */
>              int resource = arg1;
>              struct target_rlimit *target_rlim;
>              struct rlimit rlim;
>              if (!lock_user_struct(VERIFY_READ, target_rlim, arg2, 1))
>                  goto efault;
> -            rlim.rlim_cur = tswapl(target_rlim->rlim_cur);
> -            rlim.rlim_max = tswapl(target_rlim->rlim_max);
> +            rlim.rlim_cur = target_to_host_rlim(target_rlim->rlim_cur);
> +            rlim.rlim_max = target_to_host_rlim(target_rlim->rlim_max);
>              unlock_user_struct(target_rlim, arg2, 0);
>              ret = get_errno(setrlimit(resource, &rlim));
>          }
>          break;
>      case TARGET_NR_getrlimit:
>          {
> -            /* XXX: convert resource ? */
>              int resource = arg1;
>              struct target_rlimit *target_rlim;
>              struct rlimit rlim;
> @@ -5147,8 +5161,8 @@ abi_long do_syscall(void *cpu_env, int num, abi_long arg1,
>              if (!is_error(ret)) {
>                  if (!lock_user_struct(VERIFY_WRITE, target_rlim, arg2, 0))
>                      goto efault;
> -                target_rlim->rlim_cur = tswapl(rlim.rlim_cur);
> -                target_rlim->rlim_max = tswapl(rlim.rlim_max);
> +                target_rlim->rlim_cur = host_to_target_rlim(rlim.rlim_cur);
> +                target_rlim->rlim_max = host_to_target_rlim(rlim.rlim_max);
>                  unlock_user_struct(target_rlim, arg2, 1);
>              }
>          }
> @@ -6233,8 +6247,8 @@ abi_long do_syscall(void *cpu_env, int num, abi_long arg1,
>  	    struct target_rlimit *target_rlim;
>              if (!lock_user_struct(VERIFY_WRITE, target_rlim, arg2, 0))
>                  goto efault;
> -	    target_rlim->rlim_cur = tswapl(rlim.rlim_cur);
> -	    target_rlim->rlim_max = tswapl(rlim.rlim_max);
> +	    target_rlim->rlim_cur = host_to_target_rlim(rlim.rlim_cur);
> +	    target_rlim->rlim_max = host_to_target_rlim(rlim.rlim_max);
>              unlock_user_struct(target_rlim, arg2, 1);
>  	}
>  	break;
> diff --git a/linux-user/syscall_defs.h b/linux-user/syscall_defs.h
> index 63c2bc3..255e89c 100644
> --- a/linux-user/syscall_defs.h
> +++ b/linux-user/syscall_defs.h
> @@ -669,6 +669,14 @@ struct target_rlimit {
>          abi_ulong   rlim_max;
>  };
>  
> +#if defined(TARGET_ALPHA)
> +#define TARGET_RLIM_INFINITY	0x7ffffffffffffffful
> +#elif defined(TARGET_MIPS) || defined(TARGET_SPARC)
> +#define TARGET_RLIM_INFINITY	0x7fffffffUL
> +#else
> +#define TARGET_RLIM_INFINITY	((target_ulong)~0UL)
> +#endif
> +
>  struct target_pollfd {
>      int fd;           /* file descriptor */
>      short events;     /* requested events */