On 25 July 2012 23:10, Richard Henderson <r...@twiddle.net> wrote:
> Alpha uses unbiased priority values in the syscall, with the a3
> return value signaling error conditions. Therefore, properly
> interpret the libc getpriority as needed for the guest rather
> than passing the host value through unchanged.
>
> Signed-off-by: Richard Henderson <r...@twiddle.net>
> ---
> linux-user/syscall.c | 20 +++++++++++++++-----
> 1 files changed, 15 insertions(+), 5 deletions(-)
>
> diff --git a/linux-user/syscall.c b/linux-user/syscall.c
> index 2e1c1c0..b487635 100644
> --- a/linux-user/syscall.c
> +++ b/linux-user/syscall.c
> @@ -218,7 +218,6 @@ _syscall3(int, sys_getdents, uint, fd, struct
> linux_dirent *, dirp, uint, count)
> #if defined(TARGET_NR_getdents64) && defined(__NR_getdents64)
> _syscall3(int, sys_getdents64, uint, fd, struct linux_dirent64 *, dirp,
> uint, count);
> #endif
> -_syscall2(int, sys_getpriority, int, which, int, who);
> #if defined(TARGET_NR__llseek) && defined(__NR_llseek)
> _syscall5(int, _llseek, uint, fd, ulong, hi, ulong, lo,
> loff_t *, res, uint, wh);
> @@ -6445,10 +6444,21 @@ abi_long do_syscall(void *cpu_env, int num, abi_long
> arg1,
> break;
> #endif
> case TARGET_NR_getpriority:
> - /* libc does special remapping of the return value of
> - * sys_getpriority() so it's just easiest to call
> - * sys_getpriority() directly rather than through libc. */
> - ret = get_errno(sys_getpriority(arg1, arg2));
> + /* Note that negative values are valid for getpriority, so we must
> + differentiate based on errno settings. */
> + errno = 0;
> + ret = getpriority(arg1, arg2);
> + if (ret == -1 && errno != 0) {
> + ret = get_errno(errno);
> + break;
> + }
> +#ifdef TARGET_ALPHA
> + /* Return value is the unbiased priority. Signal no error. */
> + ((CPUAlphaState *)cpu_env)->ir[IR_V0] = 0;
Having do_syscall fish around in the cpu register struct seems a
bit ugly, but we do it elsewhere so I guess this is OK.
> +#else
> + /* Return value is a biased priority to avoid negative numbers. */
> + ret = 20 - ret;
> +#endif
> break;
> case TARGET_NR_setpriority:
> ret = get_errno(setpriority(arg1, arg2, arg3));
Sanity check -- it is only getpriority that has the biasing, not
setpriority?
-- PMM
