alpha-linux-user: Fix the getpriority syscall

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 <rth@twiddle.net>

diff --git a/linux-user/syscall.c b/linux-user/syscall.c
index 0d3fff52e98a05bbda02b74275fb0e3e0e9e5d20..3ba3ef57192d61afd541ee611603be662a1b0f21 100644 (file)
--- 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 = -host_to_target_errno(errno);
+            break;
+        }
+#ifdef TARGET_ALPHA
+        /* Return value is the unbiased priority.  Signal no error.  */
+        ((CPUAlphaState *)cpu_env)->ir[IR_V0] = 0;
+#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));