target/nios2: Honour -semihosting-config userspace=on

Honour the commandline -semihosting-config userspace=on option,
instead of always permitting userspace semihosting calls in system
emulation mode, by passing the correct value to the is_userspace
argument of semihosting_enabled().

Note that this is a behaviour change: if the user wants to
do semihosting calls from userspace they must now specifically
enable them on the command line.

nios2 semihosting is not implemented for linux-user builds.

Signed-off-by: Peter Maydell <[email protected]>
Reviewed-by: Richard Henderson <[email protected]>
Message-Id: <[email protected]>
Signed-off-by: Richard Henderson <[email protected]>
(cherry picked from commit cab9f19)

Author: pm215

target/nios2/translate.c

@@ -649,8 +649,9 @@ static void gen_break(DisasContext *dc, uint32_t code, uint32_t flags)
 {
 #ifndef CONFIG_USER_ONLY
     /* The semihosting instruction is "break 1".  */
+    bool is_user = dc->base.tb->flags & CR_STATUS_U;
     R_TYPE(instr, code);
-    if (semihosting_enabled() && instr.imm5 == 1) {
+    if (semihosting_enabled(is_user) && instr.imm5 == 1) {
         t_gen_helper_raise_exception(dc, EXCP_SEMIHOST);
         return;
     }