linux-user/sparc64: Fix the handling of window spill trap

Fix the handling of window spill traps by keeping cansave into account
when calculating the new CWP.

Signed-off-by: Giuseppe Musacchio <thatlemon@gmail.com>
Signed-off-by: Laurent Vivier <laurent@vivier.eu>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <20200625091204.3186186-3-laurent@vivier.eu>

bsd-user/main.c

@@ -413,7 +413,11 @@ static void save_window(CPUSPARCState *env)
     save_window_offset(env, cpu_cwp_dec(env, env->cwp - 2));
     env->wim = new_wim;
 #else
-    save_window_offset(env, cpu_cwp_dec(env, env->cwp - 2));
+    /*
+     * cansave is zero if the spill trap handler is triggered by `save` and
+     * nonzero if triggered by a `flushw`
+     */
+    save_window_offset(env, cpu_cwp_dec(env, env->cwp - env->cansave - 2));
     env->cansave++;
     env->canrestore--;
 #endif

linux-user/sparc/cpu_loop.c

@@ -69,7 +69,11 @@ static void save_window(CPUSPARCState *env)
     save_window_offset(env, cpu_cwp_dec(env, env->cwp - 2));
     env->wim = new_wim;
 #else
-    save_window_offset(env, cpu_cwp_dec(env, env->cwp - 2));
+    /*
+     * cansave is zero if the spill trap handler is triggered by `save` and
+     * nonzero if triggered by a `flushw`
+     */
+    save_window_offset(env, cpu_cwp_dec(env, env->cwp - env->cansave - 2));
     env->cansave++;
     env->canrestore--;
 #endif