target-mips: improve exception handling

This patch improves exception handling in MIPS.
Instructions generate several types of exceptions.
When exception is generated, it breaks the execution of the current
translation block. Implementation of the exceptions handling does not
correctly restore icount for the instruction which caused the exception.
In most cases icount will be decreased by the value equal to the size of
TB. This patch passes pointer to the translation block internals to the
exception handler. It allows correct restoring of the icount value.

Signed-off-by: Pavel Dovgalyuk <pavel.dovgaluk@ispras.ru>
Reviewed-by: Aurelien Jarno <aurelien@aurel32.net>
Reviewed-by: Leon Alrae <leon.alrae@imgtec.com>
[leon.alrae@imgtec.com: avoid retranslation in linux-user SC, break lines
 which are over 80 chars, remove v3 changelog from the commit message]
Signed-off-by: Leon Alrae <leon.alrae@imgtec.com>

target-mips/cpu.h

@@ -1049,4 +1049,28 @@ static inline void cpu_mips_store_cause(CPUMIPSState *env, target_ulong val)
 }
 #endif
 
+static inline void QEMU_NORETURN do_raise_exception_err(CPUMIPSState *env,
+                                                        uint32_t exception,
+                                                        int error_code,
+                                                        uintptr_t pc)
+{
+    CPUState *cs = CPU(mips_env_get_cpu(env));
+
+    if (exception < EXCP_SC) {
+        qemu_log_mask(CPU_LOG_INT, "%s: %d %d\n",
+                      __func__, exception, error_code);
+    }
+    cs->exception_index = exception;
+    env->error_code = error_code;
+
+    cpu_loop_exit_restore(cs, pc);
+}
+
+static inline void QEMU_NORETURN do_raise_exception(CPUMIPSState *env,
+                                                    uint32_t exception,
+                                                    uintptr_t pc)
+{
+    do_raise_exception_err(env, exception, 0, pc);
+}
+
 #endif /* !defined (__MIPS_CPU_H__) */

target-mips/helper.h

@@ -1,5 +1,6 @@
 DEF_HELPER_3(raise_exception_err, noreturn, env, i32, int)
 DEF_HELPER_2(raise_exception, noreturn, env, i32)
+DEF_HELPER_1(raise_exception_debug, noreturn, env)
 
 DEF_HELPER_1(do_semihosting, void, env)