1 /*
2  *  M68K helper routines
3  *
4  *  Copyright (c) 2007 CodeSourcery
5  *
6  * This library is free software; you can redistribute it and/or
7  * modify it under the terms of the GNU Lesser General Public
8  * License as published by the Free Software Foundation; either
9  * version 2 of the License, or (at your option) any later version.
10  *
11  * This library is distributed in the hope that it will be useful,
12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
14  * Lesser General Public License for more details.
15  *
16  * You should have received a copy of the GNU Lesser General Public
17  * License along with this library; if not, see <http://www.gnu.org/licenses/>.
18  */
19 #include "exec.h"
20 #include "helpers.h"
21 
22 #if defined(CONFIG_USER_ONLY)
23 
do_interrupt(int is_hw)24 void do_interrupt(int is_hw)
25 {
26     env->exception_index = -1;
27 }
28 
29 #else
30 
31 extern int semihosting_enabled;
32 
33 #define MMUSUFFIX _mmu
34 
35 #define SHIFT 0
36 #include "softmmu_template.h"
37 
38 #define SHIFT 1
39 #include "softmmu_template.h"
40 
41 #define SHIFT 2
42 #include "softmmu_template.h"
43 
44 #define SHIFT 3
45 #include "softmmu_template.h"
46 
47 /* Try to fill the TLB and return an exception if error. If retaddr is
48    NULL, it means that the function was called in C code (i.e. not
49    from generated code or from helper.c) */
50 /* XXX: fix it to restore all registers */
tlb_fill(target_ulong addr,int is_write,int mmu_idx,void * retaddr)51 void tlb_fill (target_ulong addr, int is_write, int mmu_idx, void *retaddr)
52 {
53     TranslationBlock *tb;
54     CPUState *saved_env;
55     unsigned long pc;
56     int ret;
57 
58     /* XXX: hack to restore env in all cases, even if not called from
59        generated code */
60     saved_env = env;
61     env = cpu_single_env;
62     ret = cpu_m68k_handle_mmu_fault(env, addr, is_write, mmu_idx, 1);
63     if (unlikely(ret)) {
64         if (retaddr) {
65             /* now we have a real cpu fault */
66             pc = (unsigned long)retaddr;
67             tb = tb_find_pc(pc);
68             if (tb) {
69                 /* the PC is inside the translated code. It means that we have
70                    a virtual CPU fault */
71                 cpu_restore_state(tb, env, pc, NULL);
72             }
73         }
74         cpu_loop_exit();
75     }
76     env = saved_env;
77 }
78 
do_rte(void)79 static void do_rte(void)
80 {
81     uint32_t sp;
82     uint32_t fmt;
83 
84     sp = env->aregs[7];
85     fmt = ldl_kernel(sp);
86     env->pc = ldl_kernel(sp + 4);
87     sp |= (fmt >> 28) & 3;
88     env->sr = fmt & 0xffff;
89     m68k_switch_sp(env);
90     env->aregs[7] = sp + 8;
91 }
92 
do_interrupt(int is_hw)93 void do_interrupt(int is_hw)
94 {
95     uint32_t sp;
96     uint32_t fmt;
97     uint32_t retaddr;
98     uint32_t vector;
99 
100     fmt = 0;
101     retaddr = env->pc;
102 
103     if (!is_hw) {
104         switch (env->exception_index) {
105         case EXCP_RTE:
106             /* Return from an exception.  */
107             do_rte();
108             return;
109         case EXCP_HALT_INSN:
110             if (semihosting_enabled
111                     && (env->sr & SR_S) != 0
112                     && (env->pc & 3) == 0
113                     && lduw_code(env->pc - 4) == 0x4e71
114                     && ldl_code(env->pc) == 0x4e7bf000) {
115                 env->pc += 4;
116                 do_m68k_semihosting(env, env->dregs[0]);
117                 return;
118             }
119             env->halted = 1;
120             env->exception_index = EXCP_HLT;
121             cpu_loop_exit();
122             return;
123         }
124         if (env->exception_index >= EXCP_TRAP0
125             && env->exception_index <= EXCP_TRAP15) {
126             /* Move the PC after the trap instruction.  */
127             retaddr += 2;
128         }
129     }
130 
131     vector = env->exception_index << 2;
132 
133     sp = env->aregs[7];
134 
135     fmt |= 0x40000000;
136     fmt |= (sp & 3) << 28;
137     fmt |= vector << 16;
138     fmt |= env->sr;
139 
140     env->sr |= SR_S;
141     if (is_hw) {
142         env->sr = (env->sr & ~SR_I) | (env->pending_level << SR_I_SHIFT);
143         env->sr &= ~SR_M;
144     }
145     m68k_switch_sp(env);
146 
147     /* ??? This could cause MMU faults.  */
148     sp &= ~3;
149     sp -= 4;
150     stl_kernel(sp, retaddr);
151     sp -= 4;
152     stl_kernel(sp, fmt);
153     env->aregs[7] = sp;
154     /* Jump to vector.  */
155     env->pc = ldl_kernel(env->vbr + vector);
156 }
157 
158 #endif
159 
raise_exception(int tt)160 static void raise_exception(int tt)
161 {
162     env->exception_index = tt;
163     cpu_loop_exit();
164 }
165 
HELPER(raise_exception)166 void HELPER(raise_exception)(uint32_t tt)
167 {
168     raise_exception(tt);
169 }
170 
HELPER(divu)171 void HELPER(divu)(CPUState *env, uint32_t word)
172 {
173     uint32_t num;
174     uint32_t den;
175     uint32_t quot;
176     uint32_t rem;
177     uint32_t flags;
178 
179     num = env->div1;
180     den = env->div2;
181     /* ??? This needs to make sure the throwing location is accurate.  */
182     if (den == 0)
183         raise_exception(EXCP_DIV0);
184     quot = num / den;
185     rem = num % den;
186     flags = 0;
187     /* Avoid using a PARAM1 of zero.  This breaks dyngen because it uses
188        the address of a symbol, and gcc knows symbols can't have address
189        zero.  */
190     if (word && quot > 0xffff)
191         flags |= CCF_V;
192     if (quot == 0)
193         flags |= CCF_Z;
194     else if ((int32_t)quot < 0)
195         flags |= CCF_N;
196     env->div1 = quot;
197     env->div2 = rem;
198     env->cc_dest = flags;
199 }
200 
HELPER(divs)201 void HELPER(divs)(CPUState *env, uint32_t word)
202 {
203     int32_t num;
204     int32_t den;
205     int32_t quot;
206     int32_t rem;
207     int32_t flags;
208 
209     num = env->div1;
210     den = env->div2;
211     if (den == 0)
212         raise_exception(EXCP_DIV0);
213     quot = num / den;
214     rem = num % den;
215     flags = 0;
216     if (word && quot != (int16_t)quot)
217         flags |= CCF_V;
218     if (quot == 0)
219         flags |= CCF_Z;
220     else if (quot < 0)
221         flags |= CCF_N;
222     env->div1 = quot;
223     env->div2 = rem;
224     env->cc_dest = flags;
225 }
226