1
2#include <linux/err.h>
3#include <linux/slab.h>
4#include <linux/mm_types.h>
5#include <linux/sched/task.h>
6
7#include <asm/branch.h>
8#include <asm/cacheflush.h>
9#include <asm/fpu_emulator.h>
10#include <asm/inst.h>
11#include <asm/mipsregs.h>
12#include <linux/uaccess.h>
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63struct emuframe {
64 mips_instruction emul;
65 mips_instruction badinst;
66};
67
68static const int emupage_frame_count = PAGE_SIZE / sizeof(struct emuframe);
69
70static inline __user struct emuframe *dsemul_page(void)
71{
72 return (__user struct emuframe *)STACK_TOP;
73}
74
75static int alloc_emuframe(void)
76{
77 mm_context_t *mm_ctx = ¤t->mm->context;
78 int idx;
79
80retry:
81 spin_lock(&mm_ctx->bd_emupage_lock);
82
83
84 if (!mm_ctx->bd_emupage_allocmap) {
85 mm_ctx->bd_emupage_allocmap =
86 kcalloc(BITS_TO_LONGS(emupage_frame_count),
87 sizeof(unsigned long),
88 GFP_ATOMIC);
89
90 if (!mm_ctx->bd_emupage_allocmap) {
91 idx = BD_EMUFRAME_NONE;
92 goto out_unlock;
93 }
94 }
95
96
97 idx = bitmap_find_free_region(mm_ctx->bd_emupage_allocmap,
98 emupage_frame_count, 0);
99 if (idx < 0) {
100
101
102
103
104
105
106
107
108 spin_unlock(&mm_ctx->bd_emupage_lock);
109 if (!wait_event_killable(mm_ctx->bd_emupage_queue,
110 !bitmap_full(mm_ctx->bd_emupage_allocmap,
111 emupage_frame_count)))
112 goto retry;
113
114
115 return BD_EMUFRAME_NONE;
116 }
117
118
119 pr_debug("allocate emuframe %d to %d\n", idx, current->pid);
120out_unlock:
121 spin_unlock(&mm_ctx->bd_emupage_lock);
122 return idx;
123}
124
125static void free_emuframe(int idx, struct mm_struct *mm)
126{
127 mm_context_t *mm_ctx = &mm->context;
128
129 spin_lock(&mm_ctx->bd_emupage_lock);
130
131 pr_debug("free emuframe %d from %d\n", idx, current->pid);
132 bitmap_clear(mm_ctx->bd_emupage_allocmap, idx, 1);
133
134
135 wake_up(&mm_ctx->bd_emupage_queue);
136
137 spin_unlock(&mm_ctx->bd_emupage_lock);
138}
139
140static bool within_emuframe(struct pt_regs *regs)
141{
142 unsigned long base = (unsigned long)dsemul_page();
143
144 if (regs->cp0_epc < base)
145 return false;
146 if (regs->cp0_epc >= (base + PAGE_SIZE))
147 return false;
148
149 return true;
150}
151
152bool dsemul_thread_cleanup(struct task_struct *tsk)
153{
154 int fr_idx;
155
156
157 fr_idx = atomic_xchg(&tsk->thread.bd_emu_frame, BD_EMUFRAME_NONE);
158
159
160 if (fr_idx == BD_EMUFRAME_NONE)
161 return false;
162
163 task_lock(tsk);
164
165
166 if (tsk->mm)
167 free_emuframe(fr_idx, tsk->mm);
168
169 task_unlock(tsk);
170 return true;
171}
172
173bool dsemul_thread_rollback(struct pt_regs *regs)
174{
175 struct emuframe __user *fr;
176 int fr_idx;
177
178
179 if (!within_emuframe(regs))
180 return false;
181
182
183 fr_idx = atomic_read(¤t->thread.bd_emu_frame);
184 if (fr_idx == BD_EMUFRAME_NONE)
185 return false;
186 fr = &dsemul_page()[fr_idx];
187
188
189
190
191
192
193
194
195 if (msk_isa16_mode(regs->cp0_epc) == (unsigned long)&fr->emul)
196 regs->cp0_epc = current->thread.bd_emu_branch_pc;
197 else if (msk_isa16_mode(regs->cp0_epc) == (unsigned long)&fr->badinst)
198 regs->cp0_epc = current->thread.bd_emu_cont_pc;
199
200 atomic_set(¤t->thread.bd_emu_frame, BD_EMUFRAME_NONE);
201 free_emuframe(fr_idx, current->mm);
202 return true;
203}
204
205void dsemul_mm_cleanup(struct mm_struct *mm)
206{
207 mm_context_t *mm_ctx = &mm->context;
208
209 kfree(mm_ctx->bd_emupage_allocmap);
210}
211
212int mips_dsemul(struct pt_regs *regs, mips_instruction ir,
213 unsigned long branch_pc, unsigned long cont_pc)
214{
215 int isa16 = get_isa16_mode(regs->cp0_epc);
216 mips_instruction break_math;
217 struct emuframe __user *fr;
218 int err, fr_idx;
219
220
221 if (ir == 0)
222 return -1;
223
224
225 if (isa16) {
226 union mips_instruction insn = { .word = ir };
227
228
229 if ((ir >> 16) == MM_NOP16)
230 return -1;
231
232
233 if (insn.mm_a_format.opcode == mm_addiupc_op) {
234 unsigned int rs;
235 s32 v;
236
237 rs = (((insn.mm_a_format.rs + 0xe) & 0xf) + 2);
238 v = regs->cp0_epc & ~3;
239 v += insn.mm_a_format.simmediate << 2;
240 regs->regs[rs] = (long)v;
241 return -1;
242 }
243 }
244
245 pr_debug("dsemul 0x%08lx cont at 0x%08lx\n", regs->cp0_epc, cont_pc);
246
247
248 fr_idx = atomic_read(¤t->thread.bd_emu_frame);
249 if (fr_idx == BD_EMUFRAME_NONE)
250 fr_idx = alloc_emuframe();
251 if (fr_idx == BD_EMUFRAME_NONE)
252 return SIGBUS;
253 fr = &dsemul_page()[fr_idx];
254
255
256 break_math = BREAK_MATH(isa16);
257
258
259 if (isa16) {
260 err = __put_user(ir >> 16,
261 (u16 __user *)(&fr->emul));
262 err |= __put_user(ir & 0xffff,
263 (u16 __user *)((long)(&fr->emul) + 2));
264 err |= __put_user(break_math >> 16,
265 (u16 __user *)(&fr->badinst));
266 err |= __put_user(break_math & 0xffff,
267 (u16 __user *)((long)(&fr->badinst) + 2));
268 } else {
269 err = __put_user(ir, &fr->emul);
270 err |= __put_user(break_math, &fr->badinst);
271 }
272
273 if (unlikely(err)) {
274 MIPS_FPU_EMU_INC_STATS(errors);
275 free_emuframe(fr_idx, current->mm);
276 return SIGBUS;
277 }
278
279
280 current->thread.bd_emu_branch_pc = branch_pc;
281 current->thread.bd_emu_cont_pc = cont_pc;
282 atomic_set(¤t->thread.bd_emu_frame, fr_idx);
283
284
285 regs->cp0_epc = (unsigned long)&fr->emul | isa16;
286
287
288 flush_cache_sigtramp((unsigned long)&fr->emul);
289
290 return 0;
291}
292
293bool do_dsemulret(struct pt_regs *xcp)
294{
295
296 if (!dsemul_thread_cleanup(current)) {
297 MIPS_FPU_EMU_INC_STATS(errors);
298 return false;
299 }
300
301
302 xcp->cp0_epc = current->thread.bd_emu_cont_pc;
303 pr_debug("dsemulret to 0x%08lx\n", xcp->cp0_epc);
304 MIPS_FPU_EMU_INC_STATS(ds_emul);
305 return true;
306}
307