sparc: prepare kernel/ for unification
[linux-2.6.git] / arch / sparc / kernel / unaligned_32.c
1 /*
2  * unaligned.c: Unaligned load/store trap handling with special
3  *              cases for the kernel to do them more quickly.
4  *
5  * Copyright (C) 1996 David S. Miller (davem@caip.rutgers.edu)
6  * Copyright (C) 1996 Jakub Jelinek (jj@sunsite.mff.cuni.cz)
7  */
8
9
10 #include <linux/kernel.h>
11 #include <linux/sched.h>
12 #include <linux/mm.h>
13 #include <linux/module.h>
14 #include <asm/ptrace.h>
15 #include <asm/processor.h>
16 #include <asm/system.h>
17 #include <asm/uaccess.h>
18 #include <linux/smp.h>
19 #include <linux/smp_lock.h>
20
21 /* #define DEBUG_MNA */
22
23 enum direction {
24         load,    /* ld, ldd, ldh, ldsh */
25         store,   /* st, std, sth, stsh */
26         both,    /* Swap, ldstub, etc. */
27         fpload,
28         fpstore,
29         invalid,
30 };
31
32 #ifdef DEBUG_MNA
33 static char *dirstrings[] = {
34   "load", "store", "both", "fpload", "fpstore", "invalid"
35 };
36 #endif
37
38 static inline enum direction decode_direction(unsigned int insn)
39 {
40         unsigned long tmp = (insn >> 21) & 1;
41
42         if(!tmp)
43                 return load;
44         else {
45                 if(((insn>>19)&0x3f) == 15)
46                         return both;
47                 else
48                         return store;
49         }
50 }
51
52 /* 8 = double-word, 4 = word, 2 = half-word */
53 static inline int decode_access_size(unsigned int insn)
54 {
55         insn = (insn >> 19) & 3;
56
57         if(!insn)
58                 return 4;
59         else if(insn == 3)
60                 return 8;
61         else if(insn == 2)
62                 return 2;
63         else {
64                 printk("Impossible unaligned trap. insn=%08x\n", insn);
65                 die_if_kernel("Byte sized unaligned access?!?!", current->thread.kregs);
66                 return 4; /* just to keep gcc happy. */
67         }
68 }
69
70 /* 0x400000 = signed, 0 = unsigned */
71 static inline int decode_signedness(unsigned int insn)
72 {
73         return (insn & 0x400000);
74 }
75
76 static inline void maybe_flush_windows(unsigned int rs1, unsigned int rs2,
77                                        unsigned int rd)
78 {
79         if(rs2 >= 16 || rs1 >= 16 || rd >= 16) {
80                 /* Wheee... */
81                 __asm__ __volatile__("save %sp, -0x40, %sp\n\t"
82                                      "save %sp, -0x40, %sp\n\t"
83                                      "save %sp, -0x40, %sp\n\t"
84                                      "save %sp, -0x40, %sp\n\t"
85                                      "save %sp, -0x40, %sp\n\t"
86                                      "save %sp, -0x40, %sp\n\t"
87                                      "save %sp, -0x40, %sp\n\t"
88                                      "restore; restore; restore; restore;\n\t"
89                                      "restore; restore; restore;\n\t");
90         }
91 }
92
93 static inline int sign_extend_imm13(int imm)
94 {
95         return imm << 19 >> 19;
96 }
97
98 static inline unsigned long fetch_reg(unsigned int reg, struct pt_regs *regs)
99 {
100         struct reg_window *win;
101
102         if(reg < 16)
103                 return (!reg ? 0 : regs->u_regs[reg]);
104
105         /* Ho hum, the slightly complicated case. */
106         win = (struct reg_window *) regs->u_regs[UREG_FP];
107         return win->locals[reg - 16]; /* yes, I know what this does... */
108 }
109
110 static inline unsigned long safe_fetch_reg(unsigned int reg, struct pt_regs *regs)
111 {
112         struct reg_window __user *win;
113         unsigned long ret;
114
115         if (reg < 16)
116                 return (!reg ? 0 : regs->u_regs[reg]);
117
118         /* Ho hum, the slightly complicated case. */
119         win = (struct reg_window __user *) regs->u_regs[UREG_FP];
120
121         if ((unsigned long)win & 3)
122                 return -1;
123
124         if (get_user(ret, &win->locals[reg - 16]))
125                 return -1;
126
127         return ret;
128 }
129
130 static inline unsigned long *fetch_reg_addr(unsigned int reg, struct pt_regs *regs)
131 {
132         struct reg_window *win;
133
134         if(reg < 16)
135                 return &regs->u_regs[reg];
136         win = (struct reg_window *) regs->u_regs[UREG_FP];
137         return &win->locals[reg - 16];
138 }
139
140 static unsigned long compute_effective_address(struct pt_regs *regs,
141                                                unsigned int insn)
142 {
143         unsigned int rs1 = (insn >> 14) & 0x1f;
144         unsigned int rs2 = insn & 0x1f;
145         unsigned int rd = (insn >> 25) & 0x1f;
146
147         if(insn & 0x2000) {
148                 maybe_flush_windows(rs1, 0, rd);
149                 return (fetch_reg(rs1, regs) + sign_extend_imm13(insn));
150         } else {
151                 maybe_flush_windows(rs1, rs2, rd);
152                 return (fetch_reg(rs1, regs) + fetch_reg(rs2, regs));
153         }
154 }
155
156 unsigned long safe_compute_effective_address(struct pt_regs *regs,
157                                              unsigned int insn)
158 {
159         unsigned int rs1 = (insn >> 14) & 0x1f;
160         unsigned int rs2 = insn & 0x1f;
161         unsigned int rd = (insn >> 25) & 0x1f;
162
163         if(insn & 0x2000) {
164                 maybe_flush_windows(rs1, 0, rd);
165                 return (safe_fetch_reg(rs1, regs) + sign_extend_imm13(insn));
166         } else {
167                 maybe_flush_windows(rs1, rs2, rd);
168                 return (safe_fetch_reg(rs1, regs) + safe_fetch_reg(rs2, regs));
169         }
170 }
171
172 /* This is just to make gcc think panic does return... */
173 static void unaligned_panic(char *str)
174 {
175         panic(str);
176 }
177
178 /* una_asm.S */
179 extern int do_int_load(unsigned long *dest_reg, int size,
180                        unsigned long *saddr, int is_signed);
181 extern int __do_int_store(unsigned long *dst_addr, int size,
182                           unsigned long *src_val);
183
184 static int do_int_store(int reg_num, int size, unsigned long *dst_addr,
185                         struct pt_regs *regs)
186 {
187         unsigned long zero[2] = { 0, 0 };
188         unsigned long *src_val;
189
190         if (reg_num)
191                 src_val = fetch_reg_addr(reg_num, regs);
192         else {
193                 src_val = &zero[0];
194                 if (size == 8)
195                         zero[1] = fetch_reg(1, regs);
196         }
197         return __do_int_store(dst_addr, size, src_val);
198 }
199
200 extern void smp_capture(void);
201 extern void smp_release(void);
202
203 static inline void advance(struct pt_regs *regs)
204 {
205         regs->pc   = regs->npc;
206         regs->npc += 4;
207 }
208
209 static inline int floating_point_load_or_store_p(unsigned int insn)
210 {
211         return (insn >> 24) & 1;
212 }
213
214 static inline int ok_for_kernel(unsigned int insn)
215 {
216         return !floating_point_load_or_store_p(insn);
217 }
218
219 static void kernel_mna_trap_fault(struct pt_regs *regs, unsigned int insn)
220 {
221         unsigned long g2 = regs->u_regs [UREG_G2];
222         unsigned long fixup = search_extables_range(regs->pc, &g2);
223
224         if (!fixup) {
225                 unsigned long address = compute_effective_address(regs, insn);
226                 if(address < PAGE_SIZE) {
227                         printk(KERN_ALERT "Unable to handle kernel NULL pointer dereference in mna handler");
228                 } else
229                         printk(KERN_ALERT "Unable to handle kernel paging request in mna handler");
230                 printk(KERN_ALERT " at virtual address %08lx\n",address);
231                 printk(KERN_ALERT "current->{mm,active_mm}->context = %08lx\n",
232                         (current->mm ? current->mm->context :
233                         current->active_mm->context));
234                 printk(KERN_ALERT "current->{mm,active_mm}->pgd = %08lx\n",
235                         (current->mm ? (unsigned long) current->mm->pgd :
236                         (unsigned long) current->active_mm->pgd));
237                 die_if_kernel("Oops", regs);
238                 /* Not reached */
239         }
240         regs->pc = fixup;
241         regs->npc = regs->pc + 4;
242         regs->u_regs [UREG_G2] = g2;
243 }
244
245 asmlinkage void kernel_unaligned_trap(struct pt_regs *regs, unsigned int insn)
246 {
247         enum direction dir = decode_direction(insn);
248         int size = decode_access_size(insn);
249
250         if(!ok_for_kernel(insn) || dir == both) {
251                 printk("Unsupported unaligned load/store trap for kernel at <%08lx>.\n",
252                        regs->pc);
253                 unaligned_panic("Wheee. Kernel does fpu/atomic unaligned load/store.");
254         } else {
255                 unsigned long addr = compute_effective_address(regs, insn);
256                 int err;
257
258 #ifdef DEBUG_MNA
259                 printk("KMNA: pc=%08lx [dir=%s addr=%08lx size=%d] retpc[%08lx]\n",
260                        regs->pc, dirstrings[dir], addr, size, regs->u_regs[UREG_RETPC]);
261 #endif
262                 switch (dir) {
263                 case load:
264                         err = do_int_load(fetch_reg_addr(((insn>>25)&0x1f),
265                                                          regs),
266                                           size, (unsigned long *) addr,
267                                           decode_signedness(insn));
268                         break;
269
270                 case store:
271                         err = do_int_store(((insn>>25)&0x1f), size,
272                                            (unsigned long *) addr, regs);
273                         break;
274                 default:
275                         panic("Impossible kernel unaligned trap.");
276                         /* Not reached... */
277                 }
278                 if (err)
279                         kernel_mna_trap_fault(regs, insn);
280                 else
281                         advance(regs);
282         }
283 }
284
285 static inline int ok_for_user(struct pt_regs *regs, unsigned int insn,
286                               enum direction dir)
287 {
288         unsigned int reg;
289         int check = (dir == load) ? VERIFY_READ : VERIFY_WRITE;
290         int size = ((insn >> 19) & 3) == 3 ? 8 : 4;
291
292         if ((regs->pc | regs->npc) & 3)
293                 return 0;
294
295         /* Must access_ok() in all the necessary places. */
296 #define WINREG_ADDR(regnum) \
297         ((void __user *)(((unsigned long *)regs->u_regs[UREG_FP])+(regnum)))
298
299         reg = (insn >> 25) & 0x1f;
300         if (reg >= 16) {
301                 if (!access_ok(check, WINREG_ADDR(reg - 16), size))
302                         return -EFAULT;
303         }
304         reg = (insn >> 14) & 0x1f;
305         if (reg >= 16) {
306                 if (!access_ok(check, WINREG_ADDR(reg - 16), size))
307                         return -EFAULT;
308         }
309         if (!(insn & 0x2000)) {
310                 reg = (insn & 0x1f);
311                 if (reg >= 16) {
312                         if (!access_ok(check, WINREG_ADDR(reg - 16), size))
313                                 return -EFAULT;
314                 }
315         }
316 #undef WINREG_ADDR
317         return 0;
318 }
319
320 static void user_mna_trap_fault(struct pt_regs *regs, unsigned int insn)
321 {
322         siginfo_t info;
323
324         info.si_signo = SIGBUS;
325         info.si_errno = 0;
326         info.si_code = BUS_ADRALN;
327         info.si_addr = (void __user *)safe_compute_effective_address(regs, insn);
328         info.si_trapno = 0;
329         send_sig_info(SIGBUS, &info, current);
330 }
331
332 asmlinkage void user_unaligned_trap(struct pt_regs *regs, unsigned int insn)
333 {
334         enum direction dir;
335
336         lock_kernel();
337         if(!(current->thread.flags & SPARC_FLAG_UNALIGNED) ||
338            (((insn >> 30) & 3) != 3))
339                 goto kill_user;
340         dir = decode_direction(insn);
341         if(!ok_for_user(regs, insn, dir)) {
342                 goto kill_user;
343         } else {
344                 int err, size = decode_access_size(insn);
345                 unsigned long addr;
346
347                 if(floating_point_load_or_store_p(insn)) {
348                         printk("User FPU load/store unaligned unsupported.\n");
349                         goto kill_user;
350                 }
351
352                 addr = compute_effective_address(regs, insn);
353                 switch(dir) {
354                 case load:
355                         err = do_int_load(fetch_reg_addr(((insn>>25)&0x1f),
356                                                          regs),
357                                           size, (unsigned long *) addr,
358                                           decode_signedness(insn));
359                         break;
360
361                 case store:
362                         err = do_int_store(((insn>>25)&0x1f), size,
363                                            (unsigned long *) addr, regs);
364                         break;
365
366                 case both:
367                         /*
368                          * This was supported in 2.4. However, we question
369                          * the value of SWAP instruction across word boundaries.
370                          */
371                         printk("Unaligned SWAP unsupported.\n");
372                         err = -EFAULT;
373                         break;
374
375                 default:
376                         unaligned_panic("Impossible user unaligned trap.");
377                         goto out;
378                 }
379                 if (err)
380                         goto kill_user;
381                 else
382                         advance(regs);
383                 goto out;
384         }
385
386 kill_user:
387         user_mna_trap_fault(regs, insn);
388 out:
389         unlock_kernel();
390 }