Make do_execve() take a const filename pointer
[linux-3.10.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 #include <linux/perf_event.h>
21
22 enum direction {
23         load,    /* ld, ldd, ldh, ldsh */
24         store,   /* st, std, sth, stsh */
25         both,    /* Swap, ldstub, etc. */
26         fpload,
27         fpstore,
28         invalid,
29 };
30
31 static inline enum direction decode_direction(unsigned int insn)
32 {
33         unsigned long tmp = (insn >> 21) & 1;
34
35         if(!tmp)
36                 return load;
37         else {
38                 if(((insn>>19)&0x3f) == 15)
39                         return both;
40                 else
41                         return store;
42         }
43 }
44
45 /* 8 = double-word, 4 = word, 2 = half-word */
46 static inline int decode_access_size(unsigned int insn)
47 {
48         insn = (insn >> 19) & 3;
49
50         if(!insn)
51                 return 4;
52         else if(insn == 3)
53                 return 8;
54         else if(insn == 2)
55                 return 2;
56         else {
57                 printk("Impossible unaligned trap. insn=%08x\n", insn);
58                 die_if_kernel("Byte sized unaligned access?!?!", current->thread.kregs);
59                 return 4; /* just to keep gcc happy. */
60         }
61 }
62
63 /* 0x400000 = signed, 0 = unsigned */
64 static inline int decode_signedness(unsigned int insn)
65 {
66         return (insn & 0x400000);
67 }
68
69 static inline void maybe_flush_windows(unsigned int rs1, unsigned int rs2,
70                                        unsigned int rd)
71 {
72         if(rs2 >= 16 || rs1 >= 16 || rd >= 16) {
73                 /* Wheee... */
74                 __asm__ __volatile__("save %sp, -0x40, %sp\n\t"
75                                      "save %sp, -0x40, %sp\n\t"
76                                      "save %sp, -0x40, %sp\n\t"
77                                      "save %sp, -0x40, %sp\n\t"
78                                      "save %sp, -0x40, %sp\n\t"
79                                      "save %sp, -0x40, %sp\n\t"
80                                      "save %sp, -0x40, %sp\n\t"
81                                      "restore; restore; restore; restore;\n\t"
82                                      "restore; restore; restore;\n\t");
83         }
84 }
85
86 static inline int sign_extend_imm13(int imm)
87 {
88         return imm << 19 >> 19;
89 }
90
91 static inline unsigned long fetch_reg(unsigned int reg, struct pt_regs *regs)
92 {
93         struct reg_window32 *win;
94
95         if(reg < 16)
96                 return (!reg ? 0 : regs->u_regs[reg]);
97
98         /* Ho hum, the slightly complicated case. */
99         win = (struct reg_window32 *) regs->u_regs[UREG_FP];
100         return win->locals[reg - 16]; /* yes, I know what this does... */
101 }
102
103 static inline unsigned long safe_fetch_reg(unsigned int reg, struct pt_regs *regs)
104 {
105         struct reg_window32 __user *win;
106         unsigned long ret;
107
108         if (reg < 16)
109                 return (!reg ? 0 : regs->u_regs[reg]);
110
111         /* Ho hum, the slightly complicated case. */
112         win = (struct reg_window32 __user *) regs->u_regs[UREG_FP];
113
114         if ((unsigned long)win & 3)
115                 return -1;
116
117         if (get_user(ret, &win->locals[reg - 16]))
118                 return -1;
119
120         return ret;
121 }
122
123 static inline unsigned long *fetch_reg_addr(unsigned int reg, struct pt_regs *regs)
124 {
125         struct reg_window32 *win;
126
127         if(reg < 16)
128                 return &regs->u_regs[reg];
129         win = (struct reg_window32 *) regs->u_regs[UREG_FP];
130         return &win->locals[reg - 16];
131 }
132
133 static unsigned long compute_effective_address(struct pt_regs *regs,
134                                                unsigned int insn)
135 {
136         unsigned int rs1 = (insn >> 14) & 0x1f;
137         unsigned int rs2 = insn & 0x1f;
138         unsigned int rd = (insn >> 25) & 0x1f;
139
140         if(insn & 0x2000) {
141                 maybe_flush_windows(rs1, 0, rd);
142                 return (fetch_reg(rs1, regs) + sign_extend_imm13(insn));
143         } else {
144                 maybe_flush_windows(rs1, rs2, rd);
145                 return (fetch_reg(rs1, regs) + fetch_reg(rs2, regs));
146         }
147 }
148
149 unsigned long safe_compute_effective_address(struct pt_regs *regs,
150                                              unsigned int insn)
151 {
152         unsigned int rs1 = (insn >> 14) & 0x1f;
153         unsigned int rs2 = insn & 0x1f;
154         unsigned int rd = (insn >> 25) & 0x1f;
155
156         if(insn & 0x2000) {
157                 maybe_flush_windows(rs1, 0, rd);
158                 return (safe_fetch_reg(rs1, regs) + sign_extend_imm13(insn));
159         } else {
160                 maybe_flush_windows(rs1, rs2, rd);
161                 return (safe_fetch_reg(rs1, regs) + safe_fetch_reg(rs2, regs));
162         }
163 }
164
165 /* This is just to make gcc think panic does return... */
166 static void unaligned_panic(char *str)
167 {
168         panic(str);
169 }
170
171 /* una_asm.S */
172 extern int do_int_load(unsigned long *dest_reg, int size,
173                        unsigned long *saddr, int is_signed);
174 extern int __do_int_store(unsigned long *dst_addr, int size,
175                           unsigned long *src_val);
176
177 static int do_int_store(int reg_num, int size, unsigned long *dst_addr,
178                         struct pt_regs *regs)
179 {
180         unsigned long zero[2] = { 0, 0 };
181         unsigned long *src_val;
182
183         if (reg_num)
184                 src_val = fetch_reg_addr(reg_num, regs);
185         else {
186                 src_val = &zero[0];
187                 if (size == 8)
188                         zero[1] = fetch_reg(1, regs);
189         }
190         return __do_int_store(dst_addr, size, src_val);
191 }
192
193 extern void smp_capture(void);
194 extern void smp_release(void);
195
196 static inline void advance(struct pt_regs *regs)
197 {
198         regs->pc   = regs->npc;
199         regs->npc += 4;
200 }
201
202 static inline int floating_point_load_or_store_p(unsigned int insn)
203 {
204         return (insn >> 24) & 1;
205 }
206
207 static inline int ok_for_kernel(unsigned int insn)
208 {
209         return !floating_point_load_or_store_p(insn);
210 }
211
212 static void kernel_mna_trap_fault(struct pt_regs *regs, unsigned int insn)
213 {
214         unsigned long g2 = regs->u_regs [UREG_G2];
215         unsigned long fixup = search_extables_range(regs->pc, &g2);
216
217         if (!fixup) {
218                 unsigned long address = compute_effective_address(regs, insn);
219                 if(address < PAGE_SIZE) {
220                         printk(KERN_ALERT "Unable to handle kernel NULL pointer dereference in mna handler");
221                 } else
222                         printk(KERN_ALERT "Unable to handle kernel paging request in mna handler");
223                 printk(KERN_ALERT " at virtual address %08lx\n",address);
224                 printk(KERN_ALERT "current->{mm,active_mm}->context = %08lx\n",
225                         (current->mm ? current->mm->context :
226                         current->active_mm->context));
227                 printk(KERN_ALERT "current->{mm,active_mm}->pgd = %08lx\n",
228                         (current->mm ? (unsigned long) current->mm->pgd :
229                         (unsigned long) current->active_mm->pgd));
230                 die_if_kernel("Oops", regs);
231                 /* Not reached */
232         }
233         regs->pc = fixup;
234         regs->npc = regs->pc + 4;
235         regs->u_regs [UREG_G2] = g2;
236 }
237
238 asmlinkage void kernel_unaligned_trap(struct pt_regs *regs, unsigned int insn)
239 {
240         enum direction dir = decode_direction(insn);
241         int size = decode_access_size(insn);
242
243         if(!ok_for_kernel(insn) || dir == both) {
244                 printk("Unsupported unaligned load/store trap for kernel at <%08lx>.\n",
245                        regs->pc);
246                 unaligned_panic("Wheee. Kernel does fpu/atomic unaligned load/store.");
247         } else {
248                 unsigned long addr = compute_effective_address(regs, insn);
249                 int err;
250
251                 perf_sw_event(PERF_COUNT_SW_ALIGNMENT_FAULTS, 1, 0, regs, addr);
252                 switch (dir) {
253                 case load:
254                         err = do_int_load(fetch_reg_addr(((insn>>25)&0x1f),
255                                                          regs),
256                                           size, (unsigned long *) addr,
257                                           decode_signedness(insn));
258                         break;
259
260                 case store:
261                         err = do_int_store(((insn>>25)&0x1f), size,
262                                            (unsigned long *) addr, regs);
263                         break;
264                 default:
265                         panic("Impossible kernel unaligned trap.");
266                         /* Not reached... */
267                 }
268                 if (err)
269                         kernel_mna_trap_fault(regs, insn);
270                 else
271                         advance(regs);
272         }
273 }
274
275 static inline int ok_for_user(struct pt_regs *regs, unsigned int insn,
276                               enum direction dir)
277 {
278         unsigned int reg;
279         int check = (dir == load) ? VERIFY_READ : VERIFY_WRITE;
280         int size = ((insn >> 19) & 3) == 3 ? 8 : 4;
281
282         if ((regs->pc | regs->npc) & 3)
283                 return 0;
284
285         /* Must access_ok() in all the necessary places. */
286 #define WINREG_ADDR(regnum) \
287         ((void __user *)(((unsigned long *)regs->u_regs[UREG_FP])+(regnum)))
288
289         reg = (insn >> 25) & 0x1f;
290         if (reg >= 16) {
291                 if (!access_ok(check, WINREG_ADDR(reg - 16), size))
292                         return -EFAULT;
293         }
294         reg = (insn >> 14) & 0x1f;
295         if (reg >= 16) {
296                 if (!access_ok(check, WINREG_ADDR(reg - 16), size))
297                         return -EFAULT;
298         }
299         if (!(insn & 0x2000)) {
300                 reg = (insn & 0x1f);
301                 if (reg >= 16) {
302                         if (!access_ok(check, WINREG_ADDR(reg - 16), size))
303                                 return -EFAULT;
304                 }
305         }
306 #undef WINREG_ADDR
307         return 0;
308 }
309
310 static void user_mna_trap_fault(struct pt_regs *regs, unsigned int insn)
311 {
312         siginfo_t info;
313
314         info.si_signo = SIGBUS;
315         info.si_errno = 0;
316         info.si_code = BUS_ADRALN;
317         info.si_addr = (void __user *)safe_compute_effective_address(regs, insn);
318         info.si_trapno = 0;
319         send_sig_info(SIGBUS, &info, current);
320 }
321
322 asmlinkage void user_unaligned_trap(struct pt_regs *regs, unsigned int insn)
323 {
324         enum direction dir;
325
326         lock_kernel();
327         if(!(current->thread.flags & SPARC_FLAG_UNALIGNED) ||
328            (((insn >> 30) & 3) != 3))
329                 goto kill_user;
330         dir = decode_direction(insn);
331         if(!ok_for_user(regs, insn, dir)) {
332                 goto kill_user;
333         } else {
334                 int err, size = decode_access_size(insn);
335                 unsigned long addr;
336
337                 if(floating_point_load_or_store_p(insn)) {
338                         printk("User FPU load/store unaligned unsupported.\n");
339                         goto kill_user;
340                 }
341
342                 addr = compute_effective_address(regs, insn);
343                 perf_sw_event(PERF_COUNT_SW_ALIGNMENT_FAULTS, 1, 0, regs, addr);
344                 switch(dir) {
345                 case load:
346                         err = do_int_load(fetch_reg_addr(((insn>>25)&0x1f),
347                                                          regs),
348                                           size, (unsigned long *) addr,
349                                           decode_signedness(insn));
350                         break;
351
352                 case store:
353                         err = do_int_store(((insn>>25)&0x1f), size,
354                                            (unsigned long *) addr, regs);
355                         break;
356
357                 case both:
358                         /*
359                          * This was supported in 2.4. However, we question
360                          * the value of SWAP instruction across word boundaries.
361                          */
362                         printk("Unaligned SWAP unsupported.\n");
363                         err = -EFAULT;
364                         break;
365
366                 default:
367                         unaligned_panic("Impossible user unaligned trap.");
368                         goto out;
369                 }
370                 if (err)
371                         goto kill_user;
372                 else
373                         advance(regs);
374                 goto out;
375         }
376
377 kill_user:
378         user_mna_trap_fault(regs, insn);
379 out:
380         unlock_kernel();
381 }