1 /*
2 * This file is subject to the terms and conditions of the GNU General Public
3 * License. See the file "COPYING" in the main directory of this archive
4 * for more details.
5 *
6 *
7 * Copyright (C) 1995, 1996, 1997, 1998 by Ralf Baechle
8 * Copyright 1999 SuSE GmbH (Philipp Rumpf, prumpf@tux.org)
9 * Copyright 1999 Hewlett Packard Co.
10 *
11 */
12
13 #include <linux/mm.h>
14 #include <linux/ptrace.h>
15 #include <linux/sched.h>
16 #include <linux/interrupt.h>
17 #include <linux/module.h>
18
19 #include <asm/uaccess.h>
20 #include <asm/traps.h>
21
22 /* Various important other fields */
23 #define bit22set(x) (x & 0x00000200)
24 #define bits23_25set(x) (x & 0x000001c0)
25 #define isGraphicsFlushRead(x) ((x & 0xfc003fdf) == 0x04001a80)
26 /* extended opcode is 0x6a */
27
28 #define BITSSET 0x1c0 /* for identifying LDCW */
29
30
31 DEFINE_PER_CPU(struct exception_data, exception_data);
32
33 int show_unhandled_signals = 1;
34
35 /*
36 * parisc_acctyp(unsigned int inst) --
37 * Given a PA-RISC memory access instruction, determine if the
38 * the instruction would perform a memory read or memory write
39 * operation.
40 *
41 * This function assumes that the given instruction is a memory access
42 * instruction (i.e. you should really only call it if you know that
43 * the instruction has generated some sort of a memory access fault).
44 *
45 * Returns:
46 * VM_READ if read operation
47 * VM_WRITE if write operation
48 * VM_EXEC if execute operation
49 */
50 static unsigned long
parisc_acctyp(unsigned long code,unsigned int inst)51 parisc_acctyp(unsigned long code, unsigned int inst)
52 {
53 if (code == 6 || code == 16)
54 return VM_EXEC;
55
56 switch (inst & 0xf0000000) {
57 case 0x40000000: /* load */
58 case 0x50000000: /* new load */
59 return VM_READ;
60
61 case 0x60000000: /* store */
62 case 0x70000000: /* new store */
63 return VM_WRITE;
64
65 case 0x20000000: /* coproc */
66 case 0x30000000: /* coproc2 */
67 if (bit22set(inst))
68 return VM_WRITE;
69
70 case 0x0: /* indexed/memory management */
71 if (bit22set(inst)) {
72 /*
73 * Check for the 'Graphics Flush Read' instruction.
74 * It resembles an FDC instruction, except for bits
75 * 20 and 21. Any combination other than zero will
76 * utilize the block mover functionality on some
77 * older PA-RISC platforms. The case where a block
78 * move is performed from VM to graphics IO space
79 * should be treated as a READ.
80 *
81 * The significance of bits 20,21 in the FDC
82 * instruction is:
83 *
84 * 00 Flush data cache (normal instruction behavior)
85 * 01 Graphics flush write (IO space -> VM)
86 * 10 Graphics flush read (VM -> IO space)
87 * 11 Graphics flush read/write (VM <-> IO space)
88 */
89 if (isGraphicsFlushRead(inst))
90 return VM_READ;
91 return VM_WRITE;
92 } else {
93 /*
94 * Check for LDCWX and LDCWS (semaphore instructions).
95 * If bits 23 through 25 are all 1's it is one of
96 * the above two instructions and is a write.
97 *
98 * Note: With the limited bits we are looking at,
99 * this will also catch PROBEW and PROBEWI. However,
100 * these should never get in here because they don't
101 * generate exceptions of the type:
102 * Data TLB miss fault/data page fault
103 * Data memory protection trap
104 */
105 if (bits23_25set(inst) == BITSSET)
106 return VM_WRITE;
107 }
108 return VM_READ; /* Default */
109 }
110 return VM_READ; /* Default */
111 }
112
113 #undef bit22set
114 #undef bits23_25set
115 #undef isGraphicsFlushRead
116 #undef BITSSET
117
118
119 #if 0
120 /* This is the treewalk to find a vma which is the highest that has
121 * a start < addr. We're using find_vma_prev instead right now, but
122 * we might want to use this at some point in the future. Probably
123 * not, but I want it committed to CVS so I don't lose it :-)
124 */
125 while (tree != vm_avl_empty) {
126 if (tree->vm_start > addr) {
127 tree = tree->vm_avl_left;
128 } else {
129 prev = tree;
130 if (prev->vm_next == NULL)
131 break;
132 if (prev->vm_next->vm_start > addr)
133 break;
134 tree = tree->vm_avl_right;
135 }
136 }
137 #endif
138
fixup_exception(struct pt_regs * regs)139 int fixup_exception(struct pt_regs *regs)
140 {
141 const struct exception_table_entry *fix;
142
143 /* If we only stored 32bit addresses in the exception table we can drop
144 * out if we faulted on a 64bit address. */
145 if ((sizeof(regs->iaoq[0]) > sizeof(fix->insn))
146 && (regs->iaoq[0] >> 32))
147 return 0;
148
149 fix = search_exception_tables(regs->iaoq[0]);
150 if (fix) {
151 struct exception_data *d;
152 d = this_cpu_ptr(&exception_data);
153 d->fault_ip = regs->iaoq[0];
154 d->fault_gp = regs->gr[27];
155 d->fault_space = regs->isr;
156 d->fault_addr = regs->ior;
157
158 regs->iaoq[0] = ((fix->fixup) & ~3);
159 /*
160 * NOTE: In some cases the faulting instruction
161 * may be in the delay slot of a branch. We
162 * don't want to take the branch, so we don't
163 * increment iaoq[1], instead we set it to be
164 * iaoq[0]+4, and clear the B bit in the PSW
165 */
166 regs->iaoq[1] = regs->iaoq[0] + 4;
167 regs->gr[0] &= ~PSW_B; /* IPSW in gr[0] */
168
169 return 1;
170 }
171
172 return 0;
173 }
174
175 /*
176 * Print out info about fatal segfaults, if the show_unhandled_signals
177 * sysctl is set:
178 */
179 static inline void
show_signal_msg(struct pt_regs * regs,unsigned long code,unsigned long address,struct task_struct * tsk,struct vm_area_struct * vma)180 show_signal_msg(struct pt_regs *regs, unsigned long code,
181 unsigned long address, struct task_struct *tsk,
182 struct vm_area_struct *vma)
183 {
184 if (!unhandled_signal(tsk, SIGSEGV))
185 return;
186
187 if (!printk_ratelimit())
188 return;
189
190 pr_warn("\n");
191 pr_warn("do_page_fault() command='%s' type=%lu address=0x%08lx",
192 tsk->comm, code, address);
193 print_vma_addr(KERN_CONT " in ", regs->iaoq[0]);
194 if (vma)
195 pr_warn(" vm_start = 0x%08lx, vm_end = 0x%08lx\n",
196 vma->vm_start, vma->vm_end);
197
198 show_regs(regs);
199 }
200
do_page_fault(struct pt_regs * regs,unsigned long code,unsigned long address)201 void do_page_fault(struct pt_regs *regs, unsigned long code,
202 unsigned long address)
203 {
204 struct vm_area_struct *vma, *prev_vma;
205 struct task_struct *tsk;
206 struct mm_struct *mm;
207 unsigned long acc_type;
208 int fault;
209 unsigned int flags;
210
211 if (in_atomic())
212 goto no_context;
213
214 tsk = current;
215 mm = tsk->mm;
216 if (!mm)
217 goto no_context;
218
219 flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE;
220 if (user_mode(regs))
221 flags |= FAULT_FLAG_USER;
222
223 acc_type = parisc_acctyp(code, regs->iir);
224 if (acc_type & VM_WRITE)
225 flags |= FAULT_FLAG_WRITE;
226 retry:
227 down_read(&mm->mmap_sem);
228 vma = find_vma_prev(mm, address, &prev_vma);
229 if (!vma || address < vma->vm_start)
230 goto check_expansion;
231 /*
232 * Ok, we have a good vm_area for this memory access. We still need to
233 * check the access permissions.
234 */
235
236 good_area:
237
238 if ((vma->vm_flags & acc_type) != acc_type)
239 goto bad_area;
240
241 /*
242 * If for any reason at all we couldn't handle the fault, make
243 * sure we exit gracefully rather than endlessly redo the
244 * fault.
245 */
246
247 fault = handle_mm_fault(mm, vma, address, flags);
248
249 if ((fault & VM_FAULT_RETRY) && fatal_signal_pending(current))
250 return;
251
252 if (unlikely(fault & VM_FAULT_ERROR)) {
253 /*
254 * We hit a shared mapping outside of the file, or some
255 * other thing happened to us that made us unable to
256 * handle the page fault gracefully.
257 */
258 if (fault & VM_FAULT_OOM)
259 goto out_of_memory;
260 else if (fault & VM_FAULT_SIGSEGV)
261 goto bad_area;
262 else if (fault & VM_FAULT_SIGBUS)
263 goto bad_area;
264 BUG();
265 }
266 if (flags & FAULT_FLAG_ALLOW_RETRY) {
267 if (fault & VM_FAULT_MAJOR)
268 current->maj_flt++;
269 else
270 current->min_flt++;
271 if (fault & VM_FAULT_RETRY) {
272 flags &= ~FAULT_FLAG_ALLOW_RETRY;
273
274 /*
275 * No need to up_read(&mm->mmap_sem) as we would
276 * have already released it in __lock_page_or_retry
277 * in mm/filemap.c.
278 */
279
280 goto retry;
281 }
282 }
283 up_read(&mm->mmap_sem);
284 return;
285
286 check_expansion:
287 vma = prev_vma;
288 if (vma && (expand_stack(vma, address) == 0))
289 goto good_area;
290
291 /*
292 * Something tried to access memory that isn't in our memory map..
293 */
294 bad_area:
295 up_read(&mm->mmap_sem);
296
297 if (user_mode(regs)) {
298 struct siginfo si;
299
300 show_signal_msg(regs, code, address, tsk, vma);
301
302 switch (code) {
303 case 15: /* Data TLB miss fault/Data page fault */
304 /* send SIGSEGV when outside of vma */
305 if (!vma ||
306 address < vma->vm_start || address >= vma->vm_end) {
307 si.si_signo = SIGSEGV;
308 si.si_code = SEGV_MAPERR;
309 break;
310 }
311
312 /* send SIGSEGV for wrong permissions */
313 if ((vma->vm_flags & acc_type) != acc_type) {
314 si.si_signo = SIGSEGV;
315 si.si_code = SEGV_ACCERR;
316 break;
317 }
318
319 /* probably address is outside of mapped file */
320 /* fall through */
321 case 17: /* NA data TLB miss / page fault */
322 case 18: /* Unaligned access - PCXS only */
323 si.si_signo = SIGBUS;
324 si.si_code = (code == 18) ? BUS_ADRALN : BUS_ADRERR;
325 break;
326 case 16: /* Non-access instruction TLB miss fault */
327 case 26: /* PCXL: Data memory access rights trap */
328 default:
329 si.si_signo = SIGSEGV;
330 si.si_code = (code == 26) ? SEGV_ACCERR : SEGV_MAPERR;
331 break;
332 }
333 si.si_errno = 0;
334 si.si_addr = (void __user *) address;
335 force_sig_info(si.si_signo, &si, current);
336 return;
337 }
338
339 no_context:
340
341 if (!user_mode(regs) && fixup_exception(regs)) {
342 return;
343 }
344
345 parisc_terminate("Bad Address (null pointer deref?)", regs, code, address);
346
347 out_of_memory:
348 up_read(&mm->mmap_sem);
349 if (!user_mode(regs))
350 goto no_context;
351 pagefault_out_of_memory();
352 }
353