File: /usr/src/linux/arch/parisc/mm/fault.c
1 /* $Id: fault.c,v 1.5 2000/01/26 16:20:29 jsm Exp $
2 *
3 * This file is subject to the terms and conditions of the GNU General Public
4 * License. See the file "COPYING" in the main directory of this archive
5 * for more details.
6 *
7 *
8 * Copyright (C) 1995, 1996, 1997, 1998 by Ralf Baechle
9 * Copyright 1999 SuSE GmbH (Philipp Rumpf, prumpf@tux.org)
10 * Copyright 1999 Hewlett Packard Co.
11 *
12 */
13
14 #include <linux/mm.h>
15 #include <linux/ptrace.h>
16 #include <linux/sched.h>
17 #include <linux/interrupt.h>
18
19 #include <asm/uaccess.h>
20
21
22 /* Defines for parisc_acctyp() */
23 #define READ 0
24 #define WRITE 1
25
26 /* Various important other fields */
27 #define bit22set(x) (x & 0x00000200)
28 #define bits23_25set(x) (x & 0x000001c0)
29 #define isGraphicsFlushRead(x) ((x & 0xfc003fdf) == 0x04001a80)
30 /* extended opcode is 0x6a */
31
32 #define BITSSET 0x1c0 /* for identifying LDCW */
33
34 /*
35 * parisc_acctyp(unsigned int inst) --
36 * Given a PA-RISC memory access instruction, determine if the
37 * the instruction would perform a memory read or memory write
38 * operation.
39 *
40 * This function assumes that the given instruction is a memory access
41 * instruction (i.e. you should really only call it if you know that
42 * the instruction has generated some sort of a memory access fault).
43 *
44 * Returns:
45 * VM_READ if read operation
46 * VM_WRITE if write operation
47 * VM_EXEC if execute operation
48 */
49 static unsigned long
50 parisc_acctyp(unsigned long code, unsigned int inst)
51 {
52 if (code == 6 || code == 16)
53 return VM_EXEC;
54
55 switch (inst & 0xf0000000) {
56 case 0x40000000: /* load */
57 case 0x50000000: /* new load */
58 return VM_READ;
59
60 case 0x60000000: /* store */
61 case 0x70000000: /* new store */
62 return VM_WRITE;
63
64 case 0x20000000: /* coproc */
65 case 0x30000000: /* coproc2 */
66 if (bit22set(inst))
67 return VM_WRITE;
68
69 case 0x0: /* indexed/memory management */
70 if (bit22set(inst)) {
71 /*
72 * Check for the 'Graphics Flush Read' instruction.
73 * It resembles an FDC instruction, except for bits
74 * 20 and 21. Any combination other than zero will
75 * utilize the block mover functionality on some
76 * older PA-RISC platforms. The case where a block
77 * move is performed from VM to graphics IO space
78 * should be treated as a READ.
79 *
80 * The significance of bits 20,21 in the FDC
81 * instruction is:
82 *
83 * 00 Flush data cache (normal instruction behavior)
84 * 01 Graphics flush write (IO space -> VM)
85 * 10 Graphics flush read (VM -> IO space)
86 * 11 Graphics flush read/write (VM <-> IO space)
87 */
88 if (isGraphicsFlushRead(inst))
89 return VM_READ;
90 return VM_WRITE;
91 } else {
92 /*
93 * Check for LDCWX and LDCWS (semaphore instructions).
94 * If bits 23 through 25 are all 1's it is one of
95 * the above two instructions and is a write.
96 *
97 * Note: With the limited bits we are looking at,
98 * this will also catch PROBEW and PROBEWI. However,
99 * these should never get in here because they don't
100 * generate exceptions of the type:
101 * Data TLB miss fault/data page fault
102 * Data memory protection trap
103 */
104 if (bits23_25set(inst) == BITSSET)
105 return VM_WRITE;
106 }
107 return VM_READ; /* Default */
108 }
109 return VM_READ; /* Default */
110 }
111
112 #undef bit22set
113 #undef bits23_25set
114 #undef isGraphicsFlushRead
115 #undef BITSSET
116
117 /* This is similar to expand_stack(), except that it is for stacks
118 * that grow upwards.
119 */
120
121 static inline int expand_stackup(struct vm_area_struct * vma, unsigned long address)
122 {
123 unsigned long grow;
124
125 address += 4 + PAGE_SIZE - 1;
126 address &= PAGE_MASK;
127 grow = (address - vma->vm_end) >> PAGE_SHIFT;
128 if (address - vma->vm_start > current->rlim[RLIMIT_STACK].rlim_cur ||
129 ((vma->vm_mm->total_vm + grow) << PAGE_SHIFT) > current->rlim[RLIMIT_AS].rlim_cur)
130 return -ENOMEM;
131 vma->vm_end = address;
132 vma->vm_mm->total_vm += grow;
133 if (vma->vm_flags & VM_LOCKED)
134 vma->vm_mm->locked_vm += grow;
135 return 0;
136 }
137
138
139 /* This is similar to find_vma(), except that it understands that stacks
140 * grow up rather than down.
141 * XXX Optimise by making use of cache and avl tree as per find_vma().
142 */
143
144 struct vm_area_struct * pa_find_vma(struct mm_struct * mm, unsigned long addr)
145 {
146 struct vm_area_struct *vma = NULL;
147
148 if (mm) {
149 vma = mm->mmap;
150 if (!vma || addr < vma->vm_start)
151 return NULL;
152 while (vma->vm_next && addr >= vma->vm_next->vm_start)
153 vma = vma->vm_next;
154 }
155 return vma;
156 }
157
158
159 /*
160 * This routine handles page faults. It determines the address,
161 * and the problem, and then passes it off to one of the appropriate
162 * routines.
163 */
164 extern void parisc_terminate(char *, struct pt_regs *, int, unsigned long);
165
166 void do_page_fault(struct pt_regs *regs, unsigned long code,
167 unsigned long address)
168 {
169 struct vm_area_struct * vma;
170 struct task_struct *tsk = current;
171 struct mm_struct *mm = tsk->mm;
172 const struct exception_table_entry *fix;
173 unsigned long acc_type;
174
175 if (in_interrupt() || !mm)
176 goto no_context;
177
178 down_read(&mm->mmap_sem);
179 vma = pa_find_vma(mm, address);
180 if (!vma)
181 goto bad_area;
182 if (address < vma->vm_end)
183 goto good_area;
184 if (!(vma->vm_flags & VM_GROWSUP) || expand_stackup(vma, address))
185 goto bad_area;
186 /*
187 * Ok, we have a good vm_area for this memory access. We still need to
188 * check the access permissions.
189 */
190
191 good_area:
192
193 acc_type = parisc_acctyp(code,regs->iir);
194
195 if ((vma->vm_flags & acc_type) != acc_type)
196 goto bad_area;
197
198 /*
199 * If for any reason at all we couldn't handle the fault, make
200 * sure we exit gracefully rather than endlessly redo the
201 * fault.
202 */
203
204 switch (handle_mm_fault(mm, vma, address, (acc_type & VM_WRITE) != 0)) {
205 case 1:
206 ++current->min_flt;
207 break;
208 case 2:
209 ++current->maj_flt;
210 break;
211 case 0:
212 /*
213 * We ran out of memory, or some other thing happened
214 * to us that made us unable to handle the page fault
215 * gracefully.
216 */
217 goto bad_area;
218 default:
219 goto out_of_memory;
220 }
221 up_read(&mm->mmap_sem);
222 return;
223
224 /*
225 * Something tried to access memory that isn't in our memory map..
226 */
227 bad_area:
228 up_read(&mm->mmap_sem);
229
230 if (user_mode(regs)) {
231 struct siginfo si;
232
233 printk("\ndo_page_fault() pid=%d command='%s'\n",
234 tsk->pid, tsk->comm);
235 show_regs(regs);
236 /* FIXME: actually we need to get the signo and code correct */
237 si.si_signo = SIGSEGV;
238 si.si_errno = 0;
239 si.si_code = SEGV_MAPERR;
240 si.si_addr = (void *) address;
241 force_sig_info(SIGSEGV, &si, current);
242 return;
243 }
244
245 no_context:
246
247 if (!user_mode(regs)) {
248
249 fix = search_exception_table(regs->iaoq[0]);
250
251 if (fix) {
252
253 if (fix->skip & 1)
254 regs->gr[8] = -EFAULT;
255 if (fix->skip & 2)
256 regs->gr[9] = 0;
257
258 regs->iaoq[0] += ((fix->skip) & ~3);
259
260 /*
261 * NOTE: In some cases the faulting instruction
262 * may be in the delay slot of a branch. We
263 * don't want to take the branch, so we don't
264 * increment iaoq[1], instead we set it to be
265 * iaoq[0]+4, and clear the B bit in the PSW
266 */
267
268 regs->iaoq[1] = regs->iaoq[0] + 4;
269 regs->gr[0] &= ~PSW_B; /* IPSW in gr[0] */
270
271 return;
272 }
273 }
274
275 parisc_terminate("Bad Address (null pointer deref?)",regs,code,address);
276
277 out_of_memory:
278 up_read(&mm->mmap_sem);
279 printk("VM: killing process %s\n", current->comm);
280 if (user_mode(regs))
281 do_exit(SIGKILL);
282 goto no_context;
283 }
284