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 #include <asm/traps.h>
21
22 #define PRINT_USER_FAULTS /* (turn this on if you want user faults to be */
23 /* dumped to the console via printk) */
24
25
26 /* Defines for parisc_acctyp() */
27 #define READ 0
28 #define WRITE 1
29
30 /* Various important other fields */
31 #define bit22set(x) (x & 0x00000200)
32 #define bits23_25set(x) (x & 0x000001c0)
33 #define isGraphicsFlushRead(x) ((x & 0xfc003fdf) == 0x04001a80)
34 /* extended opcode is 0x6a */
35
36 #define BITSSET 0x1c0 /* for identifying LDCW */
37
38 /*
39 * parisc_acctyp(unsigned int inst) --
40 * Given a PA-RISC memory access instruction, determine if the
41 * the instruction would perform a memory read or memory write
42 * operation.
43 *
44 * This function assumes that the given instruction is a memory access
45 * instruction (i.e. you should really only call it if you know that
46 * the instruction has generated some sort of a memory access fault).
47 *
48 * Returns:
49 * VM_READ if read operation
50 * VM_WRITE if write operation
51 * VM_EXEC if execute operation
52 */
53 static unsigned long
parisc_acctyp(unsigned long code,unsigned int inst)54 parisc_acctyp(unsigned long code, unsigned int inst)
55 {
56 if (code == 6 || code == 16)
57 return VM_EXEC;
58
59 switch (inst & 0xf0000000) {
60 case 0x40000000: /* load */
61 case 0x50000000: /* new load */
62 return VM_READ;
63
64 case 0x60000000: /* store */
65 case 0x70000000: /* new store */
66 return VM_WRITE;
67
68 case 0x20000000: /* coproc */
69 case 0x30000000: /* coproc2 */
70 if (bit22set(inst))
71 return VM_WRITE;
72
73 case 0x0: /* indexed/memory management */
74 if (bit22set(inst)) {
75 /*
76 * Check for the 'Graphics Flush Read' instruction.
77 * It resembles an FDC instruction, except for bits
78 * 20 and 21. Any combination other than zero will
79 * utilize the block mover functionality on some
80 * older PA-RISC platforms. The case where a block
81 * move is performed from VM to graphics IO space
82 * should be treated as a READ.
83 *
84 * The significance of bits 20,21 in the FDC
85 * instruction is:
86 *
87 * 00 Flush data cache (normal instruction behavior)
88 * 01 Graphics flush write (IO space -> VM)
89 * 10 Graphics flush read (VM -> IO space)
90 * 11 Graphics flush read/write (VM <-> IO space)
91 */
92 if (isGraphicsFlushRead(inst))
93 return VM_READ;
94 return VM_WRITE;
95 } else {
96 /*
97 * Check for LDCWX and LDCWS (semaphore instructions).
98 * If bits 23 through 25 are all 1's it is one of
99 * the above two instructions and is a write.
100 *
101 * Note: With the limited bits we are looking at,
102 * this will also catch PROBEW and PROBEWI. However,
103 * these should never get in here because they don't
104 * generate exceptions of the type:
105 * Data TLB miss fault/data page fault
106 * Data memory protection trap
107 */
108 if (bits23_25set(inst) == BITSSET)
109 return VM_WRITE;
110 }
111 return VM_READ; /* Default */
112 }
113 return VM_READ; /* Default */
114 }
115
116 #undef bit22set
117 #undef bits23_25set
118 #undef isGraphicsFlushRead
119 #undef BITSSET
120
121
122 #if 0
123 /* This is the treewalk to find a vma which is the highest that has
124 * a start < addr. We're using find_vma_prev instead right now, but
125 * we might want to use this at some point in the future. Probably
126 * not, but I want it committed to CVS so I don't lose it :-)
127 */
128 while (tree != vm_avl_empty) {
129 if (tree->vm_start > addr) {
130 tree = tree->vm_avl_left;
131 } else {
132 prev = tree;
133 if (prev->vm_next == NULL)
134 break;
135 if (prev->vm_next->vm_start > addr)
136 break;
137 tree = tree->vm_avl_right;
138 }
139 }
140 #endif
141
do_page_fault(struct pt_regs * regs,unsigned long code,unsigned long address)142 void do_page_fault(struct pt_regs *regs, unsigned long code,
143 unsigned long address)
144 {
145 struct vm_area_struct *vma, *prev_vma;
146 struct task_struct *tsk = current;
147 struct mm_struct *mm = tsk->mm;
148 const struct exception_table_entry *fix;
149 unsigned long acc_type;
150
151 if (in_interrupt() || !mm)
152 goto no_context;
153
154 down_read(&mm->mmap_sem);
155 vma = find_vma_prev(mm, address, &prev_vma);
156 if (!vma || address < vma->vm_start)
157 goto check_expansion;
158 /*
159 * Ok, we have a good vm_area for this memory access. We still need to
160 * check the access permissions.
161 */
162
163 good_area:
164
165 acc_type = parisc_acctyp(code,regs->iir);
166
167 if ((vma->vm_flags & acc_type) != acc_type)
168 goto bad_area;
169
170 /*
171 * If for any reason at all we couldn't handle the fault, make
172 * sure we exit gracefully rather than endlessly redo the
173 * fault.
174 */
175
176 switch (handle_mm_fault(mm, vma, address, (acc_type & VM_WRITE) != 0)) {
177 case 1:
178 ++current->min_flt;
179 break;
180 case 2:
181 ++current->maj_flt;
182 break;
183 case 0:
184 /*
185 * We ran out of memory, or some other thing happened
186 * to us that made us unable to handle the page fault
187 * gracefully.
188 */
189 goto bad_area;
190 default:
191 goto out_of_memory;
192 }
193 up_read(&mm->mmap_sem);
194 return;
195
196 check_expansion:
197 vma = prev_vma;
198 if (vma && (expand_stack(vma, address) == 0))
199 goto good_area;
200
201 /*
202 * Something tried to access memory that isn't in our memory map..
203 */
204 bad_area:
205 up_read(&mm->mmap_sem);
206
207 if (user_mode(regs)) {
208 struct siginfo si;
209
210 #ifdef PRINT_USER_FAULTS
211 printk(KERN_DEBUG "\n");
212 printk(KERN_DEBUG "do_page_fault() pid=%d command='%s' type=%lu address=0x%08lx\n",
213 tsk->pid, tsk->comm, code, address);
214 if (vma) {
215 printk(KERN_DEBUG "vm_start = 0x%08lx, vm_end = 0x%08lx\n",
216 vma->vm_start, vma->vm_end);
217 }
218 show_regs(regs);
219 #endif
220 /* FIXME: actually we need to get the signo and code correct */
221 si.si_signo = SIGSEGV;
222 si.si_errno = 0;
223 si.si_code = SEGV_MAPERR;
224 si.si_addr = (void *) address;
225 force_sig_info(SIGSEGV, &si, current);
226 return;
227 }
228
229 no_context:
230
231 if (!user_mode(regs)) {
232
233 fix = search_exception_table(regs->iaoq[0]);
234
235 if (fix) {
236
237 if (fix->skip & 1)
238 regs->gr[8] = -EFAULT;
239 if (fix->skip & 2)
240 regs->gr[9] = 0;
241
242 regs->iaoq[0] += ((fix->skip) & ~3);
243
244 /*
245 * NOTE: In some cases the faulting instruction
246 * may be in the delay slot of a branch. We
247 * don't want to take the branch, so we don't
248 * increment iaoq[1], instead we set it to be
249 * iaoq[0]+4, and clear the B bit in the PSW
250 */
251
252 regs->iaoq[1] = regs->iaoq[0] + 4;
253 regs->gr[0] &= ~PSW_B; /* IPSW in gr[0] */
254
255 return;
256 }
257 }
258
259 parisc_terminate("Bad Address (null pointer deref?)", regs, code, address);
260 /* NOT REACHED! */
261
262 out_of_memory:
263 up_read(&mm->mmap_sem);
264 printk(KERN_CRIT "VM: killing process %s\n", current->comm);
265 if (user_mode(regs))
266 do_exit(SIGKILL);
267 goto no_context;
268 }
269