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Linus Torvalds1da177e2005-04-16 15:20:36 -07001/* $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#include <linux/module.h>
19
20#include <asm/uaccess.h>
21#include <asm/traps.h>
22
23#define PRINT_USER_FAULTS /* (turn this on if you want user faults to be */
24 /* dumped to the console via printk) */
25
26
27/* Defines for parisc_acctyp() */
28#define READ 0
29#define WRITE 1
30
31/* Various important other fields */
32#define bit22set(x) (x & 0x00000200)
33#define bits23_25set(x) (x & 0x000001c0)
34#define isGraphicsFlushRead(x) ((x & 0xfc003fdf) == 0x04001a80)
35 /* extended opcode is 0x6a */
36
37#define BITSSET 0x1c0 /* for identifying LDCW */
38
39
40DEFINE_PER_CPU(struct exception_data, exception_data);
41
42/*
43 * parisc_acctyp(unsigned int inst) --
44 * Given a PA-RISC memory access instruction, determine if the
45 * the instruction would perform a memory read or memory write
46 * operation.
47 *
48 * This function assumes that the given instruction is a memory access
49 * instruction (i.e. you should really only call it if you know that
50 * the instruction has generated some sort of a memory access fault).
51 *
52 * Returns:
53 * VM_READ if read operation
54 * VM_WRITE if write operation
55 * VM_EXEC if execute operation
56 */
57static unsigned long
58parisc_acctyp(unsigned long code, unsigned int inst)
59{
60 if (code == 6 || code == 16)
61 return VM_EXEC;
62
63 switch (inst & 0xf0000000) {
64 case 0x40000000: /* load */
65 case 0x50000000: /* new load */
66 return VM_READ;
67
68 case 0x60000000: /* store */
69 case 0x70000000: /* new store */
70 return VM_WRITE;
71
72 case 0x20000000: /* coproc */
73 case 0x30000000: /* coproc2 */
74 if (bit22set(inst))
75 return VM_WRITE;
76
77 case 0x0: /* indexed/memory management */
78 if (bit22set(inst)) {
79 /*
80 * Check for the 'Graphics Flush Read' instruction.
81 * It resembles an FDC instruction, except for bits
82 * 20 and 21. Any combination other than zero will
83 * utilize the block mover functionality on some
84 * older PA-RISC platforms. The case where a block
85 * move is performed from VM to graphics IO space
86 * should be treated as a READ.
87 *
88 * The significance of bits 20,21 in the FDC
89 * instruction is:
90 *
91 * 00 Flush data cache (normal instruction behavior)
92 * 01 Graphics flush write (IO space -> VM)
93 * 10 Graphics flush read (VM -> IO space)
94 * 11 Graphics flush read/write (VM <-> IO space)
95 */
96 if (isGraphicsFlushRead(inst))
97 return VM_READ;
98 return VM_WRITE;
99 } else {
100 /*
101 * Check for LDCWX and LDCWS (semaphore instructions).
102 * If bits 23 through 25 are all 1's it is one of
103 * the above two instructions and is a write.
104 *
105 * Note: With the limited bits we are looking at,
106 * this will also catch PROBEW and PROBEWI. However,
107 * these should never get in here because they don't
108 * generate exceptions of the type:
109 * Data TLB miss fault/data page fault
110 * Data memory protection trap
111 */
112 if (bits23_25set(inst) == BITSSET)
113 return VM_WRITE;
114 }
115 return VM_READ; /* Default */
116 }
117 return VM_READ; /* Default */
118}
119
120#undef bit22set
121#undef bits23_25set
122#undef isGraphicsFlushRead
123#undef BITSSET
124
125
126#if 0
127/* This is the treewalk to find a vma which is the highest that has
128 * a start < addr. We're using find_vma_prev instead right now, but
129 * we might want to use this at some point in the future. Probably
130 * not, but I want it committed to CVS so I don't lose it :-)
131 */
132 while (tree != vm_avl_empty) {
133 if (tree->vm_start > addr) {
134 tree = tree->vm_avl_left;
135 } else {
136 prev = tree;
137 if (prev->vm_next == NULL)
138 break;
139 if (prev->vm_next->vm_start > addr)
140 break;
141 tree = tree->vm_avl_right;
142 }
143 }
144#endif
145
146void do_page_fault(struct pt_regs *regs, unsigned long code,
147 unsigned long address)
148{
149 struct vm_area_struct *vma, *prev_vma;
150 struct task_struct *tsk = current;
151 struct mm_struct *mm = tsk->mm;
152 const struct exception_table_entry *fix;
153 unsigned long acc_type;
154
155 if (in_interrupt() || !mm)
156 goto no_context;
157
158 down_read(&mm->mmap_sem);
159 vma = find_vma_prev(mm, address, &prev_vma);
160 if (!vma || address < vma->vm_start)
161 goto check_expansion;
162/*
163 * Ok, we have a good vm_area for this memory access. We still need to
164 * check the access permissions.
165 */
166
167good_area:
168
169 acc_type = parisc_acctyp(code,regs->iir);
170
171 if ((vma->vm_flags & acc_type) != acc_type)
172 goto bad_area;
173
174 /*
175 * If for any reason at all we couldn't handle the fault, make
176 * sure we exit gracefully rather than endlessly redo the
177 * fault.
178 */
179
180 switch (handle_mm_fault(mm, vma, address, (acc_type & VM_WRITE) != 0)) {
181 case 1:
182 ++current->min_flt;
183 break;
184 case 2:
185 ++current->maj_flt;
186 break;
187 case 0:
188 /*
189 * We ran out of memory, or some other thing happened
190 * to us that made us unable to handle the page fault
191 * gracefully.
192 */
193 goto bad_area;
194 default:
195 goto out_of_memory;
196 }
197 up_read(&mm->mmap_sem);
198 return;
199
200check_expansion:
201 vma = prev_vma;
202 if (vma && (expand_stack(vma, address) == 0))
203 goto good_area;
204
205/*
206 * Something tried to access memory that isn't in our memory map..
207 */
208bad_area:
209 up_read(&mm->mmap_sem);
210
211 if (user_mode(regs)) {
212 struct siginfo si;
213
214#ifdef PRINT_USER_FAULTS
215 printk(KERN_DEBUG "\n");
216 printk(KERN_DEBUG "do_page_fault() pid=%d command='%s' type=%lu address=0x%08lx\n",
217 tsk->pid, tsk->comm, code, address);
218 if (vma) {
219 printk(KERN_DEBUG "vm_start = 0x%08lx, vm_end = 0x%08lx\n",
220 vma->vm_start, vma->vm_end);
221 }
222 show_regs(regs);
223#endif
224 /* FIXME: actually we need to get the signo and code correct */
225 si.si_signo = SIGSEGV;
226 si.si_errno = 0;
227 si.si_code = SEGV_MAPERR;
228 si.si_addr = (void __user *) address;
229 force_sig_info(SIGSEGV, &si, current);
230 return;
231 }
232
233no_context:
234
235 if (!user_mode(regs)) {
236 fix = search_exception_tables(regs->iaoq[0]);
237
238 if (fix) {
239 struct exception_data *d;
240
241 d = &__get_cpu_var(exception_data);
242 d->fault_ip = regs->iaoq[0];
243 d->fault_space = regs->isr;
244 d->fault_addr = regs->ior;
245
246 regs->iaoq[0] = ((fix->fixup) & ~3);
247
248 /*
249 * NOTE: In some cases the faulting instruction
250 * may be in the delay slot of a branch. We
251 * don't want to take the branch, so we don't
252 * increment iaoq[1], instead we set it to be
253 * iaoq[0]+4, and clear the B bit in the PSW
254 */
255
256 regs->iaoq[1] = regs->iaoq[0] + 4;
257 regs->gr[0] &= ~PSW_B; /* IPSW in gr[0] */
258
259 return;
260 }
261 }
262
263 parisc_terminate("Bad Address (null pointer deref?)", regs, code, address);
264
265 out_of_memory:
266 up_read(&mm->mmap_sem);
267 printk(KERN_CRIT "VM: killing process %s\n", current->comm);
268 if (user_mode(regs))
269 do_exit(SIGKILL);
270 goto no_context;
271}