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