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Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
2 * linux/arch/alpha/mm/fault.c
3 *
4 * Copyright (C) 1995 Linus Torvalds
5 */
6
Linus Torvalds1da177e2005-04-16 15:20:36 -07007#include <linux/sched.h>
8#include <linux/kernel.h>
9#include <linux/mm.h>
10#include <asm/io.h>
11
12#define __EXTERN_INLINE inline
13#include <asm/mmu_context.h>
14#include <asm/tlbflush.h>
15#undef __EXTERN_INLINE
16
17#include <linux/signal.h>
18#include <linux/errno.h>
19#include <linux/string.h>
20#include <linux/types.h>
21#include <linux/ptrace.h>
22#include <linux/mman.h>
23#include <linux/smp.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070024#include <linux/interrupt.h>
25#include <linux/module.h>
26
27#include <asm/system.h>
28#include <asm/uaccess.h>
29
30extern void die_if_kernel(char *,struct pt_regs *,long, unsigned long *);
31
32
33/*
34 * Force a new ASN for a task.
35 */
36
37#ifndef CONFIG_SMP
38unsigned long last_asn = ASN_FIRST_VERSION;
39#endif
40
41void
42__load_new_mm_context(struct mm_struct *next_mm)
43{
44 unsigned long mmc;
45 struct pcb_struct *pcb;
46
47 mmc = __get_new_mm_context(next_mm, smp_processor_id());
48 next_mm->context[smp_processor_id()] = mmc;
49
50 pcb = &current_thread_info()->pcb;
51 pcb->asn = mmc & HARDWARE_ASN_MASK;
52 pcb->ptbr = ((unsigned long) next_mm->pgd - IDENT_ADDR) >> PAGE_SHIFT;
53
54 __reload_thread(pcb);
55}
56
57
58/*
59 * This routine handles page faults. It determines the address,
60 * and the problem, and then passes it off to handle_mm_fault().
61 *
62 * mmcsr:
63 * 0 = translation not valid
64 * 1 = access violation
65 * 2 = fault-on-read
66 * 3 = fault-on-execute
67 * 4 = fault-on-write
68 *
69 * cause:
70 * -1 = instruction fetch
71 * 0 = load
72 * 1 = store
73 *
74 * Registers $9 through $15 are saved in a block just prior to `regs' and
75 * are saved and restored around the call to allow exception code to
76 * modify them.
77 */
78
79/* Macro for exception fixup code to access integer registers. */
80#define dpf_reg(r) \
81 (((unsigned long *)regs)[(r) <= 8 ? (r) : (r) <= 15 ? (r)-16 : \
82 (r) <= 18 ? (r)+8 : (r)-10])
83
84asmlinkage void
85do_page_fault(unsigned long address, unsigned long mmcsr,
86 long cause, struct pt_regs *regs)
87{
88 struct vm_area_struct * vma;
89 struct mm_struct *mm = current->mm;
90 const struct exception_table_entry *fixup;
91 int fault, si_code = SEGV_MAPERR;
92 siginfo_t info;
93
94 /* As of EV6, a load into $31/$f31 is a prefetch, and never faults
95 (or is suppressed by the PALcode). Support that for older CPUs
96 by ignoring such an instruction. */
97 if (cause == 0) {
98 unsigned int insn;
99 __get_user(insn, (unsigned int __user *)regs->pc);
100 if ((insn >> 21 & 0x1f) == 0x1f &&
101 /* ldq ldl ldt lds ldg ldf ldwu ldbu */
102 (1ul << (insn >> 26) & 0x30f00001400ul)) {
103 regs->pc += 4;
104 return;
105 }
106 }
107
108 /* If we're in an interrupt context, or have no user context,
109 we must not take the fault. */
Peter Zijlstra6edaf682006-12-06 20:32:18 -0800110 if (!mm || in_atomic())
Linus Torvalds1da177e2005-04-16 15:20:36 -0700111 goto no_context;
112
113#ifdef CONFIG_ALPHA_LARGE_VMALLOC
114 if (address >= TASK_SIZE)
115 goto vmalloc_fault;
116#endif
117
118 down_read(&mm->mmap_sem);
119 vma = find_vma(mm, address);
120 if (!vma)
121 goto bad_area;
122 if (vma->vm_start <= address)
123 goto good_area;
124 if (!(vma->vm_flags & VM_GROWSDOWN))
125 goto bad_area;
126 if (expand_stack(vma, address))
127 goto bad_area;
128
129 /* Ok, we have a good vm_area for this memory access, so
130 we can handle it. */
131 good_area:
132 si_code = SEGV_ACCERR;
133 if (cause < 0) {
134 if (!(vma->vm_flags & VM_EXEC))
135 goto bad_area;
136 } else if (!cause) {
137 /* Allow reads even for write-only mappings */
138 if (!(vma->vm_flags & (VM_READ | VM_WRITE)))
139 goto bad_area;
140 } else {
141 if (!(vma->vm_flags & VM_WRITE))
142 goto bad_area;
143 }
144
145 survive:
146 /* If for any reason at all we couldn't handle the fault,
147 make sure we exit gracefully rather than endlessly redo
148 the fault. */
Linus Torvaldsd06063c2009-04-10 09:01:23 -0700149 fault = handle_mm_fault(mm, vma, address, cause > 0 ? FAULT_FLAG_WRITE : 0);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700150 up_read(&mm->mmap_sem);
Nick Piggin83c54072007-07-19 01:47:05 -0700151 if (unlikely(fault & VM_FAULT_ERROR)) {
152 if (fault & VM_FAULT_OOM)
153 goto out_of_memory;
154 else if (fault & VM_FAULT_SIGBUS)
155 goto do_sigbus;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700156 BUG();
157 }
Nick Piggin83c54072007-07-19 01:47:05 -0700158 if (fault & VM_FAULT_MAJOR)
159 current->maj_flt++;
160 else
161 current->min_flt++;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700162 return;
163
164 /* Something tried to access memory that isn't in our memory map.
165 Fix it, but check if it's kernel or user first. */
166 bad_area:
167 up_read(&mm->mmap_sem);
168
169 if (user_mode(regs))
170 goto do_sigsegv;
171
172 no_context:
173 /* Are we prepared to handle this fault as an exception? */
174 if ((fixup = search_exception_tables(regs->pc)) != 0) {
175 unsigned long newpc;
176 newpc = fixup_exception(dpf_reg, fixup, regs->pc);
177 regs->pc = newpc;
178 return;
179 }
180
181 /* Oops. The kernel tried to access some bad page. We'll have to
182 terminate things with extreme prejudice. */
183 printk(KERN_ALERT "Unable to handle kernel paging request at "
184 "virtual address %016lx\n", address);
185 die_if_kernel("Oops", regs, cause, (unsigned long*)regs - 16);
186 do_exit(SIGKILL);
187
188 /* We ran out of memory, or some other thing happened to us that
189 made us unable to handle the page fault gracefully. */
190 out_of_memory:
Serge E. Hallynb460cbc2007-10-18 23:39:52 -0700191 if (is_global_init(current)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700192 yield();
193 down_read(&mm->mmap_sem);
194 goto survive;
195 }
196 printk(KERN_ALERT "VM: killing process %s(%d)\n",
Alexey Dobriyan19c58702007-10-18 23:40:41 -0700197 current->comm, task_pid_nr(current));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700198 if (!user_mode(regs))
199 goto no_context;
Will Schmidtdcca2bd2007-10-16 01:24:18 -0700200 do_group_exit(SIGKILL);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700201
202 do_sigbus:
203 /* Send a sigbus, regardless of whether we were in kernel
204 or user mode. */
205 info.si_signo = SIGBUS;
206 info.si_errno = 0;
207 info.si_code = BUS_ADRERR;
208 info.si_addr = (void __user *) address;
209 force_sig_info(SIGBUS, &info, current);
210 if (!user_mode(regs))
211 goto no_context;
212 return;
213
214 do_sigsegv:
215 info.si_signo = SIGSEGV;
216 info.si_errno = 0;
217 info.si_code = si_code;
218 info.si_addr = (void __user *) address;
219 force_sig_info(SIGSEGV, &info, current);
220 return;
221
222#ifdef CONFIG_ALPHA_LARGE_VMALLOC
223 vmalloc_fault:
224 if (user_mode(regs))
225 goto do_sigsegv;
226 else {
227 /* Synchronize this task's top level page-table
228 with the "reference" page table from init. */
229 long index = pgd_index(address);
230 pgd_t *pgd, *pgd_k;
231
232 pgd = current->active_mm->pgd + index;
233 pgd_k = swapper_pg_dir + index;
234 if (!pgd_present(*pgd) && pgd_present(*pgd_k)) {
235 pgd_val(*pgd) = pgd_val(*pgd_k);
236 return;
237 }
238 goto no_context;
239 }
240#endif
241}