blob: bdd860d93f72a99442bc324bce7319dba62ceca8 [file] [log] [blame]
Chris Zankel3f65ce42005-06-23 22:01:24 -07001// TODO VM_EXEC flag work-around, cache aliasing
2/*
3 * arch/xtensa/mm/fault.c
4 *
5 * This file is subject to the terms and conditions of the GNU General Public
6 * License. See the file "COPYING" in the main directory of this archive
7 * for more details.
8 *
9 * Copyright (C) 2001 - 2005 Tensilica Inc.
10 *
11 * Chris Zankel <chris@zankel.net>
12 * Joe Taylor <joe@tensilica.com, joetylr@yahoo.com>
13 */
14
15#include <linux/mm.h>
16#include <linux/module.h>
Alexey Dobriyan5a891ed2009-03-10 12:55:49 -070017#include <linux/hardirq.h>
Chris Zankel3f65ce42005-06-23 22:01:24 -070018#include <asm/mmu_context.h>
19#include <asm/cacheflush.h>
20#include <asm/hardirq.h>
21#include <asm/uaccess.h>
22#include <asm/system.h>
23#include <asm/pgalloc.h>
24
Chris Zankel173d66812006-12-10 02:18:48 -080025unsigned long asid_cache = ASID_USER_FIRST;
Chris Zankel3f65ce42005-06-23 22:01:24 -070026void bad_page_fault(struct pt_regs*, unsigned long, int);
27
Chris Zankel66569202007-08-22 10:14:51 -070028#undef DEBUG_PAGE_FAULT
29
Chris Zankel3f65ce42005-06-23 22:01:24 -070030/*
31 * This routine handles page faults. It determines the address,
32 * and the problem, and then passes it off to one of the appropriate
33 * routines.
34 *
35 * Note: does not handle Miss and MultiHit.
36 */
37
38void do_page_fault(struct pt_regs *regs)
39{
40 struct vm_area_struct * vma;
41 struct mm_struct *mm = current->mm;
42 unsigned int exccause = regs->exccause;
43 unsigned int address = regs->excvaddr;
44 siginfo_t info;
45
46 int is_write, is_exec;
Nick Piggin83c54072007-07-19 01:47:05 -070047 int fault;
Chris Zankel3f65ce42005-06-23 22:01:24 -070048
49 info.si_code = SEGV_MAPERR;
50
51 /* We fault-in kernel-space virtual memory on-demand. The
52 * 'reference' page table is init_mm.pgd.
53 */
54 if (address >= TASK_SIZE && !user_mode(regs))
55 goto vmalloc_fault;
56
57 /* If we're in an interrupt or have no user
58 * context, we must not take the fault..
59 */
60 if (in_atomic() || !mm) {
61 bad_page_fault(regs, address, SIGSEGV);
62 return;
63 }
64
Chris Zankel173d66812006-12-10 02:18:48 -080065 is_write = (exccause == EXCCAUSE_STORE_CACHE_ATTRIBUTE) ? 1 : 0;
66 is_exec = (exccause == EXCCAUSE_ITLB_PRIVILEGE ||
67 exccause == EXCCAUSE_ITLB_MISS ||
68 exccause == EXCCAUSE_FETCH_CACHE_ATTRIBUTE) ? 1 : 0;
Chris Zankel3f65ce42005-06-23 22:01:24 -070069
Chris Zankel66569202007-08-22 10:14:51 -070070#ifdef DEBUG_PAGE_FAULT
Chris Zankel3f65ce42005-06-23 22:01:24 -070071 printk("[%s:%d:%08x:%d:%08x:%s%s]\n", current->comm, current->pid,
72 address, exccause, regs->pc, is_write? "w":"", is_exec? "x":"");
73#endif
74
75 down_read(&mm->mmap_sem);
76 vma = find_vma(mm, address);
77
78 if (!vma)
79 goto bad_area;
80 if (vma->vm_start <= address)
81 goto good_area;
82 if (!(vma->vm_flags & VM_GROWSDOWN))
83 goto bad_area;
84 if (expand_stack(vma, address))
85 goto bad_area;
86
87 /* Ok, we have a good vm_area for this memory access, so
88 * we can handle it..
89 */
90
91good_area:
92 info.si_code = SEGV_ACCERR;
93
94 if (is_write) {
95 if (!(vma->vm_flags & VM_WRITE))
96 goto bad_area;
97 } else if (is_exec) {
98 if (!(vma->vm_flags & VM_EXEC))
99 goto bad_area;
100 } else /* Allow read even from write-only pages. */
101 if (!(vma->vm_flags & (VM_READ | VM_WRITE)))
102 goto bad_area;
103
104 /* If for any reason at all we couldn't handle the fault,
105 * make sure we exit gracefully rather than endlessly redo
106 * the fault.
107 */
108survive:
Nick Piggin83c54072007-07-19 01:47:05 -0700109 fault = handle_mm_fault(mm, vma, address, is_write);
110 if (unlikely(fault & VM_FAULT_ERROR)) {
111 if (fault & VM_FAULT_OOM)
112 goto out_of_memory;
113 else if (fault & VM_FAULT_SIGBUS)
114 goto do_sigbus;
Chris Zankel3f65ce42005-06-23 22:01:24 -0700115 BUG();
116 }
Nick Piggin83c54072007-07-19 01:47:05 -0700117 if (fault & VM_FAULT_MAJOR)
118 current->maj_flt++;
119 else
120 current->min_flt++;
Chris Zankel3f65ce42005-06-23 22:01:24 -0700121
122 up_read(&mm->mmap_sem);
123 return;
124
125 /* Something tried to access memory that isn't in our memory map..
126 * Fix it, but check if it's kernel or user first..
127 */
128bad_area:
129 up_read(&mm->mmap_sem);
130 if (user_mode(regs)) {
131 current->thread.bad_vaddr = address;
132 current->thread.error_code = is_write;
133 info.si_signo = SIGSEGV;
134 info.si_errno = 0;
135 /* info.si_code has been set above */
136 info.si_addr = (void *) address;
137 force_sig_info(SIGSEGV, &info, current);
138 return;
139 }
140 bad_page_fault(regs, address, SIGSEGV);
141 return;
142
143
144 /* We ran out of memory, or some other thing happened to us that made
145 * us unable to handle the page fault gracefully.
146 */
147out_of_memory:
148 up_read(&mm->mmap_sem);
Serge E. Hallynb460cbc2007-10-18 23:39:52 -0700149 if (is_global_init(current)) {
Chris Zankel3f65ce42005-06-23 22:01:24 -0700150 yield();
151 down_read(&mm->mmap_sem);
152 goto survive;
153 }
154 printk("VM: killing process %s\n", current->comm);
155 if (user_mode(regs))
Will Schmidtdcca2bd2007-10-16 01:24:18 -0700156 do_group_exit(SIGKILL);
Chris Zankel3f65ce42005-06-23 22:01:24 -0700157 bad_page_fault(regs, address, SIGKILL);
158 return;
159
160do_sigbus:
161 up_read(&mm->mmap_sem);
162
163 /* Send a sigbus, regardless of whether we were in kernel
164 * or user mode.
165 */
166 current->thread.bad_vaddr = address;
167 info.si_code = SIGBUS;
168 info.si_errno = 0;
169 info.si_code = BUS_ADRERR;
170 info.si_addr = (void *) address;
171 force_sig_info(SIGBUS, &info, current);
172
173 /* Kernel mode? Handle exceptions or die */
174 if (!user_mode(regs))
175 bad_page_fault(regs, address, SIGBUS);
176
177vmalloc_fault:
178 {
179 /* Synchronize this task's top level page-table
180 * with the 'reference' page table.
181 */
182 struct mm_struct *act_mm = current->active_mm;
183 int index = pgd_index(address);
184 pgd_t *pgd, *pgd_k;
185 pmd_t *pmd, *pmd_k;
186 pte_t *pte_k;
187
188 if (act_mm == NULL)
189 goto bad_page_fault;
190
191 pgd = act_mm->pgd + index;
192 pgd_k = init_mm.pgd + index;
193
194 if (!pgd_present(*pgd_k))
195 goto bad_page_fault;
196
197 pgd_val(*pgd) = pgd_val(*pgd_k);
198
199 pmd = pmd_offset(pgd, address);
200 pmd_k = pmd_offset(pgd_k, address);
201 if (!pmd_present(*pmd) || !pmd_present(*pmd_k))
202 goto bad_page_fault;
203
204 pmd_val(*pmd) = pmd_val(*pmd_k);
205 pte_k = pte_offset_kernel(pmd_k, address);
206
207 if (!pte_present(*pte_k))
208 goto bad_page_fault;
209 return;
210 }
211bad_page_fault:
212 bad_page_fault(regs, address, SIGKILL);
213 return;
214}
215
216
217void
218bad_page_fault(struct pt_regs *regs, unsigned long address, int sig)
219{
220 extern void die(const char*, struct pt_regs*, long);
221 const struct exception_table_entry *entry;
222
223 /* Are we prepared to handle this kernel fault? */
224 if ((entry = search_exception_tables(regs->pc)) != NULL) {
Chris Zankel66569202007-08-22 10:14:51 -0700225#ifdef DEBUG_PAGE_FAULT
Chris Zankel3f65ce42005-06-23 22:01:24 -0700226 printk(KERN_DEBUG "%s: Exception at pc=%#010lx (%lx)\n",
227 current->comm, regs->pc, entry->fixup);
228#endif
229 current->thread.bad_uaddr = address;
230 regs->pc = entry->fixup;
231 return;
232 }
233
234 /* Oops. The kernel tried to access some bad page. We'll have to
235 * terminate things with extreme prejudice.
236 */
237 printk(KERN_ALERT "Unable to handle kernel paging request at virtual "
238 "address %08lx\n pc = %08lx, ra = %08lx\n",
239 address, regs->pc, regs->areg[0]);
240 die("Oops", regs, sig);
241 do_exit(sig);
242}
243