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authorLinus Torvalds <torvalds@ppc970.osdl.org>2005-04-16 18:20:36 -0400
committerLinus Torvalds <torvalds@ppc970.osdl.org>2005-04-16 18:20:36 -0400
commit1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 (patch)
tree0bba044c4ce775e45a88a51686b5d9f90697ea9d /arch/ia64/mm/fault.c
Linux-2.6.12-rc2v2.6.12-rc2
Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
Diffstat (limited to 'arch/ia64/mm/fault.c')
-rw-r--r--arch/ia64/mm/fault.c261
1 files changed, 261 insertions, 0 deletions
diff --git a/arch/ia64/mm/fault.c b/arch/ia64/mm/fault.c
new file mode 100644
index 000000000000..da859125aaef
--- /dev/null
+++ b/arch/ia64/mm/fault.c
@@ -0,0 +1,261 @@
1/*
2 * MMU fault handling support.
3 *
4 * Copyright (C) 1998-2002 Hewlett-Packard Co
5 * David Mosberger-Tang <davidm@hpl.hp.com>
6 */
7#include <linux/sched.h>
8#include <linux/kernel.h>
9#include <linux/mm.h>
10#include <linux/smp_lock.h>
11#include <linux/interrupt.h>
12
13#include <asm/pgtable.h>
14#include <asm/processor.h>
15#include <asm/system.h>
16#include <asm/uaccess.h>
17
18extern void die (char *, struct pt_regs *, long);
19
20/*
21 * This routine is analogous to expand_stack() but instead grows the
22 * register backing store (which grows towards higher addresses).
23 * Since the register backing store is access sequentially, we
24 * disallow growing the RBS by more than a page at a time. Note that
25 * the VM_GROWSUP flag can be set on any VM area but that's fine
26 * because the total process size is still limited by RLIMIT_STACK and
27 * RLIMIT_AS.
28 */
29static inline long
30expand_backing_store (struct vm_area_struct *vma, unsigned long address)
31{
32 unsigned long grow;
33
34 grow = PAGE_SIZE >> PAGE_SHIFT;
35 if (address - vma->vm_start > current->signal->rlim[RLIMIT_STACK].rlim_cur
36 || (((vma->vm_mm->total_vm + grow) << PAGE_SHIFT) > current->signal->rlim[RLIMIT_AS].rlim_cur))
37 return -ENOMEM;
38 vma->vm_end += PAGE_SIZE;
39 vma->vm_mm->total_vm += grow;
40 if (vma->vm_flags & VM_LOCKED)
41 vma->vm_mm->locked_vm += grow;
42 __vm_stat_account(vma->vm_mm, vma->vm_flags, vma->vm_file, grow);
43 return 0;
44}
45
46/*
47 * Return TRUE if ADDRESS points at a page in the kernel's mapped segment
48 * (inside region 5, on ia64) and that page is present.
49 */
50static int
51mapped_kernel_page_is_present (unsigned long address)
52{
53 pgd_t *pgd;
54 pud_t *pud;
55 pmd_t *pmd;
56 pte_t *ptep, pte;
57
58 pgd = pgd_offset_k(address);
59 if (pgd_none(*pgd) || pgd_bad(*pgd))
60 return 0;
61
62 pud = pud_offset(pgd, address);
63 if (pud_none(*pud) || pud_bad(*pud))
64 return 0;
65
66 pmd = pmd_offset(pud, address);
67 if (pmd_none(*pmd) || pmd_bad(*pmd))
68 return 0;
69
70 ptep = pte_offset_kernel(pmd, address);
71 if (!ptep)
72 return 0;
73
74 pte = *ptep;
75 return pte_present(pte);
76}
77
78void
79ia64_do_page_fault (unsigned long address, unsigned long isr, struct pt_regs *regs)
80{
81 int signal = SIGSEGV, code = SEGV_MAPERR;
82 struct vm_area_struct *vma, *prev_vma;
83 struct mm_struct *mm = current->mm;
84 struct siginfo si;
85 unsigned long mask;
86
87 /*
88 * If we're in an interrupt or have no user context, we must not take the fault..
89 */
90 if (in_atomic() || !mm)
91 goto no_context;
92
93#ifdef CONFIG_VIRTUAL_MEM_MAP
94 /*
95 * If fault is in region 5 and we are in the kernel, we may already
96 * have the mmap_sem (pfn_valid macro is called during mmap). There
97 * is no vma for region 5 addr's anyway, so skip getting the semaphore
98 * and go directly to the exception handling code.
99 */
100
101 if ((REGION_NUMBER(address) == 5) && !user_mode(regs))
102 goto bad_area_no_up;
103#endif
104
105 down_read(&mm->mmap_sem);
106
107 vma = find_vma_prev(mm, address, &prev_vma);
108 if (!vma)
109 goto bad_area;
110
111 /* find_vma_prev() returns vma such that address < vma->vm_end or NULL */
112 if (address < vma->vm_start)
113 goto check_expansion;
114
115 good_area:
116 code = SEGV_ACCERR;
117
118 /* OK, we've got a good vm_area for this memory area. Check the access permissions: */
119
120# define VM_READ_BIT 0
121# define VM_WRITE_BIT 1
122# define VM_EXEC_BIT 2
123
124# if (((1 << VM_READ_BIT) != VM_READ || (1 << VM_WRITE_BIT) != VM_WRITE) \
125 || (1 << VM_EXEC_BIT) != VM_EXEC)
126# error File is out of sync with <linux/mm.h>. Please update.
127# endif
128
129 mask = ( (((isr >> IA64_ISR_X_BIT) & 1UL) << VM_EXEC_BIT)
130 | (((isr >> IA64_ISR_W_BIT) & 1UL) << VM_WRITE_BIT)
131 | (((isr >> IA64_ISR_R_BIT) & 1UL) << VM_READ_BIT));
132
133 if ((vma->vm_flags & mask) != mask)
134 goto bad_area;
135
136 survive:
137 /*
138 * If for any reason at all we couldn't handle the fault, make
139 * sure we exit gracefully rather than endlessly redo the
140 * fault.
141 */
142 switch (handle_mm_fault(mm, vma, address, (mask & VM_WRITE) != 0)) {
143 case VM_FAULT_MINOR:
144 ++current->min_flt;
145 break;
146 case VM_FAULT_MAJOR:
147 ++current->maj_flt;
148 break;
149 case VM_FAULT_SIGBUS:
150 /*
151 * We ran out of memory, or some other thing happened
152 * to us that made us unable to handle the page fault
153 * gracefully.
154 */
155 signal = SIGBUS;
156 goto bad_area;
157 case VM_FAULT_OOM:
158 goto out_of_memory;
159 default:
160 BUG();
161 }
162 up_read(&mm->mmap_sem);
163 return;
164
165 check_expansion:
166 if (!(prev_vma && (prev_vma->vm_flags & VM_GROWSUP) && (address == prev_vma->vm_end))) {
167 if (!(vma->vm_flags & VM_GROWSDOWN))
168 goto bad_area;
169 if (REGION_NUMBER(address) != REGION_NUMBER(vma->vm_start)
170 || REGION_OFFSET(address) >= RGN_MAP_LIMIT)
171 goto bad_area;
172 if (expand_stack(vma, address))
173 goto bad_area;
174 } else {
175 vma = prev_vma;
176 if (REGION_NUMBER(address) != REGION_NUMBER(vma->vm_start)
177 || REGION_OFFSET(address) >= RGN_MAP_LIMIT)
178 goto bad_area;
179 if (expand_backing_store(vma, address))
180 goto bad_area;
181 }
182 goto good_area;
183
184 bad_area:
185 up_read(&mm->mmap_sem);
186#ifdef CONFIG_VIRTUAL_MEM_MAP
187 bad_area_no_up:
188#endif
189 if ((isr & IA64_ISR_SP)
190 || ((isr & IA64_ISR_NA) && (isr & IA64_ISR_CODE_MASK) == IA64_ISR_CODE_LFETCH))
191 {
192 /*
193 * This fault was due to a speculative load or lfetch.fault, set the "ed"
194 * bit in the psr to ensure forward progress. (Target register will get a
195 * NaT for ld.s, lfetch will be canceled.)
196 */
197 ia64_psr(regs)->ed = 1;
198 return;
199 }
200 if (user_mode(regs)) {
201 si.si_signo = signal;
202 si.si_errno = 0;
203 si.si_code = code;
204 si.si_addr = (void __user *) address;
205 si.si_isr = isr;
206 si.si_flags = __ISR_VALID;
207 force_sig_info(signal, &si, current);
208 return;
209 }
210
211 no_context:
212 if (isr & IA64_ISR_SP) {
213 /*
214 * This fault was due to a speculative load set the "ed" bit in the psr to
215 * ensure forward progress (target register will get a NaT).
216 */
217 ia64_psr(regs)->ed = 1;
218 return;
219 }
220
221 if (ia64_done_with_exception(regs))
222 return;
223
224 /*
225 * Since we have no vma's for region 5, we might get here even if the address is
226 * valid, due to the VHPT walker inserting a non present translation that becomes
227 * stale. If that happens, the non present fault handler already purged the stale
228 * translation, which fixed the problem. So, we check to see if the translation is
229 * valid, and return if it is.
230 */
231 if (REGION_NUMBER(address) == 5 && mapped_kernel_page_is_present(address))
232 return;
233
234 /*
235 * Oops. The kernel tried to access some bad page. We'll have to terminate things
236 * with extreme prejudice.
237 */
238 bust_spinlocks(1);
239
240 if (address < PAGE_SIZE)
241 printk(KERN_ALERT "Unable to handle kernel NULL pointer dereference (address %016lx)\n", address);
242 else
243 printk(KERN_ALERT "Unable to handle kernel paging request at "
244 "virtual address %016lx\n", address);
245 die("Oops", regs, isr);
246 bust_spinlocks(0);
247 do_exit(SIGKILL);
248 return;
249
250 out_of_memory:
251 up_read(&mm->mmap_sem);
252 if (current->pid == 1) {
253 yield();
254 down_read(&mm->mmap_sem);
255 goto survive;
256 }
257 printk(KERN_CRIT "VM: killing process %s\n", current->comm);
258 if (user_mode(regs))
259 do_exit(SIGKILL);
260 goto no_context;
261}