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1/*
2 * linux/arch/frv/mm/fault.c
3 *
4 * Copyright (C) 2003 Red Hat, Inc. All Rights Reserved.
5 * - Written by David Howells (dhowells@redhat.com)
6 * - Derived from arch/m68knommu/mm/fault.c
7 * - Copyright (C) 1998 D. Jeff Dionne <jeff@lineo.ca>,
8 * - Copyright (C) 2000 Lineo, Inc. (www.lineo.com)
9 *
10 * Based on:
11 *
12 * linux/arch/m68k/mm/fault.c
13 *
14 * Copyright (C) 1995 Hamish Macdonald
15 */
16
17#include <linux/mman.h>
18#include <linux/mm.h>
19#include <linux/kernel.h>
20#include <linux/ptrace.h>
21#include <linux/hardirq.h>
22#include <linux/uaccess.h>
23
24#include <asm/pgtable.h>
25#include <asm/gdb-stub.h>
26
27/*****************************************************************************/
28/*
29 * This routine handles page faults. It determines the problem, and
30 * then passes it off to one of the appropriate routines.
31 */
32asmlinkage void do_page_fault(int datammu, unsigned long esr0, unsigned long ear0)
33{
34 struct vm_area_struct *vma;
35 struct mm_struct *mm;
36 unsigned long _pme, lrai, lrad, fixup;
37 unsigned long flags = 0;
38 siginfo_t info;
39 pgd_t *pge;
40 pud_t *pue;
41 pte_t *pte;
42 int fault;
43
44#if 0
45 const char *atxc[16] = {
46 [0x0] = "mmu-miss", [0x8] = "multi-dat", [0x9] = "multi-sat",
47 [0xa] = "tlb-miss", [0xc] = "privilege", [0xd] = "write-prot",
48 };
49
50 printk("do_page_fault(%d,%lx [%s],%lx)\n",
51 datammu, esr0, atxc[esr0 >> 20 & 0xf], ear0);
52#endif
53
54 mm = current->mm;
55
56 /*
57 * We fault-in kernel-space virtual memory on-demand. The
58 * 'reference' page table is init_mm.pgd.
59 *
60 * NOTE! We MUST NOT take any locks for this case. We may
61 * be in an interrupt or a critical region, and should
62 * only copy the information from the master page table,
63 * nothing more.
64 *
65 * This verifies that the fault happens in kernel space
66 * and that the fault was a page not present (invalid) error
67 */
68 if (!user_mode(__frame) && (esr0 & ESR0_ATXC) == ESR0_ATXC_AMRTLB_MISS) {
69 if (ear0 >= VMALLOC_START && ear0 < VMALLOC_END)
70 goto kernel_pte_fault;
71 if (ear0 >= PKMAP_BASE && ear0 < PKMAP_END)
72 goto kernel_pte_fault;
73 }
74
75 info.si_code = SEGV_MAPERR;
76
77 /*
78 * If we're in an interrupt or have no user
79 * context, we must not take the fault..
80 */
81 if (faulthandler_disabled() || !mm)
82 goto no_context;
83
84 if (user_mode(__frame))
85 flags |= FAULT_FLAG_USER;
86
87 down_read(&mm->mmap_sem);
88
89 vma = find_vma(mm, ear0);
90 if (!vma)
91 goto bad_area;
92 if (vma->vm_start <= ear0)
93 goto good_area;
94 if (!(vma->vm_flags & VM_GROWSDOWN))
95 goto bad_area;
96
97 if (user_mode(__frame)) {
98 /*
99 * accessing the stack below %esp is always a bug.
100 * The "+ 32" is there due to some instructions (like
101 * pusha) doing post-decrement on the stack and that
102 * doesn't show up until later..
103 */
104 if ((ear0 & PAGE_MASK) + 2 * PAGE_SIZE < __frame->sp) {
105#if 0
106 printk("[%d] ### Access below stack @%lx (sp=%lx)\n",
107 current->pid, ear0, __frame->sp);
108 show_registers(__frame);
109 printk("[%d] ### Code: [%08lx] %02x %02x %02x %02x %02x %02x %02x %02x\n",
110 current->pid,
111 __frame->pc,
112 ((u8*)__frame->pc)[0],
113 ((u8*)__frame->pc)[1],
114 ((u8*)__frame->pc)[2],
115 ((u8*)__frame->pc)[3],
116 ((u8*)__frame->pc)[4],
117 ((u8*)__frame->pc)[5],
118 ((u8*)__frame->pc)[6],
119 ((u8*)__frame->pc)[7]
120 );
121#endif
122 goto bad_area;
123 }
124 }
125
126 if (expand_stack(vma, ear0))
127 goto bad_area;
128
129/*
130 * Ok, we have a good vm_area for this memory access, so
131 * we can handle it..
132 */
133 good_area:
134 info.si_code = SEGV_ACCERR;
135 switch (esr0 & ESR0_ATXC) {
136 default:
137 /* handle write to write protected page */
138 case ESR0_ATXC_WP_EXCEP:
139#ifdef TEST_VERIFY_AREA
140 if (!(user_mode(__frame)))
141 printk("WP fault at %08lx\n", __frame->pc);
142#endif
143 if (!(vma->vm_flags & VM_WRITE))
144 goto bad_area;
145 flags |= FAULT_FLAG_WRITE;
146 break;
147
148 /* handle read from protected page */
149 case ESR0_ATXC_PRIV_EXCEP:
150 goto bad_area;
151
152 /* handle read, write or exec on absent page
153 * - can't support write without permitting read
154 * - don't support execute without permitting read and vice-versa
155 */
156 case ESR0_ATXC_AMRTLB_MISS:
157 if (!(vma->vm_flags & (VM_READ | VM_WRITE | VM_EXEC)))
158 goto bad_area;
159 break;
160 }
161
162 /*
163 * If for any reason at all we couldn't handle the fault,
164 * make sure we exit gracefully rather than endlessly redo
165 * the fault.
166 */
167 fault = handle_mm_fault(mm, vma, ear0, flags);
168 if (unlikely(fault & VM_FAULT_ERROR)) {
169 if (fault & VM_FAULT_OOM)
170 goto out_of_memory;
171 else if (fault & VM_FAULT_SIGSEGV)
172 goto bad_area;
173 else if (fault & VM_FAULT_SIGBUS)
174 goto do_sigbus;
175 BUG();
176 }
177 if (fault & VM_FAULT_MAJOR)
178 current->maj_flt++;
179 else
180 current->min_flt++;
181
182 up_read(&mm->mmap_sem);
183 return;
184
185/*
186 * Something tried to access memory that isn't in our memory map..
187 * Fix it, but check if it's kernel or user first..
188 */
189 bad_area:
190 up_read(&mm->mmap_sem);
191
192 /* User mode accesses just cause a SIGSEGV */
193 if (user_mode(__frame)) {
194 info.si_signo = SIGSEGV;
195 info.si_errno = 0;
196 /* info.si_code has been set above */
197 info.si_addr = (void *) ear0;
198 force_sig_info(SIGSEGV, &info, current);
199 return;
200 }
201
202 no_context:
203 /* are we prepared to handle this kernel fault? */
204 if ((fixup = search_exception_table(__frame->pc)) != 0) {
205 __frame->pc = fixup;
206 return;
207 }
208
209/*
210 * Oops. The kernel tried to access some bad page. We'll have to
211 * terminate things with extreme prejudice.
212 */
213
214 bust_spinlocks(1);
215
216 if (ear0 < PAGE_SIZE)
217 printk(KERN_ALERT "Unable to handle kernel NULL pointer dereference");
218 else
219 printk(KERN_ALERT "Unable to handle kernel paging request");
220 printk(" at virtual addr %08lx\n", ear0);
221 printk(" PC : %08lx\n", __frame->pc);
222 printk(" EXC : esr0=%08lx ear0=%08lx\n", esr0, ear0);
223
224 asm("lrai %1,%0,#1,#0,#0" : "=&r"(lrai) : "r"(ear0));
225 asm("lrad %1,%0,#1,#0,#0" : "=&r"(lrad) : "r"(ear0));
226
227 printk(KERN_ALERT " LRAI: %08lx\n", lrai);
228 printk(KERN_ALERT " LRAD: %08lx\n", lrad);
229
230 __break_hijack_kernel_event();
231
232 pge = pgd_offset(current->mm, ear0);
233 pue = pud_offset(pge, ear0);
234 _pme = pue->pue[0].ste[0];
235
236 printk(KERN_ALERT " PGE : %8p { PME %08lx }\n", pge, _pme);
237
238 if (_pme & xAMPRx_V) {
239 unsigned long dampr, damlr, val;
240
241 asm volatile("movsg dampr2,%0 ! movgs %2,dampr2 ! movsg damlr2,%1"
242 : "=&r"(dampr), "=r"(damlr)
243 : "r" (_pme | xAMPRx_L|xAMPRx_SS_16Kb|xAMPRx_S|xAMPRx_C|xAMPRx_V)
244 );
245
246 pte = (pte_t *) damlr + __pte_index(ear0);
247 val = pte_val(*pte);
248
249 asm volatile("movgs %0,dampr2" :: "r" (dampr));
250
251 printk(KERN_ALERT " PTE : %8p { %08lx }\n", pte, val);
252 }
253
254 die_if_kernel("Oops\n");
255 do_exit(SIGKILL);
256
257/*
258 * We ran out of memory, or some other thing happened to us that made
259 * us unable to handle the page fault gracefully.
260 */
261 out_of_memory:
262 up_read(&mm->mmap_sem);
263 if (!user_mode(__frame))
264 goto no_context;
265 pagefault_out_of_memory();
266 return;
267
268 do_sigbus:
269 up_read(&mm->mmap_sem);
270
271 /*
272 * Send a sigbus, regardless of whether we were in kernel
273 * or user mode.
274 */
275 info.si_signo = SIGBUS;
276 info.si_errno = 0;
277 info.si_code = BUS_ADRERR;
278 info.si_addr = (void *) ear0;
279 force_sig_info(SIGBUS, &info, current);
280
281 /* Kernel mode? Handle exceptions or die */
282 if (!user_mode(__frame))
283 goto no_context;
284 return;
285
286/*
287 * The fault was caused by a kernel PTE (such as installed by vmalloc or kmap)
288 */
289 kernel_pte_fault:
290 {
291 /*
292 * Synchronize this task's top level page-table
293 * with the 'reference' page table.
294 *
295 * Do _not_ use "tsk" here. We might be inside
296 * an interrupt in the middle of a task switch..
297 */
298 int index = pgd_index(ear0);
299 pgd_t *pgd, *pgd_k;
300 pud_t *pud, *pud_k;
301 pmd_t *pmd, *pmd_k;
302 pte_t *pte_k;
303
304 pgd = (pgd_t *) __get_TTBR();
305 pgd = (pgd_t *)__va(pgd) + index;
306 pgd_k = ((pgd_t *)(init_mm.pgd)) + index;
307
308 if (!pgd_present(*pgd_k))
309 goto no_context;
310 //set_pgd(pgd, *pgd_k); /////// gcc ICE's on this line
311
312 pud_k = pud_offset(pgd_k, ear0);
313 if (!pud_present(*pud_k))
314 goto no_context;
315
316 pmd_k = pmd_offset(pud_k, ear0);
317 if (!pmd_present(*pmd_k))
318 goto no_context;
319
320 pud = pud_offset(pgd, ear0);
321 pmd = pmd_offset(pud, ear0);
322 set_pmd(pmd, *pmd_k);
323
324 pte_k = pte_offset_kernel(pmd_k, ear0);
325 if (!pte_present(*pte_k))
326 goto no_context;
327 return;
328 }
329} /* end do_page_fault() */