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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
23#include <asm/pgtable.h>
24#include <asm/uaccess.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 siginfo_t info;
38 pgd_t *pge;
39 pud_t *pue;
40 pte_t *pte;
41 int write;
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 (in_atomic() || !mm)
82 goto no_context;
83
84 down_read(&mm->mmap_sem);
85
86 vma = find_vma(mm, ear0);
87 if (!vma)
88 goto bad_area;
89 if (vma->vm_start <= ear0)
90 goto good_area;
91 if (!(vma->vm_flags & VM_GROWSDOWN))
92 goto bad_area;
93
94 if (user_mode(__frame)) {
95 /*
96 * accessing the stack below %esp is always a bug.
97 * The "+ 32" is there due to some instructions (like
98 * pusha) doing post-decrement on the stack and that
99 * doesn't show up until later..
100 */
101 if ((ear0 & PAGE_MASK) + 2 * PAGE_SIZE < __frame->sp) {
102#if 0
103 printk("[%d] ### Access below stack @%lx (sp=%lx)\n",
104 current->pid, ear0, __frame->sp);
105 show_registers(__frame);
106 printk("[%d] ### Code: [%08lx] %02x %02x %02x %02x %02x %02x %02x %02x\n",
107 current->pid,
108 __frame->pc,
109 ((u8*)__frame->pc)[0],
110 ((u8*)__frame->pc)[1],
111 ((u8*)__frame->pc)[2],
112 ((u8*)__frame->pc)[3],
113 ((u8*)__frame->pc)[4],
114 ((u8*)__frame->pc)[5],
115 ((u8*)__frame->pc)[6],
116 ((u8*)__frame->pc)[7]
117 );
118#endif
119 goto bad_area;
120 }
121 }
122
123 if (expand_stack(vma, ear0))
124 goto bad_area;
125
126/*
127 * Ok, we have a good vm_area for this memory access, so
128 * we can handle it..
129 */
130 good_area:
131 info.si_code = SEGV_ACCERR;
132 write = 0;
133 switch (esr0 & ESR0_ATXC) {
134 default:
135 /* handle write to write protected page */
136 case ESR0_ATXC_WP_EXCEP:
137#ifdef TEST_VERIFY_AREA
138 if (!(user_mode(__frame)))
139 printk("WP fault at %08lx\n", __frame->pc);
140#endif
141 if (!(vma->vm_flags & VM_WRITE))
142 goto bad_area;
143 write = 1;
144 break;
145
146 /* handle read from protected page */
147 case ESR0_ATXC_PRIV_EXCEP:
148 goto bad_area;
149
150 /* handle read, write or exec on absent page
151 * - can't support write without permitting read
152 * - don't support execute without permitting read and vice-versa
153 */
154 case ESR0_ATXC_AMRTLB_MISS:
155 if (!(vma->vm_flags & (VM_READ | VM_WRITE | VM_EXEC)))
156 goto bad_area;
157 break;
158 }
159
160 /*
161 * If for any reason at all we couldn't handle the fault,
162 * make sure we exit gracefully rather than endlessly redo
163 * the fault.
164 */
165 fault = handle_mm_fault(mm, vma, ear0, write ? FAULT_FLAG_WRITE : 0);
166 if (unlikely(fault & VM_FAULT_ERROR)) {
167 if (fault & VM_FAULT_OOM)
168 goto out_of_memory;
169 else if (fault & VM_FAULT_SIGBUS)
170 goto do_sigbus;
171 BUG();
172 }
173 if (fault & VM_FAULT_MAJOR)
174 current->maj_flt++;
175 else
176 current->min_flt++;
177
178 up_read(&mm->mmap_sem);
179 return;
180
181/*
182 * Something tried to access memory that isn't in our memory map..
183 * Fix it, but check if it's kernel or user first..
184 */
185 bad_area:
186 up_read(&mm->mmap_sem);
187
188 /* User mode accesses just cause a SIGSEGV */
189 if (user_mode(__frame)) {
190 info.si_signo = SIGSEGV;
191 info.si_errno = 0;
192 /* info.si_code has been set above */
193 info.si_addr = (void *) ear0;
194 force_sig_info(SIGSEGV, &info, current);
195 return;
196 }
197
198 no_context:
199 /* are we prepared to handle this kernel fault? */
200 if ((fixup = search_exception_table(__frame->pc)) != 0) {
201 __frame->pc = fixup;
202 return;
203 }
204
205/*
206 * Oops. The kernel tried to access some bad page. We'll have to
207 * terminate things with extreme prejudice.
208 */
209
210 bust_spinlocks(1);
211
212 if (ear0 < PAGE_SIZE)
213 printk(KERN_ALERT "Unable to handle kernel NULL pointer dereference");
214 else
215 printk(KERN_ALERT "Unable to handle kernel paging request");
216 printk(" at virtual addr %08lx\n", ear0);
217 printk(" PC : %08lx\n", __frame->pc);
218 printk(" EXC : esr0=%08lx ear0=%08lx\n", esr0, ear0);
219
220 asm("lrai %1,%0,#1,#0,#0" : "=&r"(lrai) : "r"(ear0));
221 asm("lrad %1,%0,#1,#0,#0" : "=&r"(lrad) : "r"(ear0));
222
223 printk(KERN_ALERT " LRAI: %08lx\n", lrai);
224 printk(KERN_ALERT " LRAD: %08lx\n", lrad);
225
226 __break_hijack_kernel_event();
227
228 pge = pgd_offset(current->mm, ear0);
229 pue = pud_offset(pge, ear0);
230 _pme = pue->pue[0].ste[0];
231
232 printk(KERN_ALERT " PGE : %8p { PME %08lx }\n", pge, _pme);
233
234 if (_pme & xAMPRx_V) {
235 unsigned long dampr, damlr, val;
236
237 asm volatile("movsg dampr2,%0 ! movgs %2,dampr2 ! movsg damlr2,%1"
238 : "=&r"(dampr), "=r"(damlr)
239 : "r" (_pme | xAMPRx_L|xAMPRx_SS_16Kb|xAMPRx_S|xAMPRx_C|xAMPRx_V)
240 );
241
242 pte = (pte_t *) damlr + __pte_index(ear0);
243 val = pte_val(*pte);
244
245 asm volatile("movgs %0,dampr2" :: "r" (dampr));
246
247 printk(KERN_ALERT " PTE : %8p { %08lx }\n", pte, val);
248 }
249
250 die_if_kernel("Oops\n");
251 do_exit(SIGKILL);
252
253/*
254 * We ran out of memory, or some other thing happened to us that made
255 * us unable to handle the page fault gracefully.
256 */
257 out_of_memory:
258 up_read(&mm->mmap_sem);
259 if (!user_mode(__frame))
260 goto no_context;
261 pagefault_out_of_memory();
262 return;
263
264 do_sigbus:
265 up_read(&mm->mmap_sem);
266
267 /*
268 * Send a sigbus, regardless of whether we were in kernel
269 * or user mode.
270 */
271 info.si_signo = SIGBUS;
272 info.si_errno = 0;
273 info.si_code = BUS_ADRERR;
274 info.si_addr = (void *) ear0;
275 force_sig_info(SIGBUS, &info, current);
276
277 /* Kernel mode? Handle exceptions or die */
278 if (!user_mode(__frame))
279 goto no_context;
280 return;
281
282/*
283 * The fault was caused by a kernel PTE (such as installed by vmalloc or kmap)
284 */
285 kernel_pte_fault:
286 {
287 /*
288 * Synchronize this task's top level page-table
289 * with the 'reference' page table.
290 *
291 * Do _not_ use "tsk" here. We might be inside
292 * an interrupt in the middle of a task switch..
293 */
294 int index = pgd_index(ear0);
295 pgd_t *pgd, *pgd_k;
296 pud_t *pud, *pud_k;
297 pmd_t *pmd, *pmd_k;
298 pte_t *pte_k;
299
300 pgd = (pgd_t *) __get_TTBR();
301 pgd = (pgd_t *)__va(pgd) + index;
302 pgd_k = ((pgd_t *)(init_mm.pgd)) + index;
303
304 if (!pgd_present(*pgd_k))
305 goto no_context;
306 //set_pgd(pgd, *pgd_k); /////// gcc ICE's on this line
307
308 pud_k = pud_offset(pgd_k, ear0);
309 if (!pud_present(*pud_k))
310 goto no_context;
311
312 pmd_k = pmd_offset(pud_k, ear0);
313 if (!pmd_present(*pmd_k))
314 goto no_context;
315
316 pud = pud_offset(pgd, ear0);
317 pmd = pmd_offset(pud, ear0);
318 set_pmd(pmd, *pmd_k);
319
320 pte_k = pte_offset_kernel(pmd_k, ear0);
321 if (!pte_present(*pte_k))
322 goto no_context;
323 return;
324 }
325} /* end do_page_fault() */