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