/arch/parisc/mm/fault.c

  1/*
  2 * This file is subject to the terms and conditions of the GNU General Public
  3 * License.  See the file "COPYING" in the main directory of this archive
  4 * for more details.
  5 *
  6 *
  7 * Copyright (C) 1995, 1996, 1997, 1998 by Ralf Baechle
  8 * Copyright 1999 SuSE GmbH (Philipp Rumpf, prumpf@tux.org)
  9 * Copyright 1999 Hewlett Packard Co.
 10 *
 11 */
 12
 13#include <linux/mm.h>
 14#include <linux/ptrace.h>
 15#include <linux/sched.h>
 16#include <linux/interrupt.h>
 17#include <linux/module.h>
 18
 19#include <asm/uaccess.h>
 20#include <asm/traps.h>
 21
 22#define PRINT_USER_FAULTS /* (turn this on if you want user faults to be */
 23			 /*  dumped to the console via printk)          */
 24
 25
 26/* Various important other fields */
 27#define bit22set(x)		(x & 0x00000200)
 28#define bits23_25set(x)		(x & 0x000001c0)
 29#define isGraphicsFlushRead(x)	((x & 0xfc003fdf) == 0x04001a80)
 30				/* extended opcode is 0x6a */
 31
 32#define BITSSET		0x1c0	/* for identifying LDCW */
 33
 34
 35DEFINE_PER_CPU(struct exception_data, exception_data);
 36
 37/*
 38 * parisc_acctyp(unsigned int inst) --
 39 *    Given a PA-RISC memory access instruction, determine if the
 40 *    the instruction would perform a memory read or memory write
 41 *    operation.
 42 *
 43 *    This function assumes that the given instruction is a memory access
 44 *    instruction (i.e. you should really only call it if you know that
 45 *    the instruction has generated some sort of a memory access fault).
 46 *
 47 * Returns:
 48 *   VM_READ  if read operation
 49 *   VM_WRITE if write operation
 50 *   VM_EXEC  if execute operation
 51 */
 52static unsigned long
 53parisc_acctyp(unsigned long code, unsigned int inst)
 54{
 55	if (code == 6 || code == 16)
 56	    return VM_EXEC;
 57
 58	switch (inst & 0xf0000000) {
 59	case 0x40000000: /* load */
 60	case 0x50000000: /* new load */
 61		return VM_READ;
 62
 63	case 0x60000000: /* store */
 64	case 0x70000000: /* new store */
 65		return VM_WRITE;
 66
 67	case 0x20000000: /* coproc */
 68	case 0x30000000: /* coproc2 */
 69		if (bit22set(inst))
 70			return VM_WRITE;
 71
 72	case 0x0: /* indexed/memory management */
 73		if (bit22set(inst)) {
 74			/*
 75			 * Check for the 'Graphics Flush Read' instruction.
 76			 * It resembles an FDC instruction, except for bits
 77			 * 20 and 21. Any combination other than zero will
 78			 * utilize the block mover functionality on some
 79			 * older PA-RISC platforms.  The case where a block
 80			 * move is performed from VM to graphics IO space
 81			 * should be treated as a READ.
 82			 *
 83			 * The significance of bits 20,21 in the FDC
 84			 * instruction is:
 85			 *
 86			 *   00  Flush data cache (normal instruction behavior)
 87			 *   01  Graphics flush write  (IO space -> VM)
 88			 *   10  Graphics flush read   (VM -> IO space)
 89			 *   11  Graphics flush read/write (VM <-> IO space)
 90			 */
 91			if (isGraphicsFlushRead(inst))
 92				return VM_READ;
 93			return VM_WRITE;
 94		} else {
 95			/*
 96			 * Check for LDCWX and LDCWS (semaphore instructions).
 97			 * If bits 23 through 25 are all 1's it is one of
 98			 * the above two instructions and is a write.
 99			 *
100			 * Note: With the limited bits we are looking at,
101			 * this will also catch PROBEW and PROBEWI. However,
102			 * these should never get in here because they don't
103			 * generate exceptions of the type:
104			 *   Data TLB miss fault/data page fault
105			 *   Data memory protection trap
106			 */
107			if (bits23_25set(inst) == BITSSET)
108				return VM_WRITE;
109		}
110		return VM_READ; /* Default */
111	}
112	return VM_READ; /* Default */
113}
114
115#undef bit22set
116#undef bits23_25set
117#undef isGraphicsFlushRead
118#undef BITSSET
119
120
121#if 0
122/* This is the treewalk to find a vma which is the highest that has
123 * a start < addr.  We're using find_vma_prev instead right now, but
124 * we might want to use this at some point in the future.  Probably
125 * not, but I want it committed to CVS so I don't lose it :-)
126 */
127			while (tree != vm_avl_empty) {
128				if (tree->vm_start > addr) {
129					tree = tree->vm_avl_left;
130				} else {
131					prev = tree;
132					if (prev->vm_next == NULL)
133						break;
134					if (prev->vm_next->vm_start > addr)
135						break;
136					tree = tree->vm_avl_right;
137				}
138			}
139#endif
140
141int fixup_exception(struct pt_regs *regs)
142{
143	const struct exception_table_entry *fix;
144
145	fix = search_exception_tables(regs->iaoq[0]);
146	if (fix) {
147		struct exception_data *d;
148		d = &__get_cpu_var(exception_data);
149		d->fault_ip = regs->iaoq[0];
150		d->fault_space = regs->isr;
151		d->fault_addr = regs->ior;
152
153		regs->iaoq[0] = ((fix->fixup) & ~3);
154		/*
155		 * NOTE: In some cases the faulting instruction
156		 * may be in the delay slot of a branch. We
157		 * don't want to take the branch, so we don't
158		 * increment iaoq[1], instead we set it to be
159		 * iaoq[0]+4, and clear the B bit in the PSW
160		 */
161		regs->iaoq[1] = regs->iaoq[0] + 4;
162		regs->gr[0] &= ~PSW_B; /* IPSW in gr[0] */
163
164		return 1;
165	}
166
167	return 0;
168}
169
170void do_page_fault(struct pt_regs *regs, unsigned long code,
171			      unsigned long address)
172{
173	struct vm_area_struct *vma, *prev_vma;
174	struct task_struct *tsk = current;
175	struct mm_struct *mm = tsk->mm;
176	unsigned long acc_type;
177	int fault;
178
179	if (in_atomic() || !mm)
180		goto no_context;
181
182	down_read(&mm->mmap_sem);
183	vma = find_vma_prev(mm, address, &prev_vma);
184	if (!vma || address < vma->vm_start)
185		goto check_expansion;
186/*
187 * Ok, we have a good vm_area for this memory access. We still need to
188 * check the access permissions.
189 */
190
191good_area:
192
193	acc_type = parisc_acctyp(code,regs->iir);
194
195	if ((vma->vm_flags & acc_type) != acc_type)
196		goto bad_area;
197
198	/*
199	 * If for any reason at all we couldn't handle the fault, make
200	 * sure we exit gracefully rather than endlessly redo the
201	 * fault.
202	 */
203
204	fault = handle_mm_fault(mm, vma, address, (acc_type & VM_WRITE) ? FAULT_FLAG_WRITE : 0);
205	if (unlikely(fault & VM_FAULT_ERROR)) {
206		/*
207		 * We hit a shared mapping outside of the file, or some
208		 * other thing happened to us that made us unable to
209		 * handle the page fault gracefully.
210		 */
211		if (fault & VM_FAULT_OOM)
212			goto out_of_memory;
213		else if (fault & VM_FAULT_SIGBUS)
214			goto bad_area;
215		BUG();
216	}
217	if (fault & VM_FAULT_MAJOR)
218		current->maj_flt++;
219	else
220		current->min_flt++;
221	up_read(&mm->mmap_sem);
222	return;
223
224check_expansion:
225	vma = prev_vma;
226	if (vma && (expand_stack(vma, address) == 0))
227		goto good_area;
228
229/*
230 * Something tried to access memory that isn't in our memory map..
231 */
232bad_area:
233	up_read(&mm->mmap_sem);
234
235	if (user_mode(regs)) {
236		struct siginfo si;
237
238#ifdef PRINT_USER_FAULTS
239		printk(KERN_DEBUG "\n");
240		printk(KERN_DEBUG "do_page_fault() pid=%d command='%s' type=%lu address=0x%08lx\n",
241		    task_pid_nr(tsk), tsk->comm, code, address);
242		if (vma) {
243			printk(KERN_DEBUG "vm_start = 0x%08lx, vm_end = 0x%08lx\n",
244					vma->vm_start, vma->vm_end);
245		}
246		show_regs(regs);
247#endif
248		/* FIXME: actually we need to get the signo and code correct */
249		si.si_signo = SIGSEGV;
250		si.si_errno = 0;
251		si.si_code = SEGV_MAPERR;
252		si.si_addr = (void __user *) address;
253		force_sig_info(SIGSEGV, &si, current);
254		return;
255	}
256
257no_context:
258
259	if (!user_mode(regs) && fixup_exception(regs)) {
260		return;
261	}
262
263	parisc_terminate("Bad Address (null pointer deref?)", regs, code, address);
264
265  out_of_memory:
266	up_read(&mm->mmap_sem);
267	if (!user_mode(regs))
268		goto no_context;
269	pagefault_out_of_memory();
270}