1/* $Id: fault.c,v 1.1.1.1 2007/08/03 18:52:04 Exp $ 2 * 3 * This file is subject to the terms and conditions of the GNU General Public 4 * License. See the file "COPYING" in the main directory of this archive 5 * for more details. 6 * 7 * 8 * Copyright (C) 1995, 1996, 1997, 1998 by Ralf Baechle 9 * Copyright 1999 SuSE GmbH (Philipp Rumpf, prumpf@tux.org) 10 * Copyright 1999 Hewlett Packard Co. 11 * 12 */ 13 14#include <linux/mm.h> 15#include <linux/ptrace.h> 16#include <linux/sched.h> 17#include <linux/interrupt.h> 18#include <linux/module.h> 19 20#include <asm/uaccess.h> 21#include <asm/traps.h> 22 23#define PRINT_USER_FAULTS /* (turn this on if you want user faults to be */ 24 /* dumped to the console via printk) */ 25 26 27/* Various important other fields */ 28#define bit22set(x) (x & 0x00000200) 29#define bits23_25set(x) (x & 0x000001c0) 30#define isGraphicsFlushRead(x) ((x & 0xfc003fdf) == 0x04001a80) 31 /* extended opcode is 0x6a */ 32 33#define BITSSET 0x1c0 /* for identifying LDCW */ 34 35 36DEFINE_PER_CPU(struct exception_data, exception_data); 37 38/* 39 * parisc_acctyp(unsigned int inst) -- 40 * Given a PA-RISC memory access instruction, determine if the 41 * the instruction would perform a memory read or memory write 42 * operation. 43 * 44 * This function assumes that the given instruction is a memory access 45 * instruction (i.e. you should really only call it if you know that 46 * the instruction has generated some sort of a memory access fault). 47 * 48 * Returns: 49 * VM_READ if read operation 50 * VM_WRITE if write operation 51 * VM_EXEC if execute operation 52 */ 53static unsigned long 54parisc_acctyp(unsigned long code, unsigned int inst) 55{ 56 if (code == 6 || code == 16) 57 return VM_EXEC; 58 59 switch (inst & 0xf0000000) { 60 case 0x40000000: /* load */ 61 case 0x50000000: /* new load */ 62 return VM_READ; 63 64 case 0x60000000: /* store */ 65 case 0x70000000: /* new store */ 66 return VM_WRITE; 67 68 case 0x20000000: /* coproc */ 69 case 0x30000000: /* coproc2 */ 70 if (bit22set(inst)) 71 return VM_WRITE; 72 73 case 0x0: /* indexed/memory management */ 74 if (bit22set(inst)) { 75 /* 76 * Check for the 'Graphics Flush Read' instruction. 77 * It resembles an FDC instruction, except for bits 78 * 20 and 21. Any combination other than zero will 79 * utilize the block mover functionality on some 80 * older PA-RISC platforms. The case where a block 81 * move is performed from VM to graphics IO space 82 * should be treated as a READ. 83 * 84 * The significance of bits 20,21 in the FDC 85 * instruction is: 86 * 87 * 00 Flush data cache (normal instruction behavior) 88 * 01 Graphics flush write (IO space -> VM) 89 * 10 Graphics flush read (VM -> IO space) 90 * 11 Graphics flush read/write (VM <-> IO space) 91 */ 92 if (isGraphicsFlushRead(inst)) 93 return VM_READ; 94 return VM_WRITE; 95 } else { 96 /* 97 * Check for LDCWX and LDCWS (semaphore instructions). 98 * If bits 23 through 25 are all 1's it is one of 99 * the above two instructions and is a write. 100 * 101 * Note: With the limited bits we are looking at, 102 * this will also catch PROBEW and PROBEWI. However, 103 * these should never get in here because they don't 104 * generate exceptions of the type: 105 * Data TLB miss fault/data page fault 106 * Data memory protection trap 107 */ 108 if (bits23_25set(inst) == BITSSET) 109 return VM_WRITE; 110 } 111 return VM_READ; /* Default */ 112 } 113 return VM_READ; /* Default */ 114} 115 116#undef bit22set 117#undef bits23_25set 118#undef isGraphicsFlushRead 119#undef BITSSET 120 121 122 123void do_page_fault(struct pt_regs *regs, unsigned long code, 124 unsigned long address) 125{ 126 struct vm_area_struct *vma, *prev_vma; 127 struct task_struct *tsk = current; 128 struct mm_struct *mm = tsk->mm; 129 const struct exception_table_entry *fix; 130 unsigned long acc_type; 131 132 if (in_atomic() || !mm) 133 goto no_context; 134 135 down_read(&mm->mmap_sem); 136 vma = find_vma_prev(mm, address, &prev_vma); 137 if (!vma || address < vma->vm_start) 138 goto check_expansion; 139/* 140 * Ok, we have a good vm_area for this memory access. We still need to 141 * check the access permissions. 142 */ 143 144good_area: 145 146 acc_type = parisc_acctyp(code,regs->iir); 147 148 if ((vma->vm_flags & acc_type) != acc_type) 149 goto bad_area; 150 151 /* 152 * If for any reason at all we couldn't handle the fault, make 153 * sure we exit gracefully rather than endlessly redo the 154 * fault. 155 */ 156 157 switch (handle_mm_fault(mm, vma, address, (acc_type & VM_WRITE) != 0)) { 158 case VM_FAULT_MINOR: 159 ++current->min_flt; 160 break; 161 case VM_FAULT_MAJOR: 162 ++current->maj_flt; 163 break; 164 case VM_FAULT_SIGBUS: 165 /* 166 * We hit a shared mapping outside of the file, or some 167 * other thing happened to us that made us unable to 168 * handle the page fault gracefully. 169 */ 170 goto bad_area; 171 default: 172 goto out_of_memory; 173 } 174 up_read(&mm->mmap_sem); 175 return; 176 177check_expansion: 178 vma = prev_vma; 179 if (vma && (expand_stack(vma, address) == 0)) 180 goto good_area; 181 182/* 183 * Something tried to access memory that isn't in our memory map.. 184 */ 185bad_area: 186 up_read(&mm->mmap_sem); 187 188 if (user_mode(regs)) { 189 struct siginfo si; 190 191#ifdef PRINT_USER_FAULTS 192 printk(KERN_DEBUG "\n"); 193 printk(KERN_DEBUG "do_page_fault() pid=%d command='%s' type=%lu address=0x%08lx\n", 194 tsk->pid, tsk->comm, code, address); 195 if (vma) { 196 printk(KERN_DEBUG "vm_start = 0x%08lx, vm_end = 0x%08lx\n", 197 vma->vm_start, vma->vm_end); 198 } 199 show_regs(regs); 200#endif 201 si.si_signo = SIGSEGV; 202 si.si_errno = 0; 203 si.si_code = SEGV_MAPERR; 204 si.si_addr = (void __user *) address; 205 force_sig_info(SIGSEGV, &si, current); 206 return; 207 } 208 209no_context: 210 211 if (!user_mode(regs)) { 212 fix = search_exception_tables(regs->iaoq[0]); 213 214 if (fix) { 215 struct exception_data *d; 216 217 d = &__get_cpu_var(exception_data); 218 d->fault_ip = regs->iaoq[0]; 219 d->fault_space = regs->isr; 220 d->fault_addr = regs->ior; 221 222 regs->iaoq[0] = ((fix->fixup) & ~3); 223 224 /* 225 * NOTE: In some cases the faulting instruction 226 * may be in the delay slot of a branch. We 227 * don't want to take the branch, so we don't 228 * increment iaoq[1], instead we set it to be 229 * iaoq[0]+4, and clear the B bit in the PSW 230 */ 231 232 regs->iaoq[1] = regs->iaoq[0] + 4; 233 regs->gr[0] &= ~PSW_B; /* IPSW in gr[0] */ 234 235 return; 236 } 237 } 238 239 parisc_terminate("Bad Address (null pointer deref?)", regs, code, address); 240 241 out_of_memory: 242 up_read(&mm->mmap_sem); 243 printk(KERN_CRIT "VM: killing process %s\n", current->comm); 244 if (user_mode(regs)) 245 do_exit(SIGKILL); 246 goto no_context; 247} 248