1 /* $Id: fault.c,v 1.5 2000/01/26 16:20:29 jsm 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 36 DEFINE_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 */ 53 static unsigned long 54 parisc_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 #if 0 123 /* This is the treewalk to find a vma which is the highest that has 124 * a start < addr. We're using find_vma_prev instead right now, but 125 * we might want to use this at some point in the future. Probably 126 * not, but I want it committed to CVS so I don't lose it :-) 127 */ 128 while (tree != vm_avl_empty) { 129 if (tree->vm_start > addr) { 130 tree = tree->vm_avl_left; 131 } else { 132 prev = tree; 133 if (prev->vm_next == NULL) 134 break; 135 if (prev->vm_next->vm_start > addr) 136 break; 137 tree = tree->vm_avl_right; 138 } 139 } 140 #endif 141 142 void do_page_fault(struct pt_regs *regs, unsigned long code, 143 unsigned long address) 144 { 145 struct vm_area_struct *vma, *prev_vma; 146 struct task_struct *tsk = current; 147 struct mm_struct *mm = tsk->mm; 148 const struct exception_table_entry *fix; 149 unsigned long acc_type; 150 151 if (in_atomic() || !mm) 152 goto no_context; 153 154 down_read(&mm->mmap_sem); 155 vma = find_vma_prev(mm, address, &prev_vma); 156 if (!vma || address < vma->vm_start) 157 goto check_expansion; 158 /* 159 * Ok, we have a good vm_area for this memory access. We still need to 160 * check the access permissions. 161 */ 162 163 good_area: 164 165 acc_type = parisc_acctyp(code,regs->iir); 166 167 if ((vma->vm_flags & acc_type) != acc_type) 168 goto bad_area; 169 170 /* 171 * If for any reason at all we couldn't handle the fault, make 172 * sure we exit gracefully rather than endlessly redo the 173 * fault. 174 */ 175 176 switch (handle_mm_fault(mm, vma, address, (acc_type & VM_WRITE) != 0)) { 177 case VM_FAULT_MINOR: 178 ++current->min_flt; 179 break; 180 case VM_FAULT_MAJOR: 181 ++current->maj_flt; 182 break; 183 case VM_FAULT_SIGBUS: 184 /* 185 * We hit a shared mapping outside of the file, or some 186 * other thing happened to us that made us unable to 187 * handle the page fault gracefully. 188 */ 189 goto bad_area; 190 default: 191 goto out_of_memory; 192 } 193 up_read(&mm->mmap_sem); 194 return; 195 196 check_expansion: 197 vma = prev_vma; 198 if (vma && (expand_stack(vma, address) == 0)) 199 goto good_area; 200 201 /* 202 * Something tried to access memory that isn't in our memory map.. 203 */ 204 bad_area: 205 up_read(&mm->mmap_sem); 206 207 if (user_mode(regs)) { 208 struct siginfo si; 209 210 #ifdef PRINT_USER_FAULTS 211 printk(KERN_DEBUG "\n"); 212 printk(KERN_DEBUG "do_page_fault() pid=%d command='%s' type=%lu address=0x%08lx\n", 213 tsk->pid, tsk->comm, code, address); 214 if (vma) { 215 printk(KERN_DEBUG "vm_start = 0x%08lx, vm_end = 0x%08lx\n", 216 vma->vm_start, vma->vm_end); 217 } 218 show_regs(regs); 219 #endif 220 /* FIXME: actually we need to get the signo and code correct */ 221 si.si_signo = SIGSEGV; 222 si.si_errno = 0; 223 si.si_code = SEGV_MAPERR; 224 si.si_addr = (void __user *) address; 225 force_sig_info(SIGSEGV, &si, current); 226 return; 227 } 228 229 no_context: 230 231 if (!user_mode(regs)) { 232 fix = search_exception_tables(regs->iaoq[0]); 233 234 if (fix) { 235 struct exception_data *d; 236 237 d = &__get_cpu_var(exception_data); 238 d->fault_ip = regs->iaoq[0]; 239 d->fault_space = regs->isr; 240 d->fault_addr = regs->ior; 241 242 regs->iaoq[0] = ((fix->fixup) & ~3); 243 244 /* 245 * NOTE: In some cases the faulting instruction 246 * may be in the delay slot of a branch. We 247 * don't want to take the branch, so we don't 248 * increment iaoq[1], instead we set it to be 249 * iaoq[0]+4, and clear the B bit in the PSW 250 */ 251 252 regs->iaoq[1] = regs->iaoq[0] + 4; 253 regs->gr[0] &= ~PSW_B; /* IPSW in gr[0] */ 254 255 return; 256 } 257 } 258 259 parisc_terminate("Bad Address (null pointer deref?)", regs, code, address); 260 261 out_of_memory: 262 up_read(&mm->mmap_sem); 263 printk(KERN_CRIT "VM: killing process %s\n", current->comm); 264 if (user_mode(regs)) 265 do_exit(SIGKILL); 266 goto no_context; 267 } 268