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 35 DEFINE_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 */ 52 static unsigned long 53 parisc_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 140 141 int 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 } 169 170 void 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 unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE; 179 180 if (in_atomic() || !mm) 181 goto no_context; 182 183 retry: 184 down_read(&mm->mmap_sem); 185 vma = find_vma_prev(mm, address, &prev_vma); 186 if (!vma || address < vma->vm_start) 187 goto check_expansion; 188 /* 189 * Ok, we have a good vm_area for this memory access. We still need to 190 * check the access permissions. 191 */ 192 193 good_area: 194 195 acc_type = parisc_acctyp(code,regs->iir); 196 197 if ((vma->vm_flags & acc_type) != acc_type) 198 goto bad_area; 199 200 /* 201 * If for any reason at all we couldn't handle the fault, make 202 * sure we exit gracefully rather than endlessly redo the 203 * fault. 204 */ 205 206 fault = handle_mm_fault(mm, vma, address, 207 flags | ((acc_type & VM_WRITE) ? FAULT_FLAG_WRITE : 0)); 208 209 if ((fault & VM_FAULT_RETRY) && fatal_signal_pending(current)) 210 return; 211 212 if (unlikely(fault & VM_FAULT_ERROR)) { 213 /* 214 * We hit a shared mapping outside of the file, or some 215 * other thing happened to us that made us unable to 216 * handle the page fault gracefully. 217 */ 218 if (fault & VM_FAULT_OOM) 219 goto out_of_memory; 220 else if (fault & VM_FAULT_SIGBUS) 221 goto bad_area; 222 BUG(); 223 } 224 if (flags & FAULT_FLAG_ALLOW_RETRY) { 225 if (fault & VM_FAULT_MAJOR) 226 current->maj_flt++; 227 else 228 current->min_flt++; 229 if (fault & VM_FAULT_RETRY) { 230 flags &= ~FAULT_FLAG_ALLOW_RETRY; 231 232 /* 233 * No need to up_read(&mm->mmap_sem) as we would 234 * have already released it in __lock_page_or_retry 235 * in mm/filemap.c. 236 */ 237 238 goto retry; 239 } 240 } 241 up_read(&mm->mmap_sem); 242 return; 243 244 check_expansion: 245 vma = prev_vma; 246 if (vma && (expand_stack(vma, address) == 0)) 247 goto good_area; 248 249 /* 250 * Something tried to access memory that isn't in our memory map.. 251 */ 252 bad_area: 253 up_read(&mm->mmap_sem); 254 255 if (user_mode(regs)) { 256 struct siginfo si; 257 258 #ifdef PRINT_USER_FAULTS 259 printk(KERN_DEBUG "\n"); 260 printk(KERN_DEBUG "do_page_fault() pid=%d command='%s' type=%lu address=0x%08lx\n", 261 task_pid_nr(tsk), tsk->comm, code, address); 262 if (vma) { 263 printk(KERN_DEBUG "vm_start = 0x%08lx, vm_end = 0x%08lx\n", 264 vma->vm_start, vma->vm_end); 265 } 266 show_regs(regs); 267 #endif 268 /* FIXME: actually we need to get the signo and code correct */ 269 si.si_signo = SIGSEGV; 270 si.si_errno = 0; 271 si.si_code = SEGV_MAPERR; 272 si.si_addr = (void __user *) address; 273 force_sig_info(SIGSEGV, &si, current); 274 return; 275 } 276 277 no_context: 278 279 if (!user_mode(regs) && fixup_exception(regs)) { 280 return; 281 } 282 283 parisc_terminate("Bad Address (null pointer deref?)", regs, code, address); 284 285 out_of_memory: 286 up_read(&mm->mmap_sem); 287 if (!user_mode(regs)) 288 goto no_context; 289 pagefault_out_of_memory(); 290 } 291