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 #include <linux/uaccess.h> 19 20 #include <asm/traps.h> 21 22 /* Various important other fields */ 23 #define bit22set(x) (x & 0x00000200) 24 #define bits23_25set(x) (x & 0x000001c0) 25 #define isGraphicsFlushRead(x) ((x & 0xfc003fdf) == 0x04001a80) 26 /* extended opcode is 0x6a */ 27 28 #define BITSSET 0x1c0 /* for identifying LDCW */ 29 30 31 DEFINE_PER_CPU(struct exception_data, exception_data); 32 33 int show_unhandled_signals = 1; 34 35 /* 36 * parisc_acctyp(unsigned int inst) -- 37 * Given a PA-RISC memory access instruction, determine if the 38 * the instruction would perform a memory read or memory write 39 * operation. 40 * 41 * This function assumes that the given instruction is a memory access 42 * instruction (i.e. you should really only call it if you know that 43 * the instruction has generated some sort of a memory access fault). 44 * 45 * Returns: 46 * VM_READ if read operation 47 * VM_WRITE if write operation 48 * VM_EXEC if execute operation 49 */ 50 static unsigned long 51 parisc_acctyp(unsigned long code, unsigned int inst) 52 { 53 if (code == 6 || code == 16) 54 return VM_EXEC; 55 56 switch (inst & 0xf0000000) { 57 case 0x40000000: /* load */ 58 case 0x50000000: /* new load */ 59 return VM_READ; 60 61 case 0x60000000: /* store */ 62 case 0x70000000: /* new store */ 63 return VM_WRITE; 64 65 case 0x20000000: /* coproc */ 66 case 0x30000000: /* coproc2 */ 67 if (bit22set(inst)) 68 return VM_WRITE; 69 70 case 0x0: /* indexed/memory management */ 71 if (bit22set(inst)) { 72 /* 73 * Check for the 'Graphics Flush Read' instruction. 74 * It resembles an FDC instruction, except for bits 75 * 20 and 21. Any combination other than zero will 76 * utilize the block mover functionality on some 77 * older PA-RISC platforms. The case where a block 78 * move is performed from VM to graphics IO space 79 * should be treated as a READ. 80 * 81 * The significance of bits 20,21 in the FDC 82 * instruction is: 83 * 84 * 00 Flush data cache (normal instruction behavior) 85 * 01 Graphics flush write (IO space -> VM) 86 * 10 Graphics flush read (VM -> IO space) 87 * 11 Graphics flush read/write (VM <-> IO space) 88 */ 89 if (isGraphicsFlushRead(inst)) 90 return VM_READ; 91 return VM_WRITE; 92 } else { 93 /* 94 * Check for LDCWX and LDCWS (semaphore instructions). 95 * If bits 23 through 25 are all 1's it is one of 96 * the above two instructions and is a write. 97 * 98 * Note: With the limited bits we are looking at, 99 * this will also catch PROBEW and PROBEWI. However, 100 * these should never get in here because they don't 101 * generate exceptions of the type: 102 * Data TLB miss fault/data page fault 103 * Data memory protection trap 104 */ 105 if (bits23_25set(inst) == BITSSET) 106 return VM_WRITE; 107 } 108 return VM_READ; /* Default */ 109 } 110 return VM_READ; /* Default */ 111 } 112 113 #undef bit22set 114 #undef bits23_25set 115 #undef isGraphicsFlushRead 116 #undef BITSSET 117 118 119 #if 0 120 /* This is the treewalk to find a vma which is the highest that has 121 * a start < addr. We're using find_vma_prev instead right now, but 122 * we might want to use this at some point in the future. Probably 123 * not, but I want it committed to CVS so I don't lose it :-) 124 */ 125 while (tree != vm_avl_empty) { 126 if (tree->vm_start > addr) { 127 tree = tree->vm_avl_left; 128 } else { 129 prev = tree; 130 if (prev->vm_next == NULL) 131 break; 132 if (prev->vm_next->vm_start > addr) 133 break; 134 tree = tree->vm_avl_right; 135 } 136 } 137 #endif 138 139 int fixup_exception(struct pt_regs *regs) 140 { 141 const struct exception_table_entry *fix; 142 143 /* If we only stored 32bit addresses in the exception table we can drop 144 * out if we faulted on a 64bit address. */ 145 if ((sizeof(regs->iaoq[0]) > sizeof(fix->insn)) 146 && (regs->iaoq[0] >> 32)) 147 return 0; 148 149 fix = search_exception_tables(regs->iaoq[0]); 150 if (fix) { 151 struct exception_data *d; 152 d = this_cpu_ptr(&exception_data); 153 d->fault_ip = regs->iaoq[0]; 154 d->fault_space = regs->isr; 155 d->fault_addr = regs->ior; 156 157 regs->iaoq[0] = ((fix->fixup) & ~3); 158 /* 159 * NOTE: In some cases the faulting instruction 160 * may be in the delay slot of a branch. We 161 * don't want to take the branch, so we don't 162 * increment iaoq[1], instead we set it to be 163 * iaoq[0]+4, and clear the B bit in the PSW 164 */ 165 regs->iaoq[1] = regs->iaoq[0] + 4; 166 regs->gr[0] &= ~PSW_B; /* IPSW in gr[0] */ 167 168 return 1; 169 } 170 171 return 0; 172 } 173 174 /* 175 * Print out info about fatal segfaults, if the show_unhandled_signals 176 * sysctl is set: 177 */ 178 static inline void 179 show_signal_msg(struct pt_regs *regs, unsigned long code, 180 unsigned long address, struct task_struct *tsk, 181 struct vm_area_struct *vma) 182 { 183 if (!unhandled_signal(tsk, SIGSEGV)) 184 return; 185 186 if (!printk_ratelimit()) 187 return; 188 189 pr_warn("\n"); 190 pr_warn("do_page_fault() command='%s' type=%lu address=0x%08lx", 191 tsk->comm, code, address); 192 print_vma_addr(KERN_CONT " in ", regs->iaoq[0]); 193 if (vma) 194 pr_warn(" vm_start = 0x%08lx, vm_end = 0x%08lx\n", 195 vma->vm_start, vma->vm_end); 196 197 show_regs(regs); 198 } 199 200 void do_page_fault(struct pt_regs *regs, unsigned long code, 201 unsigned long address) 202 { 203 struct vm_area_struct *vma, *prev_vma; 204 struct task_struct *tsk; 205 struct mm_struct *mm; 206 unsigned long acc_type; 207 int fault; 208 unsigned int flags; 209 210 if (faulthandler_disabled()) 211 goto no_context; 212 213 tsk = current; 214 mm = tsk->mm; 215 if (!mm) 216 goto no_context; 217 218 flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE; 219 if (user_mode(regs)) 220 flags |= FAULT_FLAG_USER; 221 222 acc_type = parisc_acctyp(code, regs->iir); 223 if (acc_type & VM_WRITE) 224 flags |= FAULT_FLAG_WRITE; 225 retry: 226 down_read(&mm->mmap_sem); 227 vma = find_vma_prev(mm, address, &prev_vma); 228 if (!vma || address < vma->vm_start) 229 goto check_expansion; 230 /* 231 * Ok, we have a good vm_area for this memory access. We still need to 232 * check the access permissions. 233 */ 234 235 good_area: 236 237 if ((vma->vm_flags & acc_type) != acc_type) 238 goto bad_area; 239 240 /* 241 * If for any reason at all we couldn't handle the fault, make 242 * sure we exit gracefully rather than endlessly redo the 243 * fault. 244 */ 245 246 fault = handle_mm_fault(mm, vma, address, flags); 247 248 if ((fault & VM_FAULT_RETRY) && fatal_signal_pending(current)) 249 return; 250 251 if (unlikely(fault & VM_FAULT_ERROR)) { 252 /* 253 * We hit a shared mapping outside of the file, or some 254 * other thing happened to us that made us unable to 255 * handle the page fault gracefully. 256 */ 257 if (fault & VM_FAULT_OOM) 258 goto out_of_memory; 259 else if (fault & VM_FAULT_SIGSEGV) 260 goto bad_area; 261 else if (fault & VM_FAULT_SIGBUS) 262 goto bad_area; 263 BUG(); 264 } 265 if (flags & FAULT_FLAG_ALLOW_RETRY) { 266 if (fault & VM_FAULT_MAJOR) 267 current->maj_flt++; 268 else 269 current->min_flt++; 270 if (fault & VM_FAULT_RETRY) { 271 flags &= ~FAULT_FLAG_ALLOW_RETRY; 272 273 /* 274 * No need to up_read(&mm->mmap_sem) as we would 275 * have already released it in __lock_page_or_retry 276 * in mm/filemap.c. 277 */ 278 279 goto retry; 280 } 281 } 282 up_read(&mm->mmap_sem); 283 return; 284 285 check_expansion: 286 vma = prev_vma; 287 if (vma && (expand_stack(vma, address) == 0)) 288 goto good_area; 289 290 /* 291 * Something tried to access memory that isn't in our memory map.. 292 */ 293 bad_area: 294 up_read(&mm->mmap_sem); 295 296 if (user_mode(regs)) { 297 struct siginfo si; 298 299 show_signal_msg(regs, code, address, tsk, vma); 300 301 switch (code) { 302 case 15: /* Data TLB miss fault/Data page fault */ 303 /* send SIGSEGV when outside of vma */ 304 if (!vma || 305 address < vma->vm_start || address > vma->vm_end) { 306 si.si_signo = SIGSEGV; 307 si.si_code = SEGV_MAPERR; 308 break; 309 } 310 311 /* send SIGSEGV for wrong permissions */ 312 if ((vma->vm_flags & acc_type) != acc_type) { 313 si.si_signo = SIGSEGV; 314 si.si_code = SEGV_ACCERR; 315 break; 316 } 317 318 /* probably address is outside of mapped file */ 319 /* fall through */ 320 case 17: /* NA data TLB miss / page fault */ 321 case 18: /* Unaligned access - PCXS only */ 322 si.si_signo = SIGBUS; 323 si.si_code = (code == 18) ? BUS_ADRALN : BUS_ADRERR; 324 break; 325 case 16: /* Non-access instruction TLB miss fault */ 326 case 26: /* PCXL: Data memory access rights trap */ 327 default: 328 si.si_signo = SIGSEGV; 329 si.si_code = (code == 26) ? SEGV_ACCERR : SEGV_MAPERR; 330 break; 331 } 332 si.si_errno = 0; 333 si.si_addr = (void __user *) address; 334 force_sig_info(si.si_signo, &si, current); 335 return; 336 } 337 338 no_context: 339 340 if (!user_mode(regs) && fixup_exception(regs)) { 341 return; 342 } 343 344 parisc_terminate("Bad Address (null pointer deref?)", regs, code, address); 345 346 out_of_memory: 347 up_read(&mm->mmap_sem); 348 if (!user_mode(regs)) 349 goto no_context; 350 pagefault_out_of_memory(); 351 } 352