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 int fixup_exception(struct pt_regs *regs) 143 { 144 const struct exception_table_entry *fix; 145 146 fix = search_exception_tables(regs->iaoq[0]); 147 if (fix) { 148 struct exception_data *d; 149 d = &__get_cpu_var(exception_data); 150 d->fault_ip = regs->iaoq[0]; 151 d->fault_space = regs->isr; 152 d->fault_addr = regs->ior; 153 154 regs->iaoq[0] = ((fix->fixup) & ~3); 155 /* 156 * NOTE: In some cases the faulting instruction 157 * may be in the delay slot of a branch. We 158 * don't want to take the branch, so we don't 159 * increment iaoq[1], instead we set it to be 160 * iaoq[0]+4, and clear the B bit in the PSW 161 */ 162 regs->iaoq[1] = regs->iaoq[0] + 4; 163 regs->gr[0] &= ~PSW_B; /* IPSW in gr[0] */ 164 165 return 1; 166 } 167 168 return 0; 169 } 170 171 void do_page_fault(struct pt_regs *regs, unsigned long code, 172 unsigned long address) 173 { 174 struct vm_area_struct *vma, *prev_vma; 175 struct task_struct *tsk = current; 176 struct mm_struct *mm = tsk->mm; 177 unsigned long acc_type; 178 int fault; 179 180 if (in_atomic() || !mm) 181 goto no_context; 182 183 down_read(&mm->mmap_sem); 184 vma = find_vma_prev(mm, address, &prev_vma); 185 if (!vma || address < vma->vm_start) 186 goto check_expansion; 187 /* 188 * Ok, we have a good vm_area for this memory access. We still need to 189 * check the access permissions. 190 */ 191 192 good_area: 193 194 acc_type = parisc_acctyp(code,regs->iir); 195 196 if ((vma->vm_flags & acc_type) != acc_type) 197 goto bad_area; 198 199 /* 200 * If for any reason at all we couldn't handle the fault, make 201 * sure we exit gracefully rather than endlessly redo the 202 * fault. 203 */ 204 205 fault = handle_mm_fault(mm, vma, address, (acc_type & VM_WRITE) != 0); 206 if (unlikely(fault & VM_FAULT_ERROR)) { 207 /* 208 * We hit a shared mapping outside of the file, or some 209 * other thing happened to us that made us unable to 210 * handle the page fault gracefully. 211 */ 212 if (fault & VM_FAULT_OOM) 213 goto out_of_memory; 214 else if (fault & VM_FAULT_SIGBUS) 215 goto bad_area; 216 BUG(); 217 } 218 if (fault & VM_FAULT_MAJOR) 219 current->maj_flt++; 220 else 221 current->min_flt++; 222 up_read(&mm->mmap_sem); 223 return; 224 225 check_expansion: 226 vma = prev_vma; 227 if (vma && (expand_stack(vma, address) == 0)) 228 goto good_area; 229 230 /* 231 * Something tried to access memory that isn't in our memory map.. 232 */ 233 bad_area: 234 up_read(&mm->mmap_sem); 235 236 if (user_mode(regs)) { 237 struct siginfo si; 238 239 #ifdef PRINT_USER_FAULTS 240 printk(KERN_DEBUG "\n"); 241 printk(KERN_DEBUG "do_page_fault() pid=%d command='%s' type=%lu address=0x%08lx\n", 242 task_pid_nr(tsk), tsk->comm, code, address); 243 if (vma) { 244 printk(KERN_DEBUG "vm_start = 0x%08lx, vm_end = 0x%08lx\n", 245 vma->vm_start, vma->vm_end); 246 } 247 show_regs(regs); 248 #endif 249 /* FIXME: actually we need to get the signo and code correct */ 250 si.si_signo = SIGSEGV; 251 si.si_errno = 0; 252 si.si_code = SEGV_MAPERR; 253 si.si_addr = (void __user *) address; 254 force_sig_info(SIGSEGV, &si, current); 255 return; 256 } 257 258 no_context: 259 260 if (!user_mode(regs) && fixup_exception(regs)) { 261 return; 262 } 263 264 parisc_terminate("Bad Address (null pointer deref?)", regs, code, address); 265 266 out_of_memory: 267 up_read(&mm->mmap_sem); 268 printk(KERN_CRIT "VM: killing process %s\n", current->comm); 269 if (user_mode(regs)) 270 do_group_exit(SIGKILL); 271 goto no_context; 272 } 273