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 * Copyright (C) 1995 - 2000 by Ralf Baechle 7 */ 8 #include <linux/signal.h> 9 #include <linux/sched.h> 10 #include <linux/interrupt.h> 11 #include <linux/kernel.h> 12 #include <linux/errno.h> 13 #include <linux/string.h> 14 #include <linux/types.h> 15 #include <linux/ptrace.h> 16 #include <linux/mman.h> 17 #include <linux/mm.h> 18 #include <linux/smp.h> 19 #include <linux/vt_kern.h> /* For unblank_screen() */ 20 #include <linux/module.h> 21 22 #include <asm/branch.h> 23 #include <asm/mmu_context.h> 24 #include <asm/system.h> 25 #include <asm/uaccess.h> 26 #include <asm/ptrace.h> 27 #include <asm/highmem.h> /* For VMALLOC_END */ 28 29 /* 30 * This routine handles page faults. It determines the address, 31 * and the problem, and then passes it off to one of the appropriate 32 * routines. 33 */ 34 asmlinkage void do_page_fault(struct pt_regs *regs, unsigned long write, 35 unsigned long address) 36 { 37 struct vm_area_struct * vma = NULL; 38 struct task_struct *tsk = current; 39 struct mm_struct *mm = tsk->mm; 40 const int field = sizeof(unsigned long) * 2; 41 siginfo_t info; 42 int fault; 43 44 #if 0 45 printk("Cpu%d[%s:%d:%0*lx:%ld:%0*lx]\n", raw_smp_processor_id(), 46 current->comm, current->pid, field, address, write, 47 field, regs->cp0_epc); 48 #endif 49 50 info.si_code = SEGV_MAPERR; 51 52 /* 53 * We fault-in kernel-space virtual memory on-demand. The 54 * 'reference' page table is init_mm.pgd. 55 * 56 * NOTE! We MUST NOT take any locks for this case. We may 57 * be in an interrupt or a critical region, and should 58 * only copy the information from the master page table, 59 * nothing more. 60 */ 61 #ifdef CONFIG_64BIT 62 # define VMALLOC_FAULT_TARGET no_context 63 #else 64 # define VMALLOC_FAULT_TARGET vmalloc_fault 65 #endif 66 67 if (unlikely(address >= VMALLOC_START && address <= VMALLOC_END)) 68 goto VMALLOC_FAULT_TARGET; 69 #ifdef MODULE_START 70 if (unlikely(address >= MODULE_START && address < MODULE_END)) 71 goto VMALLOC_FAULT_TARGET; 72 #endif 73 74 /* 75 * If we're in an interrupt or have no user 76 * context, we must not take the fault.. 77 */ 78 if (in_atomic() || !mm) 79 goto bad_area_nosemaphore; 80 81 down_read(&mm->mmap_sem); 82 vma = find_vma(mm, address); 83 if (!vma) 84 goto bad_area; 85 if (vma->vm_start <= address) 86 goto good_area; 87 if (!(vma->vm_flags & VM_GROWSDOWN)) 88 goto bad_area; 89 if (expand_stack(vma, address)) 90 goto bad_area; 91 /* 92 * Ok, we have a good vm_area for this memory access, so 93 * we can handle it.. 94 */ 95 good_area: 96 info.si_code = SEGV_ACCERR; 97 98 if (write) { 99 if (!(vma->vm_flags & VM_WRITE)) 100 goto bad_area; 101 } else { 102 if (kernel_uses_smartmips_rixi) { 103 if (address == regs->cp0_epc && !(vma->vm_flags & VM_EXEC)) { 104 #if 0 105 pr_notice("Cpu%d[%s:%d:%0*lx:%ld:%0*lx] XI violation\n", 106 raw_smp_processor_id(), 107 current->comm, current->pid, 108 field, address, write, 109 field, regs->cp0_epc); 110 #endif 111 goto bad_area; 112 } 113 if (!(vma->vm_flags & VM_READ)) { 114 #if 0 115 pr_notice("Cpu%d[%s:%d:%0*lx:%ld:%0*lx] RI violation\n", 116 raw_smp_processor_id(), 117 current->comm, current->pid, 118 field, address, write, 119 field, regs->cp0_epc); 120 #endif 121 goto bad_area; 122 } 123 } else { 124 if (!(vma->vm_flags & (VM_READ | VM_WRITE | VM_EXEC))) 125 goto bad_area; 126 } 127 } 128 129 /* 130 * If for any reason at all we couldn't handle the fault, 131 * make sure we exit gracefully rather than endlessly redo 132 * the fault. 133 */ 134 fault = handle_mm_fault(mm, vma, address, write ? FAULT_FLAG_WRITE : 0); 135 if (unlikely(fault & VM_FAULT_ERROR)) { 136 if (fault & VM_FAULT_OOM) 137 goto out_of_memory; 138 else if (fault & VM_FAULT_SIGBUS) 139 goto do_sigbus; 140 BUG(); 141 } 142 if (fault & VM_FAULT_MAJOR) 143 tsk->maj_flt++; 144 else 145 tsk->min_flt++; 146 147 up_read(&mm->mmap_sem); 148 return; 149 150 /* 151 * Something tried to access memory that isn't in our memory map.. 152 * Fix it, but check if it's kernel or user first.. 153 */ 154 bad_area: 155 up_read(&mm->mmap_sem); 156 157 bad_area_nosemaphore: 158 /* User mode accesses just cause a SIGSEGV */ 159 if (user_mode(regs)) { 160 tsk->thread.cp0_badvaddr = address; 161 tsk->thread.error_code = write; 162 #if 0 163 printk("do_page_fault() #2: sending SIGSEGV to %s for " 164 "invalid %s\n%0*lx (epc == %0*lx, ra == %0*lx)\n", 165 tsk->comm, 166 write ? "write access to" : "read access from", 167 field, address, 168 field, (unsigned long) regs->cp0_epc, 169 field, (unsigned long) regs->regs[31]); 170 #endif 171 info.si_signo = SIGSEGV; 172 info.si_errno = 0; 173 /* info.si_code has been set above */ 174 info.si_addr = (void __user *) address; 175 force_sig_info(SIGSEGV, &info, tsk); 176 return; 177 } 178 179 no_context: 180 /* Are we prepared to handle this kernel fault? */ 181 if (fixup_exception(regs)) { 182 current->thread.cp0_baduaddr = address; 183 return; 184 } 185 186 /* 187 * Oops. The kernel tried to access some bad page. We'll have to 188 * terminate things with extreme prejudice. 189 */ 190 bust_spinlocks(1); 191 192 printk(KERN_ALERT "CPU %d Unable to handle kernel paging request at " 193 "virtual address %0*lx, epc == %0*lx, ra == %0*lx\n", 194 raw_smp_processor_id(), field, address, field, regs->cp0_epc, 195 field, regs->regs[31]); 196 die("Oops", regs); 197 198 out_of_memory: 199 /* 200 * We ran out of memory, call the OOM killer, and return the userspace 201 * (which will retry the fault, or kill us if we got oom-killed). 202 */ 203 up_read(&mm->mmap_sem); 204 pagefault_out_of_memory(); 205 return; 206 207 do_sigbus: 208 up_read(&mm->mmap_sem); 209 210 /* Kernel mode? Handle exceptions or die */ 211 if (!user_mode(regs)) 212 goto no_context; 213 else 214 /* 215 * Send a sigbus, regardless of whether we were in kernel 216 * or user mode. 217 */ 218 #if 0 219 printk("do_page_fault() #3: sending SIGBUS to %s for " 220 "invalid %s\n%0*lx (epc == %0*lx, ra == %0*lx)\n", 221 tsk->comm, 222 write ? "write access to" : "read access from", 223 field, address, 224 field, (unsigned long) regs->cp0_epc, 225 field, (unsigned long) regs->regs[31]); 226 #endif 227 tsk->thread.cp0_badvaddr = address; 228 info.si_signo = SIGBUS; 229 info.si_errno = 0; 230 info.si_code = BUS_ADRERR; 231 info.si_addr = (void __user *) address; 232 force_sig_info(SIGBUS, &info, tsk); 233 234 return; 235 #ifndef CONFIG_64BIT 236 vmalloc_fault: 237 { 238 /* 239 * Synchronize this task's top level page-table 240 * with the 'reference' page table. 241 * 242 * Do _not_ use "tsk" here. We might be inside 243 * an interrupt in the middle of a task switch.. 244 */ 245 int offset = __pgd_offset(address); 246 pgd_t *pgd, *pgd_k; 247 pud_t *pud, *pud_k; 248 pmd_t *pmd, *pmd_k; 249 pte_t *pte_k; 250 251 pgd = (pgd_t *) pgd_current[raw_smp_processor_id()] + offset; 252 pgd_k = init_mm.pgd + offset; 253 254 if (!pgd_present(*pgd_k)) 255 goto no_context; 256 set_pgd(pgd, *pgd_k); 257 258 pud = pud_offset(pgd, address); 259 pud_k = pud_offset(pgd_k, address); 260 if (!pud_present(*pud_k)) 261 goto no_context; 262 263 pmd = pmd_offset(pud, address); 264 pmd_k = pmd_offset(pud_k, address); 265 if (!pmd_present(*pmd_k)) 266 goto no_context; 267 set_pmd(pmd, *pmd_k); 268 269 pte_k = pte_offset_kernel(pmd_k, address); 270 if (!pte_present(*pte_k)) 271 goto no_context; 272 return; 273 } 274 #endif 275 } 276