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 (!(vma->vm_flags & (VM_READ | VM_WRITE | VM_EXEC))) 103 goto bad_area; 104 } 105 106 /* 107 * If for any reason at all we couldn't handle the fault, 108 * make sure we exit gracefully rather than endlessly redo 109 * the fault. 110 */ 111 fault = handle_mm_fault(mm, vma, address, write ? FAULT_FLAG_WRITE : 0); 112 if (unlikely(fault & VM_FAULT_ERROR)) { 113 if (fault & VM_FAULT_OOM) 114 goto out_of_memory; 115 else if (fault & VM_FAULT_SIGBUS) 116 goto do_sigbus; 117 BUG(); 118 } 119 if (fault & VM_FAULT_MAJOR) 120 tsk->maj_flt++; 121 else 122 tsk->min_flt++; 123 124 up_read(&mm->mmap_sem); 125 return; 126 127 /* 128 * Something tried to access memory that isn't in our memory map.. 129 * Fix it, but check if it's kernel or user first.. 130 */ 131 bad_area: 132 up_read(&mm->mmap_sem); 133 134 bad_area_nosemaphore: 135 /* User mode accesses just cause a SIGSEGV */ 136 if (user_mode(regs)) { 137 tsk->thread.cp0_badvaddr = address; 138 tsk->thread.error_code = write; 139 #if 0 140 printk("do_page_fault() #2: sending SIGSEGV to %s for " 141 "invalid %s\n%0*lx (epc == %0*lx, ra == %0*lx)\n", 142 tsk->comm, 143 write ? "write access to" : "read access from", 144 field, address, 145 field, (unsigned long) regs->cp0_epc, 146 field, (unsigned long) regs->regs[31]); 147 #endif 148 info.si_signo = SIGSEGV; 149 info.si_errno = 0; 150 /* info.si_code has been set above */ 151 info.si_addr = (void __user *) address; 152 force_sig_info(SIGSEGV, &info, tsk); 153 return; 154 } 155 156 no_context: 157 /* Are we prepared to handle this kernel fault? */ 158 if (fixup_exception(regs)) { 159 current->thread.cp0_baduaddr = address; 160 return; 161 } 162 163 /* 164 * Oops. The kernel tried to access some bad page. We'll have to 165 * terminate things with extreme prejudice. 166 */ 167 bust_spinlocks(1); 168 169 printk(KERN_ALERT "CPU %d Unable to handle kernel paging request at " 170 "virtual address %0*lx, epc == %0*lx, ra == %0*lx\n", 171 raw_smp_processor_id(), field, address, field, regs->cp0_epc, 172 field, regs->regs[31]); 173 die("Oops", regs); 174 175 out_of_memory: 176 /* 177 * We ran out of memory, call the OOM killer, and return the userspace 178 * (which will retry the fault, or kill us if we got oom-killed). 179 */ 180 up_read(&mm->mmap_sem); 181 pagefault_out_of_memory(); 182 return; 183 184 do_sigbus: 185 up_read(&mm->mmap_sem); 186 187 /* Kernel mode? Handle exceptions or die */ 188 if (!user_mode(regs)) 189 goto no_context; 190 else 191 /* 192 * Send a sigbus, regardless of whether we were in kernel 193 * or user mode. 194 */ 195 #if 0 196 printk("do_page_fault() #3: sending SIGBUS to %s for " 197 "invalid %s\n%0*lx (epc == %0*lx, ra == %0*lx)\n", 198 tsk->comm, 199 write ? "write access to" : "read access from", 200 field, address, 201 field, (unsigned long) regs->cp0_epc, 202 field, (unsigned long) regs->regs[31]); 203 #endif 204 tsk->thread.cp0_badvaddr = address; 205 info.si_signo = SIGBUS; 206 info.si_errno = 0; 207 info.si_code = BUS_ADRERR; 208 info.si_addr = (void __user *) address; 209 force_sig_info(SIGBUS, &info, tsk); 210 211 return; 212 #ifndef CONFIG_64BIT 213 vmalloc_fault: 214 { 215 /* 216 * Synchronize this task's top level page-table 217 * with the 'reference' page table. 218 * 219 * Do _not_ use "tsk" here. We might be inside 220 * an interrupt in the middle of a task switch.. 221 */ 222 int offset = __pgd_offset(address); 223 pgd_t *pgd, *pgd_k; 224 pud_t *pud, *pud_k; 225 pmd_t *pmd, *pmd_k; 226 pte_t *pte_k; 227 228 pgd = (pgd_t *) pgd_current[raw_smp_processor_id()] + offset; 229 pgd_k = init_mm.pgd + offset; 230 231 if (!pgd_present(*pgd_k)) 232 goto no_context; 233 set_pgd(pgd, *pgd_k); 234 235 pud = pud_offset(pgd, address); 236 pud_k = pud_offset(pgd_k, address); 237 if (!pud_present(*pud_k)) 238 goto no_context; 239 240 pmd = pmd_offset(pud, address); 241 pmd_k = pmd_offset(pud_k, address); 242 if (!pmd_present(*pmd_k)) 243 goto no_context; 244 set_pmd(pmd, *pmd_k); 245 246 pte_k = pte_offset_kernel(pmd_k, address); 247 if (!pte_present(*pte_k)) 248 goto no_context; 249 return; 250 } 251 #endif 252 } 253