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/config.h> 9#include <linux/signal.h> 10#include <linux/sched.h> 11#include <linux/interrupt.h> 12#include <linux/kernel.h> 13#include <linux/errno.h> 14#include <linux/string.h> 15#include <linux/types.h> 16#include <linux/ptrace.h> 17#include <linux/mman.h> 18#include <linux/mm.h> 19#include <linux/smp.h> 20#include <linux/smp_lock.h> 21#include <linux/version.h> 22 23#include <asm/branch.h> 24#include <asm/hardirq.h> 25#include <asm/pgalloc.h> 26#include <asm/mmu_context.h> 27#include <asm/softirq.h> 28#include <asm/system.h> 29#include <asm/uaccess.h> 30 31#define development_version (LINUX_VERSION_CODE & 0x100) 32 33/* 34 * Macro for exception fixup code to access integer registers. 35 */ 36#define dpf_reg(r) (regs->regs[r]) 37 38extern spinlock_t timerlist_lock; 39 40/* 41 * Unlock any spinlocks which will prevent us from getting the 42 * message out (timerlist_lock is acquired through the 43 * console unblank code) 44 */ 45void bust_spinlocks(int yes) 46{ 47 spin_lock_init(&timerlist_lock); 48 if (yes) { 49 oops_in_progress = 1; 50#ifdef CONFIG_SMP 51 /* Many serial drivers do __global_cli() */ 52 global_irq_lock = SPIN_LOCK_UNLOCKED; 53#endif 54 } else { 55 int loglevel_save = console_loglevel; 56#ifdef CONFIG_VT 57 unblank_screen(); 58#endif 59 oops_in_progress = 0; 60 /* 61 * OK, the message is on the console. Now we call printk() 62 * without oops_in_progress set so that printk will give klogd 63 * a poke. Hold onto your hats... 64 */ 65 console_loglevel = 15; /* NMI oopser may have shut the console up */ 66 printk(" "); 67 console_loglevel = loglevel_save; 68 } 69} 70 71/* 72 * This routine handles page faults. It determines the address, 73 * and the problem, and then passes it off to one of the appropriate 74 * routines. 75 */ 76asmlinkage void do_page_fault(struct pt_regs *regs, unsigned long write, 77 unsigned long address) 78{ 79 struct vm_area_struct * vma; 80 struct task_struct *tsk = current; 81 struct mm_struct *mm = tsk->mm; 82 unsigned long fixup; 83 siginfo_t info; 84 85 /* 86 * We fault-in kernel-space virtual memory on-demand. The 87 * 'reference' page table is init_mm.pgd. 88 * 89 * NOTE! We MUST NOT take any locks for this case. We may 90 * be in an interrupt or a critical region, and should 91 * only copy the information from the master page table, 92 * nothing more. 93 */ 94 if (address >= VMALLOC_START) 95 goto vmalloc_fault; 96 97 info.si_code = SEGV_MAPERR; 98 /* 99 * If we're in an interrupt or have no user 100 * context, we must not take the fault.. 101 */ 102 if (in_interrupt() || !mm) 103 goto no_context; 104 down_read(&mm->mmap_sem); 105 vma = find_vma(mm, address); 106 if (!vma) 107 goto bad_area; 108 if (vma->vm_start <= address) 109 goto good_area; 110 if (!(vma->vm_flags & VM_GROWSDOWN)) 111 goto bad_area; 112 if (expand_stack(vma, address)) 113 goto bad_area; 114/* 115 * Ok, we have a good vm_area for this memory access, so 116 * we can handle it.. 117 */ 118good_area: 119 info.si_code = SEGV_ACCERR; 120 121 if (write) { 122 if (!(vma->vm_flags & VM_WRITE)) 123 goto bad_area; 124 } else { 125 if (!(vma->vm_flags & (VM_READ | VM_EXEC))) 126 goto bad_area; 127 } 128 129survive: 130 /* 131 * If for any reason at all we couldn't handle the fault, 132 * make sure we exit gracefully rather than endlessly redo 133 * the fault. 134 */ 135 switch (handle_mm_fault(mm, vma, address, write)) { 136 case 1: 137 tsk->min_flt++; 138 break; 139 case 2: 140 tsk->maj_flt++; 141 break; 142 case 0: 143 goto do_sigbus; 144 default: 145 goto out_of_memory; 146 } 147 148 up_read(&mm->mmap_sem); 149 return; 150 151/* 152 * Something tried to access memory that isn't in our memory map.. 153 * Fix it, but check if it's kernel or user first.. 154 */ 155bad_area: 156 up_read(&mm->mmap_sem); 157 158 /* 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 info.si_signo = SIGSEGV; 163 info.si_errno = 0; 164 /* info.si_code has been set above */ 165 info.si_addr = (void *) address; 166 force_sig_info(SIGSEGV, &info, tsk); 167 return; 168 } 169 170no_context: 171 /* Are we prepared to handle this kernel fault? */ 172 fixup = search_exception_table(exception_epc(regs)); 173 if (fixup) { 174 long new_epc; 175 176 tsk->thread.cp0_baduaddr = address; 177 new_epc = fixup_exception(dpf_reg, fixup, regs->cp0_epc); 178 if (development_version) 179 printk(KERN_DEBUG "%s: Exception at [<%lx>] (%lx)\n", 180 tsk->comm, regs->cp0_epc, new_epc); 181 regs->cp0_epc = new_epc; 182 return; 183 } 184 185 /* 186 * Oops. The kernel tried to access some bad page. We'll have to 187 * terminate things with extreme prejudice. 188 */ 189 printk(KERN_ALERT "Unable to handle kernel paging request at virtual " 190 "address %08lx, epc == %08lx, ra == %08lx\n", 191 address, regs->cp0_epc, regs->regs[31]); 192 die("Oops", regs); 193 /* Game over. */ 194 195/* 196 * We ran out of memory, or some other thing happened to us that made 197 * us unable to handle the page fault gracefully. 198 */ 199out_of_memory: 200 if (tsk->pid == 1) { 201 yield(); 202 goto survive; 203 } 204 up_read(&mm->mmap_sem); 205 printk(KERN_NOTICE "VM: killing process %s\n", tsk->comm); 206 if (user_mode(regs)) 207 do_exit(SIGKILL); 208 goto no_context; 209 210do_sigbus: 211 up_read(&mm->mmap_sem); 212 213 /* 214 * Send a sigbus, regardless of whether we were in kernel 215 * or user mode. 216 */ 217 tsk->thread.cp0_badvaddr = address; 218 info.si_signo = SIGBUS; 219 info.si_errno = 0; 220 info.si_code = BUS_ADRERR; 221 info.si_addr = (void *) address; 222 force_sig_info(SIGBUS, &info, tsk); 223 224 /* Kernel mode? Handle exceptions or die */ 225 if (!user_mode(regs)) 226 goto no_context; 227 228 return; 229 230vmalloc_fault: 231 { 232 /* 233 * Synchronize this task's top level page-table 234 * with the 'reference' page table. 235 * 236 * Do _not_ use "tsk" here. We might be inside 237 * an interrupt in the middle of a task switch.. 238 */ 239 int offset = __pgd_offset(address); 240 pgd_t *pgd, *pgd_k; 241 pmd_t *pmd, *pmd_k; 242 pte_t *pte_k; 243 244 pgd = (pgd_t *) pgd_current[smp_processor_id()] + offset; 245 pgd_k = init_mm.pgd + offset; 246 247 if (!pgd_present(*pgd_k)) 248 goto no_context; 249 set_pgd(pgd, *pgd_k); 250 251 pmd = pmd_offset(pgd, address); 252 pmd_k = pmd_offset(pgd_k, address); 253 if (!pmd_present(*pmd_k)) 254 goto no_context; 255 set_pmd(pmd, *pmd_k); 256 257 pte_k = pte_offset(pmd_k, address); 258 if (!pte_present(*pte_k)) 259 goto no_context; 260 return; 261 } 262} 263