2 * linux/arch/alpha/mm/fault.c
4 * Copyright (C) 1995 Linus Torvalds
7 #include <linux/config.h>
8 #include <linux/sched.h>
9 #include <linux/kernel.h>
13 #define __EXTERN_INLINE inline
14 #include <asm/mmu_context.h>
15 #include <asm/pgalloc.h>
16 #undef __EXTERN_INLINE
18 #include <linux/signal.h>
19 #include <linux/errno.h>
20 #include <linux/string.h>
21 #include <linux/types.h>
22 #include <linux/ptrace.h>
23 #include <linux/mman.h>
24 #include <linux/smp.h>
25 #include <linux/smp_lock.h>
26 #include <linux/interrupt.h>
28 #include <asm/system.h>
29 #include <asm/uaccess.h>
31 extern void die_if_kernel(char *,struct pt_regs *,long, unsigned long *);
35 * Force a new ASN for a task.
39 unsigned long last_asn = ASN_FIRST_VERSION;
43 __load_new_mm_context(struct mm_struct *next_mm)
47 mmc = __get_new_mm_context(next_mm, smp_processor_id());
48 next_mm->context[smp_processor_id()] = mmc;
49 current->thread.asn = mmc & HARDWARE_ASN_MASK;
51 = ((unsigned long) next_mm->pgd - IDENT_ADDR) >> PAGE_SHIFT;
53 __reload_thread(¤t->thread);
58 * This routine handles page faults. It determines the address,
59 * and the problem, and then passes it off to handle_mm_fault().
62 * 0 = translation not valid
63 * 1 = access violation
65 * 3 = fault-on-execute
69 * -1 = instruction fetch
73 * Registers $9 through $15 are saved in a block just prior to `regs' and
74 * are saved and restored around the call to allow exception code to
78 /* Macro for exception fixup code to access integer registers. */
80 (((unsigned long *)regs)[(r) <= 8 ? (r) : (r) <= 15 ? (r)-16 : \
81 (r) <= 18 ? (r)+8 : (r)-10])
84 do_page_fault(unsigned long address, unsigned long mmcsr,
85 long cause, struct pt_regs *regs)
87 struct vm_area_struct * vma;
88 struct mm_struct *mm = current->mm;
93 /* As of EV6, a load into $31/$f31 is a prefetch, and never faults
94 (or is suppressed by the PALcode). Support that for older CPUs
95 by ignoring such an instruction. */
98 __get_user(insn, (unsigned int *)regs->pc);
99 if ((insn >> 21 & 0x1f) == 0x1f &&
100 /* ldq ldl ldt lds ldg ldf ldwu ldbu */
101 (1ul << (insn >> 26) & 0x30f00001400ul)) {
107 /* If we're in an interrupt context, or have no user context,
108 we must not take the fault. */
109 if (!mm || in_interrupt())
112 info.si_code = SEGV_MAPERR;
114 #ifdef CONFIG_ALPHA_LARGE_VMALLOC
115 if (address >= TASK_SIZE)
119 down_read(&mm->mmap_sem);
120 vma = find_vma(mm, address);
123 if (vma->vm_start <= address)
125 if (!(vma->vm_flags & VM_GROWSDOWN))
127 if (expand_stack(vma, address))
130 * Ok, we have a good vm_area for this memory access, so
134 info.si_code = SEGV_ACCERR;
136 if (!(vma->vm_flags & VM_EXEC))
139 /* Allow reads even for write-only mappings */
140 if (!(vma->vm_flags & (VM_READ | VM_WRITE)))
143 if (!(vma->vm_flags & VM_WRITE))
149 * If for any reason at all we couldn't handle the fault,
150 * make sure we exit gracefully rather than endlessly redo
153 fault = handle_mm_fault(mm, vma, address, cause > 0);
159 up_read(&mm->mmap_sem);
163 * Something tried to access memory that isn't in our memory map..
164 * Fix it, but check if it's kernel or user first..
167 up_read(&mm->mmap_sem);
169 if (user_mode(regs)) {
171 info.si_signo = SIGSEGV;
173 /* info.si_code has been set above */
174 info.si_addr = (void *)address;
175 force_sig_info(SIGSEGV,&info,current);
180 /* Are we prepared to handle this fault as an exception? */
181 if ((fixup = search_exception_table(regs->pc, regs->gp)) != 0) {
183 newpc = fixup_exception(dpf_reg, fixup, regs->pc);
185 printk("%s: Exception at [<%lx>] (%lx) handled successfully\n",
186 current->comm, regs->pc, newpc);
193 * Oops. The kernel tried to access some bad page. We'll have to
194 * terminate things with extreme prejudice.
196 printk(KERN_ALERT "Unable to handle kernel paging request at "
197 "virtual address %016lx\n", address);
198 die_if_kernel("Oops", regs, cause, (unsigned long*)regs - 16);
202 * We ran out of memory, or some other thing happened to us that made
203 * us unable to handle the page fault gracefully.
206 if (current->pid == 1) {
210 up_read(&mm->mmap_sem);
211 printk(KERN_ALERT "VM: killing process %s(%d)\n",
212 current->comm, current->pid);
213 if (!user_mode(regs))
218 up_read(&mm->mmap_sem);
220 * Send a sigbus, regardless of whether we were in kernel
223 info.si_signo = SIGBUS;
225 /* not sure si_code value here */
226 info.si_code = BUS_ADRERR;
227 info.si_addr = (void *)address;
228 force_sig_info(SIGBUS,&info,current);
229 if (!user_mode(regs))
233 #ifdef CONFIG_ALPHA_LARGE_VMALLOC
235 if (user_mode(regs)) {
236 info.si_signo = SIGSEGV;
238 /* info.si_code has been set above */
239 info.si_addr = (void *)address;
240 force_sig_info(SIGSEGV,&info,current);
243 /* Synchronize this task's top level page-table
244 with the "reference" page table from init. */
245 long offset = __pgd_offset(address);
248 pgd = current->active_mm->pgd + offset;
249 pgd_k = swapper_pg_dir + offset;
250 if (!pgd_present(*pgd) && pgd_present(*pgd_k)) {
251 pgd_val(*pgd) = pgd_val(*pgd_k);