2 * linux/arch/alpha/mm/fault.c
4 * Copyright (C) 1995 Linus Torvalds
7 #include <linux/sched/signal.h>
8 #include <linux/kernel.h>
12 #define __EXTERN_INLINE inline
13 #include <asm/mmu_context.h>
14 #include <asm/tlbflush.h>
15 #undef __EXTERN_INLINE
17 #include <linux/signal.h>
18 #include <linux/errno.h>
19 #include <linux/string.h>
20 #include <linux/types.h>
21 #include <linux/ptrace.h>
22 #include <linux/mman.h>
23 #include <linux/smp.h>
24 #include <linux/interrupt.h>
25 #include <linux/extable.h>
26 #include <linux/uaccess.h>
28 extern void die_if_kernel(char *,struct pt_regs
*,long, unsigned long *);
32 * Force a new ASN for a task.
36 unsigned long last_asn
= ASN_FIRST_VERSION
;
40 __load_new_mm_context(struct mm_struct
*next_mm
)
43 struct pcb_struct
*pcb
;
45 mmc
= __get_new_mm_context(next_mm
, smp_processor_id());
46 next_mm
->context
[smp_processor_id()] = mmc
;
48 pcb
= ¤t_thread_info()->pcb
;
49 pcb
->asn
= mmc
& HARDWARE_ASN_MASK
;
50 pcb
->ptbr
= ((unsigned long) next_mm
->pgd
- IDENT_ADDR
) >> PAGE_SHIFT
;
57 * This routine handles page faults. It determines the address,
58 * and the problem, and then passes it off to handle_mm_fault().
61 * 0 = translation not valid
62 * 1 = access violation
64 * 3 = fault-on-execute
68 * -1 = instruction fetch
72 * Registers $9 through $15 are saved in a block just prior to `regs' and
73 * are saved and restored around the call to allow exception code to
77 /* Macro for exception fixup code to access integer registers. */
79 (((unsigned long *)regs)[(r) <= 8 ? (r) : (r) <= 15 ? (r)-16 : \
80 (r) <= 18 ? (r)+8 : (r)-10])
83 do_page_fault(unsigned long address
, unsigned long mmcsr
,
84 long cause
, struct pt_regs
*regs
)
86 struct vm_area_struct
* vma
;
87 struct mm_struct
*mm
= current
->mm
;
88 const struct exception_table_entry
*fixup
;
89 int fault
, si_code
= SEGV_MAPERR
;
91 unsigned int flags
= FAULT_FLAG_ALLOW_RETRY
| FAULT_FLAG_KILLABLE
;
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 __user
*)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
|| faulthandler_disabled())
112 #ifdef CONFIG_ALPHA_LARGE_VMALLOC
113 if (address
>= TASK_SIZE
)
117 flags
|= FAULT_FLAG_USER
;
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
133 si_code
= SEGV_ACCERR
;
135 if (!(vma
->vm_flags
& VM_EXEC
))
138 /* Allow reads even for write-only mappings */
139 if (!(vma
->vm_flags
& (VM_READ
| VM_WRITE
)))
142 if (!(vma
->vm_flags
& VM_WRITE
))
144 flags
|= FAULT_FLAG_WRITE
;
147 /* If for any reason at all we couldn't handle the fault,
148 make sure we exit gracefully rather than endlessly redo
150 fault
= handle_mm_fault(vma
, address
, flags
);
152 if ((fault
& VM_FAULT_RETRY
) && fatal_signal_pending(current
))
155 if (unlikely(fault
& VM_FAULT_ERROR
)) {
156 if (fault
& VM_FAULT_OOM
)
158 else if (fault
& VM_FAULT_SIGSEGV
)
160 else if (fault
& VM_FAULT_SIGBUS
)
165 if (flags
& FAULT_FLAG_ALLOW_RETRY
) {
166 if (fault
& VM_FAULT_MAJOR
)
170 if (fault
& VM_FAULT_RETRY
) {
171 flags
&= ~FAULT_FLAG_ALLOW_RETRY
;
173 /* No need to up_read(&mm->mmap_sem) as we would
174 * have already released it in __lock_page_or_retry
182 up_read(&mm
->mmap_sem
);
186 /* Something tried to access memory that isn't in our memory map.
187 Fix it, but check if it's kernel or user first. */
189 up_read(&mm
->mmap_sem
);
195 /* Are we prepared to handle this fault as an exception? */
196 if ((fixup
= search_exception_tables(regs
->pc
)) != 0) {
198 newpc
= fixup_exception(dpf_reg
, fixup
, regs
->pc
);
203 /* Oops. The kernel tried to access some bad page. We'll have to
204 terminate things with extreme prejudice. */
205 printk(KERN_ALERT
"Unable to handle kernel paging request at "
206 "virtual address %016lx\n", address
);
207 die_if_kernel("Oops", regs
, cause
, (unsigned long*)regs
- 16);
210 /* We ran out of memory, or some other thing happened to us that
211 made us unable to handle the page fault gracefully. */
213 up_read(&mm
->mmap_sem
);
214 if (!user_mode(regs
))
216 pagefault_out_of_memory();
220 up_read(&mm
->mmap_sem
);
221 /* Send a sigbus, regardless of whether we were in kernel
223 info
.si_signo
= SIGBUS
;
225 info
.si_code
= BUS_ADRERR
;
226 info
.si_addr
= (void __user
*) address
;
227 force_sig_info(SIGBUS
, &info
, current
);
228 if (!user_mode(regs
))
233 info
.si_signo
= SIGSEGV
;
235 info
.si_code
= si_code
;
236 info
.si_addr
= (void __user
*) address
;
237 force_sig_info(SIGSEGV
, &info
, current
);
240 #ifdef CONFIG_ALPHA_LARGE_VMALLOC
245 /* Synchronize this task's top level page-table
246 with the "reference" page table from init. */
247 long index
= pgd_index(address
);
250 pgd
= current
->active_mm
->pgd
+ index
;
251 pgd_k
= swapper_pg_dir
+ index
;
252 if (!pgd_present(*pgd
) && pgd_present(*pgd_k
)) {
253 pgd_val(*pgd
) = pgd_val(*pgd_k
);