40f850e9766c78a0d790a040937b2d053b8ac4bd
4 * Linux architectural port borrowing liberally from similar works of
5 * others. All original copyrights apply as per the original source
8 * Modifications for the OpenRISC architecture:
9 * Copyright (C) 2003 Matjaz Breskvar <phoenix@bsemi.com>
10 * Copyright (C) 2010-2011 Jonas Bonn <jonas@southpole.se>
12 * This program is free software; you can redistribute it and/or
13 * modify it under the terms of the GNU General Public License
14 * as published by the Free Software Foundation; either version
15 * 2 of the License, or (at your option) any later version.
19 #include <linux/interrupt.h>
20 #include <linux/module.h>
21 #include <linux/sched.h>
23 #include <asm/uaccess.h>
24 #include <asm/siginfo.h>
25 #include <asm/signal.h>
27 #define NUM_TLB_ENTRIES 64
28 #define TLB_OFFSET(add) (((add) >> PAGE_SHIFT) & (NUM_TLB_ENTRIES-1))
30 unsigned long pte_misses
; /* updated by do_page_fault() */
31 unsigned long pte_errors
; /* updated by do_page_fault() */
33 /* __PHX__ :: - check the vmalloc_fault in do_page_fault()
34 * - also look into include/asm-or32/mmu_context.h
36 volatile pgd_t
*current_pgd
;
38 extern void die(char *, struct pt_regs
*, long);
41 * This routine handles page faults. It determines the address,
42 * and the problem, and then passes it off to one of the appropriate
45 * If this routine detects a bad access, it returns 1, otherwise it
49 asmlinkage
void do_page_fault(struct pt_regs
*regs
, unsigned long address
,
50 unsigned long vector
, int write_acc
)
52 struct task_struct
*tsk
;
54 struct vm_area_struct
*vma
;
57 unsigned int flags
= FAULT_FLAG_ALLOW_RETRY
| FAULT_FLAG_KILLABLE
;
62 * We fault-in kernel-space virtual memory on-demand. The
63 * 'reference' page table is init_mm.pgd.
65 * NOTE! We MUST NOT take any locks for this case. We may
66 * be in an interrupt or a critical region, and should
67 * only copy the information from the master page table,
70 * NOTE2: This is done so that, when updating the vmalloc
71 * mappings we don't have to walk all processes pgdirs and
72 * add the high mappings all at once. Instead we do it as they
73 * are used. However vmalloc'ed page entries have the PAGE_GLOBAL
74 * bit set so sometimes the TLB can use a lingering entry.
76 * This verifies that the fault happens in kernel space
77 * and that the fault was not a protection error.
80 if (address
>= VMALLOC_START
&&
81 (vector
!= 0x300 && vector
!= 0x400) &&
85 /* If exceptions were enabled, we can reenable them here */
86 if (user_mode(regs
)) {
87 /* Exception was in userspace: reenable interrupts */
90 /* If exception was in a syscall, then IRQ's may have
91 * been enabled or disabled. If they were enabled,
94 if (regs
->sr
&& (SPR_SR_IEE
| SPR_SR_TEE
))
99 info
.si_code
= SEGV_MAPERR
;
102 * If we're in an interrupt or have no user
103 * context, we must not take the fault..
106 if (in_interrupt() || !mm
)
110 down_read(&mm
->mmap_sem
);
111 vma
= find_vma(mm
, address
);
116 if (vma
->vm_start
<= address
)
119 if (!(vma
->vm_flags
& VM_GROWSDOWN
))
122 if (user_mode(regs
)) {
124 * accessing the stack below usp is always a bug.
125 * we get page-aligned addresses so we can only check
126 * if we're within a page from usp, but that might be
127 * enough to catch brutal errors at least.
129 if (address
+ PAGE_SIZE
< regs
->sp
)
132 if (expand_stack(vma
, address
))
136 * Ok, we have a good vm_area for this memory access, so
141 info
.si_code
= SEGV_ACCERR
;
143 /* first do some preliminary protection checks */
146 if (!(vma
->vm_flags
& VM_WRITE
))
148 flags
|= FAULT_FLAG_WRITE
;
151 if (!(vma
->vm_flags
& (VM_READ
| VM_EXEC
)))
155 /* are we trying to execute nonexecutable area */
156 if ((vector
== 0x400) && !(vma
->vm_page_prot
.pgprot
& _PAGE_EXEC
))
160 * If for any reason at all we couldn't handle the fault,
161 * make sure we exit gracefully rather than endlessly redo
165 fault
= handle_mm_fault(mm
, vma
, address
, flags
);
167 if ((fault
& VM_FAULT_RETRY
) && fatal_signal_pending(current
))
170 if (unlikely(fault
& VM_FAULT_ERROR
)) {
171 if (fault
& VM_FAULT_OOM
)
173 else if (fault
& VM_FAULT_SIGBUS
)
178 if (flags
& FAULT_FLAG_ALLOW_RETRY
) {
179 /*RGD modeled on Cris */
180 if (fault
& VM_FAULT_MAJOR
)
184 if (fault
& VM_FAULT_RETRY
) {
185 flags
&= ~FAULT_FLAG_ALLOW_RETRY
;
187 /* No need to up_read(&mm->mmap_sem) as we would
188 * have already released it in __lock_page_or_retry
196 up_read(&mm
->mmap_sem
);
200 * Something tried to access memory that isn't in our memory map..
201 * Fix it, but check if it's kernel or user first..
205 up_read(&mm
->mmap_sem
);
207 bad_area_nosemaphore
:
209 /* User mode accesses just cause a SIGSEGV */
211 if (user_mode(regs
)) {
212 info
.si_signo
= SIGSEGV
;
214 /* info.si_code has been set above */
215 info
.si_addr
= (void *)address
;
216 force_sig_info(SIGSEGV
, &info
, tsk
);
222 /* Are we prepared to handle this kernel fault?
224 * (The kernel has valid exception-points in the source
225 * when it acesses user-memory. When it fails in one
226 * of those points, we find it in a table and do a jump
227 * to some fixup code that loads an appropriate error
232 const struct exception_table_entry
*entry
;
234 __asm__
__volatile__("l.nop 42");
236 if ((entry
= search_exception_tables(regs
->pc
)) != NULL
) {
237 /* Adjust the instruction pointer in the stackframe */
238 regs
->pc
= entry
->fixup
;
244 * Oops. The kernel tried to access some bad page. We'll have to
245 * terminate things with extreme prejudice.
248 if ((unsigned long)(address
) < PAGE_SIZE
)
250 "Unable to handle kernel NULL pointer dereference");
252 printk(KERN_ALERT
"Unable to handle kernel access");
253 printk(" at virtual address 0x%08lx\n", address
);
255 die("Oops", regs
, write_acc
);
260 * We ran out of memory, or some other thing happened to us that made
261 * us unable to handle the page fault gracefully.
265 __asm__
__volatile__("l.nop 42");
266 __asm__
__volatile__("l.nop 1");
268 up_read(&mm
->mmap_sem
);
269 printk("VM: killing process %s\n", tsk
->comm
);
275 up_read(&mm
->mmap_sem
);
278 * Send a sigbus, regardless of whether we were in kernel
281 info
.si_signo
= SIGBUS
;
283 info
.si_code
= BUS_ADRERR
;
284 info
.si_addr
= (void *)address
;
285 force_sig_info(SIGBUS
, &info
, tsk
);
287 /* Kernel mode? Handle exceptions or die */
288 if (!user_mode(regs
))
295 * Synchronize this task's top level page-table
296 * with the 'reference' page table.
298 * Use current_pgd instead of tsk->active_mm->pgd
299 * since the latter might be unavailable if this
300 * code is executed in a misfortunately run irq
301 * (like inside schedule() between switch_mm and
305 int offset
= pgd_index(address
);
312 phx_warn("do_page_fault(): vmalloc_fault will not work, "
313 "since current_pgd assign a proper value somewhere\n"
314 "anyhow we don't need this at the moment\n");
316 phx_mmu("vmalloc_fault");
318 pgd
= (pgd_t
*)current_pgd
+ offset
;
319 pgd_k
= init_mm
.pgd
+ offset
;
321 /* Since we're two-level, we don't need to do both
322 * set_pgd and set_pmd (they do the same thing). If
323 * we go three-level at some point, do the right thing
324 * with pgd_present and set_pgd here.
326 * Also, since the vmalloc area is global, we don't
327 * need to copy individual PTE's, it is enough to
328 * copy the pgd pointer into the pte page of the
329 * root task. If that is there, we'll find our pte if
333 pud
= pud_offset(pgd
, address
);
334 pud_k
= pud_offset(pgd_k
, address
);
335 if (!pud_present(*pud_k
))
338 pmd
= pmd_offset(pud
, address
);
339 pmd_k
= pmd_offset(pud_k
, address
);
341 if (!pmd_present(*pmd_k
))
342 goto bad_area_nosemaphore
;
344 set_pmd(pmd
, *pmd_k
);
346 /* Make sure the actual PTE exists as well to
347 * catch kernel vmalloc-area accesses to non-mapped
348 * addresses. If we don't do this, this will just
349 * silently loop forever.
352 pte_k
= pte_offset_kernel(pmd_k
, address
);
353 if (!pte_present(*pte_k
))
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