2 * Based on arch/arm/mm/fault.c
4 * Copyright (C) 1995 Linus Torvalds
5 * Copyright (C) 1995-2004 Russell King
6 * Copyright (C) 2012 ARM Ltd.
8 * This program is free software; you can redistribute it and/or modify
9 * it under the terms of the GNU General Public License version 2 as
10 * published by the Free Software Foundation.
12 * This program is distributed in the hope that it will be useful,
13 * but WITHOUT ANY WARRANTY; without even the implied warranty of
14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15 * GNU General Public License for more details.
17 * You should have received a copy of the GNU General Public License
18 * along with this program. If not, see <http://www.gnu.org/licenses/>.
21 #include <linux/module.h>
22 #include <linux/signal.h>
24 #include <linux/hardirq.h>
25 #include <linux/init.h>
26 #include <linux/kprobes.h>
27 #include <linux/uaccess.h>
28 #include <linux/page-flags.h>
29 #include <linux/sched.h>
30 #include <linux/highmem.h>
31 #include <linux/perf_event.h>
33 #include <asm/exception.h>
34 #include <asm/debug-monitors.h>
35 #include <asm/system_misc.h>
36 #include <asm/pgtable.h>
37 #include <asm/tlbflush.h>
40 * Dump out the page tables associated with 'addr' in mm 'mm'.
42 void show_pte(struct mm_struct
*mm
, unsigned long addr
)
49 pr_alert("pgd = %p\n", mm
->pgd
);
50 pgd
= pgd_offset(mm
, addr
);
51 pr_alert("[%08lx] *pgd=%016llx", addr
, pgd_val(*pgd
));
58 if (pgd_none_or_clear_bad(pgd
))
61 pud
= pud_offset(pgd
, addr
);
62 if (pud_none_or_clear_bad(pud
))
65 pmd
= pmd_offset(pud
, addr
);
66 printk(", *pmd=%016llx", pmd_val(*pmd
));
67 if (pmd_none_or_clear_bad(pmd
))
70 pte
= pte_offset_map(pmd
, addr
);
71 printk(", *pte=%016llx", pte_val(*pte
));
79 * The kernel tried to access some page that wasn't present.
81 static void __do_kernel_fault(struct mm_struct
*mm
, unsigned long addr
,
82 unsigned int esr
, struct pt_regs
*regs
)
85 * Are we prepared to handle this kernel fault?
87 if (fixup_exception(regs
))
91 * No handler, we'll have to terminate things with extreme prejudice.
94 pr_alert("Unable to handle kernel %s at virtual address %08lx\n",
95 (addr
< PAGE_SIZE
) ? "NULL pointer dereference" :
96 "paging request", addr
);
99 die("Oops", regs
, esr
);
105 * Something tried to access memory that isn't in our memory map. User mode
106 * accesses just cause a SIGSEGV
108 static void __do_user_fault(struct task_struct
*tsk
, unsigned long addr
,
109 unsigned int esr
, unsigned int sig
, int code
,
110 struct pt_regs
*regs
)
114 if (show_unhandled_signals
) {
115 pr_info("%s[%d]: unhandled page fault (%d) at 0x%08lx, code 0x%03x\n",
116 tsk
->comm
, task_pid_nr(tsk
), sig
, addr
, esr
);
117 show_pte(tsk
->mm
, addr
);
121 tsk
->thread
.fault_address
= addr
;
125 si
.si_addr
= (void __user
*)addr
;
126 force_sig_info(sig
, &si
, tsk
);
129 void do_bad_area(unsigned long addr
, unsigned int esr
, struct pt_regs
*regs
)
131 struct task_struct
*tsk
= current
;
132 struct mm_struct
*mm
= tsk
->active_mm
;
135 * If we are in kernel mode at this point, we have no context to
136 * handle this fault with.
139 __do_user_fault(tsk
, addr
, esr
, SIGSEGV
, SEGV_MAPERR
, regs
);
141 __do_kernel_fault(mm
, addr
, esr
, regs
);
144 #define VM_FAULT_BADMAP 0x010000
145 #define VM_FAULT_BADACCESS 0x020000
147 #define ESR_WRITE (1 << 6)
148 #define ESR_LNX_EXEC (1 << 24)
151 * Check that the permissions on the VMA allow for the fault which occurred.
152 * If we encountered a write fault, we must have write permission, otherwise
153 * we allow any permission.
155 static inline bool access_error(unsigned int esr
, struct vm_area_struct
*vma
)
157 unsigned int mask
= VM_READ
| VM_WRITE
| VM_EXEC
;
161 if (esr
& ESR_LNX_EXEC
)
164 return vma
->vm_flags
& mask
? false : true;
167 static int __do_page_fault(struct mm_struct
*mm
, unsigned long addr
,
168 unsigned int esr
, unsigned int flags
,
169 struct task_struct
*tsk
)
171 struct vm_area_struct
*vma
;
174 vma
= find_vma(mm
, addr
);
175 fault
= VM_FAULT_BADMAP
;
178 if (unlikely(vma
->vm_start
> addr
))
182 * Ok, we have a good vm_area for this memory access, so we can handle
186 if (access_error(esr
, vma
)) {
187 fault
= VM_FAULT_BADACCESS
;
191 return handle_mm_fault(mm
, vma
, addr
& PAGE_MASK
, flags
);
194 if (vma
->vm_flags
& VM_GROWSDOWN
&& !expand_stack(vma
, addr
))
200 static int __kprobes
do_page_fault(unsigned long addr
, unsigned int esr
,
201 struct pt_regs
*regs
)
203 struct task_struct
*tsk
;
204 struct mm_struct
*mm
;
205 int fault
, sig
, code
;
206 int write
= esr
& ESR_WRITE
;
207 unsigned int flags
= FAULT_FLAG_ALLOW_RETRY
| FAULT_FLAG_KILLABLE
|
208 (write
? FAULT_FLAG_WRITE
: 0);
213 /* Enable interrupts if they were enabled in the parent context. */
214 if (interrupts_enabled(regs
))
218 * If we're in an interrupt or have no user context, we must not take
221 if (in_atomic() || !mm
)
225 * As per x86, we may deadlock here. However, since the kernel only
226 * validly references user space from well defined areas of the code,
227 * we can bug out early if this is from code which shouldn't.
229 if (!down_read_trylock(&mm
->mmap_sem
)) {
230 if (!user_mode(regs
) && !search_exception_tables(regs
->pc
))
233 down_read(&mm
->mmap_sem
);
236 * The above down_read_trylock() might have succeeded in which
237 * case, we'll have missed the might_sleep() from down_read().
240 #ifdef CONFIG_DEBUG_VM
241 if (!user_mode(regs
) && !search_exception_tables(regs
->pc
))
246 fault
= __do_page_fault(mm
, addr
, esr
, flags
, tsk
);
249 * If we need to retry but a fatal signal is pending, handle the
250 * signal first. We do not need to release the mmap_sem because it
251 * would already be released in __lock_page_or_retry in mm/filemap.c.
253 if ((fault
& VM_FAULT_RETRY
) && fatal_signal_pending(current
))
257 * Major/minor page fault accounting is only done on the initial
258 * attempt. If we go through a retry, it is extremely likely that the
259 * page will be found in page cache at that point.
262 perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS
, 1, regs
, addr
);
263 if (flags
& FAULT_FLAG_ALLOW_RETRY
) {
264 if (fault
& VM_FAULT_MAJOR
) {
266 perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MAJ
, 1, regs
,
270 perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MIN
, 1, regs
,
273 if (fault
& VM_FAULT_RETRY
) {
275 * Clear FAULT_FLAG_ALLOW_RETRY to avoid any risk of
278 flags
&= ~FAULT_FLAG_ALLOW_RETRY
;
283 up_read(&mm
->mmap_sem
);
286 * Handle the "normal" case first - VM_FAULT_MAJOR / VM_FAULT_MINOR
288 if (likely(!(fault
& (VM_FAULT_ERROR
| VM_FAULT_BADMAP
|
289 VM_FAULT_BADACCESS
))))
292 if (fault
& VM_FAULT_OOM
) {
294 * We ran out of memory, call the OOM killer, and return to
295 * userspace (which will retry the fault, or kill us if we got
298 pagefault_out_of_memory();
303 * If we are in kernel mode at this point, we have no context to
304 * handle this fault with.
306 if (!user_mode(regs
))
309 if (fault
& VM_FAULT_SIGBUS
) {
311 * We had some memory, but were unable to successfully fix up
318 * Something tried to access memory that isn't in our memory
322 code
= fault
== VM_FAULT_BADACCESS
?
323 SEGV_ACCERR
: SEGV_MAPERR
;
326 __do_user_fault(tsk
, addr
, esr
, sig
, code
, regs
);
330 __do_kernel_fault(mm
, addr
, esr
, regs
);
335 * First Level Translation Fault Handler
337 * We enter here because the first level page table doesn't contain a valid
338 * entry for the address.
340 * If the address is in kernel space (>= TASK_SIZE), then we are probably
341 * faulting in the vmalloc() area.
343 * If the init_task's first level page tables contains the relevant entry, we
344 * copy the it to this task. If not, we send the process a signal, fixup the
345 * exception, or oops the kernel.
347 * NOTE! We MUST NOT take any locks for this case. We may be in an interrupt
348 * or a critical region, and should only copy the information from the master
349 * page table, nothing more.
351 static int __kprobes
do_translation_fault(unsigned long addr
,
353 struct pt_regs
*regs
)
355 if (addr
< TASK_SIZE
)
356 return do_page_fault(addr
, esr
, regs
);
358 do_bad_area(addr
, esr
, regs
);
363 * Some section permission faults need to be handled gracefully. They can
364 * happen due to a __{get,put}_user during an oops.
366 static int do_sect_fault(unsigned long addr
, unsigned int esr
,
367 struct pt_regs
*regs
)
369 do_bad_area(addr
, esr
, regs
);
374 * This abort handler always returns "fault".
376 static int do_bad(unsigned long addr
, unsigned int esr
, struct pt_regs
*regs
)
381 static struct fault_info
{
382 int (*fn
)(unsigned long addr
, unsigned int esr
, struct pt_regs
*regs
);
387 { do_bad
, SIGBUS
, 0, "ttbr address size fault" },
388 { do_bad
, SIGBUS
, 0, "level 1 address size fault" },
389 { do_bad
, SIGBUS
, 0, "level 2 address size fault" },
390 { do_bad
, SIGBUS
, 0, "level 3 address size fault" },
391 { do_translation_fault
, SIGSEGV
, SEGV_MAPERR
, "input address range fault" },
392 { do_translation_fault
, SIGSEGV
, SEGV_MAPERR
, "level 1 translation fault" },
393 { do_translation_fault
, SIGSEGV
, SEGV_MAPERR
, "level 2 translation fault" },
394 { do_page_fault
, SIGSEGV
, SEGV_MAPERR
, "level 3 translation fault" },
395 { do_bad
, SIGBUS
, 0, "reserved access flag fault" },
396 { do_bad
, SIGSEGV
, SEGV_ACCERR
, "level 1 access flag fault" },
397 { do_bad
, SIGSEGV
, SEGV_ACCERR
, "level 2 access flag fault" },
398 { do_page_fault
, SIGSEGV
, SEGV_ACCERR
, "level 3 access flag fault" },
399 { do_bad
, SIGBUS
, 0, "reserved permission fault" },
400 { do_bad
, SIGSEGV
, SEGV_ACCERR
, "level 1 permission fault" },
401 { do_sect_fault
, SIGSEGV
, SEGV_ACCERR
, "level 2 permission fault" },
402 { do_page_fault
, SIGSEGV
, SEGV_ACCERR
, "level 3 permission fault" },
403 { do_bad
, SIGBUS
, 0, "synchronous external abort" },
404 { do_bad
, SIGBUS
, 0, "asynchronous external abort" },
405 { do_bad
, SIGBUS
, 0, "unknown 18" },
406 { do_bad
, SIGBUS
, 0, "unknown 19" },
407 { do_bad
, SIGBUS
, 0, "synchronous abort (translation table walk)" },
408 { do_bad
, SIGBUS
, 0, "synchronous abort (translation table walk)" },
409 { do_bad
, SIGBUS
, 0, "synchronous abort (translation table walk)" },
410 { do_bad
, SIGBUS
, 0, "synchronous abort (translation table walk)" },
411 { do_bad
, SIGBUS
, 0, "synchronous parity error" },
412 { do_bad
, SIGBUS
, 0, "asynchronous parity error" },
413 { do_bad
, SIGBUS
, 0, "unknown 26" },
414 { do_bad
, SIGBUS
, 0, "unknown 27" },
415 { do_bad
, SIGBUS
, 0, "synchronous parity error (translation table walk" },
416 { do_bad
, SIGBUS
, 0, "synchronous parity error (translation table walk" },
417 { do_bad
, SIGBUS
, 0, "synchronous parity error (translation table walk" },
418 { do_bad
, SIGBUS
, 0, "synchronous parity error (translation table walk" },
419 { do_bad
, SIGBUS
, 0, "unknown 32" },
420 { do_bad
, SIGBUS
, BUS_ADRALN
, "alignment fault" },
421 { do_bad
, SIGBUS
, 0, "debug event" },
422 { do_bad
, SIGBUS
, 0, "unknown 35" },
423 { do_bad
, SIGBUS
, 0, "unknown 36" },
424 { do_bad
, SIGBUS
, 0, "unknown 37" },
425 { do_bad
, SIGBUS
, 0, "unknown 38" },
426 { do_bad
, SIGBUS
, 0, "unknown 39" },
427 { do_bad
, SIGBUS
, 0, "unknown 40" },
428 { do_bad
, SIGBUS
, 0, "unknown 41" },
429 { do_bad
, SIGBUS
, 0, "unknown 42" },
430 { do_bad
, SIGBUS
, 0, "unknown 43" },
431 { do_bad
, SIGBUS
, 0, "unknown 44" },
432 { do_bad
, SIGBUS
, 0, "unknown 45" },
433 { do_bad
, SIGBUS
, 0, "unknown 46" },
434 { do_bad
, SIGBUS
, 0, "unknown 47" },
435 { do_bad
, SIGBUS
, 0, "unknown 48" },
436 { do_bad
, SIGBUS
, 0, "unknown 49" },
437 { do_bad
, SIGBUS
, 0, "unknown 50" },
438 { do_bad
, SIGBUS
, 0, "unknown 51" },
439 { do_bad
, SIGBUS
, 0, "implementation fault (lockdown abort)" },
440 { do_bad
, SIGBUS
, 0, "unknown 53" },
441 { do_bad
, SIGBUS
, 0, "unknown 54" },
442 { do_bad
, SIGBUS
, 0, "unknown 55" },
443 { do_bad
, SIGBUS
, 0, "unknown 56" },
444 { do_bad
, SIGBUS
, 0, "unknown 57" },
445 { do_bad
, SIGBUS
, 0, "implementation fault (coprocessor abort)" },
446 { do_bad
, SIGBUS
, 0, "unknown 59" },
447 { do_bad
, SIGBUS
, 0, "unknown 60" },
448 { do_bad
, SIGBUS
, 0, "unknown 61" },
449 { do_bad
, SIGBUS
, 0, "unknown 62" },
450 { do_bad
, SIGBUS
, 0, "unknown 63" },
454 * Dispatch a data abort to the relevant handler.
456 asmlinkage
void __exception
do_mem_abort(unsigned long addr
, unsigned int esr
,
457 struct pt_regs
*regs
)
459 const struct fault_info
*inf
= fault_info
+ (esr
& 63);
462 if (!inf
->fn(addr
, esr
, regs
))
465 pr_alert("Unhandled fault: %s (0x%08x) at 0x%016lx\n",
466 inf
->name
, esr
, addr
);
468 info
.si_signo
= inf
->sig
;
470 info
.si_code
= inf
->code
;
471 info
.si_addr
= (void __user
*)addr
;
472 arm64_notify_die("", regs
, &info
, esr
);
476 * Handle stack alignment exceptions.
478 asmlinkage
void __exception
do_sp_pc_abort(unsigned long addr
,
480 struct pt_regs
*regs
)
484 info
.si_signo
= SIGBUS
;
486 info
.si_code
= BUS_ADRALN
;
487 info
.si_addr
= (void __user
*)addr
;
488 arm64_notify_die("", regs
, &info
, esr
);
491 static struct fault_info debug_fault_info
[] = {
492 { do_bad
, SIGTRAP
, TRAP_HWBKPT
, "hardware breakpoint" },
493 { do_bad
, SIGTRAP
, TRAP_HWBKPT
, "hardware single-step" },
494 { do_bad
, SIGTRAP
, TRAP_HWBKPT
, "hardware watchpoint" },
495 { do_bad
, SIGBUS
, 0, "unknown 3" },
496 { do_bad
, SIGTRAP
, TRAP_BRKPT
, "aarch32 BKPT" },
497 { do_bad
, SIGTRAP
, 0, "aarch32 vector catch" },
498 { do_bad
, SIGTRAP
, TRAP_BRKPT
, "aarch64 BRK" },
499 { do_bad
, SIGBUS
, 0, "unknown 7" },
502 void __init
hook_debug_fault_code(int nr
,
503 int (*fn
)(unsigned long, unsigned int, struct pt_regs
*),
504 int sig
, int code
, const char *name
)
506 BUG_ON(nr
< 0 || nr
>= ARRAY_SIZE(debug_fault_info
));
508 debug_fault_info
[nr
].fn
= fn
;
509 debug_fault_info
[nr
].sig
= sig
;
510 debug_fault_info
[nr
].code
= code
;
511 debug_fault_info
[nr
].name
= name
;
514 asmlinkage
int __exception
do_debug_exception(unsigned long addr
,
516 struct pt_regs
*regs
)
518 const struct fault_info
*inf
= debug_fault_info
+ DBG_ESR_EVT(esr
);
521 if (!inf
->fn(addr
, esr
, regs
))
524 pr_alert("Unhandled debug exception: %s (0x%08x) at 0x%016lx\n",
525 inf
->name
, esr
, addr
);
527 info
.si_signo
= inf
->sig
;
529 info
.si_code
= inf
->code
;
530 info
.si_addr
= (void __user
*)addr
;
531 arm64_notify_die("", regs
, &info
, esr
);