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>
39 static const char *fault_name(unsigned int esr);
42 * Dump out the page tables associated with 'addr' in mm 'mm'.
44 void show_pte(struct mm_struct *mm, unsigned long addr)
51 pr_alert("pgd = %p\n", mm->pgd);
52 pgd = pgd_offset(mm, addr);
53 pr_alert("[%08lx] *pgd=%016llx", addr, pgd_val(*pgd));
60 if (pgd_none(*pgd) || pgd_bad(*pgd))
63 pud = pud_offset(pgd, addr);
64 if (pud_none(*pud) || pud_bad(*pud))
67 pmd = pmd_offset(pud, addr);
68 printk(", *pmd=%016llx", pmd_val(*pmd));
69 if (pmd_none(*pmd) || pmd_bad(*pmd))
72 pte = pte_offset_map(pmd, addr);
73 printk(", *pte=%016llx", pte_val(*pte));
81 * The kernel tried to access some page that wasn't present.
83 static void __do_kernel_fault(struct mm_struct *mm, unsigned long addr,
84 unsigned int esr, struct pt_regs *regs)
87 * Are we prepared to handle this kernel fault?
89 if (fixup_exception(regs))
93 * No handler, we'll have to terminate things with extreme prejudice.
96 pr_alert("Unable to handle kernel %s at virtual address %08lx\n",
97 (addr < PAGE_SIZE) ? "NULL pointer dereference" :
98 "paging request", addr);
101 die("Oops", regs, esr);
107 * Something tried to access memory that isn't in our memory map. User mode
108 * accesses just cause a SIGSEGV
110 static void __do_user_fault(struct task_struct *tsk, unsigned long addr,
111 unsigned int esr, unsigned int sig, int code,
112 struct pt_regs *regs)
116 if (show_unhandled_signals && unhandled_signal(tsk, sig) &&
117 printk_ratelimit()) {
118 pr_info("%s[%d]: unhandled %s (%d) at 0x%08lx, esr 0x%03x\n",
119 tsk->comm, task_pid_nr(tsk), fault_name(esr), sig,
121 show_pte(tsk->mm, addr);
125 tsk->thread.fault_address = addr;
129 si.si_addr = (void __user *)addr;
130 force_sig_info(sig, &si, tsk);
133 void do_bad_area(unsigned long addr, unsigned int esr, struct pt_regs *regs)
135 struct task_struct *tsk = current;
136 struct mm_struct *mm = tsk->active_mm;
139 * If we are in kernel mode at this point, we have no context to
140 * handle this fault with.
143 __do_user_fault(tsk, addr, esr, SIGSEGV, SEGV_MAPERR, regs);
145 __do_kernel_fault(mm, addr, esr, regs);
148 #define VM_FAULT_BADMAP 0x010000
149 #define VM_FAULT_BADACCESS 0x020000
151 #define ESR_WRITE (1 << 6)
152 #define ESR_CM (1 << 8)
153 #define ESR_LNX_EXEC (1 << 24)
156 * Check that the permissions on the VMA allow for the fault which occurred.
157 * If we encountered a write fault, we must have write permission, otherwise
158 * we allow any permission.
160 static inline bool access_error(unsigned int esr, struct vm_area_struct *vma)
162 unsigned int mask = VM_READ | VM_WRITE | VM_EXEC;
166 if (esr & ESR_LNX_EXEC)
169 return vma->vm_flags & mask ? false : true;
172 static int __do_page_fault(struct mm_struct *mm, unsigned long addr,
173 unsigned int esr, unsigned int flags,
174 struct task_struct *tsk)
176 struct vm_area_struct *vma;
179 vma = find_vma(mm, addr);
180 fault = VM_FAULT_BADMAP;
183 if (unlikely(vma->vm_start > addr))
187 * Ok, we have a good vm_area for this memory access, so we can handle
191 if (access_error(esr, vma)) {
192 fault = VM_FAULT_BADACCESS;
196 return handle_mm_fault(mm, vma, addr & PAGE_MASK, flags);
199 if (vma->vm_flags & VM_GROWSDOWN && !expand_stack(vma, addr))
205 static int __kprobes do_page_fault(unsigned long addr, unsigned int esr,
206 struct pt_regs *regs)
208 struct task_struct *tsk;
209 struct mm_struct *mm;
210 int fault, sig, code;
211 bool write = (esr & ESR_WRITE) && !(esr & ESR_CM);
212 unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE |
213 (write ? FAULT_FLAG_WRITE : 0);
218 /* Enable interrupts if they were enabled in the parent context. */
219 if (interrupts_enabled(regs))
223 * If we're in an interrupt or have no user context, we must not take
226 if (in_atomic() || !mm)
230 * As per x86, we may deadlock here. However, since the kernel only
231 * validly references user space from well defined areas of the code,
232 * we can bug out early if this is from code which shouldn't.
234 if (!down_read_trylock(&mm->mmap_sem)) {
235 if (!user_mode(regs) && !search_exception_tables(regs->pc))
238 down_read(&mm->mmap_sem);
241 * The above down_read_trylock() might have succeeded in which
242 * case, we'll have missed the might_sleep() from down_read().
245 #ifdef CONFIG_DEBUG_VM
246 if (!user_mode(regs) && !search_exception_tables(regs->pc))
251 fault = __do_page_fault(mm, addr, esr, flags, tsk);
254 * If we need to retry but a fatal signal is pending, handle the
255 * signal first. We do not need to release the mmap_sem because it
256 * would already be released in __lock_page_or_retry in mm/filemap.c.
258 if ((fault & VM_FAULT_RETRY) && fatal_signal_pending(current))
262 * Major/minor page fault accounting is only done on the initial
263 * attempt. If we go through a retry, it is extremely likely that the
264 * page will be found in page cache at that point.
267 perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, addr);
268 if (flags & FAULT_FLAG_ALLOW_RETRY) {
269 if (fault & VM_FAULT_MAJOR) {
271 perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MAJ, 1, regs,
275 perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MIN, 1, regs,
278 if (fault & VM_FAULT_RETRY) {
280 * Clear FAULT_FLAG_ALLOW_RETRY to avoid any risk of
283 flags &= ~FAULT_FLAG_ALLOW_RETRY;
288 up_read(&mm->mmap_sem);
291 * Handle the "normal" case first - VM_FAULT_MAJOR / VM_FAULT_MINOR
293 if (likely(!(fault & (VM_FAULT_ERROR | VM_FAULT_BADMAP |
294 VM_FAULT_BADACCESS))))
297 if (fault & VM_FAULT_OOM) {
299 * We ran out of memory, call the OOM killer, and return to
300 * userspace (which will retry the fault, or kill us if we got
303 pagefault_out_of_memory();
308 * If we are in kernel mode at this point, we have no context to
309 * handle this fault with.
311 if (!user_mode(regs))
314 if (fault & VM_FAULT_SIGBUS) {
316 * We had some memory, but were unable to successfully fix up
323 * Something tried to access memory that isn't in our memory
327 code = fault == VM_FAULT_BADACCESS ?
328 SEGV_ACCERR : SEGV_MAPERR;
331 __do_user_fault(tsk, addr, esr, sig, code, regs);
335 __do_kernel_fault(mm, addr, esr, regs);
340 * First Level Translation Fault Handler
342 * We enter here because the first level page table doesn't contain a valid
343 * entry for the address.
345 * If the address is in kernel space (>= TASK_SIZE), then we are probably
346 * faulting in the vmalloc() area.
348 * If the init_task's first level page tables contains the relevant entry, we
349 * copy the it to this task. If not, we send the process a signal, fixup the
350 * exception, or oops the kernel.
352 * NOTE! We MUST NOT take any locks for this case. We may be in an interrupt
353 * or a critical region, and should only copy the information from the master
354 * page table, nothing more.
356 static int __kprobes do_translation_fault(unsigned long addr,
358 struct pt_regs *regs)
360 if (addr < TASK_SIZE)
361 return do_page_fault(addr, esr, regs);
363 do_bad_area(addr, esr, regs);
368 * Some section permission faults need to be handled gracefully. They can
369 * happen due to a __{get,put}_user during an oops.
371 static int do_sect_fault(unsigned long addr, unsigned int esr,
372 struct pt_regs *regs)
374 do_bad_area(addr, esr, regs);
379 * This abort handler always returns "fault".
381 static int do_bad(unsigned long addr, unsigned int esr, struct pt_regs *regs)
386 static struct fault_info {
387 int (*fn)(unsigned long addr, unsigned int esr, struct pt_regs *regs);
392 { do_bad, SIGBUS, 0, "ttbr address size fault" },
393 { do_bad, SIGBUS, 0, "level 1 address size fault" },
394 { do_bad, SIGBUS, 0, "level 2 address size fault" },
395 { do_bad, SIGBUS, 0, "level 3 address size fault" },
396 { do_translation_fault, SIGSEGV, SEGV_MAPERR, "input address range fault" },
397 { do_translation_fault, SIGSEGV, SEGV_MAPERR, "level 1 translation fault" },
398 { do_translation_fault, SIGSEGV, SEGV_MAPERR, "level 2 translation fault" },
399 { do_page_fault, SIGSEGV, SEGV_MAPERR, "level 3 translation fault" },
400 { do_bad, SIGBUS, 0, "reserved access flag fault" },
401 { do_bad, SIGSEGV, SEGV_ACCERR, "level 1 access flag fault" },
402 { do_bad, SIGSEGV, SEGV_ACCERR, "level 2 access flag fault" },
403 { do_page_fault, SIGSEGV, SEGV_ACCERR, "level 3 access flag fault" },
404 { do_bad, SIGBUS, 0, "reserved permission fault" },
405 { do_bad, SIGSEGV, SEGV_ACCERR, "level 1 permission fault" },
406 { do_sect_fault, SIGSEGV, SEGV_ACCERR, "level 2 permission fault" },
407 { do_page_fault, SIGSEGV, SEGV_ACCERR, "level 3 permission fault" },
408 { do_bad, SIGBUS, 0, "synchronous external abort" },
409 { do_bad, SIGBUS, 0, "asynchronous external abort" },
410 { do_bad, SIGBUS, 0, "unknown 18" },
411 { do_bad, SIGBUS, 0, "unknown 19" },
412 { do_bad, SIGBUS, 0, "synchronous abort (translation table walk)" },
413 { do_bad, SIGBUS, 0, "synchronous abort (translation table walk)" },
414 { do_bad, SIGBUS, 0, "synchronous abort (translation table walk)" },
415 { do_bad, SIGBUS, 0, "synchronous abort (translation table walk)" },
416 { do_bad, SIGBUS, 0, "synchronous parity error" },
417 { do_bad, SIGBUS, 0, "asynchronous parity error" },
418 { do_bad, SIGBUS, 0, "unknown 26" },
419 { do_bad, SIGBUS, 0, "unknown 27" },
420 { do_bad, SIGBUS, 0, "synchronous parity error (translation table walk" },
421 { do_bad, SIGBUS, 0, "synchronous parity error (translation table walk" },
422 { do_bad, SIGBUS, 0, "synchronous parity error (translation table walk" },
423 { do_bad, SIGBUS, 0, "synchronous parity error (translation table walk" },
424 { do_bad, SIGBUS, 0, "unknown 32" },
425 { do_bad, SIGBUS, BUS_ADRALN, "alignment fault" },
426 { do_bad, SIGBUS, 0, "debug event" },
427 { do_bad, SIGBUS, 0, "unknown 35" },
428 { do_bad, SIGBUS, 0, "unknown 36" },
429 { do_bad, SIGBUS, 0, "unknown 37" },
430 { do_bad, SIGBUS, 0, "unknown 38" },
431 { do_bad, SIGBUS, 0, "unknown 39" },
432 { do_bad, SIGBUS, 0, "unknown 40" },
433 { do_bad, SIGBUS, 0, "unknown 41" },
434 { do_bad, SIGBUS, 0, "unknown 42" },
435 { do_bad, SIGBUS, 0, "unknown 43" },
436 { do_bad, SIGBUS, 0, "unknown 44" },
437 { do_bad, SIGBUS, 0, "unknown 45" },
438 { do_bad, SIGBUS, 0, "unknown 46" },
439 { do_bad, SIGBUS, 0, "unknown 47" },
440 { do_bad, SIGBUS, 0, "unknown 48" },
441 { do_bad, SIGBUS, 0, "unknown 49" },
442 { do_bad, SIGBUS, 0, "unknown 50" },
443 { do_bad, SIGBUS, 0, "unknown 51" },
444 { do_bad, SIGBUS, 0, "implementation fault (lockdown abort)" },
445 { do_bad, SIGBUS, 0, "unknown 53" },
446 { do_bad, SIGBUS, 0, "unknown 54" },
447 { do_bad, SIGBUS, 0, "unknown 55" },
448 { do_bad, SIGBUS, 0, "unknown 56" },
449 { do_bad, SIGBUS, 0, "unknown 57" },
450 { do_bad, SIGBUS, 0, "implementation fault (coprocessor abort)" },
451 { do_bad, SIGBUS, 0, "unknown 59" },
452 { do_bad, SIGBUS, 0, "unknown 60" },
453 { do_bad, SIGBUS, 0, "unknown 61" },
454 { do_bad, SIGBUS, 0, "unknown 62" },
455 { do_bad, SIGBUS, 0, "unknown 63" },
458 static const char *fault_name(unsigned int esr)
460 const struct fault_info *inf = fault_info + (esr & 63);
465 * Dispatch a data abort to the relevant handler.
467 asmlinkage void __exception do_mem_abort(unsigned long addr, unsigned int esr,
468 struct pt_regs *regs)
470 const struct fault_info *inf = fault_info + (esr & 63);
473 if (!inf->fn(addr, esr, regs))
476 pr_alert("Unhandled fault: %s (0x%08x) at 0x%016lx\n",
477 inf->name, esr, addr);
479 info.si_signo = inf->sig;
481 info.si_code = inf->code;
482 info.si_addr = (void __user *)addr;
483 arm64_notify_die("", regs, &info, esr);
487 * Handle stack alignment exceptions.
489 asmlinkage void __exception do_sp_pc_abort(unsigned long addr,
491 struct pt_regs *regs)
495 info.si_signo = SIGBUS;
497 info.si_code = BUS_ADRALN;
498 info.si_addr = (void __user *)addr;
499 arm64_notify_die("", regs, &info, esr);
502 static struct fault_info debug_fault_info[] = {
503 { do_bad, SIGTRAP, TRAP_HWBKPT, "hardware breakpoint" },
504 { do_bad, SIGTRAP, TRAP_HWBKPT, "hardware single-step" },
505 { do_bad, SIGTRAP, TRAP_HWBKPT, "hardware watchpoint" },
506 { do_bad, SIGBUS, 0, "unknown 3" },
507 { do_bad, SIGTRAP, TRAP_BRKPT, "aarch32 BKPT" },
508 { do_bad, SIGTRAP, 0, "aarch32 vector catch" },
509 { do_bad, SIGTRAP, TRAP_BRKPT, "aarch64 BRK" },
510 { do_bad, SIGBUS, 0, "unknown 7" },
513 void __init hook_debug_fault_code(int nr,
514 int (*fn)(unsigned long, unsigned int, struct pt_regs *),
515 int sig, int code, const char *name)
517 BUG_ON(nr < 0 || nr >= ARRAY_SIZE(debug_fault_info));
519 debug_fault_info[nr].fn = fn;
520 debug_fault_info[nr].sig = sig;
521 debug_fault_info[nr].code = code;
522 debug_fault_info[nr].name = name;
525 asmlinkage int __exception do_debug_exception(unsigned long addr,
527 struct pt_regs *regs)
529 const struct fault_info *inf = debug_fault_info + DBG_ESR_EVT(esr);
532 if (!inf->fn(addr, esr, regs))
535 pr_alert("Unhandled debug exception: %s (0x%08x) at 0x%016lx\n",
536 inf->name, esr, addr);
538 info.si_signo = inf->sig;
540 info.si_code = inf->code;
541 info.si_addr = (void __user *)addr;
542 arm64_notify_die("", regs, &info, esr);