5 * Copyright (C) 1999 IBM Deutschland Entwicklung GmbH, IBM Corporation
6 * Author(s): Hartmut Penner (hp@de.ibm.com)
7 * Ulrich Weigand (uweigand@de.ibm.com)
9 * Derived from "arch/i386/mm/fault.c"
10 * Copyright (C) 1995 Linus Torvalds
13 #include <linux/perf_event.h>
14 #include <linux/signal.h>
15 #include <linux/sched.h>
16 #include <linux/kernel.h>
17 #include <linux/errno.h>
18 #include <linux/string.h>
19 #include <linux/types.h>
20 #include <linux/ptrace.h>
21 #include <linux/mman.h>
23 #include <linux/compat.h>
24 #include <linux/smp.h>
25 #include <linux/kdebug.h>
26 #include <linux/init.h>
27 #include <linux/console.h>
28 #include <linux/module.h>
29 #include <linux/hardirq.h>
30 #include <linux/kprobes.h>
31 #include <linux/uaccess.h>
32 #include <linux/hugetlb.h>
33 #include <asm/system.h>
34 #include <asm/pgtable.h>
35 #include <asm/s390_ext.h>
36 #include <asm/mmu_context.h>
37 #include <asm/compat.h>
38 #include "../kernel/entry.h"
41 #define __FAIL_ADDR_MASK 0x7ffff000
42 #define __SUBCODE_MASK 0x0200
43 #define __PF_RES_FIELD 0ULL
44 #else /* CONFIG_64BIT */
45 #define __FAIL_ADDR_MASK -4096L
46 #define __SUBCODE_MASK 0x0600
47 #define __PF_RES_FIELD 0x8000000000000000ULL
48 #endif /* CONFIG_64BIT */
51 extern int sysctl_userprocess_debug;
54 #define VM_FAULT_BADCONTEXT 0x010000
55 #define VM_FAULT_BADMAP 0x020000
56 #define VM_FAULT_BADACCESS 0x040000
58 static inline int notify_page_fault(struct pt_regs *regs)
63 /* kprobe_running() needs smp_processor_id() */
64 if (!user_mode(regs)) {
66 if (kprobe_running() && kprobe_fault_handler(regs, 14))
76 * Unlock any spinlocks which will prevent us from getting the
79 void bust_spinlocks(int yes)
84 int loglevel_save = console_loglevel;
88 * OK, the message is on the console. Now we call printk()
89 * without oops_in_progress set so that printk will give klogd
90 * a poke. Hold onto your hats...
92 console_loglevel = 15;
94 console_loglevel = loglevel_save;
99 * Returns the address space associated with the fault.
100 * Returns 0 for kernel space and 1 for user space.
102 static inline int user_space_fault(unsigned long trans_exc_code)
105 * The lowest two bits of the translation exception
106 * identification indicate which paging table was used.
109 if (trans_exc_code == 2)
110 /* Access via secondary space, set_fs setting decides */
111 return current->thread.mm_segment.ar4;
112 if (user_mode == HOME_SPACE_MODE)
113 /* User space if the access has been done via home space. */
114 return trans_exc_code == 3;
116 * If the user space is not the home space the kernel runs in home
117 * space. Access via secondary space has already been covered,
118 * access via primary space or access register is from user space
119 * and access via home space is from the kernel.
121 return trans_exc_code != 3;
125 * Send SIGSEGV to task. This is an external routine
126 * to keep the stack usage of do_page_fault small.
128 static noinline void do_sigsegv(struct pt_regs *regs, long int_code,
129 int si_code, unsigned long trans_exc_code)
132 unsigned long address;
134 address = trans_exc_code & __FAIL_ADDR_MASK;
135 current->thread.prot_addr = address;
136 current->thread.trap_no = int_code;
137 #if defined(CONFIG_SYSCTL) || defined(CONFIG_PROCESS_DEBUG)
138 #if defined(CONFIG_SYSCTL)
139 if (sysctl_userprocess_debug)
142 printk("User process fault: interruption code 0x%lX\n",
144 printk("failing address: %lX\n", address);
148 si.si_signo = SIGSEGV;
149 si.si_code = si_code;
150 si.si_addr = (void __user *) address;
151 force_sig_info(SIGSEGV, &si, current);
154 static noinline void do_no_context(struct pt_regs *regs, long int_code,
155 unsigned long trans_exc_code)
157 const struct exception_table_entry *fixup;
158 unsigned long address;
160 /* Are we prepared to handle this kernel fault? */
161 fixup = search_exception_tables(regs->psw.addr & PSW_ADDR_INSN);
163 regs->psw.addr = fixup->fixup | PSW_ADDR_AMODE;
168 * Oops. The kernel tried to access some bad page. We'll have to
169 * terminate things with extreme prejudice.
171 address = trans_exc_code & __FAIL_ADDR_MASK;
172 if (!user_space_fault(trans_exc_code))
173 printk(KERN_ALERT "Unable to handle kernel pointer dereference"
174 " at virtual kernel address %p\n", (void *)address);
176 printk(KERN_ALERT "Unable to handle kernel paging request"
177 " at virtual user address %p\n", (void *)address);
179 die("Oops", regs, int_code);
183 static noinline void do_low_address(struct pt_regs *regs, long int_code,
184 unsigned long trans_exc_code)
186 /* Low-address protection hit in kernel mode means
187 NULL pointer write access in kernel mode. */
188 if (regs->psw.mask & PSW_MASK_PSTATE) {
189 /* Low-address protection hit in user mode 'cannot happen'. */
190 die ("Low-address protection", regs, int_code);
194 do_no_context(regs, int_code, trans_exc_code);
197 static noinline void do_sigbus(struct pt_regs *regs, long int_code,
198 unsigned long trans_exc_code)
200 struct task_struct *tsk = current;
203 * Send a sigbus, regardless of whether we were in kernel
206 tsk->thread.prot_addr = trans_exc_code & __FAIL_ADDR_MASK;
207 tsk->thread.trap_no = int_code;
208 force_sig(SIGBUS, tsk);
211 #ifdef CONFIG_S390_EXEC_PROTECT
212 static noinline int signal_return(struct pt_regs *regs, long int_code,
213 unsigned long trans_exc_code)
218 rc = __get_user(instruction, (u16 __user *) regs->psw.addr);
220 if (!rc && instruction == 0x0a77) {
221 clear_tsk_thread_flag(current, TIF_SINGLE_STEP);
222 if (is_compat_task())
226 } else if (!rc && instruction == 0x0aad) {
227 clear_tsk_thread_flag(current, TIF_SINGLE_STEP);
228 if (is_compat_task())
229 sys32_rt_sigreturn();
233 do_sigsegv(regs, int_code, SEGV_MAPERR, trans_exc_code);
236 #endif /* CONFIG_S390_EXEC_PROTECT */
238 static noinline void do_fault_error(struct pt_regs *regs, long int_code,
239 unsigned long trans_exc_code, int fault)
244 case VM_FAULT_BADACCESS:
245 #ifdef CONFIG_S390_EXEC_PROTECT
246 if ((regs->psw.mask & PSW_MASK_ASC) == PSW_ASC_SECONDARY &&
247 (trans_exc_code & 3) == 0) {
248 signal_return(regs, int_code, trans_exc_code);
251 #endif /* CONFIG_S390_EXEC_PROTECT */
252 case VM_FAULT_BADMAP:
253 /* Bad memory access. Check if it is kernel or user space. */
254 if (regs->psw.mask & PSW_MASK_PSTATE) {
255 /* User mode accesses just cause a SIGSEGV */
256 si_code = (fault == VM_FAULT_BADMAP) ?
257 SEGV_MAPERR : SEGV_ACCERR;
258 do_sigsegv(regs, int_code, si_code, trans_exc_code);
261 case VM_FAULT_BADCONTEXT:
262 do_no_context(regs, int_code, trans_exc_code);
264 default: /* fault & VM_FAULT_ERROR */
265 if (fault & VM_FAULT_OOM)
266 pagefault_out_of_memory();
267 else if (fault & VM_FAULT_SIGBUS) {
268 do_sigbus(regs, int_code, trans_exc_code);
269 /* Kernel mode? Handle exceptions or die */
270 if (!(regs->psw.mask & PSW_MASK_PSTATE))
271 do_no_context(regs, int_code, trans_exc_code);
279 * This routine handles page faults. It determines the address,
280 * and the problem, and then passes it off to one of the appropriate
283 * interruption code (int_code):
284 * 04 Protection -> Write-Protection (suprression)
285 * 10 Segment translation -> Not present (nullification)
286 * 11 Page translation -> Not present (nullification)
287 * 3b Region third trans. -> Not present (nullification)
289 static inline int do_exception(struct pt_regs *regs, int access,
290 unsigned long trans_exc_code)
292 struct task_struct *tsk;
293 struct mm_struct *mm;
294 struct vm_area_struct *vma;
295 unsigned long address;
298 if (notify_page_fault(regs))
305 * Verify that the fault happened in user space, that
306 * we are not in an interrupt and that there is a
309 fault = VM_FAULT_BADCONTEXT;
310 if (unlikely(!user_space_fault(trans_exc_code) || in_atomic() || !mm))
313 address = trans_exc_code & __FAIL_ADDR_MASK;
315 * When we get here, the fault happened in the current
316 * task's user address space, so we can switch on the
317 * interrupts again and then search the VMAs
320 perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, 0, regs, address);
321 down_read(&mm->mmap_sem);
323 fault = VM_FAULT_BADMAP;
324 vma = find_vma(mm, address);
328 if (unlikely(vma->vm_start > address)) {
329 if (!(vma->vm_flags & VM_GROWSDOWN))
331 if (expand_stack(vma, address))
336 * Ok, we have a good vm_area for this memory access, so
339 fault = VM_FAULT_BADACCESS;
340 if (unlikely(!(vma->vm_flags & access)))
343 if (is_vm_hugetlb_page(vma))
344 address &= HPAGE_MASK;
346 * If for any reason at all we couldn't handle the fault,
347 * make sure we exit gracefully rather than endlessly redo
350 fault = handle_mm_fault(mm, vma, address,
351 (access == VM_WRITE) ? FAULT_FLAG_WRITE : 0);
352 if (unlikely(fault & VM_FAULT_ERROR))
355 if (fault & VM_FAULT_MAJOR) {
357 perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MAJ, 1, 0,
361 perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MIN, 1, 0,
365 * The instruction that caused the program check will
366 * be repeated. Don't signal single step via SIGTRAP.
368 clear_tsk_thread_flag(tsk, TIF_SINGLE_STEP);
371 up_read(&mm->mmap_sem);
376 void __kprobes do_protection_exception(struct pt_regs *regs, long int_code)
378 unsigned long trans_exc_code = S390_lowcore.trans_exc_code;
381 /* Protection exception is supressing, decrement psw address. */
382 regs->psw.addr -= (int_code >> 16);
384 * Check for low-address protection. This needs to be treated
385 * as a special case because the translation exception code
386 * field is not guaranteed to contain valid data in this case.
388 if (unlikely(!(trans_exc_code & 4))) {
389 do_low_address(regs, int_code, trans_exc_code);
392 fault = do_exception(regs, VM_WRITE, trans_exc_code);
394 do_fault_error(regs, 4, trans_exc_code, fault);
397 void __kprobes do_dat_exception(struct pt_regs *regs, long int_code)
399 unsigned long trans_exc_code = S390_lowcore.trans_exc_code;
402 access = VM_READ | VM_EXEC | VM_WRITE;
403 #ifdef CONFIG_S390_EXEC_PROTECT
404 if ((regs->psw.mask & PSW_MASK_ASC) == PSW_ASC_SECONDARY &&
405 (trans_exc_code & 3) == 0)
408 fault = do_exception(regs, access, trans_exc_code);
410 do_fault_error(regs, int_code & 255, trans_exc_code, fault);
414 void __kprobes do_asce_exception(struct pt_regs *regs, long int_code)
416 unsigned long trans_exc_code = S390_lowcore.trans_exc_code;
417 struct mm_struct *mm = current->mm;
418 struct vm_area_struct *vma;
420 if (unlikely(!user_space_fault(trans_exc_code) || in_atomic() || !mm))
425 down_read(&mm->mmap_sem);
426 vma = find_vma(mm, trans_exc_code & __FAIL_ADDR_MASK);
427 up_read(&mm->mmap_sem);
430 update_mm(mm, current);
434 /* User mode accesses just cause a SIGSEGV */
435 if (regs->psw.mask & PSW_MASK_PSTATE) {
436 do_sigsegv(regs, int_code, SEGV_MAPERR, trans_exc_code);
441 do_no_context(regs, int_code, trans_exc_code);
445 int __handle_fault(unsigned long uaddr, unsigned long int_code, int write_user)
450 regs.psw.mask = psw_kernel_bits;
451 if (!irqs_disabled())
452 regs.psw.mask |= PSW_MASK_IO | PSW_MASK_EXT;
453 regs.psw.addr = (unsigned long) __builtin_return_address(0);
454 regs.psw.addr |= PSW_ADDR_AMODE;
456 access = write_user ? VM_WRITE : VM_READ;
457 fault = do_exception(®s, access, uaddr | 2);
458 if (unlikely(fault)) {
459 if (fault & VM_FAULT_OOM) {
460 pagefault_out_of_memory();
462 } else if (fault & VM_FAULT_SIGBUS)
463 do_sigbus(®s, int_code, uaddr);
465 return fault ? -EFAULT : 0;
470 * 'pfault' pseudo page faults routines.
472 static ext_int_info_t ext_int_pfault;
473 static int pfault_disable = 0;
475 static int __init nopfault(char *str)
481 __setup("nopfault", nopfault);
492 } __attribute__ ((packed, aligned(8))) pfault_refbk_t;
494 int pfault_init(void)
496 pfault_refbk_t refbk =
497 { 0x258, 0, 5, 2, __LC_CURRENT, 1ULL << 48, 1ULL << 48,
501 if (!MACHINE_IS_VM || pfault_disable)
504 " diag %1,%0,0x258\n"
509 : "=d" (rc) : "a" (&refbk), "m" (refbk) : "cc");
514 void pfault_fini(void)
516 pfault_refbk_t refbk =
517 { 0x258, 1, 5, 2, 0ULL, 0ULL, 0ULL, 0ULL };
519 if (!MACHINE_IS_VM || pfault_disable)
521 __ctl_clear_bit(0,9);
526 : : "a" (&refbk), "m" (refbk) : "cc");
529 static void pfault_interrupt(__u16 int_code)
531 struct task_struct *tsk;
535 * Get the external interruption subcode & pfault
536 * initial/completion signal bit. VM stores this
537 * in the 'cpu address' field associated with the
538 * external interrupt.
540 subcode = S390_lowcore.cpu_addr;
541 if ((subcode & 0xff00) != __SUBCODE_MASK)
545 * Get the token (= address of the task structure of the affected task).
547 tsk = *(struct task_struct **) __LC_PFAULT_INTPARM;
549 if (subcode & 0x0080) {
550 /* signal bit is set -> a page has been swapped in by VM */
551 if (xchg(&tsk->thread.pfault_wait, -1) != 0) {
552 /* Initial interrupt was faster than the completion
553 * interrupt. pfault_wait is valid. Set pfault_wait
554 * back to zero and wake up the process. This can
555 * safely be done because the task is still sleeping
556 * and can't produce new pfaults. */
557 tsk->thread.pfault_wait = 0;
558 wake_up_process(tsk);
559 put_task_struct(tsk);
562 /* signal bit not set -> a real page is missing. */
563 get_task_struct(tsk);
564 set_task_state(tsk, TASK_UNINTERRUPTIBLE);
565 if (xchg(&tsk->thread.pfault_wait, 1) != 0) {
566 /* Completion interrupt was faster than the initial
567 * interrupt (swapped in a -1 for pfault_wait). Set
568 * pfault_wait back to zero and exit. This can be
569 * done safely because tsk is running in kernel
570 * mode and can't produce new pfaults. */
571 tsk->thread.pfault_wait = 0;
572 set_task_state(tsk, TASK_RUNNING);
573 put_task_struct(tsk);
575 set_tsk_need_resched(tsk);
579 void __init pfault_irq_init(void)
585 * Try to get pfault pseudo page faults going.
587 if (register_early_external_interrupt(0x2603, pfault_interrupt,
588 &ext_int_pfault) != 0)
589 panic("Couldn't request external interrupt 0x2603");
591 if (pfault_init() == 0)
594 /* Tough luck, no pfault. */
596 unregister_early_external_interrupt(0x2603, pfault_interrupt,