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fault.c
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/* * arch/s390/mm/fault.c * * S390 version * Copyright (C) 1999 IBM Deutschland Entwicklung GmbH, IBM Corporation * Author(s): Hartmut Penner (hp@de.ibm.com) * Ulrich Weigand (uweigand@de.ibm.com) * * Derived from "arch/i386/mm/fault.c" * Copyright (C) 1995 Linus Torvalds */ #include <linux/kernel_stat.h> #include <linux/perf_event.h> #include <linux/signal.h> #include <linux/sched.h> #include <linux/kernel.h> #include <linux/errno.h> #include <linux/string.h> #include <linux/types.h> #include <linux/ptrace.h> #include <linux/mman.h> #include <linux/mm.h> #include <linux/compat.h> #include <linux/smp.h> #include <linux/kdebug.h> #include <linux/init.h> #include <linux/console.h> #include <linux/module.h> #include <linux/hardirq.h> #include <linux/kprobes.h> #include <linux/uaccess.h> #include <linux/hugetlb.h> #include <asm/asm-offsets.h> #include <asm/system.h> #include <asm/pgtable.h> #include <asm/s390_ext.h> #include <asm/mmu_context.h> #include <asm/compat.h> #include "../kernel/entry.h" #ifndef CONFIG_64BIT #define __FAIL_ADDR_MASK 0x7ffff000 #define __SUBCODE_MASK 0x0200 #define __PF_RES_FIELD 0ULL #else /* CONFIG_64BIT */ #define __FAIL_ADDR_MASK -4096L #define __SUBCODE_MASK 0x0600 #define __PF_RES_FIELD 0x8000000000000000ULL #endif /* CONFIG_64BIT */ #define VM_FAULT_BADCONTEXT 0x010000 #define VM_FAULT_BADMAP 0x020000 #define VM_FAULT_BADACCESS 0x040000 static unsigned long store_indication; void fault_init(void) { if (test_facility(2) && test_facility(75)) store_indication = 0xc00; } static inline int notify_page_fault(struct pt_regs *regs) { int ret = 0; /* kprobe_running() needs smp_processor_id() */ if (kprobes_built_in() && !user_mode(regs)) { preempt_disable(); if (kprobe_running() && kprobe_fault_handler(regs, 14)) ret = 1; preempt_enable(); } return ret; } /* * Unlock any spinlocks which will prevent us from getting the * message out. */ void bust_spinlocks(int yes) { if (yes) { oops_in_progress = 1; } else { int loglevel_save = console_loglevel; console_unblank(); oops_in_progress = 0; /* * OK, the message is on the console. Now we call printk() * without oops_in_progress set so that printk will give klogd * a poke. Hold onto your hats... */ console_loglevel = 15; printk(" "); console_loglevel = loglevel_save; } } /* * Returns the address space associated with the fault. * Returns 0 for kernel space and 1 for user space. */ static inline int user_space_fault(unsigned long trans_exc_code) { /* * The lowest two bits of the translation exception * identification indicate which paging table was used. */ trans_exc_code &= 3; if (trans_exc_code == 2) /* Access via secondary space, set_fs setting decides */ return current->thread.mm_segment.ar4; if (user_mode == HOME_SPACE_MODE) /* User space if the access has been done via home space. */ return trans_exc_code == 3; /* * If the user space is not the home space the kernel runs in home * space. Access via secondary space has already been covered, * access via primary space or access register is from user space * and access via home space is from the kernel. */ return trans_exc_code != 3; } static inline void report_user_fault(struct pt_regs *regs, long int_code, int signr, unsigned long address) { if ((task_pid_nr(current) > 1) && !show_unhandled_signals) return; if (!unhandled_signal(current, signr)) return; if (!printk_ratelimit()) return; printk("User process fault: interruption code 0x%lX ", int_code); print_vma_addr(KERN_CONT "in ", regs->psw.addr & PSW_ADDR_INSN); printk("\n"); printk("failing address: %lX\n", address); show_regs(regs); } /* * Send SIGSEGV to task. This is an external routine * to keep the stack usage of do_page_fault small. */ static noinline void do_sigsegv(struct pt_regs *regs, long int_code, int si_code, unsigned long trans_exc_code) { struct siginfo si; unsigned long address; address = trans_exc_code & __FAIL_ADDR_MASK; current->thread.prot_addr = address; current->thread.trap_no = int_code; report_user_fault(regs, int_code, SIGSEGV, address); si.si_signo = SIGSEGV; si.si_code = si_code; si.si_addr = (void __user *) address; force_sig_info(SIGSEGV, &si, current); } static noinline void do_no_context(struct pt_regs *regs, long int_code, unsigned long trans_exc_code) { const struct exception_table_entry *fixup; unsigned long address; /* Are we prepared to handle this kernel fault? */ fixup = search_exception_tables(regs->psw.addr & PSW_ADDR_INSN); if (fixup) { regs->psw.addr = fixup->fixup | PSW_ADDR_AMODE; return; } /* * Oops. The kernel tried to access some bad page. We'll have to * terminate things with extreme prejudice. */ address = trans_exc_code & __FAIL_ADDR_MASK; if (!user_space_fault(trans_exc_code)) printk(KERN_ALERT "Unable to handle kernel pointer dereference" " at virtual kernel address %p\n", (void *)address); else printk(KERN_ALERT "Unable to handle kernel paging request" " at virtual user address %p\n", (void *)address); die("Oops", regs, int_code); do_exit(SIGKILL); } static noinline void do_low_address(struct pt_regs *regs, long int_code, unsigned long trans_exc_code) { /* Low-address protection hit in kernel mode means NULL pointer write access in kernel mode. */ if (regs->psw.mask & PSW_MASK_PSTATE) { /* Low-address protection hit in user mode 'cannot happen'. */ die ("Low-address protection", regs, int_code); do_exit(SIGKILL); } do_no_context(regs, int_code, trans_exc_code); } static noinline void do_sigbus(struct pt_regs *regs, long int_code, unsigned long trans_exc_code) { struct task_struct *tsk = current; unsigned long address; struct siginfo si; /* * Send a sigbus, regardless of whether we were in kernel * or user mode. */ address = trans_exc_code & __FAIL_ADDR_MASK; tsk->thread.prot_addr = address; tsk->thread.trap_no = int_code; si.si_signo = SIGBUS; si.si_errno = 0; si.si_code = BUS_ADRERR; si.si_addr = (void __user *) address; force_sig_info(SIGBUS, &si, tsk); } #ifdef CONFIG_S390_EXEC_PROTECT static noinline int signal_return(struct pt_regs *regs, long int_code, unsigned long trans_exc_code) { u16 instruction; int rc; rc = __get_user(instruction, (u16 __user *) regs->psw.addr); if (!rc && instruction == 0x0a77) { clear_tsk_thread_flag(current, TIF_SINGLE_STEP); if (is_compat_task()) sys32_sigreturn(); else sys_sigreturn(); } else if (!rc && instruction == 0x0aad) { clear_tsk_thread_flag(current, TIF_SINGLE_STEP); if (is_compat_task()) sys32_rt_sigreturn(); else sys_rt_sigreturn(); } else do_sigsegv(regs, int_code, SEGV_MAPERR, trans_exc_code); return 0; } #endif /* CONFIG_S390_EXEC_PROTECT */ static noinline void do_fault_error(struct pt_regs *regs, long int_code, unsigned long trans_exc_code, int fault) { int si_code; switch (fault) { case VM_FAULT_BADACCESS: #ifdef CONFIG_S390_EXEC_PROTECT if ((regs->psw.mask & PSW_MASK_ASC) == PSW_ASC_SECONDARY && (trans_exc_code & 3) == 0) { signal_return(regs, int_code, trans_exc_code); break; } #endif /* CONFIG_S390_EXEC_PROTECT */ case VM_FAULT_BADMAP: /* Bad memory access. Check if it is kernel or user space. */ if (regs->psw.mask & PSW_MASK_PSTATE) { /* User mode accesses just cause a SIGSEGV */ si_code = (fault == VM_FAULT_BADMAP) ? SEGV_MAPERR : SEGV_ACCERR; do_sigsegv(regs, int_code, si_code, trans_exc_code); return; } case VM_FAULT_BADCONTEXT: do_no_context(regs, int_code, trans_exc_code); break; default: /* fault & VM_FAULT_ERROR */ if (fault & VM_FAULT_OOM) pagefault_out_of_memory(); else if (fault & VM_FAULT_SIGBUS) { /* Kernel mode? Handle exceptions or die */ if (!(regs->psw.mask & PSW_MASK_PSTATE)) do_no_context(regs, int_code, trans_exc_code); else do_sigbus(regs, int_code, trans_exc_code); } else BUG(); break; } } /* * This routine handles page faults. It determines the address, * and the problem, and then passes it off to one of the appropriate * routines. * * interruption code (int_code): * 04 Protection -> Write-Protection (suprression) * 10 Segment translation -> Not present (nullification) * 11 Page translation -> Not present (nullification) * 3b Region third trans. -> Not present (nullification) */ static inline int do_exception(struct pt_regs *regs, int access, unsigned long trans_exc_code) { struct task_struct *tsk; struct mm_struct *mm; struct vm_area_struct *vma; unsigned long address; int fault, write; if (notify_page_fault(regs)) return 0; tsk = current; mm = tsk->mm; /* * Verify that the fault happened in user space, that * we are not in an interrupt and that there is a * user context. */ fault = VM_FAULT_BADCONTEXT; if (unlikely(!user_space_fault(trans_exc_code) || in_atomic() || !mm)) goto out; address = trans_exc_code & __FAIL_ADDR_MASK; perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, 0, regs, address); down_read(&mm->mmap_sem); fault = VM_FAULT_BADMAP; vma = find_vma(mm, address); if (!vma) goto out_up; if (unlikely(vma->vm_start > address)) { if (!(vma->vm_flags & VM_GROWSDOWN)) goto out_up; if (expand_stack(vma, address)) goto out_up; } /* * Ok, we have a good vm_area for this memory access, so * we can handle it.. */ fault = VM_FAULT_BADACCESS; if (unlikely(!(vma->vm_flags & access))) goto out_up; if (is_vm_hugetlb_page(vma)) address &= HPAGE_MASK; /* * If for any reason at all we couldn't handle the fault, * make sure we exit gracefully rather than endlessly redo * the fault. */ write = (access == VM_WRITE || (trans_exc_code & store_indication) == 0x400) ? FAULT_FLAG_WRITE : 0; fault = handle_mm_fault(mm, vma, address, write); if (unlikely(fault & VM_FAULT_ERROR)) goto out_up; if (fault & VM_FAULT_MAJOR) { tsk->maj_flt++; perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MAJ, 1, 0, regs, address); } else { tsk->min_flt++; perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MIN, 1, 0, regs, address); } /* * The instruction that caused the program check will * be repeated. Don't signal single step via SIGTRAP. */ clear_tsk_thread_flag(tsk, TIF_SINGLE_STEP); fault = 0; out_up: up_read(&mm->mmap_sem); out: return fault; } void __kprobes do_protection_exception(struct pt_regs *regs, long pgm_int_code, unsigned long trans_exc_code) { int fault; /* Protection exception is supressing, decrement psw address. */ regs->psw.addr -= (pgm_int_code >> 16); /* * Check for low-address protection. This needs to be treated * as a special case because the translation exception code * field is not guaranteed to contain valid data in this case. */ if (unlikely(!(trans_exc_code & 4))) { do_low_address(regs, pgm_int_code, trans_exc_code); return; } fault = do_exception(regs, VM_WRITE, trans_exc_code); if (unlikely(fault)) do_fault_error(regs, 4, trans_exc_code, fault); } void __kprobes do_dat_exception(struct pt_regs *regs, long pgm_int_code, unsigned long trans_exc_code) { int access, fault; access = VM_READ | VM_EXEC | VM_WRITE; #ifdef CONFIG_S390_EXEC_PROTECT if ((regs->psw.mask & PSW_MASK_ASC) == PSW_ASC_SECONDARY && (trans_exc_code & 3) == 0) access = VM_EXEC; #endif fault = do_exception(regs, access, trans_exc_code); if (unlikely(fault)) do_fault_error(regs, pgm_int_code & 255, trans_exc_code, fault); } #ifdef CONFIG_64BIT void __kprobes do_asce_exception(struct pt_regs *regs, long pgm_int_code, unsigned long trans_exc_code) { struct mm_struct *mm = current->mm; struct vm_area_struct *vma; if (unlikely(!user_space_fault(trans_exc_code) || in_atomic() || !mm)) goto no_context; down_read(&mm->mmap_sem); vma = find_vma(mm, trans_exc_code & __FAIL_ADDR_MASK); up_read(&mm->mmap_sem); if (vma) { update_mm(mm, current); return; } /* User mode accesses just cause a SIGSEGV */ if (regs->psw.mask & PSW_MASK_PSTATE) { do_sigsegv(regs, pgm_int_code, SEGV_MAPERR, trans_exc_code); return; } no_context: do_no_context(regs, pgm_int_code, trans_exc_code); } #endif int __handle_fault(unsigned long uaddr, unsigned long pgm_int_code, int write) { struct pt_regs regs; int access, fault; regs.psw.mask = psw_kernel_bits; if (!irqs_disabled()) regs.psw.mask |= PSW_MASK_IO | PSW_MASK_EXT; regs.psw.addr = (unsigned long) __builtin_return_address(0); regs.psw.addr |= PSW_ADDR_AMODE; uaddr &= PAGE_MASK; access = write ? VM_WRITE : VM_READ; fault = do_exception(®s, access, uaddr | 2); if (unlikely(fault)) { if (fault & VM_FAULT_OOM) { pagefault_out_of_memory(); fault = 0; } else if (fault & VM_FAULT_SIGBUS) do_sigbus(®s, pgm_int_code, uaddr); } return fault ? -EFAULT : 0; } #ifdef CONFIG_PFAULT /* * 'pfault' pseudo page faults routines. */ static ext_int_info_t ext_int_pfault; static int pfault_disable = 0; static int __init nopfault(char *str) { pfault_disable = 1; return 1; } __setup("nopfault", nopfault); typedef struct { __u16 refdiagc; __u16 reffcode; __u16 refdwlen; __u16 refversn; __u64 refgaddr; __u64 refselmk; __u64 refcmpmk; __u64 reserved; } __attribute__ ((packed, aligned(8))) pfault_refbk_t; int pfault_init(void) { pfault_refbk_t refbk = { 0x258, 0, 5, 2, __LC_CURRENT, 1ULL << 48, 1ULL << 48, __PF_RES_FIELD }; int rc; if (!MACHINE_IS_VM || pfault_disable) return -1; asm volatile( " diag %1,%0,0x258\n" "0: j 2f\n" "1: la %0,8\n" "2:\n" EX_TABLE(0b,1b) : "=d" (rc) : "a" (&refbk), "m" (refbk) : "cc"); __ctl_set_bit(0, 9); return rc; } void pfault_fini(void) { pfault_refbk_t refbk = { 0x258, 1, 5, 2, 0ULL, 0ULL, 0ULL, 0ULL }; if (!MACHINE_IS_VM || pfault_disable) return; __ctl_clear_bit(0,9); asm volatile( " diag %0,0,0x258\n" "0:\n" EX_TABLE(0b,0b) : : "a" (&refbk), "m" (refbk) : "cc"); } static void pfault_interrupt(unsigned int ext_int_code, unsigned int param32, unsigned long param64) { struct task_struct *tsk; __u16 subcode; kstat_cpu(smp_processor_id()).irqs[EXTINT_PFL]++; /* * Get the external interruption subcode & pfault * initial/completion signal bit. VM stores this * in the 'cpu address' field associated with the * external interrupt. */ subcode = ext_int_code >> 16; if ((subcode & 0xff00) != __SUBCODE_MASK) return; /* * Get the token (= address of the task structure of the affected task). */ #ifdef CONFIG_64BIT tsk = *(struct task_struct **) param64; #else tsk = *(struct task_struct **) param32; #endif if (subcode & 0x0080) { /* signal bit is set -> a page has been swapped in by VM */ if (xchg(&tsk->thread.pfault_wait, -1) != 0) { /* Initial interrupt was faster than the completion * interrupt. pfault_wait is valid. Set pfault_wait * back to zero and wake up the process. This can * safely be done because the task is still sleeping * and can't produce new pfaults. */ tsk->thread.pfault_wait = 0; wake_up_process(tsk); put_task_struct(tsk); } } else { /* signal bit not set -> a real page is missing. */ get_task_struct(tsk); set_task_state(tsk, TASK_UNINTERRUPTIBLE); if (xchg(&tsk->thread.pfault_wait, 1) != 0) { /* Completion interrupt was faster than the initial * interrupt (swapped in a -1 for pfault_wait). Set * pfault_wait back to zero and exit. This can be * done safely because tsk is running in kernel * mode and can't produce new pfaults. */ tsk->thread.pfault_wait = 0; set_task_state(tsk, TASK_RUNNING); put_task_struct(tsk); } else set_tsk_need_resched(tsk); } } void __init pfault_irq_init(void) { if (!MACHINE_IS_VM) return; /* * Try to get pfault pseudo page faults going. */ if (register_early_external_interrupt(0x2603, pfault_interrupt, &ext_int_pfault) != 0) panic("Couldn't request external interrupt 0x2603"); if (pfault_init() == 0) return; /* Tough luck, no pfault. */ pfault_disable = 1; unregister_early_external_interrupt(0x2603, pfault_interrupt, &ext_int_pfault); } #endif
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