/* * linux/arch/arm/mm/fault.c * * Copyright (C) 1995 Linus Torvalds * Modifications for ARM processor (c) 1995-2004 Russell King * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License version 2 as * published by the Free Software Foundation. */ #include <linux/module.h> #include <linux/signal.h> #include <linux/mm.h> #include <linux/hardirq.h> #include <linux/init.h> #include <linux/kprobes.h> #include <linux/uaccess.h> #include <linux/page-flags.h> #include <linux/sched.h> #include <linux/highmem.h> #include <linux/perf_event.h> #include <asm/system.h> #include <asm/pgtable.h> #include <asm/tlbflush.h> #include "fault.h" /* * Fault status register encodings. We steal bit 31 for our own purposes. */ #define FSR_LNX_PF (1 << 31) #define FSR_WRITE (1 << 11) #define FSR_FS4 (1 << 10) #define FSR_FS3_0 (15) static inline int fsr_fs(unsigned int fsr) { return (fsr & FSR_FS3_0) | (fsr & FSR_FS4) >> 6; } #ifdef CONFIG_MMU #ifdef CONFIG_KPROBES static inline int notify_page_fault(struct pt_regs *regs, unsigned int fsr) { int ret = 0; if (!user_mode(regs)) { /* kprobe_running() needs smp_processor_id() */ preempt_disable(); if (kprobe_running() && kprobe_fault_handler(regs, fsr)) ret = 1; preempt_enable(); } return ret; } #else static inline int notify_page_fault(struct pt_regs *regs, unsigned int fsr) { return 0; } #endif /* * This is useful to dump out the page tables associated with * 'addr' in mm 'mm'. */ void show_pte(struct mm_struct *mm, unsigned long addr) { pgd_t *pgd; if (!mm) mm = &init_mm; printk(KERN_ALERT "pgd = %p\n", mm->pgd); pgd = pgd_offset(mm, addr); printk(KERN_ALERT "[%08lx] *pgd=%08lx", addr, pgd_val(*pgd)); do { pmd_t *pmd; pte_t *pte; if (pgd_none(*pgd)) break; if (pgd_bad(*pgd)) { printk("(bad)"); break; } pmd = pmd_offset(pgd, addr); if (PTRS_PER_PMD != 1) printk(", *pmd=%08lx", pmd_val(*pmd)); if (pmd_none(*pmd)) break; if (pmd_bad(*pmd)) { printk("(bad)"); break; } /* We must not map this if we have highmem enabled */ if (PageHighMem(pfn_to_page(pmd_val(*pmd) >> PAGE_SHIFT))) break; pte = pte_offset_map(pmd, addr); printk(", *pte=%08lx", pte_val(*pte)); printk(", *ppte=%08lx", pte_val(pte[-PTRS_PER_PTE])); pte_unmap(pte); } while(0); printk("\n"); } #else /* CONFIG_MMU */ void show_pte(struct mm_struct *mm, unsigned long addr) { } #endif /* CONFIG_MMU */ /* * Oops. The kernel tried to access some page that wasn't present. */ static void __do_kernel_fault(struct mm_struct *mm, unsigned long addr, unsigned int fsr, struct pt_regs *regs) { /* * Are we prepared to handle this kernel fault? */ if (fixup_exception(regs)) return; /* * No handler, we'll have to terminate things with extreme prejudice. */ bust_spinlocks(1); printk(KERN_ALERT "Unable to handle kernel %s at virtual address %08lx\n", (addr < PAGE_SIZE) ? "NULL pointer dereference" : "paging request", addr); show_pte(mm, addr); die("Oops", regs, fsr); bust_spinlocks(0); do_exit(SIGKILL); } /* * Something tried to access memory that isn't in our memory map.. * User mode accesses just cause a SIGSEGV */ static void __do_user_fault(struct task_struct *tsk, unsigned long addr, unsigned int fsr, unsigned int sig, int code, struct pt_regs *regs) { struct siginfo si; #ifdef CONFIG_DEBUG_USER if (user_debug & UDBG_SEGV) { printk(KERN_DEBUG "%s: unhandled page fault (%d) at 0x%08lx, code 0x%03x\n", tsk->comm, sig, addr, fsr); show_pte(tsk->mm, addr); show_regs(regs); } #endif tsk->thread.address = addr; tsk->thread.error_code = fsr; tsk->thread.trap_no = 14; si.si_signo = sig; si.si_errno = 0; si.si_code = code; si.si_addr = (void __user *)addr; force_sig_info(sig, &si, tsk); } void do_bad_area(unsigned long addr, unsigned int fsr, struct pt_regs *regs) { struct task_struct *tsk = current; struct mm_struct *mm = tsk->active_mm; /* * If we are in kernel mode at this point, we * have no context to handle this fault with. */ if (user_mode(regs)) __do_user_fault(tsk, addr, fsr, SIGSEGV, SEGV_MAPERR, regs); else __do_kernel_fault(mm, addr, fsr, regs); } #ifdef CONFIG_MMU #define VM_FAULT_BADMAP 0x010000 #define VM_FAULT_BADACCESS 0x020000 /* * Check that the permissions on the VMA allow for the fault which occurred. * If we encountered a write fault, we must have write permission, otherwise * we allow any permission. */ static inline bool access_error(unsigned int fsr, struct vm_area_struct *vma) { unsigned int mask = VM_READ | VM_WRITE | VM_EXEC; if (fsr & FSR_WRITE) mask = VM_WRITE; if (fsr & FSR_LNX_PF) mask = VM_EXEC; return vma->vm_flags & mask ? false : true; } static int __kprobes __do_page_fault(struct mm_struct *mm, unsigned long addr, unsigned int fsr, struct task_struct *tsk) { struct vm_area_struct *vma; int fault; vma = find_vma(mm, addr); fault = VM_FAULT_BADMAP; if (unlikely(!vma)) goto out; if (unlikely(vma->vm_start > addr)) goto check_stack; /* * Ok, we have a good vm_area for this * memory access, so we can handle it. */ good_area: if (access_error(fsr, vma)) { fault = VM_FAULT_BADACCESS; goto out; } /* * If for any reason at all we couldn't handle the fault, make * sure we exit gracefully rather than endlessly redo the fault. */ fault = handle_mm_fault(mm, vma, addr & PAGE_MASK, (fsr & FSR_WRITE) ? FAULT_FLAG_WRITE : 0); if (unlikely(fault & VM_FAULT_ERROR)) return fault; if (fault & VM_FAULT_MAJOR) tsk->maj_flt++; else tsk->min_flt++; return fault; check_stack: if (vma->vm_flags & VM_GROWSDOWN && !expand_stack(vma, addr)) goto good_area; out: return fault; } static int __kprobes do_page_fault(unsigned long addr, unsigned int fsr, struct pt_regs *regs) { struct task_struct *tsk; struct mm_struct *mm; int fault, sig, code; if (notify_page_fault(regs, fsr)) return 0; tsk = current; mm = tsk->mm; /* * If we're in an interrupt or have no user * context, we must not take the fault.. */ if (in_atomic() || !mm) goto no_context; /* * As per x86, we may deadlock here. However, since the kernel only * validly references user space from well defined areas of the code, * we can bug out early if this is from code which shouldn't. */ if (!down_read_trylock(&mm->mmap_sem)) { if (!user_mode(regs) && !search_exception_tables(regs->ARM_pc)) goto no_context; down_read(&mm->mmap_sem); } else { /* * The above down_read_trylock() might have succeeded in * which case, we'll have missed the might_sleep() from * down_read() */ might_sleep(); #ifdef CONFIG_DEBUG_VM if (!user_mode(regs) && !search_exception_tables(regs->ARM_pc)) goto no_context; #endif } fault = __do_page_fault(mm, addr, fsr, tsk); up_read(&mm->mmap_sem); perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, 0, regs, addr); if (fault & VM_FAULT_MAJOR) perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MAJ, 1, 0, regs, addr); else if (fault & VM_FAULT_MINOR) perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MIN, 1, 0, regs, addr); /* * Handle the "normal" case first - VM_FAULT_MAJOR / VM_FAULT_MINOR */ if (likely(!(fault & (VM_FAULT_ERROR | VM_FAULT_BADMAP | VM_FAULT_BADACCESS)))) return 0; if (fault & VM_FAULT_OOM) { /* * We ran out of memory, call the OOM killer, and return to * userspace (which will retry the fault, or kill us if we * got oom-killed) */ pagefault_out_of_memory(); return 0; } /* * If we are in kernel mode at this point, we * have no context to handle this fault with. */ if (!user_mode(regs)) goto no_context; if (fault & VM_FAULT_SIGBUS) { /* * We had some memory, but were unable to * successfully fix up this page fault. */ sig = SIGBUS; code = BUS_ADRERR; } else { /* * Something tried to access memory that * isn't in our memory map.. */ sig = SIGSEGV; code = fault == VM_FAULT_BADACCESS ? SEGV_ACCERR : SEGV_MAPERR; } __do_user_fault(tsk, addr, fsr, sig, code, regs); return 0; no_context: __do_kernel_fault(mm, addr, fsr, regs); return 0; } #else /* CONFIG_MMU */ static int do_page_fault(unsigned long addr, unsigned int fsr, struct pt_regs *regs) { return 0; } #endif /* CONFIG_MMU */ /* * First Level Translation Fault Handler * * We enter here because the first level page table doesn't contain * a valid entry for the address. * * If the address is in kernel space (>= TASK_SIZE), then we are * probably faulting in the vmalloc() area. * * If the init_task's first level page tables contains the relevant * entry, we copy the it to this task. If not, we send the process * a signal, fixup the exception, or oops the kernel. * * NOTE! We MUST NOT take any locks for this case. We may be in an * interrupt or a critical region, and should only copy the information * from the master page table, nothing more. */ #ifdef CONFIG_MMU static int __kprobes do_translation_fault(unsigned long addr, unsigned int fsr, struct pt_regs *regs) { unsigned int index; pgd_t *pgd, *pgd_k; pmd_t *pmd, *pmd_k; if (addr < TASK_SIZE) return do_page_fault(addr, fsr, regs); index = pgd_index(addr); /* * FIXME: CP15 C1 is write only on ARMv3 architectures. */ pgd = cpu_get_pgd() + index; pgd_k = init_mm.pgd + index; if (pgd_none(*pgd_k)) goto bad_area; if (!pgd_present(*pgd)) set_pgd(pgd, *pgd_k); pmd_k = pmd_offset(pgd_k, addr); pmd = pmd_offset(pgd, addr); if (pmd_none(*pmd_k)) goto bad_area; copy_pmd(pmd, pmd_k); return 0; bad_area: do_bad_area(addr, fsr, regs); return 0; } #else /* CONFIG_MMU */ static int do_translation_fault(unsigned long addr, unsigned int fsr, struct pt_regs *regs) { return 0; } #endif /* CONFIG_MMU */ /* * Some section permission faults need to be handled gracefully. * They can happen due to a __{get,put}_user during an oops. */ static int do_sect_fault(unsigned long addr, unsigned int fsr, struct pt_regs *regs) { do_bad_area(addr, fsr, regs); return 0; } /* * This abort handler always returns "fault". */ static int do_bad(unsigned long addr, unsigned int fsr, struct pt_regs *regs) { return 1; } static struct fsr_info { int (*fn)(unsigned long addr, unsigned int fsr, struct pt_regs *regs); int sig; int code; const char *name; } fsr_info[] = { /* * The following are the standard ARMv3 and ARMv4 aborts. ARMv5 * defines these to be "precise" aborts. */ { do_bad, SIGSEGV, 0, "vector exception" }, { do_bad, SIGILL, BUS_ADRALN, "alignment exception" }, { do_bad, SIGKILL, 0, "terminal exception" }, { do_bad, SIGILL, BUS_ADRALN, "alignment exception" }, /* Do we need runtime check ? */ #if __LINUX_ARM_ARCH__ < 6 { do_bad, SIGBUS, 0, "external abort on linefetch" }, #else { do_translation_fault, SIGSEGV, SEGV_MAPERR, "I-cache maintenance fault" }, #endif { do_translation_fault, SIGSEGV, SEGV_MAPERR, "section translation fault" }, { do_bad, SIGBUS, 0, "external abort on linefetch" }, { do_page_fault, SIGSEGV, SEGV_MAPERR, "page translation fault" }, { do_bad, SIGBUS, 0, "external abort on non-linefetch" }, { do_bad, SIGSEGV, SEGV_ACCERR, "section domain fault" }, { do_bad, SIGBUS, 0, "external abort on non-linefetch" }, { do_bad, SIGSEGV, SEGV_ACCERR, "page domain fault" }, { do_bad, SIGBUS, 0, "external abort on translation" }, { do_sect_fault, SIGSEGV, SEGV_ACCERR, "section permission fault" }, { do_bad, SIGBUS, 0, "external abort on translation" }, { do_page_fault, SIGSEGV, SEGV_ACCERR, "page permission fault" }, /* * The following are "imprecise" aborts, which are signalled by bit * 10 of the FSR, and may not be recoverable. These are only * supported if the CPU abort handler supports bit 10. */ { do_bad, SIGBUS, 0, "unknown 16" }, { do_bad, SIGBUS, 0, "unknown 17" }, { do_bad, SIGBUS, 0, "unknown 18" }, { do_bad, SIGBUS, 0, "unknown 19" }, { do_bad, SIGBUS, 0, "lock abort" }, /* xscale */ { do_bad, SIGBUS, 0, "unknown 21" }, { do_bad, SIGBUS, BUS_OBJERR, "imprecise external abort" }, /* xscale */ { do_bad, SIGBUS, 0, "unknown 23" }, { do_bad, SIGBUS, 0, "dcache parity error" }, /* xscale */ { do_bad, SIGBUS, 0, "unknown 25" }, { do_bad, SIGBUS, 0, "unknown 26" }, { do_bad, SIGBUS, 0, "unknown 27" }, { do_bad, SIGBUS, 0, "unknown 28" }, { do_bad, SIGBUS, 0, "unknown 29" }, { do_bad, SIGBUS, 0, "unknown 30" }, { do_bad, SIGBUS, 0, "unknown 31" } }; void __init hook_fault_code(int nr, int (*fn)(unsigned long, unsigned int, struct pt_regs *), int sig, const char *name) { if (nr >= 0 && nr < ARRAY_SIZE(fsr_info)) { fsr_info[nr].fn = fn; fsr_info[nr].sig = sig; fsr_info[nr].name = name; } } /* * Dispatch a data abort to the relevant handler. */ asmlinkage void __exception do_DataAbort(unsigned long addr, unsigned int fsr, struct pt_regs *regs) { const struct fsr_info *inf = fsr_info + fsr_fs(fsr); struct siginfo info; if (!inf->fn(addr, fsr & ~FSR_LNX_PF, regs)) return; printk(KERN_ALERT "Unhandled fault: %s (0x%03x) at 0x%08lx\n", inf->name, fsr, addr); info.si_signo = inf->sig; info.si_errno = 0; info.si_code = inf->code; info.si_addr = (void __user *)addr; arm_notify_die("", regs, &info, fsr, 0); } static struct fsr_info ifsr_info[] = { { do_bad, SIGBUS, 0, "unknown 0" }, { do_bad, SIGBUS, 0, "unknown 1" }, { do_bad, SIGBUS, 0, "debug event" }, { do_bad, SIGSEGV, SEGV_ACCERR, "section access flag fault" }, { do_bad, SIGBUS, 0, "unknown 4" }, { do_translation_fault, SIGSEGV, SEGV_MAPERR, "section translation fault" }, { do_bad, SIGSEGV, SEGV_ACCERR, "page access flag fault" }, { do_page_fault, SIGSEGV, SEGV_MAPERR, "page translation fault" }, { do_bad, SIGBUS, 0, "external abort on non-linefetch" }, { do_bad, SIGSEGV, SEGV_ACCERR, "section domain fault" }, { do_bad, SIGBUS, 0, "unknown 10" }, { do_bad, SIGSEGV, SEGV_ACCERR, "page domain fault" }, { do_bad, SIGBUS, 0, "external abort on translation" }, { do_sect_fault, SIGSEGV, SEGV_ACCERR, "section permission fault" }, { do_bad, SIGBUS, 0, "external abort on translation" }, { do_page_fault, SIGSEGV, SEGV_ACCERR, "page permission fault" }, { do_bad, SIGBUS, 0, "unknown 16" }, { do_bad, SIGBUS, 0, "unknown 17" }, { do_bad, SIGBUS, 0, "unknown 18" }, { do_bad, SIGBUS, 0, "unknown 19" }, { do_bad, SIGBUS, 0, "unknown 20" }, { do_bad, SIGBUS, 0, "unknown 21" }, { do_bad, SIGBUS, 0, "unknown 22" }, { do_bad, SIGBUS, 0, "unknown 23" }, { do_bad, SIGBUS, 0, "unknown 24" }, { do_bad, SIGBUS, 0, "unknown 25" }, { do_bad, SIGBUS, 0, "unknown 26" }, { do_bad, SIGBUS, 0, "unknown 27" }, { do_bad, SIGBUS, 0, "unknown 28" }, { do_bad, SIGBUS, 0, "unknown 29" }, { do_bad, SIGBUS, 0, "unknown 30" }, { do_bad, SIGBUS, 0, "unknown 31" }, }; asmlinkage void __exception do_PrefetchAbort(unsigned long addr, unsigned int ifsr, struct pt_regs *regs) { const struct fsr_info *inf = ifsr_info + fsr_fs(ifsr); struct siginfo info; if (!inf->fn(addr, ifsr | FSR_LNX_PF, regs)) return; printk(KERN_ALERT "Unhandled prefetch abort: %s (0x%03x) at 0x%08lx\n", inf->name, ifsr, addr); info.si_signo = inf->sig; info.si_errno = 0; info.si_code = inf->code; info.si_addr = (void __user *)addr; arm_notify_die("", regs, &info, ifsr, 0); }