/* * 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 #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #if defined(CONFIG_AVM_SIMPLE_PROFILING) #include #endif/*--- #if defined(CONFIG_AVM_SIMPLE_PROFILING) ---*/ #if defined(CONFIG_AVM_POWER) #include #endif /*--- #if defined(CONFIG_AVM_POWER) ---*/ #include "fault.h" #include #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; pr_alert("pgd = %p\n", mm->pgd); pgd = pgd_offset(mm, addr); pr_alert("[%08lx] *pgd=%08llx", addr, (long long)pgd_val(*pgd)); do { pud_t *pud; pmd_t *pmd; pte_t *pte; if (pgd_none(*pgd)) break; if (pgd_bad(*pgd)) { pr_cont("(bad)"); break; } pud = pud_offset(pgd, addr); if (PTRS_PER_PUD != 1) pr_cont(", *pud=%08llx", (long long)pud_val(*pud)); if (pud_none(*pud)) break; if (pud_bad(*pud)) { pr_cont("(bad)"); break; } pmd = pmd_offset(pud, addr); if (PTRS_PER_PMD != 1) pr_cont(", *pmd=%08llx", (long long)pmd_val(*pmd)); if (pmd_none(*pmd)) break; if (pmd_bad(*pmd)) { pr_cont("(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); pr_cont(", *pte=%08llx", (long long)pte_val(*pte)); #ifndef CONFIG_ARM_LPAE pr_cont(", *ppte=%08llx", (long long)pte_val(pte[PTE_HWTABLE_PTRS])); #endif pte_unmap(pte); } while(0); pr_cont("\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); pr_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; trace_user_fault(tsk, addr, fsr); #ifdef CONFIG_DEBUG_USER if (((user_debug & UDBG_SEGV) && (sig == SIGSEGV)) || ((user_debug & UDBG_BUS) && (sig == SIGBUS))) { 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, unsigned int flags, 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. */ #if defined(CONFIG_AVM_POWER) avm_page_statistic_fault_get(); #endif/*--- #if defined(CONFIG_AVM_POWER) ---*/ fault = handle_mm_fault(mm, vma, addr & PAGE_MASK, flags); #if defined(CONFIG_AVM_POWER) avm_page_statistic_fault_put(); #endif/*--- #if defined(CONFIG_AVM_POWER) ---*/ return fault; check_stack: /* Don't allow expansion below FIRST_USER_ADDRESS */ if (vma->vm_flags & VM_GROWSDOWN && addr >= FIRST_USER_ADDRESS && !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; unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE; #if defined(CONFIG_AVM_SIMPLE_PROFILING) avm_simple_profiling_enter_irq_context(regs->ARM_pc, regs->ARM_lr); #endif/*--- #if defined(CONFIG_AVM_SIMPLE_PROFILING) ---*/ if (notify_page_fault(regs, fsr)) return 0; tsk = current; mm = tsk->mm; /* Enable interrupts if they were enabled in the parent context. */ if (interrupts_enabled(regs)) local_irq_enable(); /* * If we're in an interrupt or have no user * context, we must not take the fault.. */ if (faulthandler_disabled() || !mm) goto no_context; if (user_mode(regs)) flags |= FAULT_FLAG_USER; if (fsr & FSR_WRITE) flags |= FAULT_FLAG_WRITE; /* * 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; retry: 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 } #if defined(CONFIG_AVM_SIMPLE_PROFILING) avm_simple_profiling_log(avm_profile_data_type_hw_irq_begin, (unsigned int)regs->ARM_pc, AVM_PROFILE_PAGE_FAULT_ID); #endif/*--- #if defined(CONFIG_AVM_SIMPLE_PROFILING) ---*/ fault = __do_page_fault(mm, addr, fsr, flags, tsk); #if defined(CONFIG_AVM_SIMPLE_PROFILING) avm_simple_profiling_log(avm_profile_data_type_hw_irq_end, (unsigned int)regs->ARM_pc, AVM_PROFILE_PAGE_FAULT_ID); #endif/*--- #if defined(CONFIG_AVM_SIMPLE_PROFILING) ---*/ /* If we need to retry but a fatal signal is pending, handle the * signal first. We do not need to release the mmap_sem because * it would already be released in __lock_page_or_retry in * mm/filemap.c. */ if ((fault & VM_FAULT_RETRY) && fatal_signal_pending(current)) return 0; /* * Major/minor page fault accounting is only done on the * initial attempt. If we go through a retry, it is extremely * likely that the page will be found in page cache at that point. */ perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, addr); if (!(fault & VM_FAULT_ERROR) && flags & FAULT_FLAG_ALLOW_RETRY) { if (fault & VM_FAULT_MAJOR) { tsk->maj_flt++; perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MAJ, 1, regs, addr); } else { tsk->min_flt++; perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MIN, 1, regs, addr); } if (fault & VM_FAULT_RETRY) { /* Clear FAULT_FLAG_ALLOW_RETRY to avoid any risk * of starvation. */ flags &= ~FAULT_FLAG_ALLOW_RETRY; flags |= FAULT_FLAG_TRIED; goto retry; } } up_read(&mm->mmap_sem); /* * 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 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_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 (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; pud_t *pud, *pud_k; pmd_t *pmd, *pmd_k; if (addr < TASK_SIZE) return do_page_fault(addr, fsr, regs); #if defined(CONFIG_AVM_SIMPLE_PROFILING) avm_simple_profiling_enter_irq_context(regs->ARM_pc, regs->ARM_lr); #endif/*--- #if defined(CONFIG_AVM_SIMPLE_PROFILING) ---*/ if (user_mode(regs)) goto bad_area; index = pgd_index(addr); 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); pud = pud_offset(pgd, addr); pud_k = pud_offset(pgd_k, addr); if (pud_none(*pud_k)) goto bad_area; if (!pud_present(*pud)) set_pud(pud, *pud_k); pmd = pmd_offset(pud, addr); pmd_k = pmd_offset(pud_k, addr); #ifdef CONFIG_ARM_LPAE /* * Only one hardware entry per PMD with LPAE. */ index = 0; #else /* * On ARM one Linux PGD entry contains two hardware entries (see page * tables layout in pgtable.h). We normally guarantee that we always * fill both L1 entries. But create_mapping() doesn't follow the rule. * It can create inidividual L1 entries, so here we have to call * pmd_none() check for the entry really corresponded to address, not * for the first of pair. */ index = (addr >> SECTION_SHIFT) & 1; #endif if (pmd_none(pmd_k[index])) 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. */ #ifndef CONFIG_ARM_LPAE static int do_sect_fault(unsigned long addr, unsigned int fsr, struct pt_regs *regs) { do_bad_area(addr, fsr, regs); return 0; } #endif /* CONFIG_ARM_LPAE */ /* * This abort handler always returns "fault". */ static int do_bad(unsigned long addr, unsigned int fsr, struct pt_regs *regs) { return 1; } struct fsr_info { int (*fn)(unsigned long addr, unsigned int fsr, struct pt_regs *regs); int sig; int code; const char *name; }; /* FSR definition */ #ifdef CONFIG_ARM_LPAE #include "fsr-3level.c" #else #include "fsr-2level.c" #endif void __init hook_fault_code(int nr, int (*fn)(unsigned long, unsigned int, struct pt_regs *), int sig, int code, const char *name) { if (nr < 0 || nr >= ARRAY_SIZE(fsr_info)) BUG(); fsr_info[nr].fn = fn; fsr_info[nr].sig = sig; fsr_info[nr].code = code; 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; pr_alert("Unhandled fault: %s (0x%03x) at 0x%08lx\n", inf->name, fsr, addr); show_pte(current->mm, 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); } void __init hook_ifault_code(int nr, int (*fn)(unsigned long, unsigned int, struct pt_regs *), int sig, int code, const char *name) { if (nr < 0 || nr >= ARRAY_SIZE(ifsr_info)) BUG(); ifsr_info[nr].fn = fn; ifsr_info[nr].sig = sig; ifsr_info[nr].code = code; ifsr_info[nr].name = name; } 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; pr_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); } /* * Abort handler to be used only during first unmasking of asynchronous aborts * on the boot CPU. This makes sure that the machine will not die if the * firmware/bootloader left an imprecise abort pending for us to trip over. */ static int __init early_abort_handler(unsigned long addr, unsigned int fsr, struct pt_regs *regs) { pr_warn("Hit pending asynchronous external abort (FSR=0x%08x) during " "first unmask, this is most likely caused by a " "firmware/bootloader bug.\n", fsr); return 0; } void __init early_abt_enable(void) { fsr_info[FSR_FS_AEA].fn = early_abort_handler; local_abt_enable(); fsr_info[FSR_FS_AEA].fn = do_bad; } #ifndef CONFIG_ARM_LPAE static int __init exceptions_init(void) { if (cpu_architecture() >= CPU_ARCH_ARMv6) { hook_fault_code(4, do_translation_fault, SIGSEGV, SEGV_MAPERR, "I-cache maintenance fault"); } if (cpu_architecture() >= CPU_ARCH_ARMv7) { /* * TODO: Access flag faults introduced in ARMv6K. * Runtime check for 'K' extension is needed */ hook_fault_code(3, do_bad, SIGSEGV, SEGV_MAPERR, "section access flag fault"); hook_fault_code(6, do_bad, SIGSEGV, SEGV_MAPERR, "section access flag fault"); } return 0; } arch_initcall(exceptions_init); #endif