| /* |
| * 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 <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(); |
| } |
| |
| fault = __do_page_fault(mm, addr, fsr, tsk); |
| 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 (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_bad, SIGBUS, 0, "external abort on linefetch" }, |
| { 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); |
| } |
| |