| /* |
| * Based on arch/arm/mm/fault.c |
| * |
| * Copyright (C) 1995 Linus Torvalds |
| * Copyright (C) 1995-2004 Russell King |
| * Copyright (C) 2012 ARM Ltd. |
| * |
| * 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. |
| * |
| * This program is distributed in the hope that it will be useful, |
| * but WITHOUT ANY WARRANTY; without even the implied warranty of |
| * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| * GNU General Public License for more details. |
| * |
| * You should have received a copy of the GNU General Public License |
| * along with this program. If not, see <http://www.gnu.org/licenses/>. |
| */ |
| |
| #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/exception.h> |
| #include <asm/debug-monitors.h> |
| #include <asm/esr.h> |
| #include <asm/system_misc.h> |
| #include <asm/pgtable.h> |
| #include <asm/tlbflush.h> |
| |
| static const char *fault_name(unsigned int esr); |
| |
| /* |
| * 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=%016llx", addr, pgd_val(*pgd)); |
| |
| do { |
| pud_t *pud; |
| pmd_t *pmd; |
| pte_t *pte; |
| |
| if (pgd_none(*pgd) || pgd_bad(*pgd)) |
| break; |
| |
| pud = pud_offset(pgd, addr); |
| printk(", *pud=%016llx", pud_val(*pud)); |
| if (pud_none(*pud) || pud_bad(*pud)) |
| break; |
| |
| pmd = pmd_offset(pud, addr); |
| printk(", *pmd=%016llx", pmd_val(*pmd)); |
| if (pmd_none(*pmd) || pmd_bad(*pmd)) |
| break; |
| |
| pte = pte_offset_map(pmd, addr); |
| printk(", *pte=%016llx", pte_val(*pte)); |
| pte_unmap(pte); |
| } while(0); |
| |
| printk("\n"); |
| } |
| |
| /* |
| * 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 esr, 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, esr); |
| 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 esr, unsigned int sig, int code, |
| struct pt_regs *regs) |
| { |
| struct siginfo si; |
| |
| if (show_unhandled_signals_ratelimited() && unhandled_signal(tsk, sig)) { |
| pr_info("%s[%d]: unhandled %s (%d) at 0x%08lx, esr 0x%03x\n", |
| tsk->comm, task_pid_nr(tsk), fault_name(esr), sig, |
| addr, esr); |
| show_pte(tsk->mm, addr); |
| show_regs(regs); |
| } |
| |
| tsk->thread.fault_address = addr; |
| tsk->thread.fault_code = esr; |
| si.si_signo = sig; |
| si.si_errno = 0; |
| si.si_code = code; |
| si.si_addr = (void __user *)addr; |
| force_sig_info(sig, &si, tsk); |
| } |
| |
| static void do_bad_area(unsigned long addr, unsigned int esr, 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, esr, SIGSEGV, SEGV_MAPERR, regs); |
| else |
| __do_kernel_fault(mm, addr, esr, regs); |
| } |
| |
| #define VM_FAULT_BADMAP 0x010000 |
| #define VM_FAULT_BADACCESS 0x020000 |
| |
| #define ESR_LNX_EXEC (1 << 24) |
| |
| static int __do_page_fault(struct mm_struct *mm, unsigned long addr, |
| unsigned int mm_flags, unsigned long vm_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: |
| /* |
| * Check that the permissions on the VMA allow for the fault which |
| * occurred. If we encountered a write or exec fault, we must have |
| * appropriate permissions, otherwise we allow any permission. |
| */ |
| if (!(vma->vm_flags & vm_flags)) { |
| fault = VM_FAULT_BADACCESS; |
| goto out; |
| } |
| |
| return handle_mm_fault(mm, vma, addr & PAGE_MASK, mm_flags); |
| |
| 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 esr, |
| struct pt_regs *regs) |
| { |
| struct task_struct *tsk; |
| struct mm_struct *mm; |
| int fault, sig, code; |
| unsigned long vm_flags = VM_READ | VM_WRITE | VM_EXEC; |
| unsigned int mm_flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE; |
| |
| 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)) |
| mm_flags |= FAULT_FLAG_USER; |
| |
| if (esr & ESR_LNX_EXEC) { |
| vm_flags = VM_EXEC; |
| } else if ((esr & ESR_ELx_WNR) && !(esr & ESR_ELx_CM)) { |
| vm_flags = VM_WRITE; |
| mm_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->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->pc)) |
| goto no_context; |
| #endif |
| } |
| |
| fault = __do_page_fault(mm, addr, mm_flags, vm_flags, tsk); |
| |
| /* |
| * 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 (mm_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. |
| */ |
| mm_flags &= ~FAULT_FLAG_ALLOW_RETRY; |
| 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, esr, sig, code, regs); |
| return 0; |
| |
| no_context: |
| __do_kernel_fault(mm, addr, esr, regs); |
| return 0; |
| } |
| |
| /* |
| * 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. |
| */ |
| static int __kprobes do_translation_fault(unsigned long addr, |
| unsigned int esr, |
| struct pt_regs *regs) |
| { |
| if (addr < TASK_SIZE) |
| return do_page_fault(addr, esr, regs); |
| |
| do_bad_area(addr, esr, regs); |
| return 0; |
| } |
| |
| /* |
| * This abort handler always returns "fault". |
| */ |
| static int do_bad(unsigned long addr, unsigned int esr, struct pt_regs *regs) |
| { |
| return 1; |
| } |
| |
| static struct fault_info { |
| int (*fn)(unsigned long addr, unsigned int esr, struct pt_regs *regs); |
| int sig; |
| int code; |
| const char *name; |
| } fault_info[] = { |
| { do_bad, SIGBUS, 0, "ttbr address size fault" }, |
| { do_bad, SIGBUS, 0, "level 1 address size fault" }, |
| { do_bad, SIGBUS, 0, "level 2 address size fault" }, |
| { do_bad, SIGBUS, 0, "level 3 address size fault" }, |
| { do_translation_fault, SIGSEGV, SEGV_MAPERR, "level 0 translation fault" }, |
| { do_translation_fault, SIGSEGV, SEGV_MAPERR, "level 1 translation fault" }, |
| { do_translation_fault, SIGSEGV, SEGV_MAPERR, "level 2 translation fault" }, |
| { do_page_fault, SIGSEGV, SEGV_MAPERR, "level 3 translation fault" }, |
| { do_bad, SIGBUS, 0, "reserved access flag fault" }, |
| { do_page_fault, SIGSEGV, SEGV_ACCERR, "level 1 access flag fault" }, |
| { do_page_fault, SIGSEGV, SEGV_ACCERR, "level 2 access flag fault" }, |
| { do_page_fault, SIGSEGV, SEGV_ACCERR, "level 3 access flag fault" }, |
| { do_bad, SIGBUS, 0, "reserved permission fault" }, |
| { do_page_fault, SIGSEGV, SEGV_ACCERR, "level 1 permission fault" }, |
| { do_page_fault, SIGSEGV, SEGV_ACCERR, "level 2 permission fault" }, |
| { do_page_fault, SIGSEGV, SEGV_ACCERR, "level 3 permission fault" }, |
| { do_bad, SIGBUS, 0, "synchronous external abort" }, |
| { do_bad, SIGBUS, 0, "asynchronous external abort" }, |
| { do_bad, SIGBUS, 0, "unknown 18" }, |
| { do_bad, SIGBUS, 0, "unknown 19" }, |
| { do_bad, SIGBUS, 0, "synchronous abort (translation table walk)" }, |
| { do_bad, SIGBUS, 0, "synchronous abort (translation table walk)" }, |
| { do_bad, SIGBUS, 0, "synchronous abort (translation table walk)" }, |
| { do_bad, SIGBUS, 0, "synchronous abort (translation table walk)" }, |
| { do_bad, SIGBUS, 0, "synchronous parity error" }, |
| { do_bad, SIGBUS, 0, "asynchronous parity error" }, |
| { do_bad, SIGBUS, 0, "unknown 26" }, |
| { do_bad, SIGBUS, 0, "unknown 27" }, |
| { do_bad, SIGBUS, 0, "synchronous parity error (translation table walk" }, |
| { do_bad, SIGBUS, 0, "synchronous parity error (translation table walk" }, |
| { do_bad, SIGBUS, 0, "synchronous parity error (translation table walk" }, |
| { do_bad, SIGBUS, 0, "synchronous parity error (translation table walk" }, |
| { do_bad, SIGBUS, 0, "unknown 32" }, |
| { do_bad, SIGBUS, BUS_ADRALN, "alignment fault" }, |
| { do_bad, SIGBUS, 0, "debug event" }, |
| { do_bad, SIGBUS, 0, "unknown 35" }, |
| { do_bad, SIGBUS, 0, "unknown 36" }, |
| { do_bad, SIGBUS, 0, "unknown 37" }, |
| { do_bad, SIGBUS, 0, "unknown 38" }, |
| { do_bad, SIGBUS, 0, "unknown 39" }, |
| { do_bad, SIGBUS, 0, "unknown 40" }, |
| { do_bad, SIGBUS, 0, "unknown 41" }, |
| { do_bad, SIGBUS, 0, "unknown 42" }, |
| { do_bad, SIGBUS, 0, "unknown 43" }, |
| { do_bad, SIGBUS, 0, "unknown 44" }, |
| { do_bad, SIGBUS, 0, "unknown 45" }, |
| { do_bad, SIGBUS, 0, "unknown 46" }, |
| { do_bad, SIGBUS, 0, "unknown 47" }, |
| { do_bad, SIGBUS, 0, "unknown 48" }, |
| { do_bad, SIGBUS, 0, "unknown 49" }, |
| { do_bad, SIGBUS, 0, "unknown 50" }, |
| { do_bad, SIGBUS, 0, "unknown 51" }, |
| { do_bad, SIGBUS, 0, "implementation fault (lockdown abort)" }, |
| { do_bad, SIGBUS, 0, "unknown 53" }, |
| { do_bad, SIGBUS, 0, "unknown 54" }, |
| { do_bad, SIGBUS, 0, "unknown 55" }, |
| { do_bad, SIGBUS, 0, "unknown 56" }, |
| { do_bad, SIGBUS, 0, "unknown 57" }, |
| { do_bad, SIGBUS, 0, "implementation fault (coprocessor abort)" }, |
| { do_bad, SIGBUS, 0, "unknown 59" }, |
| { do_bad, SIGBUS, 0, "unknown 60" }, |
| { do_bad, SIGBUS, 0, "unknown 61" }, |
| { do_bad, SIGBUS, 0, "unknown 62" }, |
| { do_bad, SIGBUS, 0, "unknown 63" }, |
| }; |
| |
| static const char *fault_name(unsigned int esr) |
| { |
| const struct fault_info *inf = fault_info + (esr & 63); |
| return inf->name; |
| } |
| |
| /* |
| * Dispatch a data abort to the relevant handler. |
| */ |
| asmlinkage void __exception do_mem_abort(unsigned long addr, unsigned int esr, |
| struct pt_regs *regs) |
| { |
| const struct fault_info *inf = fault_info + (esr & 63); |
| struct siginfo info; |
| |
| if (!inf->fn(addr, esr, regs)) |
| return; |
| |
| pr_alert("Unhandled fault: %s (0x%08x) at 0x%016lx\n", |
| inf->name, esr, addr); |
| |
| info.si_signo = inf->sig; |
| info.si_errno = 0; |
| info.si_code = inf->code; |
| info.si_addr = (void __user *)addr; |
| arm64_notify_die("", regs, &info, esr); |
| } |
| |
| /* |
| * Handle stack alignment exceptions. |
| */ |
| asmlinkage void __exception do_sp_pc_abort(unsigned long addr, |
| unsigned int esr, |
| struct pt_regs *regs) |
| { |
| struct siginfo info; |
| struct task_struct *tsk = current; |
| |
| if (show_unhandled_signals && unhandled_signal(tsk, SIGBUS)) |
| pr_info_ratelimited("%s[%d]: %s exception: pc=%p sp=%p\n", |
| tsk->comm, task_pid_nr(tsk), |
| esr_get_class_string(esr), (void *)regs->pc, |
| (void *)regs->sp); |
| |
| info.si_signo = SIGBUS; |
| info.si_errno = 0; |
| info.si_code = BUS_ADRALN; |
| info.si_addr = (void __user *)addr; |
| arm64_notify_die("Oops - SP/PC alignment exception", regs, &info, esr); |
| } |
| |
| static struct fault_info debug_fault_info[] = { |
| { do_bad, SIGTRAP, TRAP_HWBKPT, "hardware breakpoint" }, |
| { do_bad, SIGTRAP, TRAP_HWBKPT, "hardware single-step" }, |
| { do_bad, SIGTRAP, TRAP_HWBKPT, "hardware watchpoint" }, |
| { do_bad, SIGBUS, 0, "unknown 3" }, |
| { do_bad, SIGTRAP, TRAP_BRKPT, "aarch32 BKPT" }, |
| { do_bad, SIGTRAP, 0, "aarch32 vector catch" }, |
| { do_bad, SIGTRAP, TRAP_BRKPT, "aarch64 BRK" }, |
| { do_bad, SIGBUS, 0, "unknown 7" }, |
| }; |
| |
| void __init hook_debug_fault_code(int nr, |
| int (*fn)(unsigned long, unsigned int, struct pt_regs *), |
| int sig, int code, const char *name) |
| { |
| BUG_ON(nr < 0 || nr >= ARRAY_SIZE(debug_fault_info)); |
| |
| debug_fault_info[nr].fn = fn; |
| debug_fault_info[nr].sig = sig; |
| debug_fault_info[nr].code = code; |
| debug_fault_info[nr].name = name; |
| } |
| |
| asmlinkage int __exception do_debug_exception(unsigned long addr, |
| unsigned int esr, |
| struct pt_regs *regs) |
| { |
| const struct fault_info *inf = debug_fault_info + DBG_ESR_EVT(esr); |
| struct siginfo info; |
| |
| if (!inf->fn(addr, esr, regs)) |
| return 1; |
| |
| pr_alert("Unhandled debug exception: %s (0x%08x) at 0x%016lx\n", |
| inf->name, esr, addr); |
| |
| info.si_signo = inf->sig; |
| info.si_errno = 0; |
| info.si_code = inf->code; |
| info.si_addr = (void __user *)addr; |
| arm64_notify_die("", regs, &info, 0); |
| |
| return 0; |
| } |