/* * linux/arch/arm/kernel/traps.c * * Copyright (C) 1995-2009 Russell King * Fragments that appear the same as linux/arch/i386/kernel/traps.c (C) Linus Torvalds * * 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. * * 'traps.c' handles hardware exceptions after we have saved some state in * 'linux/arch/arm/lib/traps.S'. Mostly a debugging aid, but will probably * kill the offending process. */ #include <linux/signal.h> #include <linux/personality.h> #include <linux/kallsyms.h> #include <linux/spinlock.h> #include <linux/uaccess.h> #include <linux/hardirq.h> #include <linux/kdebug.h> #include <linux/module.h> #include <linux/kexec.h> #include <linux/bug.h> #include <linux/delay.h> #include <linux/init.h> #include <linux/sched.h> #include <linux/atomic.h> #include <asm/cacheflush.h> #include <asm/exception.h> #include <asm/unistd.h> #include <asm/traps.h> #include <asm/unwind.h> #include <asm/tls.h> #include <asm/system_misc.h> #include <asm/opcodes.h> static const char *handler[]= { "prefetch abort", "data abort", "address exception", "interrupt", "undefined instruction", }; void *vectors_page; #ifdef CONFIG_DEBUG_USER unsigned int user_debug; static int __init user_debug_setup(char *str) { get_option(&str, &user_debug); return 1; } __setup("user_debug=", user_debug_setup); #endif static void dump_mem(const char *, const char *, unsigned long, unsigned long); void dump_backtrace_entry(unsigned long where, unsigned long from, unsigned long frame) { #ifdef CONFIG_KALLSYMS printk("[<%08lx>] (%ps) from [<%08lx>] (%pS)\n", where, (void *)where, from, (void *)from); #else printk("Function entered at [<%08lx>] from [<%08lx>]\n", where, from); #endif if (in_exception_text(where)) dump_mem("", "Exception stack", frame + 4, frame + 4 + sizeof(struct pt_regs)); } #ifndef CONFIG_ARM_UNWIND /* * Stack pointers should always be within the kernels view of * physical memory. If it is not there, then we can't dump * out any information relating to the stack. */ static int verify_stack(unsigned long sp) { if (sp < PAGE_OFFSET || (sp > (unsigned long)high_memory && high_memory != NULL)) return -EFAULT; return 0; } #endif /* * Dump out the contents of some memory nicely... */ static void dump_mem(const char *lvl, const char *str, unsigned long bottom, unsigned long top) { unsigned long first; mm_segment_t fs; int i; /* * We need to switch to kernel mode so that we can use __get_user * to safely read from kernel space. Note that we now dump the * code first, just in case the backtrace kills us. */ fs = get_fs(); set_fs(KERNEL_DS); printk("%s%s(0x%08lx to 0x%08lx)\n", lvl, str, bottom, top); for (first = bottom & ~31; first < top; first += 32) { unsigned long p; char str[sizeof(" 12345678") * 8 + 1]; memset(str, ' ', sizeof(str)); str[sizeof(str) - 1] = '\0'; for (p = first, i = 0; i < 8 && p < top; i++, p += 4) { if (p >= bottom && p < top) { unsigned long val; if (__get_user(val, (unsigned long *)p) == 0) sprintf(str + i * 9, " %08lx", val); else sprintf(str + i * 9, " ????????"); } } printk("%s%04lx:%s\n", lvl, first & 0xffff, str); } set_fs(fs); } static void dump_instr(const char *lvl, struct pt_regs *regs) { unsigned long addr = instruction_pointer(regs); const int thumb = thumb_mode(regs); const int width = thumb ? 4 : 8; mm_segment_t fs; char str[sizeof("00000000 ") * 5 + 2 + 1], *p = str; int i; /* * We need to switch to kernel mode so that we can use __get_user * to safely read from kernel space. Note that we now dump the * code first, just in case the backtrace kills us. */ fs = get_fs(); set_fs(KERNEL_DS); for (i = -4; i < 1 + !!thumb; i++) { unsigned int val, bad; if (thumb) bad = __get_user(val, &((u16 *)addr)[i]); else bad = __get_user(val, &((u32 *)addr)[i]); if (!bad) p += sprintf(p, i == 0 ? "(%0*x) " : "%0*x ", width, val); else { p += sprintf(p, "bad PC value"); break; } } printk("%sCode: %s\n", lvl, str); set_fs(fs); } #ifdef CONFIG_ARM_UNWIND static inline void dump_backtrace(struct pt_regs *regs, struct task_struct *tsk) { unwind_backtrace(regs, tsk); } #else static void dump_backtrace(struct pt_regs *regs, struct task_struct *tsk) { unsigned int fp, mode; int ok = 1; printk("Backtrace: "); if (!tsk) tsk = current; if (regs) { fp = regs->ARM_fp; mode = processor_mode(regs); } else if (tsk != current) { fp = thread_saved_fp(tsk); mode = 0x10; } else { asm("mov %0, fp" : "=r" (fp) : : "cc"); mode = 0x10; } if (!fp) { printk("no frame pointer"); ok = 0; } else if (verify_stack(fp)) { printk("invalid frame pointer 0x%08x", fp); ok = 0; } else if (fp < (unsigned long)end_of_stack(tsk)) printk("frame pointer underflow"); printk("\n"); if (ok) c_backtrace(fp, mode); } #endif void show_stack(struct task_struct *tsk, unsigned long *sp) { dump_backtrace(NULL, tsk); barrier(); } #ifdef CONFIG_PREEMPT #define S_PREEMPT " PREEMPT" #else #define S_PREEMPT "" #endif #ifdef CONFIG_SMP #define S_SMP " SMP" #else #define S_SMP "" #endif #ifdef CONFIG_THUMB2_KERNEL #define S_ISA " THUMB2" #else #define S_ISA " ARM" #endif static int __die(const char *str, int err, struct pt_regs *regs) { struct task_struct *tsk = current; static int die_counter; int ret; printk(KERN_EMERG "Internal error: %s: %x [#%d]" S_PREEMPT S_SMP S_ISA "\n", str, err, ++die_counter); /* trap and error numbers are mostly meaningless on ARM */ ret = notify_die(DIE_OOPS, str, regs, err, tsk->thread.trap_no, SIGSEGV); if (ret == NOTIFY_STOP) return 1; print_modules(); __show_regs(regs); printk(KERN_EMERG "Process %.*s (pid: %d, stack limit = 0x%p)\n", TASK_COMM_LEN, tsk->comm, task_pid_nr(tsk), end_of_stack(tsk)); if (!user_mode(regs) || in_interrupt()) { dump_mem(KERN_EMERG, "Stack: ", regs->ARM_sp, THREAD_SIZE + (unsigned long)task_stack_page(tsk)); dump_backtrace(regs, tsk); dump_instr(KERN_EMERG, regs); } return 0; } static arch_spinlock_t die_lock = __ARCH_SPIN_LOCK_UNLOCKED; static int die_owner = -1; static unsigned int die_nest_count; static unsigned long oops_begin(void) { int cpu; unsigned long flags; oops_enter(); /* racy, but better than risking deadlock. */ raw_local_irq_save(flags); cpu = smp_processor_id(); if (!arch_spin_trylock(&die_lock)) { if (cpu == die_owner) /* nested oops. should stop eventually */; else arch_spin_lock(&die_lock); } die_nest_count++; die_owner = cpu; console_verbose(); bust_spinlocks(1); return flags; } static void oops_end(unsigned long flags, struct pt_regs *regs, int signr) { if (regs && kexec_should_crash(current)) crash_kexec(regs); bust_spinlocks(0); die_owner = -1; add_taint(TAINT_DIE, LOCKDEP_NOW_UNRELIABLE); die_nest_count--; if (!die_nest_count) /* Nest count reaches zero, release the lock. */ arch_spin_unlock(&die_lock); raw_local_irq_restore(flags); oops_exit(); if (in_interrupt()) panic("Fatal exception in interrupt"); if (panic_on_oops) panic("Fatal exception"); if (signr) do_exit(signr); } /* * This function is protected against re-entrancy. */ void die(const char *str, struct pt_regs *regs, int err) { enum bug_trap_type bug_type = BUG_TRAP_TYPE_NONE; unsigned long flags = oops_begin(); int sig = SIGSEGV; if (!user_mode(regs)) bug_type = report_bug(regs->ARM_pc, regs); if (bug_type != BUG_TRAP_TYPE_NONE) str = "Oops - BUG"; if (__die(str, err, regs)) sig = 0; oops_end(flags, regs, sig); } void arm_notify_die(const char *str, struct pt_regs *regs, struct siginfo *info, unsigned long err, unsigned long trap) { if (user_mode(regs)) { current->thread.error_code = err; current->thread.trap_no = trap; force_sig_info(info->si_signo, info, current); } else { die(str, regs, err); } } #ifdef CONFIG_GENERIC_BUG int is_valid_bugaddr(unsigned long pc) { #ifdef CONFIG_THUMB2_KERNEL u16 bkpt; u16 insn = __opcode_to_mem_thumb16(BUG_INSTR_VALUE); #else u32 bkpt; u32 insn = __opcode_to_mem_arm(BUG_INSTR_VALUE); #endif if (probe_kernel_address((unsigned *)pc, bkpt)) return 0; return bkpt == insn; } #endif static LIST_HEAD(undef_hook); static DEFINE_RAW_SPINLOCK(undef_lock); void register_undef_hook(struct undef_hook *hook) { unsigned long flags; raw_spin_lock_irqsave(&undef_lock, flags); list_add(&hook->node, &undef_hook); raw_spin_unlock_irqrestore(&undef_lock, flags); } void unregister_undef_hook(struct undef_hook *hook) { unsigned long flags; raw_spin_lock_irqsave(&undef_lock, flags); list_del(&hook->node); raw_spin_unlock_irqrestore(&undef_lock, flags); } static int call_undef_hook(struct pt_regs *regs, unsigned int instr) { struct undef_hook *hook; unsigned long flags; int (*fn)(struct pt_regs *regs, unsigned int instr) = NULL; raw_spin_lock_irqsave(&undef_lock, flags); list_for_each_entry(hook, &undef_hook, node) if ((instr & hook->instr_mask) == hook->instr_val && (regs->ARM_cpsr & hook->cpsr_mask) == hook->cpsr_val) fn = hook->fn; raw_spin_unlock_irqrestore(&undef_lock, flags); return fn ? fn(regs, instr) : 1; } asmlinkage void __exception do_undefinstr(struct pt_regs *regs) { unsigned int instr; siginfo_t info; void __user *pc; pc = (void __user *)instruction_pointer(regs); if (processor_mode(regs) == SVC_MODE) { #ifdef CONFIG_THUMB2_KERNEL if (thumb_mode(regs)) { instr = __mem_to_opcode_thumb16(((u16 *)pc)[0]); if (is_wide_instruction(instr)) { u16 inst2; inst2 = __mem_to_opcode_thumb16(((u16 *)pc)[1]); instr = __opcode_thumb32_compose(instr, inst2); } } else #endif instr = __mem_to_opcode_arm(*(u32 *) pc); } else if (thumb_mode(regs)) { if (get_user(instr, (u16 __user *)pc)) goto die_sig; instr = __mem_to_opcode_thumb16(instr); if (is_wide_instruction(instr)) { unsigned int instr2; if (get_user(instr2, (u16 __user *)pc+1)) goto die_sig; instr2 = __mem_to_opcode_thumb16(instr2); instr = __opcode_thumb32_compose(instr, instr2); } } else { if (get_user(instr, (u32 __user *)pc)) goto die_sig; instr = __mem_to_opcode_arm(instr); } if (call_undef_hook(regs, instr) == 0) return; die_sig: #ifdef CONFIG_DEBUG_USER if (user_debug & UDBG_UNDEFINED) { printk(KERN_INFO "%s (%d): undefined instruction: pc=%p\n", current->comm, task_pid_nr(current), pc); dump_instr(KERN_INFO, regs); } #endif info.si_signo = SIGILL; info.si_errno = 0; info.si_code = ILL_ILLOPC; info.si_addr = pc; arm_notify_die("Oops - undefined instruction", regs, &info, 0, 6); } asmlinkage void do_unexp_fiq (struct pt_regs *regs) { printk("Hmm. Unexpected FIQ received, but trying to continue\n"); printk("You may have a hardware problem...\n"); } /* * bad_mode handles the impossible case in the vectors. If you see one of * these, then it's extremely serious, and could mean you have buggy hardware. * It never returns, and never tries to sync. We hope that we can at least * dump out some state information... */ asmlinkage void bad_mode(struct pt_regs *regs, int reason) { console_verbose(); printk(KERN_CRIT "Bad mode in %s handler detected\n", handler[reason]); die("Oops - bad mode", regs, 0); local_irq_disable(); panic("bad mode"); } static int bad_syscall(int n, struct pt_regs *regs) { struct thread_info *thread = current_thread_info(); siginfo_t info; if ((current->personality & PER_MASK) != PER_LINUX && thread->exec_domain->handler) { thread->exec_domain->handler(n, regs); return regs->ARM_r0; } #ifdef CONFIG_DEBUG_USER if (user_debug & UDBG_SYSCALL) { printk(KERN_ERR "[%d] %s: obsolete system call %08x.\n", task_pid_nr(current), current->comm, n); dump_instr(KERN_ERR, regs); } #endif info.si_signo = SIGILL; info.si_errno = 0; info.si_code = ILL_ILLTRP; info.si_addr = (void __user *)instruction_pointer(regs) - (thumb_mode(regs) ? 2 : 4); arm_notify_die("Oops - bad syscall", regs, &info, n, 0); return regs->ARM_r0; } static long do_cache_op_restart(struct restart_block *); static inline int __do_cache_op(unsigned long start, unsigned long end) { int ret; do { unsigned long chunk = min(PAGE_SIZE, end - start); if (signal_pending(current)) { struct thread_info *ti = current_thread_info(); ti->restart_block = (struct restart_block) { .fn = do_cache_op_restart, }; ti->arm_restart_block = (struct arm_restart_block) { { .cache = { .start = start, .end = end, }, }, }; return -ERESTART_RESTARTBLOCK; } ret = flush_cache_user_range(start, start + chunk); if (ret) return ret; cond_resched(); start += chunk; } while (start < end); return 0; } static long do_cache_op_restart(struct restart_block *unused) { struct arm_restart_block *restart_block; restart_block = ¤t_thread_info()->arm_restart_block; return __do_cache_op(restart_block->cache.start, restart_block->cache.end); } static inline int do_cache_op(unsigned long start, unsigned long end, int flags) { if (end < start || flags) return -EINVAL; if (!access_ok(VERIFY_READ, start, end - start)) return -EFAULT; return __do_cache_op(start, end); } /* * Handle all unrecognised system calls. * 0x9f0000 - 0x9fffff are some more esoteric system calls */ #define NR(x) ((__ARM_NR_##x) - __ARM_NR_BASE) asmlinkage int arm_syscall(int no, struct pt_regs *regs) { struct thread_info *thread = current_thread_info(); siginfo_t info; if ((no >> 16) != (__ARM_NR_BASE>> 16)) return bad_syscall(no, regs); switch (no & 0xffff) { case 0: /* branch through 0 */ info.si_signo = SIGSEGV; info.si_errno = 0; info.si_code = SEGV_MAPERR; info.si_addr = NULL; arm_notify_die("branch through zero", regs, &info, 0, 0); return 0; case NR(breakpoint): /* SWI BREAK_POINT */ regs->ARM_pc -= thumb_mode(regs) ? 2 : 4; ptrace_break(current, regs); return regs->ARM_r0; /* * Flush a region from virtual address 'r0' to virtual address 'r1' * _exclusive_. There is no alignment requirement on either address; * user space does not need to know the hardware cache layout. * * r2 contains flags. It should ALWAYS be passed as ZERO until it * is defined to be something else. For now we ignore it, but may * the fires of hell burn in your belly if you break this rule. ;) * * (at a later date, we may want to allow this call to not flush * various aspects of the cache. Passing '0' will guarantee that * everything necessary gets flushed to maintain consistency in * the specified region). */ case NR(cacheflush): return do_cache_op(regs->ARM_r0, regs->ARM_r1, regs->ARM_r2); case NR(usr26): if (!(elf_hwcap & HWCAP_26BIT)) break; regs->ARM_cpsr &= ~MODE32_BIT; return regs->ARM_r0; case NR(usr32): if (!(elf_hwcap & HWCAP_26BIT)) break; regs->ARM_cpsr |= MODE32_BIT; return regs->ARM_r0; case NR(set_tls): thread->tp_value[0] = regs->ARM_r0; if (tls_emu) return 0; if (has_tls_reg) { asm ("mcr p15, 0, %0, c13, c0, 3" : : "r" (regs->ARM_r0)); } else { /* * User space must never try to access this directly. * Expect your app to break eventually if you do so. * The user helper at 0xffff0fe0 must be used instead. * (see entry-armv.S for details) */ *((unsigned int *)0xffff0ff0) = regs->ARM_r0; } return 0; #ifdef CONFIG_NEEDS_SYSCALL_FOR_CMPXCHG /* * Atomically store r1 in *r2 if *r2 is equal to r0 for user space. * Return zero in r0 if *MEM was changed or non-zero if no exchange * happened. Also set the user C flag accordingly. * If access permissions have to be fixed up then non-zero is * returned and the operation has to be re-attempted. * * *NOTE*: This is a ghost syscall private to the kernel. Only the * __kuser_cmpxchg code in entry-armv.S should be aware of its * existence. Don't ever use this from user code. */ case NR(cmpxchg): for (;;) { extern void do_DataAbort(unsigned long addr, unsigned int fsr, struct pt_regs *regs); unsigned long val; unsigned long addr = regs->ARM_r2; struct mm_struct *mm = current->mm; pgd_t *pgd; pmd_t *pmd; pte_t *pte; spinlock_t *ptl; regs->ARM_cpsr &= ~PSR_C_BIT; down_read(&mm->mmap_sem); pgd = pgd_offset(mm, addr); if (!pgd_present(*pgd)) goto bad_access; pmd = pmd_offset(pgd, addr); if (!pmd_present(*pmd)) goto bad_access; pte = pte_offset_map_lock(mm, pmd, addr, &ptl); if (!pte_present(*pte) || !pte_write(*pte) || !pte_dirty(*pte)) { pte_unmap_unlock(pte, ptl); goto bad_access; } val = *(unsigned long *)addr; val -= regs->ARM_r0; if (val == 0) { *(unsigned long *)addr = regs->ARM_r1; regs->ARM_cpsr |= PSR_C_BIT; } pte_unmap_unlock(pte, ptl); up_read(&mm->mmap_sem); return val; bad_access: up_read(&mm->mmap_sem); /* simulate a write access fault */ do_DataAbort(addr, 15 + (1 << 11), regs); } #endif default: /* Calls 9f00xx..9f07ff are defined to return -ENOSYS if not implemented, rather than raising SIGILL. This way the calling program can gracefully determine whether a feature is supported. */ if ((no & 0xffff) <= 0x7ff) return -ENOSYS; break; } #ifdef CONFIG_DEBUG_USER /* * experience shows that these seem to indicate that * something catastrophic has happened */ if (user_debug & UDBG_SYSCALL) { printk("[%d] %s: arm syscall %d\n", task_pid_nr(current), current->comm, no); dump_instr("", regs); if (user_mode(regs)) { __show_regs(regs); c_backtrace(regs->ARM_fp, processor_mode(regs)); } } #endif info.si_signo = SIGILL; info.si_errno = 0; info.si_code = ILL_ILLTRP; info.si_addr = (void __user *)instruction_pointer(regs) - (thumb_mode(regs) ? 2 : 4); arm_notify_die("Oops - bad syscall(2)", regs, &info, no, 0); return 0; } #ifdef CONFIG_TLS_REG_EMUL /* * We might be running on an ARMv6+ processor which should have the TLS * register but for some reason we can't use it, or maybe an SMP system * using a pre-ARMv6 processor (there are apparently a few prototypes like * that in existence) and therefore access to that register must be * emulated. */ static int get_tp_trap(struct pt_regs *regs, unsigned int instr) { int reg = (instr >> 12) & 15; if (reg == 15) return 1; regs->uregs[reg] = current_thread_info()->tp_value[0]; regs->ARM_pc += 4; return 0; } static struct undef_hook arm_mrc_hook = { .instr_mask = 0x0fff0fff, .instr_val = 0x0e1d0f70, .cpsr_mask = PSR_T_BIT, .cpsr_val = 0, .fn = get_tp_trap, }; static int __init arm_mrc_hook_init(void) { register_undef_hook(&arm_mrc_hook); return 0; } late_initcall(arm_mrc_hook_init); #endif void __bad_xchg(volatile void *ptr, int size) { printk("xchg: bad data size: pc 0x%p, ptr 0x%p, size %d\n", __builtin_return_address(0), ptr, size); BUG(); } EXPORT_SYMBOL(__bad_xchg); /* * A data abort trap was taken, but we did not handle the instruction. * Try to abort the user program, or panic if it was the kernel. */ asmlinkage void baddataabort(int code, unsigned long instr, struct pt_regs *regs) { unsigned long addr = instruction_pointer(regs); siginfo_t info; #ifdef CONFIG_DEBUG_USER if (user_debug & UDBG_BADABORT) { printk(KERN_ERR "[%d] %s: bad data abort: code %d instr 0x%08lx\n", task_pid_nr(current), current->comm, code, instr); dump_instr(KERN_ERR, regs); show_pte(current->mm, addr); } #endif info.si_signo = SIGILL; info.si_errno = 0; info.si_code = ILL_ILLOPC; info.si_addr = (void __user *)addr; arm_notify_die("unknown data abort code", regs, &info, instr, 0); } void __readwrite_bug(const char *fn) { printk("%s called, but not implemented\n", fn); BUG(); } EXPORT_SYMBOL(__readwrite_bug); void __pte_error(const char *file, int line, pte_t pte) { printk("%s:%d: bad pte %08llx.\n", file, line, (long long)pte_val(pte)); } void __pmd_error(const char *file, int line, pmd_t pmd) { printk("%s:%d: bad pmd %08llx.\n", file, line, (long long)pmd_val(pmd)); } void __pgd_error(const char *file, int line, pgd_t pgd) { printk("%s:%d: bad pgd %08llx.\n", file, line, (long long)pgd_val(pgd)); } asmlinkage void __div0(void) { printk("Division by zero in kernel.\n"); dump_stack(); } EXPORT_SYMBOL(__div0); void abort(void) { BUG(); /* if that doesn't kill us, halt */ panic("Oops failed to kill thread"); } EXPORT_SYMBOL(abort); void __init trap_init(void) { return; } #ifdef CONFIG_KUSER_HELPERS static void __init kuser_init(void *vectors) { extern char __kuser_helper_start[], __kuser_helper_end[]; int kuser_sz = __kuser_helper_end - __kuser_helper_start; memcpy(vectors + 0x1000 - kuser_sz, __kuser_helper_start, kuser_sz); /* * vectors + 0xfe0 = __kuser_get_tls * vectors + 0xfe8 = hardware TLS instruction at 0xffff0fe8 */ if (tls_emu || has_tls_reg) memcpy(vectors + 0xfe0, vectors + 0xfe8, 4); } #else static inline void __init kuser_init(void *vectors) { } #endif void __init early_trap_init(void *vectors_base) { #ifndef CONFIG_CPU_V7M unsigned long vectors = (unsigned long)vectors_base; extern char __stubs_start[], __stubs_end[]; extern char __vectors_start[], __vectors_end[]; unsigned i; vectors_page = vectors_base; /* * Poison the vectors page with an undefined instruction. This * instruction is chosen to be undefined for both ARM and Thumb * ISAs. The Thumb version is an undefined instruction with a * branch back to the undefined instruction. */ for (i = 0; i < PAGE_SIZE / sizeof(u32); i++) ((u32 *)vectors_base)[i] = 0xe7fddef1; /* * Copy the vectors, stubs and kuser helpers (in entry-armv.S) * into the vector page, mapped at 0xffff0000, and ensure these * are visible to the instruction stream. */ memcpy((void *)vectors, __vectors_start, __vectors_end - __vectors_start); memcpy((void *)vectors + 0x1000, __stubs_start, __stubs_end - __stubs_start); kuser_init(vectors_base); flush_icache_range(vectors, vectors + PAGE_SIZE * 2); modify_domain(DOMAIN_USER, DOMAIN_CLIENT); #else /* ifndef CONFIG_CPU_V7M */ /* * on V7-M there is no need to copy the vector table to a dedicated * memory area. The address is configurable and so a table in the kernel * image can be used. */ #endif }