/* * Copyright (C) 1991, 1992 Linus Torvalds * Copyright (C) 2000, 2001, 2002 Andi Kleen, SuSE Labs * * Pentium III FXSR, SSE support * Gareth Hughes , May 2000 */ /* * Handle hardware traps and faults. */ #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #ifdef CONFIG_EISA #include #include #endif #if defined(CONFIG_EDAC) #include #endif #include #include #include #include #include #include #include #include #include #include #include #include #include #include #ifdef CONFIG_X86_64 #include #include #include /* No need to be aligned, but done to keep all IDTs defined the same way. */ gate_desc debug_idt_table[NR_VECTORS] __page_aligned_bss; #else #include #include asmlinkage int system_call(void); #endif /* Must be page-aligned because the real IDT is used in a fixmap. */ gate_desc idt_table[NR_VECTORS] __page_aligned_bss; DECLARE_BITMAP(used_vectors, NR_VECTORS); EXPORT_SYMBOL_GPL(used_vectors); static inline void conditional_sti(struct pt_regs *regs) { if (regs->flags & X86_EFLAGS_IF) local_irq_enable(); } static inline void preempt_conditional_sti(struct pt_regs *regs) { preempt_count_inc(); if (regs->flags & X86_EFLAGS_IF) local_irq_enable(); } static inline void conditional_cli(struct pt_regs *regs) { if (regs->flags & X86_EFLAGS_IF) local_irq_disable(); } static inline void preempt_conditional_cli(struct pt_regs *regs) { if (regs->flags & X86_EFLAGS_IF) local_irq_disable(); preempt_count_dec(); } static int __kprobes do_trap_no_signal(struct task_struct *tsk, int trapnr, char *str, struct pt_regs *regs, long error_code) { #ifdef CONFIG_X86_32 if (regs->flags & X86_VM_MASK) { /* * Traps 0, 1, 3, 4, and 5 should be forwarded to vm86. * On nmi (interrupt 2), do_trap should not be called. */ if (trapnr < X86_TRAP_UD) { if (!handle_vm86_trap((struct kernel_vm86_regs *) regs, error_code, trapnr)) return 0; } return -1; } #endif if (!user_mode(regs)) { if (!fixup_exception(regs)) { tsk->thread.error_code = error_code; tsk->thread.trap_nr = trapnr; die(str, regs, error_code); } return 0; } return -1; } static void __kprobes do_trap(int trapnr, int signr, char *str, struct pt_regs *regs, long error_code, siginfo_t *info) { struct task_struct *tsk = current; if (!do_trap_no_signal(tsk, trapnr, str, regs, error_code)) return; /* * We want error_code and trap_nr set for userspace faults and * kernelspace faults which result in die(), but not * kernelspace faults which are fixed up. die() gives the * process no chance to handle the signal and notice the * kernel fault information, so that won't result in polluting * the information about previously queued, but not yet * delivered, faults. See also do_general_protection below. */ tsk->thread.error_code = error_code; tsk->thread.trap_nr = trapnr; #ifdef CONFIG_X86_64 if (show_unhandled_signals && unhandled_signal(tsk, signr) && printk_ratelimit()) { pr_info("%s[%d] trap %s ip:%lx sp:%lx error:%lx", tsk->comm, tsk->pid, str, regs->ip, regs->sp, error_code); print_vma_addr(" in ", regs->ip); pr_cont("\n"); } #endif force_sig_info(signr, info ?: SEND_SIG_PRIV, tsk); } #define DO_ERROR(trapnr, signr, str, name) \ dotraplinkage void do_##name(struct pt_regs *regs, long error_code) \ { \ enum ctx_state prev_state; \ \ prev_state = exception_enter(); \ if (notify_die(DIE_TRAP, str, regs, error_code, \ trapnr, signr) == NOTIFY_STOP) { \ exception_exit(prev_state); \ return; \ } \ conditional_sti(regs); \ do_trap(trapnr, signr, str, regs, error_code, NULL); \ exception_exit(prev_state); \ } #define DO_ERROR_INFO(trapnr, signr, str, name, sicode, siaddr) \ dotraplinkage void do_##name(struct pt_regs *regs, long error_code) \ { \ siginfo_t info; \ enum ctx_state prev_state; \ \ info.si_signo = signr; \ info.si_errno = 0; \ info.si_code = sicode; \ info.si_addr = (void __user *)siaddr; \ prev_state = exception_enter(); \ if (notify_die(DIE_TRAP, str, regs, error_code, \ trapnr, signr) == NOTIFY_STOP) { \ exception_exit(prev_state); \ return; \ } \ conditional_sti(regs); \ do_trap(trapnr, signr, str, regs, error_code, &info); \ exception_exit(prev_state); \ } DO_ERROR_INFO(X86_TRAP_DE, SIGFPE, "divide error", divide_error, FPE_INTDIV, regs->ip ) DO_ERROR (X86_TRAP_OF, SIGSEGV, "overflow", overflow ) DO_ERROR (X86_TRAP_BR, SIGSEGV, "bounds", bounds ) DO_ERROR_INFO(X86_TRAP_UD, SIGILL, "invalid opcode", invalid_op, ILL_ILLOPN, regs->ip ) DO_ERROR (X86_TRAP_OLD_MF, SIGFPE, "coprocessor segment overrun", coprocessor_segment_overrun ) DO_ERROR (X86_TRAP_TS, SIGSEGV, "invalid TSS", invalid_TSS ) DO_ERROR (X86_TRAP_NP, SIGBUS, "segment not present", segment_not_present ) #ifdef CONFIG_X86_32 DO_ERROR (X86_TRAP_SS, SIGBUS, "stack segment", stack_segment ) #endif DO_ERROR_INFO(X86_TRAP_AC, SIGBUS, "alignment check", alignment_check, BUS_ADRALN, 0 ) #ifdef CONFIG_X86_64 /* Runs on IST stack */ dotraplinkage void do_stack_segment(struct pt_regs *regs, long error_code) { enum ctx_state prev_state; prev_state = exception_enter(); if (notify_die(DIE_TRAP, "stack segment", regs, error_code, X86_TRAP_SS, SIGBUS) != NOTIFY_STOP) { preempt_conditional_sti(regs); do_trap(X86_TRAP_SS, SIGBUS, "stack segment", regs, error_code, NULL); preempt_conditional_cli(regs); } exception_exit(prev_state); } dotraplinkage void do_double_fault(struct pt_regs *regs, long error_code) { static const char str[] = "double fault"; struct task_struct *tsk = current; exception_enter(); /* Return not checked because double check cannot be ignored */ notify_die(DIE_TRAP, str, regs, error_code, X86_TRAP_DF, SIGSEGV); tsk->thread.error_code = error_code; tsk->thread.trap_nr = X86_TRAP_DF; #ifdef CONFIG_DOUBLEFAULT df_debug(regs, error_code); #endif /* * This is always a kernel trap and never fixable (and thus must * never return). */ for (;;) die(str, regs, error_code); } #endif dotraplinkage void __kprobes do_general_protection(struct pt_regs *regs, long error_code) { struct task_struct *tsk; enum ctx_state prev_state; prev_state = exception_enter(); conditional_sti(regs); #ifdef CONFIG_X86_32 if (regs->flags & X86_VM_MASK) { local_irq_enable(); handle_vm86_fault((struct kernel_vm86_regs *) regs, error_code); goto exit; } #endif tsk = current; if (!user_mode(regs)) { if (fixup_exception(regs)) goto exit; tsk->thread.error_code = error_code; tsk->thread.trap_nr = X86_TRAP_GP; if (notify_die(DIE_GPF, "general protection fault", regs, error_code, X86_TRAP_GP, SIGSEGV) != NOTIFY_STOP) die("general protection fault", regs, error_code); goto exit; } tsk->thread.error_code = error_code; tsk->thread.trap_nr = X86_TRAP_GP; if (show_unhandled_signals && unhandled_signal(tsk, SIGSEGV) && printk_ratelimit()) { pr_info("%s[%d] general protection ip:%lx sp:%lx error:%lx", tsk->comm, task_pid_nr(tsk), regs->ip, regs->sp, error_code); print_vma_addr(" in ", regs->ip); pr_cont("\n"); } force_sig_info(SIGSEGV, SEND_SIG_PRIV, tsk); exit: exception_exit(prev_state); } /* May run on IST stack. */ dotraplinkage void __kprobes notrace do_int3(struct pt_regs *regs, long error_code) { enum ctx_state prev_state; #ifdef CONFIG_DYNAMIC_FTRACE /* * ftrace must be first, everything else may cause a recursive crash. * See note by declaration of modifying_ftrace_code in ftrace.c */ if (unlikely(atomic_read(&modifying_ftrace_code)) && ftrace_int3_handler(regs)) return; #endif if (poke_int3_handler(regs)) return; prev_state = exception_enter(); #ifdef CONFIG_KGDB_LOW_LEVEL_TRAP if (kgdb_ll_trap(DIE_INT3, "int3", regs, error_code, X86_TRAP_BP, SIGTRAP) == NOTIFY_STOP) goto exit; #endif /* CONFIG_KGDB_LOW_LEVEL_TRAP */ if (notify_die(DIE_INT3, "int3", regs, error_code, X86_TRAP_BP, SIGTRAP) == NOTIFY_STOP) goto exit; /* * Let others (NMI) know that the debug stack is in use * as we may switch to the interrupt stack. */ debug_stack_usage_inc(); preempt_conditional_sti(regs); do_trap(X86_TRAP_BP, SIGTRAP, "int3", regs, error_code, NULL); preempt_conditional_cli(regs); debug_stack_usage_dec(); exit: exception_exit(prev_state); } #ifdef CONFIG_X86_64 /* * Help handler running on IST stack to switch back to user stack * for scheduling or signal handling. The actual stack switch is done in * entry.S */ asmlinkage __kprobes struct pt_regs *sync_regs(struct pt_regs *eregs) { struct pt_regs *regs = eregs; /* Did already sync */ if (eregs == (struct pt_regs *)eregs->sp) ; /* Exception from user space */ else if (user_mode(eregs)) regs = task_pt_regs(current); /* * Exception from kernel and interrupts are enabled. Move to * kernel process stack. */ else if (eregs->flags & X86_EFLAGS_IF) regs = (struct pt_regs *)(eregs->sp -= sizeof(struct pt_regs)); if (eregs != regs) *regs = *eregs; return regs; } #endif /* * Our handling of the processor debug registers is non-trivial. * We do not clear them on entry and exit from the kernel. Therefore * it is possible to get a watchpoint trap here from inside the kernel. * However, the code in ./ptrace.c has ensured that the user can * only set watchpoints on userspace addresses. Therefore the in-kernel * watchpoint trap can only occur in code which is reading/writing * from user space. Such code must not hold kernel locks (since it * can equally take a page fault), therefore it is safe to call * force_sig_info even though that claims and releases locks. * * Code in ./signal.c ensures that the debug control register * is restored before we deliver any signal, and therefore that * user code runs with the correct debug control register even though * we clear it here. * * Being careful here means that we don't have to be as careful in a * lot of more complicated places (task switching can be a bit lazy * about restoring all the debug state, and ptrace doesn't have to * find every occurrence of the TF bit that could be saved away even * by user code) * * May run on IST stack. */ dotraplinkage void __kprobes do_debug(struct pt_regs *regs, long error_code) { struct task_struct *tsk = current; enum ctx_state prev_state; int user_icebp = 0; unsigned long dr6; int si_code; prev_state = exception_enter(); get_debugreg(dr6, 6); /* Filter out all the reserved bits which are preset to 1 */ dr6 &= ~DR6_RESERVED; /* * If dr6 has no reason to give us about the origin of this trap, * then it's very likely the result of an icebp/int01 trap. * User wants a sigtrap for that. */ if (!dr6 && user_mode(regs)) user_icebp = 1; /* Catch kmemcheck conditions first of all! */ if ((dr6 & DR_STEP) && kmemcheck_trap(regs)) goto exit; /* DR6 may or may not be cleared by the CPU */ set_debugreg(0, 6); /* * The processor cleared BTF, so don't mark that we need it set. */ clear_tsk_thread_flag(tsk, TIF_BLOCKSTEP); /* Store the virtualized DR6 value */ tsk->thread.debugreg6 = dr6; if (notify_die(DIE_DEBUG, "debug", regs, (long)&dr6, error_code, SIGTRAP) == NOTIFY_STOP) goto exit; /* * Let others (NMI) know that the debug stack is in use * as we may switch to the interrupt stack. */ debug_stack_usage_inc(); /* It's safe to allow irq's after DR6 has been saved */ preempt_conditional_sti(regs); if (regs->flags & X86_VM_MASK) { handle_vm86_trap((struct kernel_vm86_regs *) regs, error_code, X86_TRAP_DB); preempt_conditional_cli(regs); debug_stack_usage_dec(); goto exit; } /* * Single-stepping through system calls: ignore any exceptions in * kernel space, but re-enable TF when returning to user mode. * * We already checked v86 mode above, so we can check for kernel mode * by just checking the CPL of CS. */ if ((dr6 & DR_STEP) && !user_mode(regs)) { tsk->thread.debugreg6 &= ~DR_STEP; set_tsk_thread_flag(tsk, TIF_SINGLESTEP); regs->flags &= ~X86_EFLAGS_TF; } si_code = get_si_code(tsk->thread.debugreg6); if (tsk->thread.debugreg6 & (DR_STEP | DR_TRAP_BITS) || user_icebp) send_sigtrap(tsk, regs, error_code, si_code); preempt_conditional_cli(regs); debug_stack_usage_dec(); exit: exception_exit(prev_state); } /* * Note that we play around with the 'TS' bit in an attempt to get * the correct behaviour even in the presence of the asynchronous * IRQ13 behaviour */ static void math_error(struct pt_regs *regs, int error_code, int trapnr) { struct task_struct *task = current; siginfo_t info; unsigned short err; char *str = (trapnr == X86_TRAP_MF) ? "fpu exception" : "simd exception"; if (notify_die(DIE_TRAP, str, regs, error_code, trapnr, SIGFPE) == NOTIFY_STOP) return; conditional_sti(regs); if (!user_mode_vm(regs)) { if (!fixup_exception(regs)) { task->thread.error_code = error_code; task->thread.trap_nr = trapnr; die(str, regs, error_code); } return; } /* * Save the info for the exception handler and clear the error. */ save_init_fpu(task); task->thread.trap_nr = trapnr; task->thread.error_code = error_code; info.si_signo = SIGFPE; info.si_errno = 0; info.si_addr = (void __user *)regs->ip; if (trapnr == X86_TRAP_MF) { unsigned short cwd, swd; /* * (~cwd & swd) will mask out exceptions that are not set to unmasked * status. 0x3f is the exception bits in these regs, 0x200 is the * C1 reg you need in case of a stack fault, 0x040 is the stack * fault bit. We should only be taking one exception at a time, * so if this combination doesn't produce any single exception, * then we have a bad program that isn't synchronizing its FPU usage * and it will suffer the consequences since we won't be able to * fully reproduce the context of the exception */ cwd = get_fpu_cwd(task); swd = get_fpu_swd(task); err = swd & ~cwd; } else { /* * The SIMD FPU exceptions are handled a little differently, as there * is only a single status/control register. Thus, to determine which * unmasked exception was caught we must mask the exception mask bits * at 0x1f80, and then use these to mask the exception bits at 0x3f. */ unsigned short mxcsr = get_fpu_mxcsr(task); err = ~(mxcsr >> 7) & mxcsr; } if (err & 0x001) { /* Invalid op */ /* * swd & 0x240 == 0x040: Stack Underflow * swd & 0x240 == 0x240: Stack Overflow * User must clear the SF bit (0x40) if set */ info.si_code = FPE_FLTINV; } else if (err & 0x004) { /* Divide by Zero */ info.si_code = FPE_FLTDIV; } else if (err & 0x008) { /* Overflow */ info.si_code = FPE_FLTOVF; } else if (err & 0x012) { /* Denormal, Underflow */ info.si_code = FPE_FLTUND; } else if (err & 0x020) { /* Precision */ info.si_code = FPE_FLTRES; } else { /* * If we're using IRQ 13, or supposedly even some trap * X86_TRAP_MF implementations, it's possible * we get a spurious trap, which is not an error. */ return; } force_sig_info(SIGFPE, &info, task); } dotraplinkage void do_coprocessor_error(struct pt_regs *regs, long error_code) { enum ctx_state prev_state; prev_state = exception_enter(); math_error(regs, error_code, X86_TRAP_MF); exception_exit(prev_state); } dotraplinkage void do_simd_coprocessor_error(struct pt_regs *regs, long error_code) { enum ctx_state prev_state; prev_state = exception_enter(); math_error(regs, error_code, X86_TRAP_XF); exception_exit(prev_state); } dotraplinkage void do_spurious_interrupt_bug(struct pt_regs *regs, long error_code) { conditional_sti(regs); #if 0 /* No need to warn about this any longer. */ pr_info("Ignoring P6 Local APIC Spurious Interrupt Bug...\n"); #endif } asmlinkage void __attribute__((weak)) smp_thermal_interrupt(void) { } asmlinkage void __attribute__((weak)) smp_threshold_interrupt(void) { } /* * 'math_state_restore()' saves the current math information in the * old math state array, and gets the new ones from the current task * * Careful.. There are problems with IBM-designed IRQ13 behaviour. * Don't touch unless you *really* know how it works. * * Must be called with kernel preemption disabled (eg with local * local interrupts as in the case of do_device_not_available). */ void math_state_restore(void) { struct task_struct *tsk = current; if (!tsk_used_math(tsk)) { local_irq_enable(); /* * does a slab alloc which can sleep */ if (init_fpu(tsk)) { /* * ran out of memory! */ do_group_exit(SIGKILL); return; } local_irq_disable(); } __thread_fpu_begin(tsk); /* * Paranoid restore. send a SIGSEGV if we fail to restore the state. */ if (unlikely(restore_fpu_checking(tsk))) { drop_init_fpu(tsk); force_sig_info(SIGSEGV, SEND_SIG_PRIV, tsk); return; } tsk->thread.fpu_counter++; } EXPORT_SYMBOL_GPL(math_state_restore); dotraplinkage void __kprobes do_device_not_available(struct pt_regs *regs, long error_code) { enum ctx_state prev_state; prev_state = exception_enter(); BUG_ON(use_eager_fpu()); #ifdef CONFIG_MATH_EMULATION if (read_cr0() & X86_CR0_EM) { struct math_emu_info info = { }; conditional_sti(regs); info.regs = regs; math_emulate(&info); exception_exit(prev_state); return; } #endif math_state_restore(); /* interrupts still off */ #ifdef CONFIG_X86_32 conditional_sti(regs); #endif exception_exit(prev_state); } #ifdef CONFIG_X86_32 dotraplinkage void do_iret_error(struct pt_regs *regs, long error_code) { siginfo_t info; enum ctx_state prev_state; prev_state = exception_enter(); local_irq_enable(); info.si_signo = SIGILL; info.si_errno = 0; info.si_code = ILL_BADSTK; info.si_addr = NULL; if (notify_die(DIE_TRAP, "iret exception", regs, error_code, X86_TRAP_IRET, SIGILL) != NOTIFY_STOP) { do_trap(X86_TRAP_IRET, SIGILL, "iret exception", regs, error_code, &info); } exception_exit(prev_state); } #endif /* Set of traps needed for early debugging. */ void __init early_trap_init(void) { set_intr_gate_ist(X86_TRAP_DB, &debug, DEBUG_STACK); /* int3 can be called from all */ set_system_intr_gate_ist(X86_TRAP_BP, &int3, DEBUG_STACK); #ifdef CONFIG_X86_32 set_intr_gate(X86_TRAP_PF, page_fault); #endif load_idt(&idt_descr); } void __init early_trap_pf_init(void) { #ifdef CONFIG_X86_64 set_intr_gate(X86_TRAP_PF, page_fault); #endif } void __init trap_init(void) { int i; #ifdef CONFIG_EISA void __iomem *p = early_ioremap(0x0FFFD9, 4); if (readl(p) == 'E' + ('I'<<8) + ('S'<<16) + ('A'<<24)) EISA_bus = 1; early_iounmap(p, 4); #endif set_intr_gate(X86_TRAP_DE, divide_error); set_intr_gate_ist(X86_TRAP_NMI, &nmi, NMI_STACK); /* int4 can be called from all */ set_system_intr_gate(X86_TRAP_OF, &overflow); set_intr_gate(X86_TRAP_BR, bounds); set_intr_gate(X86_TRAP_UD, invalid_op); set_intr_gate(X86_TRAP_NM, device_not_available); #ifdef CONFIG_X86_32 set_task_gate(X86_TRAP_DF, GDT_ENTRY_DOUBLEFAULT_TSS); #else set_intr_gate_ist(X86_TRAP_DF, &double_fault, DOUBLEFAULT_STACK); #endif set_intr_gate(X86_TRAP_OLD_MF, coprocessor_segment_overrun); set_intr_gate(X86_TRAP_TS, invalid_TSS); set_intr_gate(X86_TRAP_NP, segment_not_present); set_intr_gate_ist(X86_TRAP_SS, &stack_segment, STACKFAULT_STACK); set_intr_gate(X86_TRAP_GP, general_protection); set_intr_gate(X86_TRAP_SPURIOUS, spurious_interrupt_bug); set_intr_gate(X86_TRAP_MF, coprocessor_error); set_intr_gate(X86_TRAP_AC, alignment_check); #ifdef CONFIG_X86_MCE set_intr_gate_ist(X86_TRAP_MC, &machine_check, MCE_STACK); #endif set_intr_gate(X86_TRAP_XF, simd_coprocessor_error); /* Reserve all the builtin and the syscall vector: */ for (i = 0; i < FIRST_EXTERNAL_VECTOR; i++) set_bit(i, used_vectors); #ifdef CONFIG_IA32_EMULATION set_system_intr_gate(IA32_SYSCALL_VECTOR, ia32_syscall); set_bit(IA32_SYSCALL_VECTOR, used_vectors); #endif #ifdef CONFIG_X86_32 set_system_trap_gate(SYSCALL_VECTOR, &system_call); set_bit(SYSCALL_VECTOR, used_vectors); #endif /* * Set the IDT descriptor to a fixed read-only location, so that the * "sidt" instruction will not leak the location of the kernel, and * to defend the IDT against arbitrary memory write vulnerabilities. * It will be reloaded in cpu_init() */ __set_fixmap(FIX_RO_IDT, __pa_symbol(idt_table), PAGE_KERNEL_RO); idt_descr.address = fix_to_virt(FIX_RO_IDT); /* * Should be a barrier for any external CPU state: */ cpu_init(); x86_init.irqs.trap_init(); #ifdef CONFIG_X86_64 memcpy(&debug_idt_table, &idt_table, IDT_ENTRIES * 16); set_nmi_gate(X86_TRAP_DB, &debug); set_nmi_gate(X86_TRAP_BP, &int3); #endif }