/* * arch/xtensa/kernel/traps.c * * Exception handling. * * Derived from code with the following copyrights: * Copyright (C) 1994 - 1999 by Ralf Baechle * Modified for R3000 by Paul M. Antoine, 1995, 1996 * Complete output from die() by Ulf Carlsson, 1998 * Copyright (C) 1999 Silicon Graphics, Inc. * * Essentially rewritten for the Xtensa architecture port. * * Copyright (C) 2001 - 2013 Tensilica Inc. * * Joe Taylor * Chris Zankel * Marc Gauthier * Kevin Chea * * This file is subject to the terms and conditions of the GNU General Public * License. See the file "COPYING" in the main directory of this archive * for more details. */ #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include /* * Machine specific interrupt handlers */ static void do_illegal_instruction(struct pt_regs *regs); static void do_div0(struct pt_regs *regs); static void do_interrupt(struct pt_regs *regs); #if XTENSA_FAKE_NMI static void do_nmi(struct pt_regs *regs); #endif #ifdef CONFIG_XTENSA_LOAD_STORE static void do_load_store(struct pt_regs *regs); #endif static void do_unaligned_user(struct pt_regs *regs); static void do_multihit(struct pt_regs *regs); #if XTENSA_HAVE_COPROCESSORS static void do_coprocessor(struct pt_regs *regs); #endif static void do_debug(struct pt_regs *regs); /* * The vector table must be preceded by a save area (which * implies it must be in RAM, unless one places RAM immediately * before a ROM and puts the vector at the start of the ROM (!)) */ #define KRNL 0x01 #define USER 0x02 #define COPROCESSOR(x) \ { EXCCAUSE_COPROCESSOR ## x ## _DISABLED, USER|KRNL, fast_coprocessor },\ { EXCCAUSE_COPROCESSOR ## x ## _DISABLED, 0, do_coprocessor } typedef struct { int cause; int fast; void* handler; } dispatch_init_table_t; static dispatch_init_table_t __initdata dispatch_init_table[] = { #ifdef CONFIG_USER_ABI_CALL0_PROBE { EXCCAUSE_ILLEGAL_INSTRUCTION, USER, fast_illegal_instruction_user }, #endif { EXCCAUSE_ILLEGAL_INSTRUCTION, 0, do_illegal_instruction}, { EXCCAUSE_SYSTEM_CALL, USER, fast_syscall_user }, { EXCCAUSE_SYSTEM_CALL, 0, system_call }, /* EXCCAUSE_INSTRUCTION_FETCH unhandled */ #ifdef CONFIG_XTENSA_LOAD_STORE { EXCCAUSE_LOAD_STORE_ERROR, USER|KRNL, fast_load_store }, { EXCCAUSE_LOAD_STORE_ERROR, 0, do_load_store }, #endif { EXCCAUSE_LEVEL1_INTERRUPT, 0, do_interrupt }, #ifdef SUPPORT_WINDOWED { EXCCAUSE_ALLOCA, USER|KRNL, fast_alloca }, #endif { EXCCAUSE_INTEGER_DIVIDE_BY_ZERO, 0, do_div0 }, /* EXCCAUSE_PRIVILEGED unhandled */ #if XCHAL_UNALIGNED_LOAD_EXCEPTION || XCHAL_UNALIGNED_STORE_EXCEPTION || \ IS_ENABLED(CONFIG_XTENSA_LOAD_STORE) #ifdef CONFIG_XTENSA_UNALIGNED_USER { EXCCAUSE_UNALIGNED, USER, fast_unaligned }, #endif { EXCCAUSE_UNALIGNED, KRNL, fast_unaligned }, #endif { EXCCAUSE_UNALIGNED, 0, do_unaligned_user }, #ifdef CONFIG_MMU { EXCCAUSE_ITLB_MISS, 0, do_page_fault }, { EXCCAUSE_ITLB_MISS, USER|KRNL, fast_second_level_miss}, { EXCCAUSE_DTLB_MISS, USER|KRNL, fast_second_level_miss}, { EXCCAUSE_DTLB_MISS, 0, do_page_fault }, { EXCCAUSE_STORE_CACHE_ATTRIBUTE, USER|KRNL, fast_store_prohibited }, #endif /* CONFIG_MMU */ #ifdef CONFIG_PFAULT { EXCCAUSE_ITLB_MULTIHIT, 0, do_multihit }, { EXCCAUSE_ITLB_PRIVILEGE, 0, do_page_fault }, { EXCCAUSE_FETCH_CACHE_ATTRIBUTE, 0, do_page_fault }, { EXCCAUSE_DTLB_MULTIHIT, 0, do_multihit }, { EXCCAUSE_DTLB_PRIVILEGE, 0, do_page_fault }, { EXCCAUSE_STORE_CACHE_ATTRIBUTE, 0, do_page_fault }, { EXCCAUSE_LOAD_CACHE_ATTRIBUTE, 0, do_page_fault }, #endif /* XCCHAL_EXCCAUSE_FLOATING_POINT unhandled */ #if XTENSA_HAVE_COPROCESSOR(0) COPROCESSOR(0), #endif #if XTENSA_HAVE_COPROCESSOR(1) COPROCESSOR(1), #endif #if XTENSA_HAVE_COPROCESSOR(2) COPROCESSOR(2), #endif #if XTENSA_HAVE_COPROCESSOR(3) COPROCESSOR(3), #endif #if XTENSA_HAVE_COPROCESSOR(4) COPROCESSOR(4), #endif #if XTENSA_HAVE_COPROCESSOR(5) COPROCESSOR(5), #endif #if XTENSA_HAVE_COPROCESSOR(6) COPROCESSOR(6), #endif #if XTENSA_HAVE_COPROCESSOR(7) COPROCESSOR(7), #endif #if XTENSA_FAKE_NMI { EXCCAUSE_MAPPED_NMI, 0, do_nmi }, #endif { EXCCAUSE_MAPPED_DEBUG, 0, do_debug }, { -1, -1, 0 } }; /* The exception table serves two functions: * 1. it contains three dispatch tables (fast_user, fast_kernel, default-c) * 2. it is a temporary memory buffer for the exception handlers. */ DEFINE_PER_CPU(struct exc_table, exc_table); DEFINE_PER_CPU(struct debug_table, debug_table); void die(const char*, struct pt_regs*, long); static inline void __die_if_kernel(const char *str, struct pt_regs *regs, long err) { if (!user_mode(regs)) die(str, regs, err); } #ifdef CONFIG_PRINT_USER_CODE_ON_UNHANDLED_EXCEPTION static inline void dump_user_code(struct pt_regs *regs) { char buf[32]; if (copy_from_user(buf, (void __user *)(regs->pc & -16), sizeof(buf)) == 0) { print_hex_dump(KERN_INFO, " ", DUMP_PREFIX_NONE, 32, 1, buf, sizeof(buf), false); } } #else static inline void dump_user_code(struct pt_regs *regs) { } #endif /* * Unhandled Exceptions. Kill user task or panic if in kernel space. */ void do_unhandled(struct pt_regs *regs) { __die_if_kernel("Caught unhandled exception - should not happen", regs, SIGKILL); /* If in user mode, send SIGILL signal to current process */ pr_info_ratelimited("Caught unhandled exception in '%s' " "(pid = %d, pc = %#010lx) - should not happen\n" "\tEXCCAUSE is %ld\n", current->comm, task_pid_nr(current), regs->pc, regs->exccause); dump_user_code(regs); force_sig(SIGILL); } /* * Multi-hit exception. This if fatal! */ static void do_multihit(struct pt_regs *regs) { die("Caught multihit exception", regs, SIGKILL); } /* * IRQ handler. */ #if XTENSA_FAKE_NMI #define IS_POW2(v) (((v) & ((v) - 1)) == 0) #if !(PROFILING_INTLEVEL == XCHAL_EXCM_LEVEL && \ IS_POW2(XTENSA_INTLEVEL_MASK(PROFILING_INTLEVEL))) #warning "Fake NMI is requested for PMM, but there are other IRQs at or above its level." #warning "Fake NMI will be used, but there will be a bugcheck if one of those IRQs fire." static inline void check_valid_nmi(void) { unsigned intread = xtensa_get_sr(interrupt); unsigned intenable = xtensa_get_sr(intenable); BUG_ON(intread & intenable & ~(XTENSA_INTLEVEL_ANDBELOW_MASK(PROFILING_INTLEVEL) ^ XTENSA_INTLEVEL_MASK(PROFILING_INTLEVEL) ^ BIT(XCHAL_PROFILING_INTERRUPT))); } #else static inline void check_valid_nmi(void) { } #endif irqreturn_t xtensa_pmu_irq_handler(int irq, void *dev_id); DEFINE_PER_CPU(unsigned long, nmi_count); static void do_nmi(struct pt_regs *regs) { struct pt_regs *old_regs = set_irq_regs(regs); nmi_enter(); ++*this_cpu_ptr(&nmi_count); check_valid_nmi(); xtensa_pmu_irq_handler(0, NULL); nmi_exit(); set_irq_regs(old_regs); } #endif static void do_interrupt(struct pt_regs *regs) { static const unsigned int_level_mask[] = { 0, XCHAL_INTLEVEL1_MASK, XCHAL_INTLEVEL2_MASK, XCHAL_INTLEVEL3_MASK, XCHAL_INTLEVEL4_MASK, XCHAL_INTLEVEL5_MASK, XCHAL_INTLEVEL6_MASK, XCHAL_INTLEVEL7_MASK, }; struct pt_regs *old_regs = set_irq_regs(regs); unsigned unhandled = ~0u; irq_enter(); for (;;) { unsigned intread = xtensa_get_sr(interrupt); unsigned intenable = xtensa_get_sr(intenable); unsigned int_at_level = intread & intenable; unsigned level; for (level = LOCKLEVEL; level > 0; --level) { if (int_at_level & int_level_mask[level]) { int_at_level &= int_level_mask[level]; if (int_at_level & unhandled) int_at_level &= unhandled; else unhandled |= int_level_mask[level]; break; } } if (level == 0) break; /* clear lowest pending irq in the unhandled mask */ unhandled ^= (int_at_level & -int_at_level); do_IRQ(__ffs(int_at_level), regs); } irq_exit(); set_irq_regs(old_regs); } static bool check_div0(struct pt_regs *regs) { static const u8 pattern[] = {'D', 'I', 'V', '0'}; const u8 *p; u8 buf[5]; if (user_mode(regs)) { if (copy_from_user(buf, (void __user *)regs->pc + 2, 5)) return false; p = buf; } else { p = (const u8 *)regs->pc + 2; } return memcmp(p, pattern, sizeof(pattern)) == 0 || memcmp(p + 1, pattern, sizeof(pattern)) == 0; } /* * Illegal instruction. Fatal if in kernel space. */ static void do_illegal_instruction(struct pt_regs *regs) { #ifdef CONFIG_USER_ABI_CALL0_PROBE /* * When call0 application encounters an illegal instruction fast * exception handler will attempt to set PS.WOE and retry failing * instruction. * If we get here we know that that instruction is also illegal * with PS.WOE set, so it's not related to the windowed option * hence PS.WOE may be cleared. */ if (regs->pc == current_thread_info()->ps_woe_fix_addr) regs->ps &= ~PS_WOE_MASK; #endif if (check_div0(regs)) { do_div0(regs); return; } __die_if_kernel("Illegal instruction in kernel", regs, SIGKILL); /* If in user mode, send SIGILL signal to current process. */ pr_info_ratelimited("Illegal Instruction in '%s' (pid = %d, pc = %#010lx)\n", current->comm, task_pid_nr(current), regs->pc); force_sig(SIGILL); } static void do_div0(struct pt_regs *regs) { __die_if_kernel("Unhandled division by 0 in kernel", regs, SIGKILL); force_sig_fault(SIGFPE, FPE_INTDIV, (void __user *)regs->pc); } #ifdef CONFIG_XTENSA_LOAD_STORE static void do_load_store(struct pt_regs *regs) { __die_if_kernel("Unhandled load/store exception in kernel", regs, SIGKILL); pr_info_ratelimited("Load/store error to %08lx in '%s' (pid = %d, pc = %#010lx)\n", regs->excvaddr, current->comm, task_pid_nr(current), regs->pc); force_sig_fault(SIGBUS, BUS_ADRERR, (void *)regs->excvaddr); } #endif /* * Handle unaligned memory accesses from user space. Kill task. * * If CONFIG_UNALIGNED_USER is not set, we don't allow unaligned memory * accesses causes from user space. */ static void do_unaligned_user(struct pt_regs *regs) { __die_if_kernel("Unhandled unaligned exception in kernel", regs, SIGKILL); pr_info_ratelimited("Unaligned memory access to %08lx in '%s' " "(pid = %d, pc = %#010lx)\n", regs->excvaddr, current->comm, task_pid_nr(current), regs->pc); force_sig_fault(SIGBUS, BUS_ADRALN, (void *) regs->excvaddr); } #if XTENSA_HAVE_COPROCESSORS static void do_coprocessor(struct pt_regs *regs) { coprocessor_flush_release_all(current_thread_info()); } #endif /* Handle debug events. * When CONFIG_HAVE_HW_BREAKPOINT is on this handler is called with * preemption disabled to avoid rescheduling and keep mapping of hardware * breakpoint structures to debug registers intact, so that * DEBUGCAUSE.DBNUM could be used in case of data breakpoint hit. */ static void do_debug(struct pt_regs *regs) { #ifdef CONFIG_HAVE_HW_BREAKPOINT int ret = check_hw_breakpoint(regs); preempt_enable(); if (ret == 0) return; #endif __die_if_kernel("Breakpoint in kernel", regs, SIGKILL); /* If in user mode, send SIGTRAP signal to current process */ force_sig(SIGTRAP); } #define set_handler(type, cause, handler) \ do { \ unsigned int cpu; \ \ for_each_possible_cpu(cpu) \ per_cpu(exc_table, cpu).type[cause] = (handler);\ } while (0) /* Set exception C handler - for temporary use when probing exceptions */ xtensa_exception_handler * __init trap_set_handler(int cause, xtensa_exception_handler *handler) { void *previous = per_cpu(exc_table, 0).default_handler[cause]; set_handler(default_handler, cause, handler); return previous; } static void trap_init_excsave(void) { xtensa_set_sr(this_cpu_ptr(&exc_table), excsave1); } static void trap_init_debug(void) { unsigned long debugsave = (unsigned long)this_cpu_ptr(&debug_table); this_cpu_ptr(&debug_table)->debug_exception = debug_exception; __asm__ __volatile__("wsr %0, excsave" __stringify(XCHAL_DEBUGLEVEL) :: "a"(debugsave)); } /* * Initialize dispatch tables. * * The exception vectors are stored compressed the __init section in the * dispatch_init_table. This function initializes the following three tables * from that compressed table: * - fast user first dispatch table for user exceptions * - fast kernel first dispatch table for kernel exceptions * - default C-handler C-handler called by the default fast handler. * * See vectors.S for more details. */ void __init trap_init(void) { int i; /* Setup default vectors. */ for (i = 0; i < EXCCAUSE_N; i++) { set_handler(fast_user_handler, i, user_exception); set_handler(fast_kernel_handler, i, kernel_exception); set_handler(default_handler, i, do_unhandled); } /* Setup specific handlers. */ for(i = 0; dispatch_init_table[i].cause >= 0; i++) { int fast = dispatch_init_table[i].fast; int cause = dispatch_init_table[i].cause; void *handler = dispatch_init_table[i].handler; if (fast == 0) set_handler(default_handler, cause, handler); if ((fast & USER) != 0) set_handler(fast_user_handler, cause, handler); if ((fast & KRNL) != 0) set_handler(fast_kernel_handler, cause, handler); } /* Initialize EXCSAVE_1 to hold the address of the exception table. */ trap_init_excsave(); trap_init_debug(); } #ifdef CONFIG_SMP void secondary_trap_init(void) { trap_init_excsave(); trap_init_debug(); } #endif /* * This function dumps the current valid window frame and other base registers. */ void show_regs(struct pt_regs * regs) { int i; show_regs_print_info(KERN_DEFAULT); for (i = 0; i < 16; i++) { if ((i % 8) == 0) pr_info("a%02d:", i); pr_cont(" %08lx", regs->areg[i]); } pr_cont("\n"); pr_info("pc: %08lx, ps: %08lx, depc: %08lx, excvaddr: %08lx\n", regs->pc, regs->ps, regs->depc, regs->excvaddr); pr_info("lbeg: %08lx, lend: %08lx lcount: %08lx, sar: %08lx\n", regs->lbeg, regs->lend, regs->lcount, regs->sar); if (user_mode(regs)) pr_cont("wb: %08lx, ws: %08lx, wmask: %08lx, syscall: %ld\n", regs->windowbase, regs->windowstart, regs->wmask, regs->syscall); } static int show_trace_cb(struct stackframe *frame, void *data) { const char *loglvl = data; if (kernel_text_address(frame->pc)) printk("%s [<%08lx>] %pB\n", loglvl, frame->pc, (void *)frame->pc); return 0; } static void show_trace(struct task_struct *task, unsigned long *sp, const char *loglvl) { if (!sp) sp = stack_pointer(task); printk("%sCall Trace:\n", loglvl); walk_stackframe(sp, show_trace_cb, (void *)loglvl); } #define STACK_DUMP_ENTRY_SIZE 4 #define STACK_DUMP_LINE_SIZE 16 static size_t kstack_depth_to_print = CONFIG_PRINT_STACK_DEPTH; struct stack_fragment { size_t len; size_t off; u8 *sp; const char *loglvl; }; static int show_stack_fragment_cb(struct stackframe *frame, void *data) { struct stack_fragment *sf = data; while (sf->off < sf->len) { u8 line[STACK_DUMP_LINE_SIZE]; size_t line_len = sf->len - sf->off > STACK_DUMP_LINE_SIZE ? STACK_DUMP_LINE_SIZE : sf->len - sf->off; bool arrow = sf->off == 0; if (frame && frame->sp == (unsigned long)(sf->sp + sf->off)) arrow = true; __memcpy(line, sf->sp + sf->off, line_len); print_hex_dump(sf->loglvl, arrow ? "> " : " ", DUMP_PREFIX_NONE, STACK_DUMP_LINE_SIZE, STACK_DUMP_ENTRY_SIZE, line, line_len, false); sf->off += STACK_DUMP_LINE_SIZE; if (arrow) return 0; } return 1; } void show_stack(struct task_struct *task, unsigned long *sp, const char *loglvl) { struct stack_fragment sf; if (!sp) sp = stack_pointer(task); sf.len = min((-(size_t)sp) & (THREAD_SIZE - STACK_DUMP_ENTRY_SIZE), kstack_depth_to_print * STACK_DUMP_ENTRY_SIZE); sf.off = 0; sf.sp = (u8 *)sp; sf.loglvl = loglvl; printk("%sStack:\n", loglvl); walk_stackframe(sp, show_stack_fragment_cb, &sf); while (sf.off < sf.len) show_stack_fragment_cb(NULL, &sf); show_trace(task, sp, loglvl); } DEFINE_SPINLOCK(die_lock); void __noreturn die(const char * str, struct pt_regs * regs, long err) { static int die_counter; const char *pr = ""; if (IS_ENABLED(CONFIG_PREEMPTION)) pr = IS_ENABLED(CONFIG_PREEMPT_RT) ? " PREEMPT_RT" : " PREEMPT"; console_verbose(); spin_lock_irq(&die_lock); pr_info("%s: sig: %ld [#%d]%s\n", str, err, ++die_counter, pr); show_regs(regs); if (!user_mode(regs)) show_stack(NULL, (unsigned long *)regs->areg[1], KERN_INFO); add_taint(TAINT_DIE, LOCKDEP_NOW_UNRELIABLE); spin_unlock_irq(&die_lock); if (in_interrupt()) panic("Fatal exception in interrupt"); if (panic_on_oops) panic("Fatal exception"); make_task_dead(err); }