/* * 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 <joe@tensilica.com, joetylr@yahoo.com> * Chris Zankel <chris@zankel.net> * Marc Gauthier<marc@tensilica.com, marc@alumni.uwaterloo.ca> * 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 <linux/kernel.h> #include <linux/sched/signal.h> #include <linux/sched/debug.h> #include <linux/sched/task_stack.h> #include <linux/init.h> #include <linux/module.h> #include <linux/stringify.h> #include <linux/kallsyms.h> #include <linux/delay.h> #include <linux/hardirq.h> #include <linux/ratelimit.h> #include <linux/pgtable.h> #include <asm/stacktrace.h> #include <asm/ptrace.h> #include <asm/timex.h> #include <linux/uaccess.h> #include <asm/processor.h> #include <asm/traps.h> #include <asm/hw_breakpoint.h> /* * Machine specific interrupt handlers */ extern void kernel_exception(void); extern void user_exception(void); extern void fast_illegal_instruction_user(void); extern void fast_syscall_user(void); extern void fast_alloca(void); extern void fast_unaligned(void); extern void fast_second_level_miss(void); extern void fast_store_prohibited(void); extern void fast_coprocessor(void); extern void do_illegal_instruction (struct pt_regs*); extern void do_interrupt (struct pt_regs*); extern void do_nmi(struct pt_regs *); extern void do_unaligned_user (struct pt_regs*); extern void do_multihit (struct pt_regs*, unsigned long); extern void do_page_fault (struct pt_regs*, unsigned long); extern void do_debug (struct pt_regs*); extern void system_call (struct pt_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, fast_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 */ /* EXCCAUSE_LOAD_STORE_ERROR unhandled*/ { EXCCAUSE_LEVEL1_INTERRUPT, 0, do_interrupt }, { EXCCAUSE_ALLOCA, USER|KRNL, fast_alloca }, /* EXCCAUSE_INTEGER_DIVIDE_BY_ZERO unhandled */ /* EXCCAUSE_PRIVILEGED unhandled */ #if XCHAL_UNALIGNED_LOAD_EXCEPTION || XCHAL_UNALIGNED_STORE_EXCEPTION #ifdef CONFIG_XTENSA_UNALIGNED_USER { EXCCAUSE_UNALIGNED, USER, fast_unaligned }, #endif { EXCCAUSE_UNALIGNED, 0, do_unaligned_user }, { EXCCAUSE_UNALIGNED, KRNL, fast_unaligned }, #endif #ifdef CONFIG_MMU { EXCCAUSE_ITLB_MISS, 0, do_page_fault }, { EXCCAUSE_ITLB_MISS, USER|KRNL, fast_second_level_miss}, { EXCCAUSE_ITLB_MULTIHIT, 0, do_multihit }, { EXCCAUSE_ITLB_PRIVILEGE, 0, do_page_fault }, /* EXCCAUSE_SIZE_RESTRICTION unhandled */ { EXCCAUSE_FETCH_CACHE_ATTRIBUTE, 0, do_page_fault }, { EXCCAUSE_DTLB_MISS, USER|KRNL, fast_second_level_miss}, { EXCCAUSE_DTLB_MISS, 0, do_page_fault }, { EXCCAUSE_DTLB_MULTIHIT, 0, do_multihit }, { EXCCAUSE_DTLB_PRIVILEGE, 0, do_page_fault }, /* EXCCAUSE_DTLB_SIZE_RESTRICTION unhandled */ { EXCCAUSE_STORE_CACHE_ATTRIBUTE, USER|KRNL, fast_store_prohibited }, { EXCCAUSE_STORE_CACHE_ATTRIBUTE, 0, do_page_fault }, { EXCCAUSE_LOAD_CACHE_ATTRIBUTE, 0, do_page_fault }, #endif /* CONFIG_MMU */ /* 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 <exc_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); } /* * Unhandled Exceptions. Kill user task or panic if in kernel space. */ void do_unhandled(struct pt_regs *regs, unsigned long exccause) { __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, exccause); force_sig(SIGILL); } /* * Multi-hit exception. This if fatal! */ void do_multihit(struct pt_regs *regs, unsigned long exccause) { die("Caught multihit exception", regs, SIGKILL); } /* * IRQ handler. */ extern void do_IRQ(int, struct pt_regs *); #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); void do_nmi(struct pt_regs *regs) { struct pt_regs *old_regs; if ((regs->ps & PS_INTLEVEL_MASK) < LOCKLEVEL) trace_hardirqs_off(); 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 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; unsigned unhandled = ~0u; trace_hardirqs_off(); old_regs = set_irq_regs(regs); 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); } /* * Illegal instruction. Fatal if in kernel space. */ void do_illegal_instruction(struct pt_regs *regs) { __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); } /* * 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. */ #if XCHAL_UNALIGNED_LOAD_EXCEPTION || XCHAL_UNALIGNED_STORE_EXCEPTION void do_unaligned_user (struct pt_regs *regs) { __die_if_kernel("Unhandled unaligned exception in kernel", regs, SIGKILL); current->thread.bad_vaddr = regs->excvaddr; current->thread.error_code = -3; 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); } #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. */ 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 */ void * __init trap_set_handler(int cause, void *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) { unsigned long excsave1 = (unsigned long)this_cpu_ptr(&exc_table); __asm__ __volatile__("wsr %0, excsave1\n" : : "a" (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, wmask; show_regs_print_info(KERN_DEFAULT); wmask = regs->wmask & ~1; 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 32 static size_t kstack_depth_to_print = CONFIG_PRINT_STACK_DEPTH; void show_stack(struct task_struct *task, unsigned long *sp, const char *loglvl) { size_t len; if (!sp) sp = stack_pointer(task); len = min((-(size_t)sp) & (THREAD_SIZE - STACK_DUMP_ENTRY_SIZE), kstack_depth_to_print * STACK_DUMP_ENTRY_SIZE); printk("%sStack:\n", loglvl); print_hex_dump(loglvl, " ", DUMP_PREFIX_NONE, STACK_DUMP_LINE_SIZE, STACK_DUMP_ENTRY_SIZE, sp, len, false); show_trace(task, sp, loglvl); } DEFINE_SPINLOCK(die_lock); void 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"); do_exit(err); }