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Diffstat (limited to 'arch/xtensa/kernel/traps.c')
| -rw-r--r-- | arch/xtensa/kernel/traps.c | 655 |
1 files changed, 655 insertions, 0 deletions
diff --git a/arch/xtensa/kernel/traps.c b/arch/xtensa/kernel/traps.c new file mode 100644 index 000000000..38092d21a --- /dev/null +++ b/arch/xtensa/kernel/traps.c @@ -0,0 +1,655 @@ +/* + * 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/cpu.h> +#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 + */ + +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 <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); +} + +#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); +} |