/*
 *  Copyright (C) 1991, 1992  Linus Torvalds
 *  Copyright (C) 2000, 2001, 2002 Andi Kleen, SuSE Labs
 */
#include <linux/kallsyms.h>
#include <linux/kprobes.h>
#include <linux/uaccess.h>
#include <linux/utsname.h>
#include <linux/hardirq.h>
#include <linux/kdebug.h>
#include <linux/module.h>
#include <linux/ptrace.h>
#include <linux/kexec.h>
#include <linux/bug.h>
#include <linux/nmi.h>
#include <linux/sysfs.h>

#include <asm/stacktrace.h>

#define STACKSLOTS_PER_LINE 4
#define get_bp(bp) asm("movq %%rbp, %0" : "=r" (bp) :)

int panic_on_unrecovered_nmi;
int kstack_depth_to_print = 3 * STACKSLOTS_PER_LINE;
static unsigned int code_bytes = 64;
static int die_counter;

void printk_address(unsigned long address, int reliable)
{
        printk(" [<%p>] %s%pS\n", (void *) address,
                        reliable ? "" : "? ", (void *) address);
}

static unsigned long *in_exception_stack(unsigned cpu, unsigned long stack,
                                        unsigned *usedp, char **idp)
{
        static char ids[][8] = {
                [DEBUG_STACK - 1] = "#DB",
                [NMI_STACK - 1] = "NMI",
                [DOUBLEFAULT_STACK - 1] = "#DF",
                [STACKFAULT_STACK - 1] = "#SS",
                [MCE_STACK - 1] = "#MC",
#if DEBUG_STKSZ > EXCEPTION_STKSZ
                [N_EXCEPTION_STACKS ...
                        N_EXCEPTION_STACKS + DEBUG_STKSZ / EXCEPTION_STKSZ - 2] = "#DB[?]"
#endif
        };
        unsigned k;

        /*
         * Iterate over all exception stacks, and figure out whether
         * 'stack' is in one of them:
         */
        for (k = 0; k < N_EXCEPTION_STACKS; k++) {
                unsigned long end = per_cpu(orig_ist, cpu).ist[k];
                /*
                 * Is 'stack' above this exception frame's end?
                 * If yes then skip to the next frame.
                 */
                if (stack >= end)
                        continue;
                /*
                 * Is 'stack' above this exception frame's start address?
                 * If yes then we found the right frame.
                 */
                if (stack >= end - EXCEPTION_STKSZ) {
                        /*
                         * Make sure we only iterate through an exception
                         * stack once. If it comes up for the second time
                         * then there's something wrong going on - just
                         * break out and return NULL:
                         */
                        if (*usedp & (1U << k))
                                break;
                        *usedp |= 1U << k;
                        *idp = ids[k];
                        return (unsigned long *)end;
                }
                /*
                 * If this is a debug stack, and if it has a larger size than
                 * the usual exception stacks, then 'stack' might still
                 * be within the lower portion of the debug stack:
                 */
#if DEBUG_STKSZ > EXCEPTION_STKSZ
                if (k == DEBUG_STACK - 1 && stack >= end - DEBUG_STKSZ) {
                        unsigned j = N_EXCEPTION_STACKS - 1;

                        /*
                         * Black magic. A large debug stack is composed of
                         * multiple exception stack entries, which we
                         * iterate through now. Dont look:
                         */
                        do {
                                ++j;
                                end -= EXCEPTION_STKSZ;
                                ids[j][4] = '1' + (j - N_EXCEPTION_STACKS);
                        } while (stack < end - EXCEPTION_STKSZ);
                        if (*usedp & (1U << j))
                                break;
                        *usedp |= 1U << j;
                        *idp = ids[j];
                        return (unsigned long *)end;
                }
#endif
        }
        return NULL;
}

/*
 * x86-64 can have up to three kernel stacks:
 * process stack
 * interrupt stack
 * severe exception (double fault, nmi, stack fault, debug, mce) hardware stack
 */

static inline int valid_stack_ptr(struct thread_info *tinfo,
                        void *p, unsigned int size, void *end)
{
        void *t = tinfo;
        if (end) {
                if (p < end && p >= (end-THREAD_SIZE))
                        return 1;
                else
                        return 0;
        }
        return p > t && p < t + THREAD_SIZE - size;
}

/* The form of the top of the frame on the stack */
struct stack_frame {
        struct stack_frame *next_frame;
        unsigned long return_address;
};

static inline unsigned long
print_context_stack(struct thread_info *tinfo,
                unsigned long *stack, unsigned long bp,
                const struct stacktrace_ops *ops, void *data,
                unsigned long *end)
{
        struct stack_frame *frame = (struct stack_frame *)bp;

        while (valid_stack_ptr(tinfo, stack, sizeof(*stack), end)) {
                unsigned long addr;

                addr = *stack;
                if (__kernel_text_address(addr)) {
                        if ((unsigned long) stack == bp + sizeof(long)) {
                                ops->address(data, addr, 1);
                                frame = frame->next_frame;
                                bp = (unsigned long) frame;
                        } else {
                                ops->address(data, addr, bp == 0);
                        }
                }
                stack++;
        }
        return bp;
}

void dump_trace(struct task_struct *task, struct pt_regs *regs,
                unsigned long *stack, unsigned long bp,
                const struct stacktrace_ops *ops, void *data)
{
        const unsigned cpu = get_cpu();
        unsigned long *irqstack_end = (unsigned long *)cpu_pda(cpu)->irqstackptr;
        unsigned used = 0;
        struct thread_info *tinfo;

        if (!task)
                task = current;

        if (!stack) {
                unsigned long dummy;
                stack = &dummy;
                if (task && task != current)
                        stack = (unsigned long *)task->thread.sp;
        }

#ifdef CONFIG_FRAME_POINTER
        if (!bp) {
                if (task == current) {
                        /* Grab bp right from our regs */
                        get_bp(bp);
                } else {
                        /* bp is the last reg pushed by switch_to */
                        bp = *(unsigned long *) task->thread.sp;
                }
        }
#endif

        /*
         * Print function call entries in all stacks, starting at the
         * current stack address. If the stacks consist of nested
         * exceptions
         */
        tinfo = task_thread_info(task);
        for (;;) {
                char *id;
                unsigned long *estack_end;
                estack_end = in_exception_stack(cpu, (unsigned long)stack,
                                                &used, &id);

                if (estack_end) {
                        if (ops->stack(data, id) < 0)
                                break;

                        bp = print_context_stack(tinfo, stack, bp, ops,
                                                        data, estack_end);
                        ops->stack(data, "<EOE>");
                        /*
                         * We link to the next stack via the
                         * second-to-last pointer (index -2 to end) in the
                         * exception stack:
                         */
                        stack = (unsigned long *) estack_end[-2];
                        continue;
                }
                if (irqstack_end) {
                        unsigned long *irqstack;
                        irqstack = irqstack_end -
                                (IRQSTACKSIZE - 64) / sizeof(*irqstack);

                        if (stack >= irqstack && stack < irqstack_end) {
                                if (ops->stack(data, "IRQ") < 0)
                                        break;
                                bp = print_context_stack(tinfo, stack, bp,
                                                ops, data, irqstack_end);
                                /*
                                 * We link to the next stack (which would be
                                 * the process stack normally) the last
                                 * pointer (index -1 to end) in the IRQ stack:
                                 */
                                stack = (unsigned long *) (irqstack_end[-1]);
                                irqstack_end = NULL;
                                ops->stack(data, "EOI");
                                continue;
                        }
                }
                break;
        }

        /*
         * This handles the process stack:
         */
        bp = print_context_stack(tinfo, stack, bp, ops, data, NULL);
        put_cpu();
}
EXPORT_SYMBOL(dump_trace);

static void
print_trace_warning_symbol(void *data, char *msg, unsigned long symbol)
{
        printk(data);
        print_symbol(msg, symbol);
        printk("\n");
}

static void print_trace_warning(void *data, char *msg)
{
        printk("%s%s\n", (char *)data, msg);
}

static int print_trace_stack(void *data, char *name)
{
        printk("%s <%s> ", (char *)data, name);
        return 0;
}

/*
 * Print one address/symbol entries per line.
 */
static void print_trace_address(void *data, unsigned long addr, int reliable)
{
        touch_nmi_watchdog();
        printk(data);
        printk_address(addr, reliable);
}

static const struct stacktrace_ops print_trace_ops = {
        .warning = print_trace_warning,
        .warning_symbol = print_trace_warning_symbol,
        .stack = print_trace_stack,
        .address = print_trace_address,
};

static void
show_trace_log_lvl(struct task_struct *task, struct pt_regs *regs,
                unsigned long *stack, unsigned long bp, char *log_lvl)
{
        printk("%sCall Trace:\n", log_lvl);
        dump_trace(task, regs, stack, bp, &print_trace_ops, log_lvl);
}

void show_trace(struct task_struct *task, struct pt_regs *regs,
                unsigned long *stack, unsigned long bp)
{
        show_trace_log_lvl(task, regs, stack, bp, "");
}

static void
show_stack_log_lvl(struct task_struct *task, struct pt_regs *regs,
                unsigned long *sp, unsigned long bp, char *log_lvl)
{
        unsigned long *stack;
        int i;
        const int cpu = smp_processor_id();
        unsigned long *irqstack_end =
                (unsigned long *) (cpu_pda(cpu)->irqstackptr);
        unsigned long *irqstack =
                (unsigned long *) (cpu_pda(cpu)->irqstackptr - IRQSTACKSIZE);

        /*
         * debugging aid: "show_stack(NULL, NULL);" prints the
         * back trace for this cpu.
         */

        if (sp == NULL) {
                if (task)
                        sp = (unsigned long *)task->thread.sp;
                else
                        sp = (unsigned long *)&sp;
        }

        stack = sp;
        for (i = 0; i < kstack_depth_to_print; i++) {
                if (stack >= irqstack && stack <= irqstack_end) {
                        if (stack == irqstack_end) {
                                stack = (unsigned long *) (irqstack_end[-1]);
                                printk(" <EOI> ");
                        }
                } else {
                if (((long) stack & (THREAD_SIZE-1)) == 0)
                        break;
                }
                if (i && ((i % STACKSLOTS_PER_LINE) == 0))
                        printk("\n%s", log_lvl);
                printk(" %016lx", *stack++);
                touch_nmi_watchdog();
        }
        printk("\n");
        show_trace_log_lvl(task, regs, sp, bp, log_lvl);
}

void show_stack(struct task_struct *task, unsigned long *sp)
{
        show_stack_log_lvl(task, NULL, sp, 0, "");
}

/*
 * The architecture-independent dump_stack generator
 */
void dump_stack(void)
{
        unsigned long bp = 0;
        unsigned long stack;

#ifdef CONFIG_FRAME_POINTER
        if (!bp)
                get_bp(bp);
#endif

        printk("Pid: %d, comm: %.20s %s %s %.*s\n",
                current->pid, current->comm, print_tainted(),
                init_utsname()->release,
                (int)strcspn(init_utsname()->version, " "),
                init_utsname()->version);
        show_trace(NULL, NULL, &stack, bp);
}
EXPORT_SYMBOL(dump_stack);

void show_registers(struct pt_regs *regs)
{
        int i;
        unsigned long sp;
        const int cpu = smp_processor_id();
        struct task_struct *cur = cpu_pda(cpu)->pcurrent;

        sp = regs->sp;
        printk("CPU %d ", cpu);
        __show_regs(regs, 1);
        printk("Process %s (pid: %d, threadinfo %p, task %p)\n",
                cur->comm, cur->pid, task_thread_info(cur), cur);

        /*
         * When in-kernel, we also print out the stack and code at the
         * time of the fault..
         */
        if (!user_mode(regs)) {
                unsigned int code_prologue = code_bytes * 43 / 64;
                unsigned int code_len = code_bytes;
                unsigned char c;
                u8 *ip;

                printk(KERN_EMERG "Stack:\n");
                show_stack_log_lvl(NULL, regs, (unsigned long *)sp,
                                regs->bp, KERN_EMERG);

                printk(KERN_EMERG "Code: ");

                ip = (u8 *)regs->ip - code_prologue;
                if (ip < (u8 *)PAGE_OFFSET || probe_kernel_address(ip, c)) {
                        /* try starting at IP */
                        ip = (u8 *)regs->ip;
                        code_len = code_len - code_prologue + 1;
                }
                for (i = 0; i < code_len; i++, ip++) {
                        if (ip < (u8 *)PAGE_OFFSET ||
                                        probe_kernel_address(ip, c)) {
                                printk(" Bad RIP value.");
                                break;
                        }
                        if (ip == (u8 *)regs->ip)
                                printk("<%02x> ", c);
                        else
                                printk("%02x ", c);
                }
        }
        printk("\n");
}

int is_valid_bugaddr(unsigned long ip)
{
        unsigned short ud2;

        if (__copy_from_user(&ud2, (const void __user *) ip, sizeof(ud2)))
                return 0;

        return ud2 == 0x0b0f;
}

static raw_spinlock_t die_lock = __RAW_SPIN_LOCK_UNLOCKED;
static int die_owner = -1;
static unsigned int die_nest_count;

unsigned __kprobes 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 (!__raw_spin_trylock(&die_lock)) {
                if (cpu == die_owner)
                        /* nested oops. should stop eventually */;
                else
                        __raw_spin_lock(&die_lock);
        }
        die_nest_count++;
        die_owner = cpu;
        console_verbose();
        bust_spinlocks(1);
        return flags;
}

void __kprobes oops_end(unsigned long flags, struct pt_regs *regs, int signr)
{
        die_owner = -1;
        bust_spinlocks(0);
        die_nest_count--;
        if (!die_nest_count)
                /* Nest count reaches zero, release the lock. */
                __raw_spin_unlock(&die_lock);
        raw_local_irq_restore(flags);
        if (!regs) {
                oops_exit();
                return;
        }
        if (in_interrupt())
                panic("Fatal exception in interrupt");
        if (panic_on_oops)
                panic("Fatal exception");
        oops_exit();
        do_exit(signr);
}

int __kprobes __die(const char *str, struct pt_regs *regs, long err)
{
        printk(KERN_EMERG "%s: %04lx [#%d] ", str, err & 0xffff, ++die_counter);
#ifdef CONFIG_PREEMPT
        printk("PREEMPT ");
#endif
#ifdef CONFIG_SMP
        printk("SMP ");
#endif
#ifdef CONFIG_DEBUG_PAGEALLOC
        printk("DEBUG_PAGEALLOC");
#endif
        printk("\n");
        sysfs_printk_last_file();
        if (notify_die(DIE_OOPS, str, regs, err,
                        current->thread.trap_no, SIGSEGV) == NOTIFY_STOP)
                return 1;

        show_registers(regs);
        add_taint(TAINT_DIE);
        /* Executive summary in case the oops scrolled away */
        printk(KERN_ALERT "RIP ");
        printk_address(regs->ip, 1);
        printk(" RSP <%016lx>\n", regs->sp);
        if (kexec_should_crash(current))
                crash_kexec(regs);
        return 0;
}

void die(const char *str, struct pt_regs *regs, long err)
{
        unsigned long flags = oops_begin();

        if (!user_mode(regs))
                report_bug(regs->ip, regs);

        if (__die(str, regs, err))
                regs = NULL;
        oops_end(flags, regs, SIGSEGV);
}

notrace __kprobes void
die_nmi(char *str, struct pt_regs *regs, int do_panic)
{
        unsigned long flags;

        if (notify_die(DIE_NMIWATCHDOG, str, regs, 0, 2, SIGINT) == NOTIFY_STOP)
                return;

        flags = oops_begin();
        /*
         * We are in trouble anyway, lets at least try
         * to get a message out.
         */
        printk(KERN_EMERG "%s", str);
        printk(" on CPU%d, ip %08lx, registers:\n",
                smp_processor_id(), regs->ip);
        show_registers(regs);
        if (kexec_should_crash(current))
                crash_kexec(regs);
        if (do_panic || panic_on_oops)
                panic("Non maskable interrupt");
        oops_end(flags, NULL, SIGBUS);
        nmi_exit();
        local_irq_enable();
        do_exit(SIGBUS);
}

static int __init oops_setup(char *s)
{
        if (!s)
                return -EINVAL;
        if (!strcmp(s, "panic"))
                panic_on_oops = 1;
        return 0;
}
early_param("oops", oops_setup);

static int __init kstack_setup(char *s)
{
        if (!s)
                return -EINVAL;
        kstack_depth_to_print = simple_strtoul(s, NULL, 0);
        return 0;
}
early_param("kstack", kstack_setup);

static int __init code_bytes_setup(char *s)
{
        code_bytes = simple_strtoul(s, NULL, 0);
        if (code_bytes > 8192)
                code_bytes = 8192;

        return 1;
}
__setup("code_bytes=", code_bytes_setup);