/*
 *  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/hardirq.h>
#include <linux/kdebug.h>
#include <linux/module.h>
#include <linux/ptrace.h>
#include <linux/kexec.h>
#include <linux/sysfs.h>
#include <linux/bug.h>
#include <linux/nmi.h>

#include <asm/stacktrace.h>


#define N_EXCEPTION_STACKS_END \
                (N_EXCEPTION_STACKS + DEBUG_STKSZ/EXCEPTION_STKSZ - 2)

static char x86_stack_ids[][8] = {
                [ DEBUG_STACK-1                 ]       = "#DB",
                [ NMI_STACK-1                   ]       = "NMI",
                [ DOUBLEFAULT_STACK-1           ]       = "#DF",
                [ MCE_STACK-1                   ]       = "#MC",
#if DEBUG_STKSZ > EXCEPTION_STKSZ
                [ N_EXCEPTION_STACKS ...
                  N_EXCEPTION_STACKS_END        ]       = "#DB[?]"
#endif
};

static unsigned long *in_exception_stack(unsigned cpu, unsigned long stack,
                                         unsigned *usedp, char **idp)
{
        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 = x86_stack_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;
                                x86_stack_ids[j][4] = '1' +
                                                (j - N_EXCEPTION_STACKS);
                        } while (stack < end - EXCEPTION_STKSZ);
                        if (*usedp & (1U << j))
                                break;
                        *usedp |= 1U << j;
                        *idp = x86_stack_ids[j];
                        return (unsigned long *)end;
                }
#endif
        }
        return NULL;
}

static inline int
in_irq_stack(unsigned long *stack, unsigned long *irq_stack,
             unsigned long *irq_stack_end)
{
        return (stack >= irq_stack && stack < irq_stack_end);
}

static const unsigned long irq_stack_size =
        (IRQ_STACK_SIZE - 64) / sizeof(unsigned long);

enum stack_type {
        STACK_IS_UNKNOWN,
        STACK_IS_NORMAL,
        STACK_IS_EXCEPTION,
        STACK_IS_IRQ,
};

static enum stack_type
analyze_stack(int cpu, struct task_struct *task, unsigned long *stack,
              unsigned long **stack_end, unsigned long *irq_stack,
              unsigned *used, char **id)
{
        unsigned long addr;

        addr = ((unsigned long)stack & (~(THREAD_SIZE - 1)));
        if ((unsigned long)task_stack_page(task) == addr)
                return STACK_IS_NORMAL;

        *stack_end = in_exception_stack(cpu, (unsigned long)stack,
                                        used, id);
        if (*stack_end)
                return STACK_IS_EXCEPTION;

        if (!irq_stack)
                return STACK_IS_NORMAL;

        *stack_end = irq_stack;
        irq_stack = irq_stack - irq_stack_size;

        if (in_irq_stack(stack, irq_stack, *stack_end))
                return STACK_IS_IRQ;

        return STACK_IS_UNKNOWN;
}

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

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();
        struct thread_info *tinfo;
        unsigned long *irq_stack = (unsigned long *)per_cpu(irq_stack_ptr, cpu);
        unsigned long dummy;
        unsigned used = 0;
        int graph = 0;
        int done = 0;

        if (!task)
                task = current;

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

        if (!bp)
                bp = stack_frame(task, regs);
        /*
         * 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);
        while (!done) {
                unsigned long *stack_end;
                enum stack_type stype;
                char *id;

                stype = analyze_stack(cpu, task, stack, &stack_end,
                                      irq_stack, &used, &id);

                /* Default finish unless specified to continue */
                done = 1;

                switch (stype) {

                /* Break out early if we are on the thread stack */
                case STACK_IS_NORMAL:
                        break;

                case STACK_IS_EXCEPTION:

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

                        bp = ops->walk_stack(tinfo, stack, bp, ops,
                                             data, stack_end, &graph);
                        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 *) stack_end[-2];
                        done = 0;
                        break;

                case STACK_IS_IRQ:

                        if (ops->stack(data, "IRQ") < 0)
                                break;
                        bp = ops->walk_stack(tinfo, stack, bp,
                                     ops, data, stack_end, &graph);
                        /*
                         * 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 *) (stack_end[-1]);
                        irq_stack = NULL;
                        ops->stack(data, "EOI");
                        done = 0;
                        break;

                case STACK_IS_UNKNOWN:
                        ops->stack(data, "UNK");
                        break;
                }
        }

        /*
         * This handles the process stack:
         */
        bp = ops->walk_stack(tinfo, stack, bp, ops, data, NULL, &graph);
        put_cpu();
}
EXPORT_SYMBOL(dump_trace);

void
show_stack_log_lvl(struct task_struct *task, struct pt_regs *regs,
                   unsigned long *sp, unsigned long bp, char *log_lvl)
{
        unsigned long *irq_stack_end;
        unsigned long *irq_stack;
        unsigned long *stack;
        int cpu;
        int i;

        preempt_disable();
        cpu = smp_processor_id();

        irq_stack_end   = (unsigned long *)(per_cpu(irq_stack_ptr, cpu));
        irq_stack       = (unsigned long *)(per_cpu(irq_stack_ptr, cpu) - IRQ_STACK_SIZE);

        /*
         * 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 >= irq_stack && stack <= irq_stack_end) {
                        if (stack == irq_stack_end) {
                                stack = (unsigned long *) (irq_stack_end[-1]);
                                pr_cont(" <EOI> ");
                        }
                } else {
                if (kstack_end(stack))
                        break;
                }
                if ((i % STACKSLOTS_PER_LINE) == 0) {
                        if (i != 0)
                                pr_cont("\n");
                        printk("%s %016lx", log_lvl, *stack++);
                } else
                        pr_cont(" %016lx", *stack++);
                touch_nmi_watchdog();
        }
        preempt_enable();

        pr_cont("\n");
        show_trace_log_lvl(task, regs, sp, bp, log_lvl);
}

void show_regs(struct pt_regs *regs)
{
        int i;
        unsigned long sp;

        sp = regs->sp;
        show_regs_print_info(KERN_DEFAULT);
        __show_regs(regs, 1);

        /*
         * 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_DEFAULT "Stack:\n");
                show_stack_log_lvl(NULL, regs, (unsigned long *)sp,
                                   0, KERN_DEFAULT);

                printk(KERN_DEFAULT "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)) {
                                pr_cont(" Bad RIP value.");
                                break;
                        }
                        if (ip == (u8 *)regs->ip)
                                pr_cont("<%02x> ", c);
                        else
                                pr_cont("%02x ", c);
                }
        }
        pr_cont("\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;
}