/*
 *  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/bug.h>
#include <linux/nmi.h>
#include <linux/sysfs.h>

#include <asm/stacktrace.h>

#include "dumpstack.h"


static char x86_stack_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
        };

int x86_is_stack_id(int id, char *name)
{
        return x86_stack_ids[id - 1] == name;
}

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;
}

/*
 * 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();
        unsigned long *irq_stack_end =
                (unsigned long *)per_cpu(irq_stack_ptr, cpu);
        unsigned used = 0;
        struct thread_info *tinfo;
        int graph = 0;

        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, &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 *) estack_end[-2];
                        continue;
                }
                if (irq_stack_end) {
                        unsigned long *irq_stack;
                        irq_stack = irq_stack_end -
                                (IRQ_STACK_SIZE - 64) / sizeof(*irq_stack);

                        if (stack >= irq_stack && stack < irq_stack_end) {
                                if (ops->stack(data, "IRQ") < 0)
                                        break;
                                bp = print_context_stack(tinfo, stack, bp,
                                        ops, data, irq_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 *) (irq_stack_end[-1]);
                                irq_stack_end = NULL;
                                ops->stack(data, "EOI");
                                continue;
                        }
                }
                break;
        }

        /*
         * This handles the process stack:
         */
        bp = print_context_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 *stack;
        int i;
        const int cpu = smp_processor_id();
        unsigned long *irq_stack_end =
                (unsigned long *)(per_cpu(irq_stack_ptr, cpu));
        unsigned long *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]);
                                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_registers(struct pt_regs *regs)
{
        int i;
        unsigned long sp;
        const int cpu = smp_processor_id();
        struct task_struct *cur = current;

        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;
}