x86_64: split out dumpstack code from traps_64.c

The dumpstack code is logically quite independent from the
hardware traps. Split it out into its own file.

Signed-off-by: Alexander van Heukelum <heukelum@fastmail.fm>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 565 insertions, 0 deletions

diff --git a/arch/x86/kernel/dumpstack_64.c b/arch/x86/kernel/dumpstack_64.c
new file mode 100644
index 000000000000..6f1505074db0
--- /dev/null
+++ b/arch/x86/kernel/dumpstack_64.c
@@ -0,0 +1,565 @@
+/*
+ *  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 <asm/stacktrace.h>
+
+int panic_on_unrecovered_nmi;
+int kstack_depth_to_print = 12;
+static unsigned int code_bytes = 64;
+static int die_counter;
+
+void printk_address(unsigned long address, int reliable)
+{
+        printk(" [<%016lx>] %s%pS\n",
+                        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 + 8) {
+                                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 */
+                        asm("movq %%rbp, %0" : "=r" (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)
+{
+        print_symbol(msg, symbol);
+        printk("\n");
+}
+
+static void print_trace_warning(void *data, char *msg)
+{
+        printk("%s\n", msg);
+}
+
+static int print_trace_stack(void *data, char *name)
+{
+        printk(" <%s> ", name);
+        return 0;
+}
+
+static void print_trace_address(void *data, unsigned long addr, int reliable)
+{
+        touch_nmi_watchdog();
+        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("Call Trace:\n");
+        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 % 4) == 0))
+                        printk("\n");
+                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)
+                asm("movq %%rbp, %0" : "=r" (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("Stack: ");
+                show_stack_log_lvl(NULL, regs, (unsigned long *)sp,
+                                regs->bp, "");
+
+                printk(KERN_EMERG "Code: ");
+
+                ip = (u8 *)regs->ip - code_prologue;
+                if (ip < (u8 *)PAGE_OFFSET || probe_kernel_address(ip, c)) {
+                        /* try starting at RIP */
+                        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 [%u] ", 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");
+        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);