LXR linux/lib/dump

   1// SPDX-License-Identifier: GPL-2.0
   2/*
   3 * Provide a default dump_stack() function for architectures
   4 * which don't implement their own.
   5 */
   6
   7#include <linux/kernel.h>
   8#include <linux/export.h>
   9#include <linux/sched.h>
  10#include <linux/sched/debug.h>
  11#include <linux/smp.h>
  12#include <linux/atomic.h>
  13#include <linux/kexec.h>
  14#include <linux/utsname.h>
  15
  16static char dump_stack_arch_desc_str[128];
  17
  18/**
  19 * dump_stack_set_arch_desc - set arch-specific str to show with task dumps
  20 * @fmt: printf-style format string
  21 * @...: arguments for the format string
  22 *
  23 * The configured string will be printed right after utsname during task
  24 * dumps.  Usually used to add arch-specific system identifiers.  If an
  25 * arch wants to make use of such an ID string, it should initialize this
  26 * as soon as possible during boot.
  27 */
  28void __init dump_stack_set_arch_desc(const char *fmt, ...)
  29{
  30        va_list args;
  31
  32        va_start(args, fmt);
  33        vsnprintf(dump_stack_arch_desc_str, sizeof(dump_stack_arch_desc_str),
  34                  fmt, args);
  35        va_end(args);
  36}
  37
  38/**
  39 * dump_stack_print_info - print generic debug info for dump_stack()
  40 * @log_lvl: log level
  41 *
  42 * Arch-specific dump_stack() implementations can use this function to
  43 * print out the same debug information as the generic dump_stack().
  44 */
  45void dump_stack_print_info(const char *log_lvl)
  46{
  47        printk("%sCPU: %d PID: %d Comm: %.20s %s%s %s %.*s\n",
  48               log_lvl, raw_smp_processor_id(), current->pid, current->comm,
  49               kexec_crash_loaded() ? "Kdump: loaded " : "",
  50               print_tainted(),
  51               init_utsname()->release,
  52               (int)strcspn(init_utsname()->version, " "),
  53               init_utsname()->version);
  54
  55        if (dump_stack_arch_desc_str[0] != '\0')
  56                printk("%sHardware name: %s\n",
  57                       log_lvl, dump_stack_arch_desc_str);
  58
  59        print_worker_info(log_lvl, current);
  60}
  61
  62/**
  63 * show_regs_print_info - print generic debug info for show_regs()
  64 * @log_lvl: log level
  65 *
  66 * show_regs() implementations can use this function to print out generic
  67 * debug information.
  68 */
  69void show_regs_print_info(const char *log_lvl)
  70{
  71        dump_stack_print_info(log_lvl);
  72}
  73
  74static void __dump_stack(void)
  75{
  76        dump_stack_print_info(KERN_DEFAULT);
  77        show_stack(NULL, NULL);
  78}
  79
  80/**
  81 * dump_stack - dump the current task information and its stack trace
  82 *
  83 * Architectures can override this implementation by implementing its own.
  84 */
  85#ifdef CONFIG_SMP
  86static atomic_t dump_lock = ATOMIC_INIT(-1);
  87
  88asmlinkage __visible void dump_stack(void)
  89{
  90        unsigned long flags;
  91        int was_locked;
  92        int old;
  93        int cpu;
  94
  95        /*
  96         * Permit this cpu to perform nested stack dumps while serialising
  97         * against other CPUs
  98         */
  99retry:
 100        local_irq_save(flags);
 101        cpu = smp_processor_id();
 102        old = atomic_cmpxchg(&dump_lock, -1, cpu);
 103        if (old == -1) {
 104                was_locked = 0;
 105        } else if (old == cpu) {
 106                was_locked = 1;
 107        } else {
 108                local_irq_restore(flags);
 109                cpu_relax();
 110                goto retry;
 111        }
 112
 113        __dump_stack();
 114
 115        if (!was_locked)
 116                atomic_set(&dump_lock, -1);
 117
 118        local_irq_restore(flags);
 119}
 120#else
 121asmlinkage __visible void dump_stack(void)
 122{
 123        __dump_stack();
 124}
 125#endif
 126EXPORT_SYMBOL(dump_stack);
 127