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#include <linux/stop_machine.h>
  16
  17static char dump_stack_arch_desc_str[128];
  18
  19/**
  20 * dump_stack_set_arch_desc - set arch-specific str to show with task dumps
  21 * @fmt: printf-style format string
  22 * @...: arguments for the format string
  23 *
  24 * The configured string will be printed right after utsname during task
  25 * dumps.  Usually used to add arch-specific system identifiers.  If an
  26 * arch wants to make use of such an ID string, it should initialize this
  27 * as soon as possible during boot.
  28 */
  29void __init dump_stack_set_arch_desc(const char *fmt, ...)
  30{
  31        va_list args;
  32
  33        va_start(args, fmt);
  34        vsnprintf(dump_stack_arch_desc_str, sizeof(dump_stack_arch_desc_str),
  35                  fmt, args);
  36        va_end(args);
  37}
  38
  39/**
  40 * dump_stack_print_info - print generic debug info for dump_stack()
  41 * @log_lvl: log level
  42 *
  43 * Arch-specific dump_stack() implementations can use this function to
  44 * print out the same debug information as the generic dump_stack().
  45 */
  46void dump_stack_print_info(const char *log_lvl)
  47{
  48        printk("%sCPU: %d PID: %d Comm: %.20s %s%s %s %.*s\n",
  49               log_lvl, raw_smp_processor_id(), current->pid, current->comm,
  50               kexec_crash_loaded() ? "Kdump: loaded " : "",
  51               print_tainted(),
  52               init_utsname()->release,
  53               (int)strcspn(init_utsname()->version, " "),
  54               init_utsname()->version);
  55
  56        if (dump_stack_arch_desc_str[0] != '\0')
  57                printk("%sHardware name: %s\n",
  58                       log_lvl, dump_stack_arch_desc_str);
  59
  60        print_worker_info(log_lvl, current);
  61        print_stop_info(log_lvl, current);
  62}
  63
  64/**
  65 * show_regs_print_info - print generic debug info for show_regs()
  66 * @log_lvl: log level
  67 *
  68 * show_regs() implementations can use this function to print out generic
  69 * debug information.
  70 */
  71void show_regs_print_info(const char *log_lvl)
  72{
  73        dump_stack_print_info(log_lvl);
  74}
  75
  76static void __dump_stack(void)
  77{
  78        dump_stack_print_info(KERN_DEFAULT);
  79        show_stack(NULL, NULL, KERN_DEFAULT);
  80}
  81
  82/**
  83 * dump_stack - dump the current task information and its stack trace
  84 *
  85 * Architectures can override this implementation by implementing its own.
  86 */
  87#ifdef CONFIG_SMP
  88static atomic_t dump_lock = ATOMIC_INIT(-1);
  89
  90asmlinkage __visible void dump_stack(void)
  91{
  92        unsigned long flags;
  93        int was_locked;
  94        int old;
  95        int cpu;
  96
  97        /*
  98         * Permit this cpu to perform nested stack dumps while serialising
  99         * against other CPUs
 100         */
 101retry:
 102        local_irq_save(flags);
 103        cpu = smp_processor_id();
 104        old = atomic_cmpxchg(&dump_lock, -1, cpu);
 105        if (old == -1) {
 106                was_locked = 0;
 107        } else if (old == cpu) {
 108                was_locked = 1;
 109        } else {
 110                local_irq_restore(flags);
 111                /*
 112                 * Wait for the lock to release before jumping to
 113                 * atomic_cmpxchg() in order to mitigate the thundering herd
 114                 * problem.
 115                 */
 116                do { cpu_relax(); } while (atomic_read(&dump_lock) != -1);
 117                goto retry;
 118        }
 119
 120        __dump_stack();
 121
 122        if (!was_locked)
 123                atomic_set(&dump_lock, -1);
 124
 125        local_irq_restore(flags);
 126}
 127#else
 128asmlinkage __visible void dump_stack(void)
 129{
 130        __dump_stack();
 131}
 132#endif
 133EXPORT_SYMBOL(dump_stack);
 134