lib/dump_stack.c

   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/buildid.h>
   9 #include <linux/export.h>
  10 #include <linux/sched.h>
  11 #include <linux/sched/debug.h>
  12 #include <linux/smp.h>
  13 #include <linux/atomic.h>
  14 #include <linux/kexec.h>
  15 #include <linux/utsname.h>
  16 #include <linux/stop_machine.h>
  17
  18 static char dump_stack_arch_desc_str[128];
  19
  20 /**
  21  * dump_stack_set_arch_desc - set arch-specific str to show with task dumps
  22  * @fmt: printf-style format string
  23  * @...: arguments for the format string
  24  *
  25  * The configured string will be printed right after utsname during task
  26  * dumps.  Usually used to add arch-specific system identifiers.  If an
  27  * arch wants to make use of such an ID string, it should initialize this
  28  * as soon as possible during boot.
  29  */
  30 void __init dump_stack_set_arch_desc(const char *fmt, ...)
  31 {
  32         va_list args;
  33
  34         va_start(args, fmt);
  35         vsnprintf(dump_stack_arch_desc_str, sizeof(dump_stack_arch_desc_str),
  36                   fmt, args);
  37         va_end(args);
  38 }
  39
  40 #if IS_ENABLED(CONFIG_STACKTRACE_BUILD_ID)
  41 #define BUILD_ID_FMT " %20phN"
  42 #define BUILD_ID_VAL vmlinux_build_id
  43 #else
  44 #define BUILD_ID_FMT "%s"
  45 #define BUILD_ID_VAL ""
  46 #endif
  47
  48 /**
  49  * dump_stack_print_info - print generic debug info for dump_stack()
  50  * @log_lvl: log level
  51  *
  52  * Arch-specific dump_stack() implementations can use this function to
  53  * print out the same debug information as the generic dump_stack().
  54  */
  55 void dump_stack_print_info(const char *log_lvl)
  56 {
  57         printk("%sCPU: %d UID: %u PID: %d Comm: %.20s %s%s %s %.*s" BUILD_ID_FMT "\n",
  58                log_lvl, raw_smp_processor_id(),
  59                __kuid_val(current_real_cred()->euid),
  60                current->pid, current->comm,
  61                kexec_crash_loaded() ? "Kdump: loaded " : "",
  62                print_tainted(),
  63                init_utsname()->release,
  64                (int)strcspn(init_utsname()->version, " "),
  65                init_utsname()->version, BUILD_ID_VAL);
  66
  67         if (get_taint())
  68                 printk("%s%s\n", log_lvl, print_tainted_verbose());
  69
  70         if (dump_stack_arch_desc_str[0] != '\0')
  71                 printk("%sHardware name: %s\n",
  72                        log_lvl, dump_stack_arch_desc_str);
  73
  74         print_worker_info(log_lvl, current);
  75         print_stop_info(log_lvl, current);
  76         print_scx_info(log_lvl, current);
  77 }
  78
  79 /**
  80  * show_regs_print_info - print generic debug info for show_regs()
  81  * @log_lvl: log level
  82  *
  83  * show_regs() implementations can use this function to print out generic
  84  * debug information.
  85  */
  86 void show_regs_print_info(const char *log_lvl)
  87 {
  88         dump_stack_print_info(log_lvl);
  89 }
  90
  91 static void __dump_stack(const char *log_lvl)
  92 {
  93         dump_stack_print_info(log_lvl);
  94         show_stack(NULL, NULL, log_lvl);
  95 }
  96
  97 /**
  98  * dump_stack_lvl - dump the current task information and its stack trace
  99  * @log_lvl: log level
 100  *
 101  * Architectures can override this implementation by implementing its own.
 102  */
 103 asmlinkage __visible void dump_stack_lvl(const char *log_lvl)
 104 {
 105         bool in_panic = this_cpu_in_panic();
 106         unsigned long flags;
 107
 108         /*
 109          * Permit this cpu to perform nested stack dumps while serialising
 110          * against other CPUs, unless this CPU is in panic.
 111          *
 112          * When in panic, non-panic CPUs are not permitted to store new
 113          * printk messages so there is no need to synchronize the output.
 114          * This avoids potential deadlock in panic() if another CPU is
 115          * holding and unable to release the printk_cpu_sync.
 116          */
 117         if (!in_panic)
 118                 printk_cpu_sync_get_irqsave(flags);
 119
 120         __dump_stack(log_lvl);
 121
 122         if (!in_panic)
 123                 printk_cpu_sync_put_irqrestore(flags);
 124 }
 125 EXPORT_SYMBOL(dump_stack_lvl);
 126
 127 asmlinkage __visible void dump_stack(void)
 128 {
 129         dump_stack_lvl(KERN_DEFAULT);
 130 }
 131 EXPORT_SYMBOL(dump_stack);