// SPDX-License-Identifier: GPL-2.0 /* * Provide a default dump_stack() function for architectures * which don't implement their own. */ #include <linux/kernel.h> #include <linux/export.h> #include <linux/sched.h> #include <linux/sched/debug.h> #include <linux/smp.h> #include <linux/atomic.h> #include <linux/kexec.h> #include <linux/utsname.h> static char dump_stack_arch_desc_str[128]; /** * dump_stack_set_arch_desc - set arch-specific str to show with task dumps * @fmt: printf-style format string * @...: arguments for the format string * * The configured string will be printed right after utsname during task * dumps. Usually used to add arch-specific system identifiers. If an * arch wants to make use of such an ID string, it should initialize this * as soon as possible during boot. */ void __init dump_stack_set_arch_desc(const char *fmt, ...) { va_list args; va_start(args, fmt); vsnprintf(dump_stack_arch_desc_str, sizeof(dump_stack_arch_desc_str), fmt, args); va_end(args); } /** * dump_stack_print_info - print generic debug info for dump_stack() * @log_lvl: log level * * Arch-specific dump_stack() implementations can use this function to * print out the same debug information as the generic dump_stack(). */ void dump_stack_print_info(const char *log_lvl) { printk("%sCPU: %d PID: %d Comm: %.20s %s%s %s %.*s\n", log_lvl, raw_smp_processor_id(), current->pid, current->comm, kexec_crash_loaded() ? "Kdump: loaded " : "", print_tainted(), init_utsname()->release, (int)strcspn(init_utsname()->version, " "), init_utsname()->version); if (dump_stack_arch_desc_str[0] != '\0') printk("%sHardware name: %s\n", log_lvl, dump_stack_arch_desc_str); print_worker_info(log_lvl, current); } /** * show_regs_print_info - print generic debug info for show_regs() * @log_lvl: log level * * show_regs() implementations can use this function to print out generic * debug information. */ void show_regs_print_info(const char *log_lvl) { dump_stack_print_info(log_lvl); } static void __dump_stack(void) { dump_stack_print_info(KERN_DEFAULT); show_stack(NULL, NULL); } /** * dump_stack - dump the current task information and its stack trace * * Architectures can override this implementation by implementing its own. */ #ifdef CONFIG_SMP static atomic_t dump_lock = ATOMIC_INIT(-1); asmlinkage __visible void dump_stack(void) { unsigned long flags; int was_locked; int old; int cpu; /* * Permit this cpu to perform nested stack dumps while serialising * against other CPUs */ retry: local_irq_save(flags); cpu = smp_processor_id(); old = atomic_cmpxchg(&dump_lock, -1, cpu); if (old == -1) { was_locked = 0; } else if (old == cpu) { was_locked = 1; } else { local_irq_restore(flags); /* * Wait for the lock to release before jumping to * atomic_cmpxchg() in order to mitigate the thundering herd * problem. */ do { cpu_relax(); } while (atomic_read(&dump_lock) != -1); goto retry; } __dump_stack(); if (!was_locked) atomic_set(&dump_lock, -1); local_irq_restore(flags); } #else asmlinkage __visible void dump_stack(void) { __dump_stack(); } #endif EXPORT_SYMBOL(dump_stack);