1 files changed, 104 insertions, 36 deletions

diff --git a/lib/dump_stack.c b/lib/dump_stack.c
index c03154173cc7..f0c78b5b5324 100644
--- a/lib/dump_stack.c
+++ b/lib/dump_stack.c
@@ -1,63 +1,131 @@
+// 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/buildid.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>
+#include <linux/stop_machine.h>
 
-static void __dump_stack(void)
+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, ...)
 {
-	dump_stack_print_info(KERN_DEFAULT);
-	show_stack(NULL, NULL);
+	va_list args;
+
+	va_start(args, fmt);
+	vsnprintf(dump_stack_arch_desc_str, sizeof(dump_stack_arch_desc_str),
+		  fmt, args);
+	va_end(args);
 }
 
+#if IS_ENABLED(CONFIG_STACKTRACE_BUILD_ID)
+#define BUILD_ID_FMT " %20phN"
+#define BUILD_ID_VAL vmlinux_build_id
+#else
+#define BUILD_ID_FMT "%s"
+#define BUILD_ID_VAL ""
+#endif
+
 /**
- * dump_stack - dump the current task information and its stack trace
+ * dump_stack_print_info - print generic debug info for dump_stack()
+ * @log_lvl: log level
  *
- * Architectures can override this implementation by implementing its own.
+ * 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 UID: %u PID: %d Comm: %.20s %s%s %s %.*s %s " BUILD_ID_FMT "\n",
+	       log_lvl, raw_smp_processor_id(),
+	       __kuid_val(current_real_cred()->euid),
+	       current->pid, current->comm,
+	       kexec_crash_loaded() ? "Kdump: loaded " : "",
+	       print_tainted(),
+	       init_utsname()->release,
+	       (int)strcspn(init_utsname()->version, " "),
+	       init_utsname()->version, preempt_model_str(), BUILD_ID_VAL);
+
+	if (get_taint())
+		printk("%s%s\n", log_lvl, print_tainted_verbose());
+
+	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);
+	print_stop_info(log_lvl, current);
+	print_scx_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.
  */
-#ifdef CONFIG_SMP
-static atomic_t dump_lock = ATOMIC_INIT(-1);
+void show_regs_print_info(const char *log_lvl)
+{
+	dump_stack_print_info(log_lvl);
+}
 
-void dump_stack(void)
+static void __dump_stack(const char *log_lvl)
+{
+	dump_stack_print_info(log_lvl);
+	show_stack(NULL, NULL, log_lvl);
+}
+
+/**
+ * dump_stack_lvl - dump the current task information and its stack trace
+ * @log_lvl: log level
+ *
+ * Architectures can override this implementation by implementing its own.
+ */
+asmlinkage __visible void dump_stack_lvl(const char *log_lvl)
 {
-	int was_locked;
-	int old;
-	int cpu;
+	bool in_panic = panic_on_this_cpu();
+	unsigned long flags;
 
 	/*
 	 * Permit this cpu to perform nested stack dumps while serialising
-	 * against other CPUs
+	 * against other CPUs, unless this CPU is in panic.
+	 *
+	 * When in panic, non-panic CPUs are not permitted to store new
+	 * printk messages so there is no need to synchronize the output.
+	 * This avoids potential deadlock in panic() if another CPU is
+	 * holding and unable to release the printk_cpu_sync.
 	 */
-	preempt_disable();
-
-retry:
-	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 {
-		cpu_relax();
-		goto retry;
-	}
-
-	__dump_stack();
-
-	if (!was_locked)
-		atomic_set(&dump_lock, -1);
-
-	preempt_enable();
+	if (!in_panic)
+		printk_cpu_sync_get_irqsave(flags);
+
+	__dump_stack(log_lvl);
+
+	if (!in_panic)
+		printk_cpu_sync_put_irqrestore(flags);
 }
-#else
-void dump_stack(void)
+EXPORT_SYMBOL(dump_stack_lvl);
+
+asmlinkage __visible void dump_stack(void)
 {
-	__dump_stack();
+	dump_stack_lvl(KERN_DEFAULT);
 }
-#endif
 EXPORT_SYMBOL(dump_stack);