1 files changed, 114 insertions, 41 deletions

diff --git a/kernel/panic.c b/kernel/panic.c
index 2807639aab51..d8635d5cecb2 100644
--- a/kernel/panic.c
+++ b/kernel/panic.c
@@ -35,6 +35,7 @@
 #include <linux/debugfs.h>
 #include <linux/sysfs.h>
 #include <linux/context_tracking.h>
+#include <linux/seq_buf.h>
 #include <trace/events/error_report.h>
 #include <asm/sections.h>
 
@@ -63,6 +64,8 @@ unsigned long panic_on_taint;
 bool panic_on_taint_nousertaint = false;
 static unsigned int warn_limit __read_mostly;
 
+bool panic_triggering_all_cpu_backtrace;
+
 int panic_timeout = CONFIG_PANIC_TIMEOUT;
 EXPORT_SYMBOL_GPL(panic_timeout);
 
@@ -73,6 +76,7 @@ EXPORT_SYMBOL_GPL(panic_timeout);
 #define PANIC_PRINT_FTRACE_INFO		0x00000010
 #define PANIC_PRINT_ALL_PRINTK_MSG	0x00000020
 #define PANIC_PRINT_ALL_CPU_BT		0x00000040
+#define PANIC_PRINT_BLOCKED_TASKS	0x00000080
 unsigned long panic_print;
 
 ATOMIC_NOTIFIER_HEAD(panic_notifier_list);
@@ -80,7 +84,7 @@ ATOMIC_NOTIFIER_HEAD(panic_notifier_list);
 EXPORT_SYMBOL(panic_notifier_list);
 
 #ifdef CONFIG_SYSCTL
-static struct ctl_table kern_panic_table[] = {
+static const struct ctl_table kern_panic_table[] = {
 #ifdef CONFIG_SMP
 	{
 		.procname       = "oops_all_cpu_backtrace",
@@ -99,7 +103,6 @@ static struct ctl_table kern_panic_table[] = {
 		.mode           = 0644,
 		.proc_handler   = proc_douintvec,
 	},
-	{ }
 };
 
 static __init int kernel_panic_sysctls_init(void)
@@ -227,6 +230,9 @@ static void panic_print_sys_info(bool console_flush)
 
 	if (panic_print & PANIC_PRINT_FTRACE_INFO)
 		ftrace_dump(DUMP_ALL);
+
+	if (panic_print & PANIC_PRINT_BLOCKED_TASKS)
+		show_state_filter(TASK_UNINTERRUPTIBLE);
 }
 
 void check_panic_on_warn(const char *origin)
@@ -249,8 +255,12 @@ void check_panic_on_warn(const char *origin)
  */
 static void panic_other_cpus_shutdown(bool crash_kexec)
 {
-	if (panic_print & PANIC_PRINT_ALL_CPU_BT)
+	if (panic_print & PANIC_PRINT_ALL_CPU_BT) {
+		/* Temporary allow non-panic CPUs to write their backtraces. */
+		panic_triggering_all_cpu_backtrace = true;
 		trigger_all_cpu_backtrace();
+		panic_triggering_all_cpu_backtrace = false;
+	}
 
 	/*
 	 * Note that smp_send_stop() is the usual SMP shutdown function,
@@ -364,6 +374,8 @@ void panic(const char *fmt, ...)
 
 	panic_other_cpus_shutdown(_crash_kexec_post_notifiers);
 
+	printk_legacy_allow_panic_sync();
+
 	/*
 	 * Run any panic handlers, including those that might need to
 	 * add information to the kmsg dump output.
@@ -372,7 +384,7 @@ void panic(const char *fmt, ...)
 
 	panic_print_sys_info(false);
 
-	kmsg_dump(KMSG_DUMP_PANIC);
+	kmsg_dump_desc(KMSG_DUMP_PANIC, buf);
 
 	/*
 	 * If you doubt kdump always works fine in any situation,
@@ -446,6 +458,15 @@ void panic(const char *fmt, ...)
 
 	/* Do not scroll important messages printed above */
 	suppress_printk = 1;
+
+	/*
+	 * The final messages may not have been printed if in a context that
+	 * defers printing (such as NMI) and irq_work is not available.
+	 * Explicitly flush the kernel log buffer one last time.
+	 */
+	console_flush_on_panic(CONSOLE_FLUSH_PENDING);
+	nbcon_atomic_flush_unsafe();
+
 	local_irq_enable();
 	for (i = 0; ; i += PANIC_TIMER_STEP) {
 		touch_softlockup_watchdog();
@@ -459,32 +480,83 @@ void panic(const char *fmt, ...)
 
 EXPORT_SYMBOL(panic);
 
+#define TAINT_FLAG(taint, _c_true, _c_false, _module)			\
+	[ TAINT_##taint ] = {						\
+		.c_true = _c_true, .c_false = _c_false,			\
+		.module = _module,					\
+		.desc = #taint,						\
+	}
+
 /*
  * TAINT_FORCED_RMMOD could be a per-module flag but the module
  * is being removed anyway.
  */
 const struct taint_flag taint_flags[TAINT_FLAGS_COUNT] = {
-	[ TAINT_PROPRIETARY_MODULE ]	= { 'P', 'G', true },
-	[ TAINT_FORCED_MODULE ]		= { 'F', ' ', true },
-	[ TAINT_CPU_OUT_OF_SPEC ]	= { 'S', ' ', false },
-	[ TAINT_FORCED_RMMOD ]		= { 'R', ' ', false },
-	[ TAINT_MACHINE_CHECK ]		= { 'M', ' ', false },
-	[ TAINT_BAD_PAGE ]		= { 'B', ' ', false },
-	[ TAINT_USER ]			= { 'U', ' ', false },
-	[ TAINT_DIE ]			= { 'D', ' ', false },
-	[ TAINT_OVERRIDDEN_ACPI_TABLE ]	= { 'A', ' ', false },
-	[ TAINT_WARN ]			= { 'W', ' ', false },
-	[ TAINT_CRAP ]			= { 'C', ' ', true },
-	[ TAINT_FIRMWARE_WORKAROUND ]	= { 'I', ' ', false },
-	[ TAINT_OOT_MODULE ]		= { 'O', ' ', true },
-	[ TAINT_UNSIGNED_MODULE ]	= { 'E', ' ', true },
-	[ TAINT_SOFTLOCKUP ]		= { 'L', ' ', false },
-	[ TAINT_LIVEPATCH ]		= { 'K', ' ', true },
-	[ TAINT_AUX ]			= { 'X', ' ', true },
-	[ TAINT_RANDSTRUCT ]		= { 'T', ' ', true },
-	[ TAINT_TEST ]			= { 'N', ' ', true },
+	TAINT_FLAG(PROPRIETARY_MODULE,		'P', 'G', true),
+	TAINT_FLAG(FORCED_MODULE,		'F', ' ', true),
+	TAINT_FLAG(CPU_OUT_OF_SPEC,		'S', ' ', false),
+	TAINT_FLAG(FORCED_RMMOD,		'R', ' ', false),
+	TAINT_FLAG(MACHINE_CHECK,		'M', ' ', false),
+	TAINT_FLAG(BAD_PAGE,			'B', ' ', false),
+	TAINT_FLAG(USER,			'U', ' ', false),
+	TAINT_FLAG(DIE,				'D', ' ', false),
+	TAINT_FLAG(OVERRIDDEN_ACPI_TABLE,	'A', ' ', false),
+	TAINT_FLAG(WARN,			'W', ' ', false),
+	TAINT_FLAG(CRAP,			'C', ' ', true),
+	TAINT_FLAG(FIRMWARE_WORKAROUND,		'I', ' ', false),
+	TAINT_FLAG(OOT_MODULE,			'O', ' ', true),
+	TAINT_FLAG(UNSIGNED_MODULE,		'E', ' ', true),
+	TAINT_FLAG(SOFTLOCKUP,			'L', ' ', false),
+	TAINT_FLAG(LIVEPATCH,			'K', ' ', true),
+	TAINT_FLAG(AUX,				'X', ' ', true),
+	TAINT_FLAG(RANDSTRUCT,			'T', ' ', true),
+	TAINT_FLAG(TEST,			'N', ' ', true),
 };
 
+#undef TAINT_FLAG
+
+static void print_tainted_seq(struct seq_buf *s, bool verbose)
+{
+	const char *sep = "";
+	int i;
+
+	if (!tainted_mask) {
+		seq_buf_puts(s, "Not tainted");
+		return;
+	}
+
+	seq_buf_printf(s, "Tainted: ");
+	for (i = 0; i < TAINT_FLAGS_COUNT; i++) {
+		const struct taint_flag *t = &taint_flags[i];
+		bool is_set = test_bit(i, &tainted_mask);
+		char c = is_set ? t->c_true : t->c_false;
+
+		if (verbose) {
+			if (is_set) {
+				seq_buf_printf(s, "%s[%c]=%s", sep, c, t->desc);
+				sep = ", ";
+			}
+		} else {
+			seq_buf_putc(s, c);
+		}
+	}
+}
+
+static const char *_print_tainted(bool verbose)
+{
+	/* FIXME: what should the size be? */
+	static char buf[sizeof(taint_flags)];
+	struct seq_buf s;
+
+	BUILD_BUG_ON(ARRAY_SIZE(taint_flags) != TAINT_FLAGS_COUNT);
+
+	seq_buf_init(&s, buf, sizeof(buf));
+
+	print_tainted_seq(&s, verbose);
+
+	return seq_buf_str(&s);
+}
+
 /**
  * print_tainted - return a string to represent the kernel taint state.
  *
@@ -495,25 +567,15 @@ const struct taint_flag taint_flags[TAINT_FLAGS_COUNT] = {
  */
 const char *print_tainted(void)
 {
-	static char buf[TAINT_FLAGS_COUNT + sizeof("Tainted: ")];
-
-	BUILD_BUG_ON(ARRAY_SIZE(taint_flags) != TAINT_FLAGS_COUNT);
-
-	if (tainted_mask) {
-		char *s;
-		int i;
-
-		s = buf + sprintf(buf, "Tainted: ");
-		for (i = 0; i < TAINT_FLAGS_COUNT; i++) {
-			const struct taint_flag *t = &taint_flags[i];
-			*s++ = test_bit(i, &tainted_mask) ?
-					t->c_true : t->c_false;
-		}
-		*s = 0;
-	} else
-		snprintf(buf, sizeof(buf), "Not tainted");
+	return _print_tainted(false);
+}
 
-	return buf;
+/**
+ * print_tainted_verbose - A more verbose version of print_tainted()
+ */
+const char *print_tainted_verbose(void)
+{
+	return _print_tainted(true);
 }
 
 int test_taint(unsigned flag)
@@ -623,6 +685,7 @@ bool oops_may_print(void)
  */
 void oops_enter(void)
 {
+	nbcon_cpu_emergency_enter();
 	tracing_off();
 	/* can't trust the integrity of the kernel anymore: */
 	debug_locks_off();
@@ -645,6 +708,7 @@ void oops_exit(void)
 {
 	do_oops_enter_exit();
 	print_oops_end_marker();
+	nbcon_cpu_emergency_exit();
 	kmsg_dump(KMSG_DUMP_OOPS);
 }
 
@@ -656,6 +720,8 @@ struct warn_args {
 void __warn(const char *file, int line, void *caller, unsigned taint,
 	    struct pt_regs *regs, struct warn_args *args)
 {
+	nbcon_cpu_emergency_enter();
+
 	disable_trace_on_warning();
 
 	if (file)
@@ -666,8 +732,13 @@ void __warn(const char *file, int line, void *caller, unsigned taint,
 		pr_warn("WARNING: CPU: %d PID: %d at %pS\n",
 			raw_smp_processor_id(), current->pid, caller);
 
+#pragma GCC diagnostic push
+#ifndef __clang__
+#pragma GCC diagnostic ignored "-Wsuggest-attribute=format"
+#endif
 	if (args)
 		vprintk(args->fmt, args->args);
+#pragma GCC diagnostic pop
 
 	print_modules();
 
@@ -686,6 +757,8 @@ void __warn(const char *file, int line, void *caller, unsigned taint,
 
 	/* Just a warning, don't kill lockdep. */
 	add_taint(taint, LOCKDEP_STILL_OK);
+
+	nbcon_cpu_emergency_exit();
 }
 
 #ifdef CONFIG_BUG