Merge branch 'objtool/core'

Bring in the UDB and objtool data annotations to avoid conflicts while further extending the bug exceptions.

Signed-off-by: Peter Zijlstra <peterz@infradead.org>

1 files changed, 131 insertions, 61 deletions

diff --git a/kernel/panic.c b/kernel/panic.c
index 830112e4ad63..b2f2470af7e5 100644
--- a/kernel/panic.c
+++ b/kernel/panic.c
@@ -36,6 +36,7 @@
 #include <linux/sysfs.h>
 #include <linux/context_tracking.h>
 #include <linux/seq_buf.h>
+#include <linux/sys_info.h>
 #include <trace/events/error_report.h>
 #include <asm/sections.h>
 
@@ -52,7 +53,7 @@ static unsigned int __read_mostly sysctl_oops_all_cpu_backtrace;
 #define sysctl_oops_all_cpu_backtrace 0
 #endif /* CONFIG_SMP */
 
-int panic_on_oops = CONFIG_PANIC_ON_OOPS_VALUE;
+int panic_on_oops = IS_ENABLED(CONFIG_PANIC_ON_OOPS);
 static unsigned long tainted_mask =
 	IS_ENABLED(CONFIG_RANDSTRUCT) ? (1 << TAINT_RANDSTRUCT) : 0;
 static int pause_on_oops;
@@ -63,26 +64,25 @@ int panic_on_warn __read_mostly;
 unsigned long panic_on_taint;
 bool panic_on_taint_nousertaint = false;
 static unsigned int warn_limit __read_mostly;
+static bool panic_console_replay;
 
 bool panic_triggering_all_cpu_backtrace;
+static bool panic_this_cpu_backtrace_printed;
 
 int panic_timeout = CONFIG_PANIC_TIMEOUT;
 EXPORT_SYMBOL_GPL(panic_timeout);
 
-#define PANIC_PRINT_TASK_INFO		0x00000001
-#define PANIC_PRINT_MEM_INFO		0x00000002
-#define PANIC_PRINT_TIMER_INFO		0x00000004
-#define PANIC_PRINT_LOCK_INFO		0x00000008
-#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);
 
 EXPORT_SYMBOL(panic_notifier_list);
 
+static void panic_print_deprecated(void)
+{
+	pr_info_once("Kernel: The 'panic_print' parameter is now deprecated. Please use 'panic_sys_info' and 'panic_console_replay' instead.\n");
+}
+
 #ifdef CONFIG_SYSCTL
 
 /*
@@ -128,6 +128,13 @@ static int proc_taint(const struct ctl_table *table, int write,
 	return err;
 }
 
+static int sysctl_panic_print_handler(const struct ctl_table *table, int write,
+			   void *buffer, size_t *lenp, loff_t *ppos)
+{
+	panic_print_deprecated();
+	return proc_doulongvec_minmax(table, write, buffer, lenp, ppos);
+}
+
 static const struct ctl_table kern_panic_table[] = {
 #ifdef CONFIG_SMP
 	{
@@ -165,7 +172,7 @@ static const struct ctl_table kern_panic_table[] = {
 		.data		= &panic_print,
 		.maxlen		= sizeof(unsigned long),
 		.mode		= 0644,
-		.proc_handler	= proc_doulongvec_minmax,
+		.proc_handler	= sysctl_panic_print_handler,
 	},
 	{
 		.procname	= "panic_on_warn",
@@ -193,6 +200,13 @@ static const struct ctl_table kern_panic_table[] = {
 		.proc_handler	= proc_dointvec,
 	},
 #endif
+	{
+		.procname	= "panic_sys_info",
+		.data		= &panic_print,
+		.maxlen         = sizeof(panic_print),
+		.mode		= 0644,
+		.proc_handler	= sysctl_sys_info_handler,
+	},
 };
 
 static __init int kernel_panic_sysctls_init(void)
@@ -203,6 +217,15 @@ static __init int kernel_panic_sysctls_init(void)
 late_initcall(kernel_panic_sysctls_init);
 #endif
 
+/* The format is "panic_sys_info=tasks,mem,locks,ftrace,..." */
+static int __init setup_panic_sys_info(char *buf)
+{
+	/* There is no risk of race in kernel boot phase */
+	panic_print = sys_info_parse_param(buf);
+	return 1;
+}
+__setup("panic_sys_info=", setup_panic_sys_info);
+
 static atomic_t warn_count = ATOMIC_INIT(0);
 
 #ifdef CONFIG_SYSFS
@@ -277,53 +300,73 @@ void __weak crash_smp_send_stop(void)
 
 atomic_t panic_cpu = ATOMIC_INIT(PANIC_CPU_INVALID);
 
-/*
- * A variant of panic() called from NMI context. We return if we've already
- * panicked on this CPU. If another CPU already panicked, loop in
- * nmi_panic_self_stop() which can provide architecture dependent code such
- * as saving register state for crash dump.
- */
-void nmi_panic(struct pt_regs *regs, const char *msg)
+bool panic_try_start(void)
 {
 	int old_cpu, this_cpu;
 
+	/*
+	 * Only one CPU is allowed to execute the crash_kexec() code as with
+	 * panic().  Otherwise parallel calls of panic() and crash_kexec()
+	 * may stop each other.  To exclude them, we use panic_cpu here too.
+	 */
 	old_cpu = PANIC_CPU_INVALID;
 	this_cpu = raw_smp_processor_id();
 
-	/* atomic_try_cmpxchg updates old_cpu on failure */
-	if (atomic_try_cmpxchg(&panic_cpu, &old_cpu, this_cpu))
-		panic("%s", msg);
-	else if (old_cpu != this_cpu)
-		nmi_panic_self_stop(regs);
+	return atomic_try_cmpxchg(&panic_cpu, &old_cpu, this_cpu);
 }
-EXPORT_SYMBOL(nmi_panic);
+EXPORT_SYMBOL(panic_try_start);
 
-static void panic_print_sys_info(bool console_flush)
+void panic_reset(void)
 {
-	if (console_flush) {
-		if (panic_print & PANIC_PRINT_ALL_PRINTK_MSG)
-			console_flush_on_panic(CONSOLE_REPLAY_ALL);
-		return;
-	}
-
-	if (panic_print & PANIC_PRINT_TASK_INFO)
-		show_state();
-
-	if (panic_print & PANIC_PRINT_MEM_INFO)
-		show_mem();
+	atomic_set(&panic_cpu, PANIC_CPU_INVALID);
+}
+EXPORT_SYMBOL(panic_reset);
 
-	if (panic_print & PANIC_PRINT_TIMER_INFO)
-		sysrq_timer_list_show();
+bool panic_in_progress(void)
+{
+	return unlikely(atomic_read(&panic_cpu) != PANIC_CPU_INVALID);
+}
+EXPORT_SYMBOL(panic_in_progress);
 
-	if (panic_print & PANIC_PRINT_LOCK_INFO)
-		debug_show_all_locks();
+/* Return true if a panic is in progress on the current CPU. */
+bool panic_on_this_cpu(void)
+{
+	/*
+	 * We can use raw_smp_processor_id() here because it is impossible for
+	 * the task to be migrated to the panic_cpu, or away from it. If
+	 * panic_cpu has already been set, and we're not currently executing on
+	 * that CPU, then we never will be.
+	 */
+	return unlikely(atomic_read(&panic_cpu) == raw_smp_processor_id());
+}
+EXPORT_SYMBOL(panic_on_this_cpu);
 
-	if (panic_print & PANIC_PRINT_FTRACE_INFO)
-		ftrace_dump(DUMP_ALL);
+/*
+ * Return true if a panic is in progress on a remote CPU.
+ *
+ * On true, the local CPU should immediately release any printing resources
+ * that may be needed by the panic CPU.
+ */
+bool panic_on_other_cpu(void)
+{
+	return (panic_in_progress() && !panic_on_this_cpu());
+}
+EXPORT_SYMBOL(panic_on_other_cpu);
 
-	if (panic_print & PANIC_PRINT_BLOCKED_TASKS)
-		show_state_filter(TASK_UNINTERRUPTIBLE);
+/*
+ * A variant of panic() called from NMI context. We return if we've already
+ * panicked on this CPU. If another CPU already panicked, loop in
+ * nmi_panic_self_stop() which can provide architecture dependent code such
+ * as saving register state for crash dump.
+ */
+void nmi_panic(struct pt_regs *regs, const char *msg)
+{
+	if (panic_try_start())
+		panic("%s", msg);
+	else if (panic_on_other_cpu())
+		nmi_panic_self_stop(regs);
 }
+EXPORT_SYMBOL(nmi_panic);
 
 void check_panic_on_warn(const char *origin)
 {
@@ -338,6 +381,19 @@ void check_panic_on_warn(const char *origin)
 		      origin, limit);
 }
 
+static void panic_trigger_all_cpu_backtrace(void)
+{
+	/* Temporary allow non-panic CPUs to write their backtraces. */
+	panic_triggering_all_cpu_backtrace = true;
+
+	if (panic_this_cpu_backtrace_printed)
+		trigger_allbutcpu_cpu_backtrace(raw_smp_processor_id());
+	else
+		trigger_all_cpu_backtrace();
+
+	panic_triggering_all_cpu_backtrace = false;
+}
+
 /*
  * Helper that triggers the NMI backtrace (if set in panic_print)
  * and then performs the secondary CPUs shutdown - we cannot have
@@ -345,12 +401,8 @@ 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) {
-		/* 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;
-	}
+	if (panic_print & SYS_INFO_ALL_CPU_BT)
+		panic_trigger_all_cpu_backtrace();
 
 	/*
 	 * Note that smp_send_stop() is the usual SMP shutdown function,
@@ -378,7 +430,6 @@ void vpanic(const char *fmt, va_list args)
 	static char buf[1024];
 	long i, i_next = 0, len;
 	int state = 0;
-	int old_cpu, this_cpu;
 	bool _crash_kexec_post_notifiers = crash_kexec_post_notifiers;
 
 	if (panic_on_warn) {
@@ -415,13 +466,10 @@ void vpanic(const char *fmt, va_list args)
 	 * `old_cpu == this_cpu' means we came from nmi_panic() which sets
 	 * panic_cpu to this CPU.  In this case, this is also the 1st CPU.
 	 */
-	old_cpu = PANIC_CPU_INVALID;
-	this_cpu = raw_smp_processor_id();
-
 	/* atomic_try_cmpxchg updates old_cpu on failure */
-	if (atomic_try_cmpxchg(&panic_cpu, &old_cpu, this_cpu)) {
+	if (panic_try_start()) {
 		/* go ahead */
-	} else if (old_cpu != this_cpu)
+	} else if (panic_on_other_cpu())
 		panic_smp_self_stop();
 
 	console_verbose();
@@ -432,13 +480,15 @@ void vpanic(const char *fmt, va_list args)
 		buf[len - 1] = '\0';
 
 	pr_emerg("Kernel panic - not syncing: %s\n", buf);
-#ifdef CONFIG_DEBUG_BUGVERBOSE
 	/*
 	 * Avoid nested stack-dumping if a panic occurs during oops processing
 	 */
-	if (!test_taint(TAINT_DIE) && oops_in_progress <= 1)
+	if (test_taint(TAINT_DIE) || oops_in_progress > 1) {
+		panic_this_cpu_backtrace_printed = true;
+	} else if (IS_ENABLED(CONFIG_DEBUG_BUGVERBOSE)) {
 		dump_stack();
-#endif
+		panic_this_cpu_backtrace_printed = true;
+	}
 
 	/*
 	 * If kgdb is enabled, give it a chance to run before we stop all
@@ -468,7 +518,7 @@ void vpanic(const char *fmt, va_list args)
 	 */
 	atomic_notifier_call_chain(&panic_notifier_list, 0, buf);
 
-	panic_print_sys_info(false);
+	sys_info(panic_print);
 
 	kmsg_dump_desc(KMSG_DUMP_PANIC, buf);
 
@@ -497,7 +547,9 @@ void vpanic(const char *fmt, va_list args)
 	debug_locks_off();
 	console_flush_on_panic(CONSOLE_FLUSH_PENDING);
 
-	panic_print_sys_info(true);
+	if ((panic_print & SYS_INFO_PANIC_CONSOLE_REPLAY) ||
+		panic_console_replay)
+		console_flush_on_panic(CONSOLE_REPLAY_ALL);
 
 	if (!panic_blink)
 		panic_blink = no_blink;
@@ -947,10 +999,28 @@ EXPORT_SYMBOL(__stack_chk_fail);
 #endif
 
 core_param(panic, panic_timeout, int, 0644);
-core_param(panic_print, panic_print, ulong, 0644);
 core_param(pause_on_oops, pause_on_oops, int, 0644);
 core_param(panic_on_warn, panic_on_warn, int, 0644);
 core_param(crash_kexec_post_notifiers, crash_kexec_post_notifiers, bool, 0644);
+core_param(panic_console_replay, panic_console_replay, bool, 0644);
+
+static int panic_print_set(const char *val, const struct kernel_param *kp)
+{
+	panic_print_deprecated();
+	return  param_set_ulong(val, kp);
+}
+
+static int panic_print_get(char *val, const struct kernel_param *kp)
+{
+	panic_print_deprecated();
+	return  param_get_ulong(val, kp);
+}
+
+static const struct kernel_param_ops panic_print_ops = {
+	.set	= panic_print_set,
+	.get	= panic_print_get,
+};
+__core_param_cb(panic_print, &panic_print_ops, &panic_print, 0644);
 
 static int __init oops_setup(char *s)
 {