Adding upstream version 4.19.249.upstream/4.19.249

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 493 insertions, 0 deletions

diff --git a/kernel/trace/trace_stack.c b/kernel/trace/trace_stack.c
new file mode 100644
index 000000000..403370940
--- /dev/null
+++ b/kernel/trace/trace_stack.c
@@ -0,0 +1,493 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2008 Steven Rostedt <srostedt@redhat.com>
+ *
+ */
+#include <linux/sched/task_stack.h>
+#include <linux/stacktrace.h>
+#include <linux/kallsyms.h>
+#include <linux/seq_file.h>
+#include <linux/spinlock.h>
+#include <linux/uaccess.h>
+#include <linux/ftrace.h>
+#include <linux/module.h>
+#include <linux/sysctl.h>
+#include <linux/init.h>
+
+#include <asm/setup.h>
+
+#include "trace.h"
+
+static unsigned long stack_dump_trace[STACK_TRACE_ENTRIES+1] =
+	 { [0 ... (STACK_TRACE_ENTRIES)] = ULONG_MAX };
+unsigned stack_trace_index[STACK_TRACE_ENTRIES];
+
+/*
+ * Reserve one entry for the passed in ip. This will allow
+ * us to remove most or all of the stack size overhead
+ * added by the stack tracer itself.
+ */
+struct stack_trace stack_trace_max = {
+	.max_entries		= STACK_TRACE_ENTRIES - 1,
+	.entries		= &stack_dump_trace[0],
+};
+
+unsigned long stack_trace_max_size;
+arch_spinlock_t stack_trace_max_lock =
+	(arch_spinlock_t)__ARCH_SPIN_LOCK_UNLOCKED;
+
+DEFINE_PER_CPU(int, disable_stack_tracer);
+static DEFINE_MUTEX(stack_sysctl_mutex);
+
+int stack_tracer_enabled;
+static int last_stack_tracer_enabled;
+
+void stack_trace_print(void)
+{
+	long i;
+	int size;
+
+	pr_emerg("        Depth    Size   Location    (%d entries)\n"
+			   "        -----    ----   --------\n",
+			   stack_trace_max.nr_entries);
+
+	for (i = 0; i < stack_trace_max.nr_entries; i++) {
+		if (stack_dump_trace[i] == ULONG_MAX)
+			break;
+		if (i+1 == stack_trace_max.nr_entries ||
+				stack_dump_trace[i+1] == ULONG_MAX)
+			size = stack_trace_index[i];
+		else
+			size = stack_trace_index[i] - stack_trace_index[i+1];
+
+		pr_emerg("%3ld) %8d   %5d   %pS\n", i, stack_trace_index[i],
+				size, (void *)stack_dump_trace[i]);
+	}
+}
+
+/*
+ * When arch-specific code overrides this function, the following
+ * data should be filled up, assuming stack_trace_max_lock is held to
+ * prevent concurrent updates.
+ *     stack_trace_index[]
+ *     stack_trace_max
+ *     stack_trace_max_size
+ */
+void __weak
+check_stack(unsigned long ip, unsigned long *stack)
+{
+	unsigned long this_size, flags; unsigned long *p, *top, *start;
+	static int tracer_frame;
+	int frame_size = READ_ONCE(tracer_frame);
+	int i, x;
+
+	this_size = ((unsigned long)stack) & (THREAD_SIZE-1);
+	this_size = THREAD_SIZE - this_size;
+	/* Remove the frame of the tracer */
+	this_size -= frame_size;
+
+	if (this_size <= stack_trace_max_size)
+		return;
+
+	/* we do not handle interrupt stacks yet */
+	if (!object_is_on_stack(stack))
+		return;
+
+	/* Can't do this from NMI context (can cause deadlocks) */
+	if (in_nmi())
+		return;
+
+	local_irq_save(flags);
+	arch_spin_lock(&stack_trace_max_lock);
+
+	/* In case another CPU set the tracer_frame on us */
+	if (unlikely(!frame_size))
+		this_size -= tracer_frame;
+
+	/* a race could have already updated it */
+	if (this_size <= stack_trace_max_size)
+		goto out;
+
+	stack_trace_max_size = this_size;
+
+	stack_trace_max.nr_entries = 0;
+	stack_trace_max.skip = 3;
+
+	save_stack_trace(&stack_trace_max);
+
+	/* Skip over the overhead of the stack tracer itself */
+	for (i = 0; i < stack_trace_max.nr_entries; i++) {
+		if (stack_dump_trace[i] == ip)
+			break;
+	}
+
+	/*
+	 * Some archs may not have the passed in ip in the dump.
+	 * If that happens, we need to show everything.
+	 */
+	if (i == stack_trace_max.nr_entries)
+		i = 0;
+
+	/*
+	 * Now find where in the stack these are.
+	 */
+	x = 0;
+	start = stack;
+	top = (unsigned long *)
+		(((unsigned long)start & ~(THREAD_SIZE-1)) + THREAD_SIZE);
+
+	/*
+	 * Loop through all the entries. One of the entries may
+	 * for some reason be missed on the stack, so we may
+	 * have to account for them. If they are all there, this
+	 * loop will only happen once. This code only takes place
+	 * on a new max, so it is far from a fast path.
+	 */
+	while (i < stack_trace_max.nr_entries) {
+		int found = 0;
+
+		stack_trace_index[x] = this_size;
+		p = start;
+
+		for (; p < top && i < stack_trace_max.nr_entries; p++) {
+			if (stack_dump_trace[i] == ULONG_MAX)
+				break;
+			/*
+			 * The READ_ONCE_NOCHECK is used to let KASAN know that
+			 * this is not a stack-out-of-bounds error.
+			 */
+			if ((READ_ONCE_NOCHECK(*p)) == stack_dump_trace[i]) {
+				stack_dump_trace[x] = stack_dump_trace[i++];
+				this_size = stack_trace_index[x++] =
+					(top - p) * sizeof(unsigned long);
+				found = 1;
+				/* Start the search from here */
+				start = p + 1;
+				/*
+				 * We do not want to show the overhead
+				 * of the stack tracer stack in the
+				 * max stack. If we haven't figured
+				 * out what that is, then figure it out
+				 * now.
+				 */
+				if (unlikely(!tracer_frame)) {
+					tracer_frame = (p - stack) *
+						sizeof(unsigned long);
+					stack_trace_max_size -= tracer_frame;
+				}
+			}
+		}
+
+		if (!found)
+			i++;
+	}
+
+	stack_trace_max.nr_entries = x;
+	for (; x < i; x++)
+		stack_dump_trace[x] = ULONG_MAX;
+
+	if (task_stack_end_corrupted(current)) {
+		stack_trace_print();
+		BUG();
+	}
+
+ out:
+	arch_spin_unlock(&stack_trace_max_lock);
+	local_irq_restore(flags);
+}
+
+/* Some archs may not define MCOUNT_INSN_SIZE */
+#ifndef MCOUNT_INSN_SIZE
+# define MCOUNT_INSN_SIZE 0
+#endif
+
+static void
+stack_trace_call(unsigned long ip, unsigned long parent_ip,
+		 struct ftrace_ops *op, struct pt_regs *pt_regs)
+{
+	unsigned long stack;
+
+	preempt_disable_notrace();
+
+	/* no atomic needed, we only modify this variable by this cpu */
+	__this_cpu_inc(disable_stack_tracer);
+	if (__this_cpu_read(disable_stack_tracer) != 1)
+		goto out;
+
+	/* If rcu is not watching, then save stack trace can fail */
+	if (!rcu_is_watching())
+		goto out;
+
+	ip += MCOUNT_INSN_SIZE;
+
+	check_stack(ip, &stack);
+
+ out:
+	__this_cpu_dec(disable_stack_tracer);
+	/* prevent recursion in schedule */
+	preempt_enable_notrace();
+}
+
+static struct ftrace_ops trace_ops __read_mostly =
+{
+	.func = stack_trace_call,
+	.flags = FTRACE_OPS_FL_RECURSION_SAFE,
+};
+
+static ssize_t
+stack_max_size_read(struct file *filp, char __user *ubuf,
+		    size_t count, loff_t *ppos)
+{
+	unsigned long *ptr = filp->private_data;
+	char buf[64];
+	int r;
+
+	r = snprintf(buf, sizeof(buf), "%ld\n", *ptr);
+	if (r > sizeof(buf))
+		r = sizeof(buf);
+	return simple_read_from_buffer(ubuf, count, ppos, buf, r);
+}
+
+static ssize_t
+stack_max_size_write(struct file *filp, const char __user *ubuf,
+		     size_t count, loff_t *ppos)
+{
+	long *ptr = filp->private_data;
+	unsigned long val, flags;
+	int ret;
+
+	ret = kstrtoul_from_user(ubuf, count, 10, &val);
+	if (ret)
+		return ret;
+
+	local_irq_save(flags);
+
+	/*
+	 * In case we trace inside arch_spin_lock() or after (NMI),
+	 * we will cause circular lock, so we also need to increase
+	 * the percpu disable_stack_tracer here.
+	 */
+	__this_cpu_inc(disable_stack_tracer);
+
+	arch_spin_lock(&stack_trace_max_lock);
+	*ptr = val;
+	arch_spin_unlock(&stack_trace_max_lock);
+
+	__this_cpu_dec(disable_stack_tracer);
+	local_irq_restore(flags);
+
+	return count;
+}
+
+static const struct file_operations stack_max_size_fops = {
+	.open		= tracing_open_generic,
+	.read		= stack_max_size_read,
+	.write		= stack_max_size_write,
+	.llseek		= default_llseek,
+};
+
+static void *
+__next(struct seq_file *m, loff_t *pos)
+{
+	long n = *pos - 1;
+
+	if (n > stack_trace_max.nr_entries || stack_dump_trace[n] == ULONG_MAX)
+		return NULL;
+
+	m->private = (void *)n;
+	return &m->private;
+}
+
+static void *
+t_next(struct seq_file *m, void *v, loff_t *pos)
+{
+	(*pos)++;
+	return __next(m, pos);
+}
+
+static void *t_start(struct seq_file *m, loff_t *pos)
+{
+	local_irq_disable();
+
+	__this_cpu_inc(disable_stack_tracer);
+
+	arch_spin_lock(&stack_trace_max_lock);
+
+	if (*pos == 0)
+		return SEQ_START_TOKEN;
+
+	return __next(m, pos);
+}
+
+static void t_stop(struct seq_file *m, void *p)
+{
+	arch_spin_unlock(&stack_trace_max_lock);
+
+	__this_cpu_dec(disable_stack_tracer);
+
+	local_irq_enable();
+}
+
+static void trace_lookup_stack(struct seq_file *m, long i)
+{
+	unsigned long addr = stack_dump_trace[i];
+
+	seq_printf(m, "%pS\n", (void *)addr);
+}
+
+static void print_disabled(struct seq_file *m)
+{
+	seq_puts(m, "#\n"
+		 "#  Stack tracer disabled\n"
+		 "#\n"
+		 "# To enable the stack tracer, either add 'stacktrace' to the\n"
+		 "# kernel command line\n"
+		 "# or 'echo 1 > /proc/sys/kernel/stack_tracer_enabled'\n"
+		 "#\n");
+}
+
+static int t_show(struct seq_file *m, void *v)
+{
+	long i;
+	int size;
+
+	if (v == SEQ_START_TOKEN) {
+		seq_printf(m, "        Depth    Size   Location"
+			   "    (%d entries)\n"
+			   "        -----    ----   --------\n",
+			   stack_trace_max.nr_entries);
+
+		if (!stack_tracer_enabled && !stack_trace_max_size)
+			print_disabled(m);
+
+		return 0;
+	}
+
+	i = *(long *)v;
+
+	if (i >= stack_trace_max.nr_entries ||
+	    stack_dump_trace[i] == ULONG_MAX)
+		return 0;
+
+	if (i+1 == stack_trace_max.nr_entries ||
+	    stack_dump_trace[i+1] == ULONG_MAX)
+		size = stack_trace_index[i];
+	else
+		size = stack_trace_index[i] - stack_trace_index[i+1];
+
+	seq_printf(m, "%3ld) %8d   %5d   ", i, stack_trace_index[i], size);
+
+	trace_lookup_stack(m, i);
+
+	return 0;
+}
+
+static const struct seq_operations stack_trace_seq_ops = {
+	.start		= t_start,
+	.next		= t_next,
+	.stop		= t_stop,
+	.show		= t_show,
+};
+
+static int stack_trace_open(struct inode *inode, struct file *file)
+{
+	return seq_open(file, &stack_trace_seq_ops);
+}
+
+static const struct file_operations stack_trace_fops = {
+	.open		= stack_trace_open,
+	.read		= seq_read,
+	.llseek		= seq_lseek,
+	.release	= seq_release,
+};
+
+#ifdef CONFIG_DYNAMIC_FTRACE
+
+static int
+stack_trace_filter_open(struct inode *inode, struct file *file)
+{
+	struct ftrace_ops *ops = inode->i_private;
+
+	return ftrace_regex_open(ops, FTRACE_ITER_FILTER,
+				 inode, file);
+}
+
+static const struct file_operations stack_trace_filter_fops = {
+	.open = stack_trace_filter_open,
+	.read = seq_read,
+	.write = ftrace_filter_write,
+	.llseek = tracing_lseek,
+	.release = ftrace_regex_release,
+};
+
+#endif /* CONFIG_DYNAMIC_FTRACE */
+
+int
+stack_trace_sysctl(struct ctl_table *table, int write,
+		   void __user *buffer, size_t *lenp,
+		   loff_t *ppos)
+{
+	int ret;
+
+	mutex_lock(&stack_sysctl_mutex);
+
+	ret = proc_dointvec(table, write, buffer, lenp, ppos);
+
+	if (ret || !write ||
+	    (last_stack_tracer_enabled == !!stack_tracer_enabled))
+		goto out;
+
+	last_stack_tracer_enabled = !!stack_tracer_enabled;
+
+	if (stack_tracer_enabled)
+		register_ftrace_function(&trace_ops);
+	else
+		unregister_ftrace_function(&trace_ops);
+
+ out:
+	mutex_unlock(&stack_sysctl_mutex);
+	return ret;
+}
+
+static char stack_trace_filter_buf[COMMAND_LINE_SIZE+1] __initdata;
+
+static __init int enable_stacktrace(char *str)
+{
+	if (strncmp(str, "_filter=", 8) == 0)
+		strncpy(stack_trace_filter_buf, str+8, COMMAND_LINE_SIZE);
+
+	stack_tracer_enabled = 1;
+	last_stack_tracer_enabled = 1;
+	return 1;
+}
+__setup("stacktrace", enable_stacktrace);
+
+static __init int stack_trace_init(void)
+{
+	struct dentry *d_tracer;
+
+	d_tracer = tracing_init_dentry();
+	if (IS_ERR(d_tracer))
+		return 0;
+
+	trace_create_file("stack_max_size", 0644, d_tracer,
+			&stack_trace_max_size, &stack_max_size_fops);
+
+	trace_create_file("stack_trace", 0444, d_tracer,
+			NULL, &stack_trace_fops);
+
+#ifdef CONFIG_DYNAMIC_FTRACE
+	trace_create_file("stack_trace_filter", 0644, d_tracer,
+			  &trace_ops, &stack_trace_filter_fops);
+#endif
+
+	if (stack_trace_filter_buf[0])
+		ftrace_set_early_filter(&trace_ops, stack_trace_filter_buf, 1);
+
+	if (stack_tracer_enabled)
+		register_ftrace_function(&trace_ops);
+
+	return 0;
+}
+
+device_initcall(stack_trace_init);