Adding upstream version 6.1.76.upstream/6.1.76

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

1 files changed, 715 insertions, 0 deletions

diff --git a/kernel/kcsan/report.c b/kernel/kcsan/report.c
new file mode 100644
index 000000000..e95ce7d7a
--- /dev/null
+++ b/kernel/kcsan/report.c
@@ -0,0 +1,715 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * KCSAN reporting.
+ *
+ * Copyright (C) 2019, Google LLC.
+ */
+
+#include <linux/debug_locks.h>
+#include <linux/delay.h>
+#include <linux/jiffies.h>
+#include <linux/kallsyms.h>
+#include <linux/kernel.h>
+#include <linux/lockdep.h>
+#include <linux/preempt.h>
+#include <linux/printk.h>
+#include <linux/sched.h>
+#include <linux/spinlock.h>
+#include <linux/stacktrace.h>
+
+#include "kcsan.h"
+#include "encoding.h"
+
+/*
+ * Max. number of stack entries to show in the report.
+ */
+#define NUM_STACK_ENTRIES 64
+
+/* Common access info. */
+struct access_info {
+	const volatile void	*ptr;
+	size_t			size;
+	int			access_type;
+	int			task_pid;
+	int			cpu_id;
+	unsigned long		ip;
+};
+
+/*
+ * Other thread info: communicated from other racing thread to thread that set
+ * up the watchpoint, which then prints the complete report atomically.
+ */
+struct other_info {
+	struct access_info	ai;
+	unsigned long		stack_entries[NUM_STACK_ENTRIES];
+	int			num_stack_entries;
+
+	/*
+	 * Optionally pass @current. Typically we do not need to pass @current
+	 * via @other_info since just @task_pid is sufficient. Passing @current
+	 * has additional overhead.
+	 *
+	 * To safely pass @current, we must either use get_task_struct/
+	 * put_task_struct, or stall the thread that populated @other_info.
+	 *
+	 * We cannot rely on get_task_struct/put_task_struct in case
+	 * release_report() races with a task being released, and would have to
+	 * free it in release_report(). This may result in deadlock if we want
+	 * to use KCSAN on the allocators.
+	 *
+	 * Since we also want to reliably print held locks for
+	 * CONFIG_KCSAN_VERBOSE, the current implementation stalls the thread
+	 * that populated @other_info until it has been consumed.
+	 */
+	struct task_struct	*task;
+};
+
+/*
+ * To never block any producers of struct other_info, we need as many elements
+ * as we have watchpoints (upper bound on concurrent races to report).
+ */
+static struct other_info other_infos[CONFIG_KCSAN_NUM_WATCHPOINTS + NUM_SLOTS-1];
+
+/*
+ * Information about reported races; used to rate limit reporting.
+ */
+struct report_time {
+	/*
+	 * The last time the race was reported.
+	 */
+	unsigned long time;
+
+	/*
+	 * The frames of the 2 threads; if only 1 thread is known, one frame
+	 * will be 0.
+	 */
+	unsigned long frame1;
+	unsigned long frame2;
+};
+
+/*
+ * Since we also want to be able to debug allocators with KCSAN, to avoid
+ * deadlock, report_times cannot be dynamically resized with krealloc in
+ * rate_limit_report.
+ *
+ * Therefore, we use a fixed-size array, which at most will occupy a page. This
+ * still adequately rate limits reports, assuming that a) number of unique data
+ * races is not excessive, and b) occurrence of unique races within the
+ * same time window is limited.
+ */
+#define REPORT_TIMES_MAX (PAGE_SIZE / sizeof(struct report_time))
+#define REPORT_TIMES_SIZE                                                      \
+	(CONFIG_KCSAN_REPORT_ONCE_IN_MS > REPORT_TIMES_MAX ?                   \
+		 REPORT_TIMES_MAX :                                            \
+		 CONFIG_KCSAN_REPORT_ONCE_IN_MS)
+static struct report_time report_times[REPORT_TIMES_SIZE];
+
+/*
+ * Spinlock serializing report generation, and access to @other_infos. Although
+ * it could make sense to have a finer-grained locking story for @other_infos,
+ * report generation needs to be serialized either way, so not much is gained.
+ */
+static DEFINE_RAW_SPINLOCK(report_lock);
+
+/*
+ * Checks if the race identified by thread frames frame1 and frame2 has
+ * been reported since (now - KCSAN_REPORT_ONCE_IN_MS).
+ */
+static bool rate_limit_report(unsigned long frame1, unsigned long frame2)
+{
+	struct report_time *use_entry = &report_times[0];
+	unsigned long invalid_before;
+	int i;
+
+	BUILD_BUG_ON(CONFIG_KCSAN_REPORT_ONCE_IN_MS != 0 && REPORT_TIMES_SIZE == 0);
+
+	if (CONFIG_KCSAN_REPORT_ONCE_IN_MS == 0)
+		return false;
+
+	invalid_before = jiffies - msecs_to_jiffies(CONFIG_KCSAN_REPORT_ONCE_IN_MS);
+
+	/* Check if a matching race report exists. */
+	for (i = 0; i < REPORT_TIMES_SIZE; ++i) {
+		struct report_time *rt = &report_times[i];
+
+		/*
+		 * Must always select an entry for use to store info as we
+		 * cannot resize report_times; at the end of the scan, use_entry
+		 * will be the oldest entry, which ideally also happened before
+		 * KCSAN_REPORT_ONCE_IN_MS ago.
+		 */
+		if (time_before(rt->time, use_entry->time))
+			use_entry = rt;
+
+		/*
+		 * Initially, no need to check any further as this entry as well
+		 * as following entries have never been used.
+		 */
+		if (rt->time == 0)
+			break;
+
+		/* Check if entry expired. */
+		if (time_before(rt->time, invalid_before))
+			continue; /* before KCSAN_REPORT_ONCE_IN_MS ago */
+
+		/* Reported recently, check if race matches. */
+		if ((rt->frame1 == frame1 && rt->frame2 == frame2) ||
+		    (rt->frame1 == frame2 && rt->frame2 == frame1))
+			return true;
+	}
+
+	use_entry->time = jiffies;
+	use_entry->frame1 = frame1;
+	use_entry->frame2 = frame2;
+	return false;
+}
+
+/*
+ * Special rules to skip reporting.
+ */
+static bool
+skip_report(enum kcsan_value_change value_change, unsigned long top_frame)
+{
+	/* Should never get here if value_change==FALSE. */
+	WARN_ON_ONCE(value_change == KCSAN_VALUE_CHANGE_FALSE);
+
+	/*
+	 * The first call to skip_report always has value_change==TRUE, since we
+	 * cannot know the value written of an instrumented access. For the 2nd
+	 * call there are 6 cases with CONFIG_KCSAN_REPORT_VALUE_CHANGE_ONLY:
+	 *
+	 * 1. read watchpoint, conflicting write (value_change==TRUE): report;
+	 * 2. read watchpoint, conflicting write (value_change==MAYBE): skip;
+	 * 3. write watchpoint, conflicting write (value_change==TRUE): report;
+	 * 4. write watchpoint, conflicting write (value_change==MAYBE): skip;
+	 * 5. write watchpoint, conflicting read (value_change==MAYBE): skip;
+	 * 6. write watchpoint, conflicting read (value_change==TRUE): report;
+	 *
+	 * Cases 1-4 are intuitive and expected; case 5 ensures we do not report
+	 * data races where the write may have rewritten the same value; case 6
+	 * is possible either if the size is larger than what we check value
+	 * changes for or the access type is KCSAN_ACCESS_ASSERT.
+	 */
+	if (IS_ENABLED(CONFIG_KCSAN_REPORT_VALUE_CHANGE_ONLY) &&
+	    value_change == KCSAN_VALUE_CHANGE_MAYBE) {
+		/*
+		 * The access is a write, but the data value did not change.
+		 *
+		 * We opt-out of this filter for certain functions at request of
+		 * maintainers.
+		 */
+		char buf[64];
+		int len = scnprintf(buf, sizeof(buf), "%ps", (void *)top_frame);
+
+		if (!strnstr(buf, "rcu_", len) &&
+		    !strnstr(buf, "_rcu", len) &&
+		    !strnstr(buf, "_srcu", len))
+			return true;
+	}
+
+	return kcsan_skip_report_debugfs(top_frame);
+}
+
+static const char *get_access_type(int type)
+{
+	if (type & KCSAN_ACCESS_ASSERT) {
+		if (type & KCSAN_ACCESS_SCOPED) {
+			if (type & KCSAN_ACCESS_WRITE)
+				return "assert no accesses (reordered)";
+			else
+				return "assert no writes (reordered)";
+		} else {
+			if (type & KCSAN_ACCESS_WRITE)
+				return "assert no accesses";
+			else
+				return "assert no writes";
+		}
+	}
+
+	switch (type) {
+	case 0:
+		return "read";
+	case KCSAN_ACCESS_ATOMIC:
+		return "read (marked)";
+	case KCSAN_ACCESS_WRITE:
+		return "write";
+	case KCSAN_ACCESS_WRITE | KCSAN_ACCESS_ATOMIC:
+		return "write (marked)";
+	case KCSAN_ACCESS_COMPOUND | KCSAN_ACCESS_WRITE:
+		return "read-write";
+	case KCSAN_ACCESS_COMPOUND | KCSAN_ACCESS_WRITE | KCSAN_ACCESS_ATOMIC:
+		return "read-write (marked)";
+	case KCSAN_ACCESS_SCOPED:
+		return "read (reordered)";
+	case KCSAN_ACCESS_SCOPED | KCSAN_ACCESS_ATOMIC:
+		return "read (marked, reordered)";
+	case KCSAN_ACCESS_SCOPED | KCSAN_ACCESS_WRITE:
+		return "write (reordered)";
+	case KCSAN_ACCESS_SCOPED | KCSAN_ACCESS_WRITE | KCSAN_ACCESS_ATOMIC:
+		return "write (marked, reordered)";
+	case KCSAN_ACCESS_SCOPED | KCSAN_ACCESS_COMPOUND | KCSAN_ACCESS_WRITE:
+		return "read-write (reordered)";
+	case KCSAN_ACCESS_SCOPED | KCSAN_ACCESS_COMPOUND | KCSAN_ACCESS_WRITE | KCSAN_ACCESS_ATOMIC:
+		return "read-write (marked, reordered)";
+	default:
+		BUG();
+	}
+}
+
+static const char *get_bug_type(int type)
+{
+	return (type & KCSAN_ACCESS_ASSERT) != 0 ? "assert: race" : "data-race";
+}
+
+/* Return thread description: in task or interrupt. */
+static const char *get_thread_desc(int task_id)
+{
+	if (task_id != -1) {
+		static char buf[32]; /* safe: protected by report_lock */
+
+		snprintf(buf, sizeof(buf), "task %i", task_id);
+		return buf;
+	}
+	return "interrupt";
+}
+
+/* Helper to skip KCSAN-related functions in stack-trace. */
+static int get_stack_skipnr(const unsigned long stack_entries[], int num_entries)
+{
+	char buf[64];
+	char *cur;
+	int len, skip;
+
+	for (skip = 0; skip < num_entries; ++skip) {
+		len = scnprintf(buf, sizeof(buf), "%ps", (void *)stack_entries[skip]);
+
+		/* Never show tsan_* or {read,write}_once_size. */
+		if (strnstr(buf, "tsan_", len) ||
+		    strnstr(buf, "_once_size", len))
+			continue;
+
+		cur = strnstr(buf, "kcsan_", len);
+		if (cur) {
+			cur += strlen("kcsan_");
+			if (!str_has_prefix(cur, "test"))
+				continue; /* KCSAN runtime function. */
+			/* KCSAN related test. */
+		}
+
+		/*
+		 * No match for runtime functions -- @skip entries to skip to
+		 * get to first frame of interest.
+		 */
+		break;
+	}
+
+	return skip;
+}
+
+/*
+ * Skips to the first entry that matches the function of @ip, and then replaces
+ * that entry with @ip, returning the entries to skip with @replaced containing
+ * the replaced entry.
+ */
+static int
+replace_stack_entry(unsigned long stack_entries[], int num_entries, unsigned long ip,
+		    unsigned long *replaced)
+{
+	unsigned long symbolsize, offset;
+	unsigned long target_func;
+	int skip;
+
+	if (kallsyms_lookup_size_offset(ip, &symbolsize, &offset))
+		target_func = ip - offset;
+	else
+		goto fallback;
+
+	for (skip = 0; skip < num_entries; ++skip) {
+		unsigned long func = stack_entries[skip];
+
+		if (!kallsyms_lookup_size_offset(func, &symbolsize, &offset))
+			goto fallback;
+		func -= offset;
+
+		if (func == target_func) {
+			*replaced = stack_entries[skip];
+			stack_entries[skip] = ip;
+			return skip;
+		}
+	}
+
+fallback:
+	/* Should not happen; the resulting stack trace is likely misleading. */
+	WARN_ONCE(1, "Cannot find frame for %pS in stack trace", (void *)ip);
+	return get_stack_skipnr(stack_entries, num_entries);
+}
+
+static int
+sanitize_stack_entries(unsigned long stack_entries[], int num_entries, unsigned long ip,
+		       unsigned long *replaced)
+{
+	return ip ? replace_stack_entry(stack_entries, num_entries, ip, replaced) :
+			  get_stack_skipnr(stack_entries, num_entries);
+}
+
+/* Compares symbolized strings of addr1 and addr2. */
+static int sym_strcmp(void *addr1, void *addr2)
+{
+	char buf1[64];
+	char buf2[64];
+
+	snprintf(buf1, sizeof(buf1), "%pS", addr1);
+	snprintf(buf2, sizeof(buf2), "%pS", addr2);
+
+	return strncmp(buf1, buf2, sizeof(buf1));
+}
+
+static void
+print_stack_trace(unsigned long stack_entries[], int num_entries, unsigned long reordered_to)
+{
+	stack_trace_print(stack_entries, num_entries, 0);
+	if (reordered_to)
+		pr_err("  |\n  +-> reordered to: %pS\n", (void *)reordered_to);
+}
+
+static void print_verbose_info(struct task_struct *task)
+{
+	if (!task)
+		return;
+
+	/* Restore IRQ state trace for printing. */
+	kcsan_restore_irqtrace(task);
+
+	pr_err("\n");
+	debug_show_held_locks(task);
+	print_irqtrace_events(task);
+}
+
+static void print_report(enum kcsan_value_change value_change,
+			 const struct access_info *ai,
+			 struct other_info *other_info,
+			 u64 old, u64 new, u64 mask)
+{
+	unsigned long reordered_to = 0;
+	unsigned long stack_entries[NUM_STACK_ENTRIES] = { 0 };
+	int num_stack_entries = stack_trace_save(stack_entries, NUM_STACK_ENTRIES, 1);
+	int skipnr = sanitize_stack_entries(stack_entries, num_stack_entries, ai->ip, &reordered_to);
+	unsigned long this_frame = stack_entries[skipnr];
+	unsigned long other_reordered_to = 0;
+	unsigned long other_frame = 0;
+	int other_skipnr = 0; /* silence uninit warnings */
+
+	/*
+	 * Must check report filter rules before starting to print.
+	 */
+	if (skip_report(KCSAN_VALUE_CHANGE_TRUE, stack_entries[skipnr]))
+		return;
+
+	if (other_info) {
+		other_skipnr = sanitize_stack_entries(other_info->stack_entries,
+						      other_info->num_stack_entries,
+						      other_info->ai.ip, &other_reordered_to);
+		other_frame = other_info->stack_entries[other_skipnr];
+
+		/* @value_change is only known for the other thread */
+		if (skip_report(value_change, other_frame))
+			return;
+	}
+
+	if (rate_limit_report(this_frame, other_frame))
+		return;
+
+	/* Print report header. */
+	pr_err("==================================================================\n");
+	if (other_info) {
+		int cmp;
+
+		/*
+		 * Order functions lexographically for consistent bug titles.
+		 * Do not print offset of functions to keep title short.
+		 */
+		cmp = sym_strcmp((void *)other_frame, (void *)this_frame);
+		pr_err("BUG: KCSAN: %s in %ps / %ps\n",
+		       get_bug_type(ai->access_type | other_info->ai.access_type),
+		       (void *)(cmp < 0 ? other_frame : this_frame),
+		       (void *)(cmp < 0 ? this_frame : other_frame));
+	} else {
+		pr_err("BUG: KCSAN: %s in %pS\n", get_bug_type(ai->access_type),
+		       (void *)this_frame);
+	}
+
+	pr_err("\n");
+
+	/* Print information about the racing accesses. */
+	if (other_info) {
+		pr_err("%s to 0x%px of %zu bytes by %s on cpu %i:\n",
+		       get_access_type(other_info->ai.access_type), other_info->ai.ptr,
+		       other_info->ai.size, get_thread_desc(other_info->ai.task_pid),
+		       other_info->ai.cpu_id);
+
+		/* Print the other thread's stack trace. */
+		print_stack_trace(other_info->stack_entries + other_skipnr,
+				  other_info->num_stack_entries - other_skipnr,
+				  other_reordered_to);
+		if (IS_ENABLED(CONFIG_KCSAN_VERBOSE))
+			print_verbose_info(other_info->task);
+
+		pr_err("\n");
+		pr_err("%s to 0x%px of %zu bytes by %s on cpu %i:\n",
+		       get_access_type(ai->access_type), ai->ptr, ai->size,
+		       get_thread_desc(ai->task_pid), ai->cpu_id);
+	} else {
+		pr_err("race at unknown origin, with %s to 0x%px of %zu bytes by %s on cpu %i:\n",
+		       get_access_type(ai->access_type), ai->ptr, ai->size,
+		       get_thread_desc(ai->task_pid), ai->cpu_id);
+	}
+	/* Print stack trace of this thread. */
+	print_stack_trace(stack_entries + skipnr, num_stack_entries - skipnr, reordered_to);
+	if (IS_ENABLED(CONFIG_KCSAN_VERBOSE))
+		print_verbose_info(current);
+
+	/* Print observed value change. */
+	if (ai->size <= 8) {
+		int hex_len = ai->size * 2;
+		u64 diff = old ^ new;
+
+		if (mask)
+			diff &= mask;
+		if (diff) {
+			pr_err("\n");
+			pr_err("value changed: 0x%0*llx -> 0x%0*llx\n",
+			       hex_len, old, hex_len, new);
+			if (mask) {
+				pr_err(" bits changed: 0x%0*llx with mask 0x%0*llx\n",
+				       hex_len, diff, hex_len, mask);
+			}
+		}
+	}
+
+	/* Print report footer. */
+	pr_err("\n");
+	pr_err("Reported by Kernel Concurrency Sanitizer on:\n");
+	dump_stack_print_info(KERN_DEFAULT);
+	pr_err("==================================================================\n");
+
+	check_panic_on_warn("KCSAN");
+}
+
+static void release_report(unsigned long *flags, struct other_info *other_info)
+{
+	/*
+	 * Use size to denote valid/invalid, since KCSAN entirely ignores
+	 * 0-sized accesses.
+	 */
+	other_info->ai.size = 0;
+	raw_spin_unlock_irqrestore(&report_lock, *flags);
+}
+
+/*
+ * Sets @other_info->task and awaits consumption of @other_info.
+ *
+ * Precondition: report_lock is held.
+ * Postcondition: report_lock is held.
+ */
+static void set_other_info_task_blocking(unsigned long *flags,
+					 const struct access_info *ai,
+					 struct other_info *other_info)
+{
+	/*
+	 * We may be instrumenting a code-path where current->state is already
+	 * something other than TASK_RUNNING.
+	 */
+	const bool is_running = task_is_running(current);
+	/*
+	 * To avoid deadlock in case we are in an interrupt here and this is a
+	 * race with a task on the same CPU (KCSAN_INTERRUPT_WATCHER), provide a
+	 * timeout to ensure this works in all contexts.
+	 *
+	 * Await approximately the worst case delay of the reporting thread (if
+	 * we are not interrupted).
+	 */
+	int timeout = max(kcsan_udelay_task, kcsan_udelay_interrupt);
+
+	other_info->task = current;
+	do {
+		if (is_running) {
+			/*
+			 * Let lockdep know the real task is sleeping, to print
+			 * the held locks (recall we turned lockdep off, so
+			 * locking/unlocking @report_lock won't be recorded).
+			 */
+			set_current_state(TASK_UNINTERRUPTIBLE);
+		}
+		raw_spin_unlock_irqrestore(&report_lock, *flags);
+		/*
+		 * We cannot call schedule() since we also cannot reliably
+		 * determine if sleeping here is permitted -- see in_atomic().
+		 */
+
+		udelay(1);
+		raw_spin_lock_irqsave(&report_lock, *flags);
+		if (timeout-- < 0) {
+			/*
+			 * Abort. Reset @other_info->task to NULL, since it
+			 * appears the other thread is still going to consume
+			 * it. It will result in no verbose info printed for
+			 * this task.
+			 */
+			other_info->task = NULL;
+			break;
+		}
+		/*
+		 * If invalid, or @ptr nor @current matches, then @other_info
+		 * has been consumed and we may continue. If not, retry.
+		 */
+	} while (other_info->ai.size && other_info->ai.ptr == ai->ptr &&
+		 other_info->task == current);
+	if (is_running)
+		set_current_state(TASK_RUNNING);
+}
+
+/* Populate @other_info; requires that the provided @other_info not in use. */
+static void prepare_report_producer(unsigned long *flags,
+				    const struct access_info *ai,
+				    struct other_info *other_info)
+{
+	raw_spin_lock_irqsave(&report_lock, *flags);
+
+	/*
+	 * The same @other_infos entry cannot be used concurrently, because
+	 * there is a one-to-one mapping to watchpoint slots (@watchpoints in
+	 * core.c), and a watchpoint is only released for reuse after reporting
+	 * is done by the consumer of @other_info. Therefore, it is impossible
+	 * for another concurrent prepare_report_producer() to set the same
+	 * @other_info, and are guaranteed exclusivity for the @other_infos
+	 * entry pointed to by @other_info.
+	 *
+	 * To check this property holds, size should never be non-zero here,
+	 * because every consumer of struct other_info resets size to 0 in
+	 * release_report().
+	 */
+	WARN_ON(other_info->ai.size);
+
+	other_info->ai = *ai;
+	other_info->num_stack_entries = stack_trace_save(other_info->stack_entries, NUM_STACK_ENTRIES, 2);
+
+	if (IS_ENABLED(CONFIG_KCSAN_VERBOSE))
+		set_other_info_task_blocking(flags, ai, other_info);
+
+	raw_spin_unlock_irqrestore(&report_lock, *flags);
+}
+
+/* Awaits producer to fill @other_info and then returns. */
+static bool prepare_report_consumer(unsigned long *flags,
+				    const struct access_info *ai,
+				    struct other_info *other_info)
+{
+
+	raw_spin_lock_irqsave(&report_lock, *flags);
+	while (!other_info->ai.size) { /* Await valid @other_info. */
+		raw_spin_unlock_irqrestore(&report_lock, *flags);
+		cpu_relax();
+		raw_spin_lock_irqsave(&report_lock, *flags);
+	}
+
+	/* Should always have a matching access based on watchpoint encoding. */
+	if (WARN_ON(!matching_access((unsigned long)other_info->ai.ptr & WATCHPOINT_ADDR_MASK, other_info->ai.size,
+				     (unsigned long)ai->ptr & WATCHPOINT_ADDR_MASK, ai->size)))
+		goto discard;
+
+	if (!matching_access((unsigned long)other_info->ai.ptr, other_info->ai.size,
+			     (unsigned long)ai->ptr, ai->size)) {
+		/*
+		 * If the actual accesses to not match, this was a false
+		 * positive due to watchpoint encoding.
+		 */
+		atomic_long_inc(&kcsan_counters[KCSAN_COUNTER_ENCODING_FALSE_POSITIVES]);
+		goto discard;
+	}
+
+	return true;
+
+discard:
+	release_report(flags, other_info);
+	return false;
+}
+
+static struct access_info prepare_access_info(const volatile void *ptr, size_t size,
+					      int access_type, unsigned long ip)
+{
+	return (struct access_info) {
+		.ptr		= ptr,
+		.size		= size,
+		.access_type	= access_type,
+		.task_pid	= in_task() ? task_pid_nr(current) : -1,
+		.cpu_id		= raw_smp_processor_id(),
+		/* Only replace stack entry with @ip if scoped access. */
+		.ip		= (access_type & KCSAN_ACCESS_SCOPED) ? ip : 0,
+	};
+}
+
+void kcsan_report_set_info(const volatile void *ptr, size_t size, int access_type,
+			   unsigned long ip, int watchpoint_idx)
+{
+	const struct access_info ai = prepare_access_info(ptr, size, access_type, ip);
+	unsigned long flags;
+
+	kcsan_disable_current();
+	lockdep_off(); /* See kcsan_report_known_origin(). */
+
+	prepare_report_producer(&flags, &ai, &other_infos[watchpoint_idx]);
+
+	lockdep_on();
+	kcsan_enable_current();
+}
+
+void kcsan_report_known_origin(const volatile void *ptr, size_t size, int access_type,
+			       unsigned long ip, enum kcsan_value_change value_change,
+			       int watchpoint_idx, u64 old, u64 new, u64 mask)
+{
+	const struct access_info ai = prepare_access_info(ptr, size, access_type, ip);
+	struct other_info *other_info = &other_infos[watchpoint_idx];
+	unsigned long flags = 0;
+
+	kcsan_disable_current();
+	/*
+	 * Because we may generate reports when we're in scheduler code, the use
+	 * of printk() could deadlock. Until such time that all printing code
+	 * called in print_report() is scheduler-safe, accept the risk, and just
+	 * get our message out. As such, also disable lockdep to hide the
+	 * warning, and avoid disabling lockdep for the rest of the kernel.
+	 */
+	lockdep_off();
+
+	if (!prepare_report_consumer(&flags, &ai, other_info))
+		goto out;
+	/*
+	 * Never report if value_change is FALSE, only when it is
+	 * either TRUE or MAYBE. In case of MAYBE, further filtering may
+	 * be done once we know the full stack trace in print_report().
+	 */
+	if (value_change != KCSAN_VALUE_CHANGE_FALSE)
+		print_report(value_change, &ai, other_info, old, new, mask);
+
+	release_report(&flags, other_info);
+out:
+	lockdep_on();
+	kcsan_enable_current();
+}
+
+void kcsan_report_unknown_origin(const volatile void *ptr, size_t size, int access_type,
+				 unsigned long ip, u64 old, u64 new, u64 mask)
+{
+	const struct access_info ai = prepare_access_info(ptr, size, access_type, ip);
+	unsigned long flags;
+
+	kcsan_disable_current();
+	lockdep_off(); /* See kcsan_report_known_origin(). */
+
+	raw_spin_lock_irqsave(&report_lock, flags);
+	print_report(KCSAN_VALUE_CHANGE_TRUE, &ai, NULL, old, new, mask);
+	raw_spin_unlock_irqrestore(&report_lock, flags);
+
+	lockdep_on();
+	kcsan_enable_current();
+}