Adding upstream version 6.6.15.upstream/6.6.15

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

1 files changed, 541 insertions, 0 deletions

diff --git a/lib/stackdepot.c b/lib/stackdepot.c
new file mode 100644
index 0000000000..2f5aa85183
--- /dev/null
+++ b/lib/stackdepot.c
@@ -0,0 +1,541 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Stack depot - a stack trace storage that avoids duplication.
+ *
+ * Internally, stack depot maintains a hash table of unique stacktraces. The
+ * stack traces themselves are stored contiguously one after another in a set
+ * of separate page allocations.
+ *
+ * Author: Alexander Potapenko <glider@google.com>
+ * Copyright (C) 2016 Google, Inc.
+ *
+ * Based on the code by Dmitry Chernenkov.
+ */
+
+#define pr_fmt(fmt) "stackdepot: " fmt
+
+#include <linux/gfp.h>
+#include <linux/jhash.h>
+#include <linux/kernel.h>
+#include <linux/kmsan.h>
+#include <linux/mm.h>
+#include <linux/mutex.h>
+#include <linux/percpu.h>
+#include <linux/printk.h>
+#include <linux/slab.h>
+#include <linux/stacktrace.h>
+#include <linux/stackdepot.h>
+#include <linux/string.h>
+#include <linux/types.h>
+#include <linux/memblock.h>
+#include <linux/kasan-enabled.h>
+
+#define DEPOT_HANDLE_BITS (sizeof(depot_stack_handle_t) * 8)
+
+#define DEPOT_VALID_BITS 1
+#define DEPOT_POOL_ORDER 2 /* Pool size order, 4 pages */
+#define DEPOT_POOL_SIZE (1LL << (PAGE_SHIFT + DEPOT_POOL_ORDER))
+#define DEPOT_STACK_ALIGN 4
+#define DEPOT_OFFSET_BITS (DEPOT_POOL_ORDER + PAGE_SHIFT - DEPOT_STACK_ALIGN)
+#define DEPOT_POOL_INDEX_BITS (DEPOT_HANDLE_BITS - DEPOT_VALID_BITS - \
+			       DEPOT_OFFSET_BITS - STACK_DEPOT_EXTRA_BITS)
+#define DEPOT_POOLS_CAP 8192
+#define DEPOT_MAX_POOLS \
+	(((1LL << (DEPOT_POOL_INDEX_BITS)) < DEPOT_POOLS_CAP) ? \
+	 (1LL << (DEPOT_POOL_INDEX_BITS)) : DEPOT_POOLS_CAP)
+
+/* Compact structure that stores a reference to a stack. */
+union handle_parts {
+	depot_stack_handle_t handle;
+	struct {
+		u32 pool_index	: DEPOT_POOL_INDEX_BITS;
+		u32 offset	: DEPOT_OFFSET_BITS;
+		u32 valid	: DEPOT_VALID_BITS;
+		u32 extra	: STACK_DEPOT_EXTRA_BITS;
+	};
+};
+
+struct stack_record {
+	struct stack_record *next;	/* Link in the hash table */
+	u32 hash;			/* Hash in the hash table */
+	u32 size;			/* Number of stored frames */
+	union handle_parts handle;
+	unsigned long entries[];	/* Variable-sized array of frames */
+};
+
+static bool stack_depot_disabled;
+static bool __stack_depot_early_init_requested __initdata = IS_ENABLED(CONFIG_STACKDEPOT_ALWAYS_INIT);
+static bool __stack_depot_early_init_passed __initdata;
+
+/* Use one hash table bucket per 16 KB of memory. */
+#define STACK_HASH_TABLE_SCALE 14
+/* Limit the number of buckets between 4K and 1M. */
+#define STACK_BUCKET_NUMBER_ORDER_MIN 12
+#define STACK_BUCKET_NUMBER_ORDER_MAX 20
+/* Initial seed for jhash2. */
+#define STACK_HASH_SEED 0x9747b28c
+
+/* Hash table of pointers to stored stack traces. */
+static struct stack_record **stack_table;
+/* Fixed order of the number of table buckets. Used when KASAN is enabled. */
+static unsigned int stack_bucket_number_order;
+/* Hash mask for indexing the table. */
+static unsigned int stack_hash_mask;
+
+/* Array of memory regions that store stack traces. */
+static void *stack_pools[DEPOT_MAX_POOLS];
+/* Currently used pool in stack_pools. */
+static int pool_index;
+/* Offset to the unused space in the currently used pool. */
+static size_t pool_offset;
+/* Lock that protects the variables above. */
+static DEFINE_RAW_SPINLOCK(pool_lock);
+/*
+ * Stack depot tries to keep an extra pool allocated even before it runs out
+ * of space in the currently used pool.
+ * This flag marks that this next extra pool needs to be allocated and
+ * initialized. It has the value 0 when either the next pool is not yet
+ * initialized or the limit on the number of pools is reached.
+ */
+static int next_pool_required = 1;
+
+static int __init disable_stack_depot(char *str)
+{
+	int ret;
+
+	ret = kstrtobool(str, &stack_depot_disabled);
+	if (!ret && stack_depot_disabled) {
+		pr_info("disabled\n");
+		stack_table = NULL;
+	}
+	return 0;
+}
+early_param("stack_depot_disable", disable_stack_depot);
+
+void __init stack_depot_request_early_init(void)
+{
+	/* Too late to request early init now. */
+	WARN_ON(__stack_depot_early_init_passed);
+
+	__stack_depot_early_init_requested = true;
+}
+
+/* Allocates a hash table via memblock. Can only be used during early boot. */
+int __init stack_depot_early_init(void)
+{
+	unsigned long entries = 0;
+
+	/* This function must be called only once, from mm_init(). */
+	if (WARN_ON(__stack_depot_early_init_passed))
+		return 0;
+	__stack_depot_early_init_passed = true;
+
+	/*
+	 * If KASAN is enabled, use the maximum order: KASAN is frequently used
+	 * in fuzzing scenarios, which leads to a large number of different
+	 * stack traces being stored in stack depot.
+	 */
+	if (kasan_enabled() && !stack_bucket_number_order)
+		stack_bucket_number_order = STACK_BUCKET_NUMBER_ORDER_MAX;
+
+	if (!__stack_depot_early_init_requested || stack_depot_disabled)
+		return 0;
+
+	/*
+	 * If stack_bucket_number_order is not set, leave entries as 0 to rely
+	 * on the automatic calculations performed by alloc_large_system_hash.
+	 */
+	if (stack_bucket_number_order)
+		entries = 1UL << stack_bucket_number_order;
+	pr_info("allocating hash table via alloc_large_system_hash\n");
+	stack_table = alloc_large_system_hash("stackdepot",
+						sizeof(struct stack_record *),
+						entries,
+						STACK_HASH_TABLE_SCALE,
+						HASH_EARLY | HASH_ZERO,
+						NULL,
+						&stack_hash_mask,
+						1UL << STACK_BUCKET_NUMBER_ORDER_MIN,
+						1UL << STACK_BUCKET_NUMBER_ORDER_MAX);
+	if (!stack_table) {
+		pr_err("hash table allocation failed, disabling\n");
+		stack_depot_disabled = true;
+		return -ENOMEM;
+	}
+
+	return 0;
+}
+
+/* Allocates a hash table via kvcalloc. Can be used after boot. */
+int stack_depot_init(void)
+{
+	static DEFINE_MUTEX(stack_depot_init_mutex);
+	unsigned long entries;
+	int ret = 0;
+
+	mutex_lock(&stack_depot_init_mutex);
+
+	if (stack_depot_disabled || stack_table)
+		goto out_unlock;
+
+	/*
+	 * Similarly to stack_depot_early_init, use stack_bucket_number_order
+	 * if assigned, and rely on automatic scaling otherwise.
+	 */
+	if (stack_bucket_number_order) {
+		entries = 1UL << stack_bucket_number_order;
+	} else {
+		int scale = STACK_HASH_TABLE_SCALE;
+
+		entries = nr_free_buffer_pages();
+		entries = roundup_pow_of_two(entries);
+
+		if (scale > PAGE_SHIFT)
+			entries >>= (scale - PAGE_SHIFT);
+		else
+			entries <<= (PAGE_SHIFT - scale);
+	}
+
+	if (entries < 1UL << STACK_BUCKET_NUMBER_ORDER_MIN)
+		entries = 1UL << STACK_BUCKET_NUMBER_ORDER_MIN;
+	if (entries > 1UL << STACK_BUCKET_NUMBER_ORDER_MAX)
+		entries = 1UL << STACK_BUCKET_NUMBER_ORDER_MAX;
+
+	pr_info("allocating hash table of %lu entries via kvcalloc\n", entries);
+	stack_table = kvcalloc(entries, sizeof(struct stack_record *), GFP_KERNEL);
+	if (!stack_table) {
+		pr_err("hash table allocation failed, disabling\n");
+		stack_depot_disabled = true;
+		ret = -ENOMEM;
+		goto out_unlock;
+	}
+	stack_hash_mask = entries - 1;
+
+out_unlock:
+	mutex_unlock(&stack_depot_init_mutex);
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(stack_depot_init);
+
+/* Uses preallocated memory to initialize a new stack depot pool. */
+static void depot_init_pool(void **prealloc)
+{
+	/*
+	 * If the next pool is already initialized or the maximum number of
+	 * pools is reached, do not use the preallocated memory.
+	 * smp_load_acquire() here pairs with smp_store_release() below and
+	 * in depot_alloc_stack().
+	 */
+	if (!smp_load_acquire(&next_pool_required))
+		return;
+
+	/* Check if the current pool is not yet allocated. */
+	if (stack_pools[pool_index] == NULL) {
+		/* Use the preallocated memory for the current pool. */
+		stack_pools[pool_index] = *prealloc;
+		*prealloc = NULL;
+	} else {
+		/*
+		 * Otherwise, use the preallocated memory for the next pool
+		 * as long as we do not exceed the maximum number of pools.
+		 */
+		if (pool_index + 1 < DEPOT_MAX_POOLS) {
+			stack_pools[pool_index + 1] = *prealloc;
+			*prealloc = NULL;
+		}
+		/*
+		 * At this point, either the next pool is initialized or the
+		 * maximum number of pools is reached. In either case, take
+		 * note that initializing another pool is not required.
+		 * This smp_store_release pairs with smp_load_acquire() above
+		 * and in stack_depot_save().
+		 */
+		smp_store_release(&next_pool_required, 0);
+	}
+}
+
+/* Allocates a new stack in a stack depot pool. */
+static struct stack_record *
+depot_alloc_stack(unsigned long *entries, int size, u32 hash, void **prealloc)
+{
+	struct stack_record *stack;
+	size_t required_size = struct_size(stack, entries, size);
+
+	required_size = ALIGN(required_size, 1 << DEPOT_STACK_ALIGN);
+
+	/* Check if there is not enough space in the current pool. */
+	if (unlikely(pool_offset + required_size > DEPOT_POOL_SIZE)) {
+		/* Bail out if we reached the pool limit. */
+		if (unlikely(pool_index + 1 >= DEPOT_MAX_POOLS)) {
+			WARN_ONCE(1, "Stack depot reached limit capacity");
+			return NULL;
+		}
+
+		/*
+		 * Move on to the next pool.
+		 * WRITE_ONCE pairs with potential concurrent read in
+		 * stack_depot_fetch().
+		 */
+		WRITE_ONCE(pool_index, pool_index + 1);
+		pool_offset = 0;
+		/*
+		 * If the maximum number of pools is not reached, take note
+		 * that the next pool needs to initialized.
+		 * smp_store_release() here pairs with smp_load_acquire() in
+		 * stack_depot_save() and depot_init_pool().
+		 */
+		if (pool_index + 1 < DEPOT_MAX_POOLS)
+			smp_store_release(&next_pool_required, 1);
+	}
+
+	/* Assign the preallocated memory to a pool if required. */
+	if (*prealloc)
+		depot_init_pool(prealloc);
+
+	/* Check if we have a pool to save the stack trace. */
+	if (stack_pools[pool_index] == NULL)
+		return NULL;
+
+	/* Save the stack trace. */
+	stack = stack_pools[pool_index] + pool_offset;
+	stack->hash = hash;
+	stack->size = size;
+	stack->handle.pool_index = pool_index;
+	stack->handle.offset = pool_offset >> DEPOT_STACK_ALIGN;
+	stack->handle.valid = 1;
+	stack->handle.extra = 0;
+	memcpy(stack->entries, entries, flex_array_size(stack, entries, size));
+	pool_offset += required_size;
+	/*
+	 * Let KMSAN know the stored stack record is initialized. This shall
+	 * prevent false positive reports if instrumented code accesses it.
+	 */
+	kmsan_unpoison_memory(stack, required_size);
+
+	return stack;
+}
+
+/* Calculates the hash for a stack. */
+static inline u32 hash_stack(unsigned long *entries, unsigned int size)
+{
+	return jhash2((u32 *)entries,
+		      array_size(size,  sizeof(*entries)) / sizeof(u32),
+		      STACK_HASH_SEED);
+}
+
+/*
+ * Non-instrumented version of memcmp().
+ * Does not check the lexicographical order, only the equality.
+ */
+static inline
+int stackdepot_memcmp(const unsigned long *u1, const unsigned long *u2,
+			unsigned int n)
+{
+	for ( ; n-- ; u1++, u2++) {
+		if (*u1 != *u2)
+			return 1;
+	}
+	return 0;
+}
+
+/* Finds a stack in a bucket of the hash table. */
+static inline struct stack_record *find_stack(struct stack_record *bucket,
+					     unsigned long *entries, int size,
+					     u32 hash)
+{
+	struct stack_record *found;
+
+	for (found = bucket; found; found = found->next) {
+		if (found->hash == hash &&
+		    found->size == size &&
+		    !stackdepot_memcmp(entries, found->entries, size))
+			return found;
+	}
+	return NULL;
+}
+
+depot_stack_handle_t __stack_depot_save(unsigned long *entries,
+					unsigned int nr_entries,
+					gfp_t alloc_flags, bool can_alloc)
+{
+	struct stack_record *found = NULL, **bucket;
+	union handle_parts retval = { .handle = 0 };
+	struct page *page = NULL;
+	void *prealloc = NULL;
+	unsigned long flags;
+	u32 hash;
+
+	/*
+	 * If this stack trace is from an interrupt, including anything before
+	 * interrupt entry usually leads to unbounded stack depot growth.
+	 *
+	 * Since use of filter_irq_stacks() is a requirement to ensure stack
+	 * depot can efficiently deduplicate interrupt stacks, always
+	 * filter_irq_stacks() to simplify all callers' use of stack depot.
+	 */
+	nr_entries = filter_irq_stacks(entries, nr_entries);
+
+	if (unlikely(nr_entries == 0) || stack_depot_disabled)
+		goto fast_exit;
+
+	hash = hash_stack(entries, nr_entries);
+	bucket = &stack_table[hash & stack_hash_mask];
+
+	/*
+	 * Fast path: look the stack trace up without locking.
+	 * The smp_load_acquire() here pairs with smp_store_release() to
+	 * |bucket| below.
+	 */
+	found = find_stack(smp_load_acquire(bucket), entries, nr_entries, hash);
+	if (found)
+		goto exit;
+
+	/*
+	 * Check if another stack pool needs to be initialized. If so, allocate
+	 * the memory now - we won't be able to do that under the lock.
+	 *
+	 * The smp_load_acquire() here pairs with smp_store_release() to
+	 * |next_pool_inited| in depot_alloc_stack() and depot_init_pool().
+	 */
+	if (unlikely(can_alloc && smp_load_acquire(&next_pool_required))) {
+		/*
+		 * Zero out zone modifiers, as we don't have specific zone
+		 * requirements. Keep the flags related to allocation in atomic
+		 * contexts and I/O.
+		 */
+		alloc_flags &= ~GFP_ZONEMASK;
+		alloc_flags &= (GFP_ATOMIC | GFP_KERNEL);
+		alloc_flags |= __GFP_NOWARN;
+		page = alloc_pages(alloc_flags, DEPOT_POOL_ORDER);
+		if (page)
+			prealloc = page_address(page);
+	}
+
+	raw_spin_lock_irqsave(&pool_lock, flags);
+
+	found = find_stack(*bucket, entries, nr_entries, hash);
+	if (!found) {
+		struct stack_record *new =
+			depot_alloc_stack(entries, nr_entries, hash, &prealloc);
+
+		if (new) {
+			new->next = *bucket;
+			/*
+			 * This smp_store_release() pairs with
+			 * smp_load_acquire() from |bucket| above.
+			 */
+			smp_store_release(bucket, new);
+			found = new;
+		}
+	} else if (prealloc) {
+		/*
+		 * Stack depot already contains this stack trace, but let's
+		 * keep the preallocated memory for the future.
+		 */
+		depot_init_pool(&prealloc);
+	}
+
+	raw_spin_unlock_irqrestore(&pool_lock, flags);
+exit:
+	if (prealloc) {
+		/* Stack depot didn't use this memory, free it. */
+		free_pages((unsigned long)prealloc, DEPOT_POOL_ORDER);
+	}
+	if (found)
+		retval.handle = found->handle.handle;
+fast_exit:
+	return retval.handle;
+}
+EXPORT_SYMBOL_GPL(__stack_depot_save);
+
+depot_stack_handle_t stack_depot_save(unsigned long *entries,
+				      unsigned int nr_entries,
+				      gfp_t alloc_flags)
+{
+	return __stack_depot_save(entries, nr_entries, alloc_flags, true);
+}
+EXPORT_SYMBOL_GPL(stack_depot_save);
+
+unsigned int stack_depot_fetch(depot_stack_handle_t handle,
+			       unsigned long **entries)
+{
+	union handle_parts parts = { .handle = handle };
+	/*
+	 * READ_ONCE pairs with potential concurrent write in
+	 * depot_alloc_stack.
+	 */
+	int pool_index_cached = READ_ONCE(pool_index);
+	void *pool;
+	size_t offset = parts.offset << DEPOT_STACK_ALIGN;
+	struct stack_record *stack;
+
+	*entries = NULL;
+	/*
+	 * Let KMSAN know *entries is initialized. This shall prevent false
+	 * positive reports if instrumented code accesses it.
+	 */
+	kmsan_unpoison_memory(entries, sizeof(*entries));
+
+	if (!handle)
+		return 0;
+
+	if (parts.pool_index > pool_index_cached) {
+		WARN(1, "pool index %d out of bounds (%d) for stack id %08x\n",
+			parts.pool_index, pool_index_cached, handle);
+		return 0;
+	}
+	pool = stack_pools[parts.pool_index];
+	if (!pool)
+		return 0;
+	stack = pool + offset;
+
+	*entries = stack->entries;
+	return stack->size;
+}
+EXPORT_SYMBOL_GPL(stack_depot_fetch);
+
+void stack_depot_print(depot_stack_handle_t stack)
+{
+	unsigned long *entries;
+	unsigned int nr_entries;
+
+	nr_entries = stack_depot_fetch(stack, &entries);
+	if (nr_entries > 0)
+		stack_trace_print(entries, nr_entries, 0);
+}
+EXPORT_SYMBOL_GPL(stack_depot_print);
+
+int stack_depot_snprint(depot_stack_handle_t handle, char *buf, size_t size,
+		       int spaces)
+{
+	unsigned long *entries;
+	unsigned int nr_entries;
+
+	nr_entries = stack_depot_fetch(handle, &entries);
+	return nr_entries ? stack_trace_snprint(buf, size, entries, nr_entries,
+						spaces) : 0;
+}
+EXPORT_SYMBOL_GPL(stack_depot_snprint);
+
+depot_stack_handle_t __must_check stack_depot_set_extra_bits(
+			depot_stack_handle_t handle, unsigned int extra_bits)
+{
+	union handle_parts parts = { .handle = handle };
+
+	/* Don't set extra bits on empty handles. */
+	if (!handle)
+		return 0;
+
+	parts.extra = extra_bits;
+	return parts.handle;
+}
+EXPORT_SYMBOL(stack_depot_set_extra_bits);
+
+unsigned int stack_depot_get_extra_bits(depot_stack_handle_t handle)
+{
+	union handle_parts parts = { .handle = handle };
+
+	return parts.extra;
+}
+EXPORT_SYMBOL(stack_depot_get_extra_bits);