Adding upstream version 6.1.76.upstream/6.1.76upstream

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

1 files changed, 535 insertions, 0 deletions

diff --git a/lib/stackdepot.c b/lib/stackdepot.c
new file mode 100644
index 000000000..79e894cf8
--- /dev/null
+++ b/lib/stackdepot.c
@@ -0,0 +1,535 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Generic stack depot for storing stack traces.
+ *
+ * Some debugging tools need to save stack traces of certain events which can
+ * be later presented to the user. For example, KASAN needs to safe alloc and
+ * free stacks for each object, but storing two stack traces per object
+ * requires too much memory (e.g. SLUB_DEBUG needs 256 bytes per object for
+ * that).
+ *
+ * Instead, stack depot maintains a hashtable of unique stacktraces. Since alloc
+ * and free stacks repeat a lot, we save about 100x space.
+ * Stacks are never removed from depot, so we store them contiguously one after
+ * another in a contiguous memory allocation.
+ *
+ * Author: Alexander Potapenko <glider@google.com>
+ * Copyright (C) 2016 Google, Inc.
+ *
+ * Based on code by Dmitry Chernenkov.
+ */
+
+#include <linux/gfp.h>
+#include <linux/jhash.h>
+#include <linux/kernel.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_STACK_BITS (sizeof(depot_stack_handle_t) * 8)
+
+#define STACK_ALLOC_NULL_PROTECTION_BITS 1
+#define STACK_ALLOC_ORDER 2 /* 'Slab' size order for stack depot, 4 pages */
+#define STACK_ALLOC_SIZE (1LL << (PAGE_SHIFT + STACK_ALLOC_ORDER))
+#define STACK_ALLOC_ALIGN 4
+#define STACK_ALLOC_OFFSET_BITS (STACK_ALLOC_ORDER + PAGE_SHIFT - \
+					STACK_ALLOC_ALIGN)
+#define STACK_ALLOC_INDEX_BITS (DEPOT_STACK_BITS - \
+		STACK_ALLOC_NULL_PROTECTION_BITS - \
+		STACK_ALLOC_OFFSET_BITS - STACK_DEPOT_EXTRA_BITS)
+#define STACK_ALLOC_SLABS_CAP 8192
+#define STACK_ALLOC_MAX_SLABS \
+	(((1LL << (STACK_ALLOC_INDEX_BITS)) < STACK_ALLOC_SLABS_CAP) ? \
+	 (1LL << (STACK_ALLOC_INDEX_BITS)) : STACK_ALLOC_SLABS_CAP)
+
+/* The compact structure to store the reference to stacks. */
+union handle_parts {
+	depot_stack_handle_t handle;
+	struct {
+		u32 slabindex : STACK_ALLOC_INDEX_BITS;
+		u32 offset : STACK_ALLOC_OFFSET_BITS;
+		u32 valid : STACK_ALLOC_NULL_PROTECTION_BITS;
+		u32 extra : STACK_DEPOT_EXTRA_BITS;
+	};
+};
+
+struct stack_record {
+	struct stack_record *next;	/* Link in the hashtable */
+	u32 hash;			/* Hash in the hastable */
+	u32 size;			/* Number of frames in the stack */
+	union handle_parts handle;
+	unsigned long entries[];	/* Variable-sized array of entries. */
+};
+
+static bool __stack_depot_want_early_init __initdata = IS_ENABLED(CONFIG_STACKDEPOT_ALWAYS_INIT);
+static bool __stack_depot_early_init_passed __initdata;
+
+static void *stack_slabs[STACK_ALLOC_MAX_SLABS];
+
+static int depot_index;
+static int next_slab_inited;
+static size_t depot_offset;
+static DEFINE_RAW_SPINLOCK(depot_lock);
+
+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);
+
+static bool init_stack_slab(void **prealloc)
+{
+	if (!*prealloc)
+		return false;
+	/*
+	 * This smp_load_acquire() pairs with smp_store_release() to
+	 * |next_slab_inited| below and in depot_alloc_stack().
+	 */
+	if (smp_load_acquire(&next_slab_inited))
+		return true;
+	if (stack_slabs[depot_index] == NULL) {
+		stack_slabs[depot_index] = *prealloc;
+		*prealloc = NULL;
+	} else {
+		/* If this is the last depot slab, do not touch the next one. */
+		if (depot_index + 1 < STACK_ALLOC_MAX_SLABS) {
+			stack_slabs[depot_index + 1] = *prealloc;
+			*prealloc = NULL;
+		}
+		/*
+		 * This smp_store_release pairs with smp_load_acquire() from
+		 * |next_slab_inited| above and in stack_depot_save().
+		 */
+		smp_store_release(&next_slab_inited, 1);
+	}
+	return true;
+}
+
+/* Allocation of a new stack in raw storage */
+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 << STACK_ALLOC_ALIGN);
+
+	if (unlikely(depot_offset + required_size > STACK_ALLOC_SIZE)) {
+		if (unlikely(depot_index + 1 >= STACK_ALLOC_MAX_SLABS)) {
+			WARN_ONCE(1, "Stack depot reached limit capacity");
+			return NULL;
+		}
+		depot_index++;
+		depot_offset = 0;
+		/*
+		 * smp_store_release() here pairs with smp_load_acquire() from
+		 * |next_slab_inited| in stack_depot_save() and
+		 * init_stack_slab().
+		 */
+		if (depot_index + 1 < STACK_ALLOC_MAX_SLABS)
+			smp_store_release(&next_slab_inited, 0);
+	}
+	init_stack_slab(prealloc);
+	if (stack_slabs[depot_index] == NULL)
+		return NULL;
+
+	stack = stack_slabs[depot_index] + depot_offset;
+
+	stack->hash = hash;
+	stack->size = size;
+	stack->handle.slabindex = depot_index;
+	stack->handle.offset = depot_offset >> STACK_ALLOC_ALIGN;
+	stack->handle.valid = 1;
+	stack->handle.extra = 0;
+	memcpy(stack->entries, entries, flex_array_size(stack, entries, size));
+	depot_offset += required_size;
+
+	return stack;
+}
+
+/* one hash table bucket entry per 16kB of memory */
+#define STACK_HASH_SCALE	14
+/* limited between 4k and 1M buckets */
+#define STACK_HASH_ORDER_MIN	12
+#define STACK_HASH_ORDER_MAX	20
+#define STACK_HASH_SEED 0x9747b28c
+
+static unsigned int stack_hash_order;
+static unsigned int stack_hash_mask;
+
+static bool stack_depot_disable;
+static struct stack_record **stack_table;
+
+static int __init is_stack_depot_disabled(char *str)
+{
+	int ret;
+
+	ret = kstrtobool(str, &stack_depot_disable);
+	if (!ret && stack_depot_disable) {
+		pr_info("Stack Depot is disabled\n");
+		stack_table = NULL;
+	}
+	return 0;
+}
+early_param("stack_depot_disable", is_stack_depot_disabled);
+
+void __init stack_depot_want_early_init(void)
+{
+	/* Too late to request early init now */
+	WARN_ON(__stack_depot_early_init_passed);
+
+	__stack_depot_want_early_init = true;
+}
+
+int __init stack_depot_early_init(void)
+{
+	unsigned long entries = 0;
+
+	/* This is supposed to 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_enabled() && !stack_hash_order)
+		stack_hash_order = STACK_HASH_ORDER_MAX;
+
+	if (!__stack_depot_want_early_init || stack_depot_disable)
+		return 0;
+
+	if (stack_hash_order)
+		entries = 1UL <<  stack_hash_order;
+	stack_table = alloc_large_system_hash("stackdepot",
+						sizeof(struct stack_record *),
+						entries,
+						STACK_HASH_SCALE,
+						HASH_EARLY | HASH_ZERO,
+						NULL,
+						&stack_hash_mask,
+						1UL << STACK_HASH_ORDER_MIN,
+						1UL << STACK_HASH_ORDER_MAX);
+
+	if (!stack_table) {
+		pr_err("Stack Depot hash table allocation failed, disabling\n");
+		stack_depot_disable = true;
+		return -ENOMEM;
+	}
+
+	return 0;
+}
+
+int stack_depot_init(void)
+{
+	static DEFINE_MUTEX(stack_depot_init_mutex);
+	int ret = 0;
+
+	mutex_lock(&stack_depot_init_mutex);
+	if (!stack_depot_disable && !stack_table) {
+		unsigned long entries;
+		int scale = STACK_HASH_SCALE;
+
+		if (stack_hash_order) {
+			entries = 1UL << stack_hash_order;
+		} else {
+			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_HASH_ORDER_MIN)
+			entries = 1UL << STACK_HASH_ORDER_MIN;
+		if (entries > 1UL << STACK_HASH_ORDER_MAX)
+			entries = 1UL << STACK_HASH_ORDER_MAX;
+
+		pr_info("Stack Depot allocating hash table of %lu entries with kvcalloc\n",
+				entries);
+		stack_table = kvcalloc(entries, sizeof(struct stack_record *), GFP_KERNEL);
+		if (!stack_table) {
+			pr_err("Stack Depot hash table allocation failed, disabling\n");
+			stack_depot_disable = true;
+			ret = -ENOMEM;
+		}
+		stack_hash_mask = entries - 1;
+	}
+	mutex_unlock(&stack_depot_init_mutex);
+	return ret;
+}
+EXPORT_SYMBOL_GPL(stack_depot_init);
+
+/* Calculate 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);
+}
+
+/* Use our own, non-instrumented version of memcmp().
+ *
+ * We actually don't care about the order, just 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;
+}
+
+/* Find a stack that is equal to the one stored in entries in the hash */
+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;
+}
+
+/**
+ * stack_depot_snprint - print stack entries from a depot into a buffer
+ *
+ * @handle:	Stack depot handle which was returned from
+ *		stack_depot_save().
+ * @buf:	Pointer to the print buffer
+ *
+ * @size:	Size of the print buffer
+ *
+ * @spaces:	Number of leading spaces to print
+ *
+ * Return:	Number of bytes printed.
+ */
+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);
+
+/**
+ * stack_depot_print - print stack entries from a depot
+ *
+ * @stack:		Stack depot handle which was returned from
+ *			stack_depot_save().
+ *
+ */
+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);
+
+/**
+ * stack_depot_fetch - Fetch stack entries from a depot
+ *
+ * @handle:		Stack depot handle which was returned from
+ *			stack_depot_save().
+ * @entries:		Pointer to store the entries address
+ *
+ * Return: The number of trace entries for this depot.
+ */
+unsigned int stack_depot_fetch(depot_stack_handle_t handle,
+			       unsigned long **entries)
+{
+	union handle_parts parts = { .handle = handle };
+	void *slab;
+	size_t offset = parts.offset << STACK_ALLOC_ALIGN;
+	struct stack_record *stack;
+
+	*entries = NULL;
+	if (!handle)
+		return 0;
+
+	if (parts.slabindex > depot_index) {
+		WARN(1, "slab index %d out of bounds (%d) for stack id %08x\n",
+			parts.slabindex, depot_index, handle);
+		return 0;
+	}
+	slab = stack_slabs[parts.slabindex];
+	if (!slab)
+		return 0;
+	stack = slab + offset;
+
+	*entries = stack->entries;
+	return stack->size;
+}
+EXPORT_SYMBOL_GPL(stack_depot_fetch);
+
+/**
+ * __stack_depot_save - Save a stack trace from an array
+ *
+ * @entries:		Pointer to storage array
+ * @nr_entries:		Size of the storage array
+ * @extra_bits:		Flags to store in unused bits of depot_stack_handle_t
+ * @alloc_flags:	Allocation gfp flags
+ * @can_alloc:		Allocate stack slabs (increased chance of failure if false)
+ *
+ * Saves a stack trace from @entries array of size @nr_entries. If @can_alloc is
+ * %true, is allowed to replenish the stack slab pool in case no space is left
+ * (allocates using GFP flags of @alloc_flags). If @can_alloc is %false, avoids
+ * any allocations and will fail if no space is left to store the stack trace.
+ *
+ * If the stack trace in @entries is from an interrupt, only the portion up to
+ * interrupt entry is saved.
+ *
+ * Additional opaque flags can be passed in @extra_bits, stored in the unused
+ * bits of the stack handle, and retrieved using stack_depot_get_extra_bits()
+ * without calling stack_depot_fetch().
+ *
+ * Context: Any context, but setting @can_alloc to %false is required if
+ *          alloc_pages() cannot be used from the current context. Currently
+ *          this is the case from contexts where neither %GFP_ATOMIC nor
+ *          %GFP_NOWAIT can be used (NMI, raw_spin_lock).
+ *
+ * Return: The handle of the stack struct stored in depot, 0 on failure.
+ */
+depot_stack_handle_t __stack_depot_save(unsigned long *entries,
+					unsigned int nr_entries,
+					unsigned int extra_bits,
+					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 stackdepot growth.
+	 *
+	 * Because use of filter_irq_stacks() is a requirement to ensure
+	 * stackdepot can efficiently deduplicate interrupt stacks, always
+	 * filter_irq_stacks() to simplify all callers' use of stackdepot.
+	 */
+	nr_entries = filter_irq_stacks(entries, nr_entries);
+
+	if (unlikely(nr_entries == 0) || stack_depot_disable)
+		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 the current or the next stack slab need to be initialized.
+	 * If so, allocate the memory - we won't be able to do that under the
+	 * lock.
+	 *
+	 * The smp_load_acquire() here pairs with smp_store_release() to
+	 * |next_slab_inited| in depot_alloc_stack() and init_stack_slab().
+	 */
+	if (unlikely(can_alloc && !smp_load_acquire(&next_slab_inited))) {
+		/*
+		 * 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, STACK_ALLOC_ORDER);
+		if (page)
+			prealloc = page_address(page);
+	}
+
+	raw_spin_lock_irqsave(&depot_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) {
+		/*
+		 * We didn't need to store this stack trace, but let's keep
+		 * the preallocated memory for the future.
+		 */
+		WARN_ON(!init_stack_slab(&prealloc));
+	}
+
+	raw_spin_unlock_irqrestore(&depot_lock, flags);
+exit:
+	if (prealloc) {
+		/* Nobody used this memory, ok to free it. */
+		free_pages((unsigned long)prealloc, STACK_ALLOC_ORDER);
+	}
+	if (found)
+		retval.handle = found->handle.handle;
+fast_exit:
+	retval.extra = extra_bits;
+
+	return retval.handle;
+}
+EXPORT_SYMBOL_GPL(__stack_depot_save);
+
+/**
+ * stack_depot_save - Save a stack trace from an array
+ *
+ * @entries:		Pointer to storage array
+ * @nr_entries:		Size of the storage array
+ * @alloc_flags:	Allocation gfp flags
+ *
+ * Context: Contexts where allocations via alloc_pages() are allowed.
+ *          See __stack_depot_save() for more details.
+ *
+ * Return: The handle of the stack struct stored in depot, 0 on failure.
+ */
+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, 0, alloc_flags, true);
+}
+EXPORT_SYMBOL_GPL(stack_depot_save);