path: root/kernel/dma/debug.c

// SPDX-License-Identifier: GPL-2.0-only
/*
 * Copyright (C) 2008 Advanced Micro Devices, Inc.
 *
 * Author: Joerg Roedel <joerg.roedel@amd.com>
 */

#define pr_fmt(fmt)	"DMA-API: " fmt

#include <linux/sched/task_stack.h>
#include <linux/scatterlist.h>
#include <linux/dma-map-ops.h>
#include <linux/sched/task.h>
#include <linux/stacktrace.h>
#include <linux/spinlock.h>
#include <linux/vmalloc.h>
#include <linux/debugfs.h>
#include <linux/uaccess.h>
#include <linux/export.h>
#include <linux/device.h>
#include <linux/types.h>
#include <linux/sched.h>
#include <linux/ctype.h>
#include <linux/list.h>
#include <linux/slab.h>
#include <asm/sections.h>
#include "debug.h"

#define HASH_SIZE       16384ULL
#define HASH_FN_SHIFT   13
#define HASH_FN_MASK    (HASH_SIZE - 1)

#define PREALLOC_DMA_DEBUG_ENTRIES (1 << 16)
/* If the pool runs out, add this many new entries at once */
#define DMA_DEBUG_DYNAMIC_ENTRIES (PAGE_SIZE / sizeof(struct dma_debug_entry))

enum {
	dma_debug_single,
	dma_debug_sg,
	dma_debug_coherent,
	dma_debug_resource,
};

enum map_err_types {
	MAP_ERR_CHECK_NOT_APPLICABLE,
	MAP_ERR_NOT_CHECKED,
	MAP_ERR_CHECKED,
};

#define DMA_DEBUG_STACKTRACE_ENTRIES 5

/**
 * struct dma_debug_entry - track a dma_map* or dma_alloc_coherent mapping
 * @list: node on pre-allocated free_entries list
 * @dev: 'dev' argument to dma_map_{page|single|sg} or dma_alloc_coherent
 * @size: length of the mapping
 * @type: single, page, sg, coherent
 * @direction: enum dma_data_direction
 * @sg_call_ents: 'nents' from dma_map_sg
 * @sg_mapped_ents: 'mapped_ents' from dma_map_sg
 * @pfn: page frame of the start address
 * @offset: offset of mapping relative to pfn
 * @map_err_type: track whether dma_mapping_error() was checked
 * @stacktrace: support backtraces when a violation is detected
 */
struct dma_debug_entry {
	struct list_head list;
	struct device    *dev;
	u64              dev_addr;
	u64              size;
	int              type;
	int              direction;
	int		 sg_call_ents;
	int		 sg_mapped_ents;
	unsigned long	 pfn;
	size_t		 offset;
	enum map_err_types  map_err_type;
#ifdef CONFIG_STACKTRACE
	unsigned int	stack_len;
	unsigned long	stack_entries[DMA_DEBUG_STACKTRACE_ENTRIES];
#endif
} ____cacheline_aligned_in_smp;

typedef bool (*match_fn)(struct dma_debug_entry *, struct dma_debug_entry *);

struct hash_bucket {
	struct list_head list;
	spinlock_t lock;
};

/* Hash list to save the allocated dma addresses */
static struct hash_bucket dma_entry_hash[HASH_SIZE];
/* List of pre-allocated dma_debug_entry's */
static LIST_HEAD(free_entries);
/* Lock for the list above */
static DEFINE_SPINLOCK(free_entries_lock);

/* Global disable flag - will be set in case of an error */
static bool global_disable __read_mostly;

/* Early initialization disable flag, set at the end of dma_debug_init */
static bool dma_debug_initialized __read_mostly;

static inline bool dma_debug_disabled(void)
{
	return global_disable || !dma_debug_initialized;
}

/* Global error count */
static u32 error_count;

/* Global error show enable*/
static u32 show_all_errors __read_mostly;
/* Number of errors to show */
static u32 show_num_errors = 1;

static u32 num_free_entries;
static u32 min_free_entries;
static u32 nr_total_entries;

/* number of preallocated entries requested by kernel cmdline */
static u32 nr_prealloc_entries = PREALLOC_DMA_DEBUG_ENTRIES;

/* per-driver filter related state */

#define NAME_MAX_LEN	64

static char                  current_driver_name[NAME_MAX_LEN] __read_mostly;
static struct device_driver *current_driver                    __read_mostly;

static DEFINE_RWLOCK(driver_name_lock);

static const char *const maperr2str[] = {
	[MAP_ERR_CHECK_NOT_APPLICABLE] = "dma map error check not applicable",
	[MAP_ERR_NOT_CHECKED] = "dma map error not checked",
	[MAP_ERR_CHECKED] = "dma map error checked",
};

static const char *type2name[] = {
	[dma_debug_single] = "single",
	[dma_debug_sg] = "scather-gather",
	[dma_debug_coherent] = "coherent",
	[dma_debug_resource] = "resource",
};

static const char *dir2name[] = {
	[DMA_BIDIRECTIONAL]	= "DMA_BIDIRECTIONAL",
	[DMA_TO_DEVICE]		= "DMA_TO_DEVICE",
	[DMA_FROM_DEVICE]	= "DMA_FROM_DEVICE",
	[DMA_NONE]		= "DMA_NONE",
};

/*
 * The access to some variables in this macro is racy. We can't use atomic_t
 * here because all these variables are exported to debugfs. Some of them even
 * writeable. This is also the reason why a lock won't help much. But anyway,
 * the races are no big deal. Here is why:
 *
 *   error_count: the addition is racy, but the worst thing that can happen is
 *                that we don't count some errors
 *   show_num_errors: the subtraction is racy. Also no big deal because in
 *                    worst case this will result in one warning more in the
 *                    system log than the user configured. This variable is
 *                    writeable via debugfs.
 */
static inline void dump_entry_trace(struct dma_debug_entry *entry)
{
#ifdef CONFIG_STACKTRACE
	if (entry) {
		pr_warn("Mapped at:\n");
		stack_trace_print(entry->stack_entries, entry->stack_len, 0);
	}