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Merge branch 'dma-api/debug' of git://git.kernel.org/pub/scm/linux/kernel/git/joro/linux-2.6-iommu into core/iommu

This commit is contained in:
Ingo Molnar 2009-03-18 10:37:48 +01:00
parent 04dfcfcb54 86f3195293
commit 95f3c4ebff
10 changed files with 1304 additions and 6 deletions
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106
Documentation/DMA-API.txt
View File

@ -609,3 +609,109 @@ size is the size (and should be a page-sized multiple).
The return value will be either a pointer to the processor virtual
address of the memory, or an error (via PTR_ERR()) if any part of the
region is occupied.
Part III - Debug drivers use of the DMA-API
-------------------------------------------
The DMA-API as described above as some constraints. DMA addresses must be
released with the corresponding function with the same size for example. With
the advent of hardware IOMMUs it becomes more and more important that drivers
do not violate those constraints. In the worst case such a violation can
result in data corruption up to destroyed filesystems.
To debug drivers and find bugs in the usage of the DMA-API checking code can
be compiled into the kernel which will tell the developer about those
violations. If your architecture supports it you can select the "Enable
debugging of DMA-API usage" option in your kernel configuration. Enabling this
option has a performance impact. Do not enable it in production kernels.
If you boot the resulting kernel will contain code which does some bookkeeping
about what DMA memory was allocated for which device. If this code detects an
error it prints a warning message with some details into your kernel log. An
example warning message may look like this:
------------[ cut here ]------------
WARNING: at /data2/repos/linux-2.6-iommu/lib/dma-debug.c:448
check_unmap+0x203/0x490()
Hardware name:
forcedeth 0000:00:08.0: DMA-API: device driver frees DMA memory with wrong
function [device address=0x00000000640444be] [size=66 bytes] [mapped as
single] [unmapped as page]
Modules linked in: nfsd exportfs bridge stp llc r8169
Pid: 0, comm: swapper Tainted: G W 2.6.28-dmatest-09289-g8bb99c0 #1
Call Trace:
<IRQ> [<ffffffff80240b22>] warn_slowpath+0xf2/0x130
[<ffffffff80647b70>] _spin_unlock+0x10/0x30
[<ffffffff80537e75>] usb_hcd_link_urb_to_ep+0x75/0xc0
[<ffffffff80647c22>] _spin_unlock_irqrestore+0x12/0x40
[<ffffffff8055347f>] ohci_urb_enqueue+0x19f/0x7c0
[<ffffffff80252f96>] queue_work+0x56/0x60
[<ffffffff80237e10>] enqueue_task_fair+0x20/0x50
[<ffffffff80539279>] usb_hcd_submit_urb+0x379/0xbc0
[<ffffffff803b78c3>] cpumask_next_and+0x23/0x40
[<ffffffff80235177>] find_busiest_group+0x207/0x8a0
[<ffffffff8064784f>] _spin_lock_irqsave+0x1f/0x50
[<ffffffff803c7ea3>] check_unmap+0x203/0x490
[<ffffffff803c8259>] debug_dma_unmap_page+0x49/0x50
[<ffffffff80485f26>] nv_tx_done_optimized+0xc6/0x2c0
[<ffffffff80486c13>] nv_nic_irq_optimized+0x73/0x2b0
[<ffffffff8026df84>] handle_IRQ_event+0x34/0x70
[<ffffffff8026ffe9>] handle_edge_irq+0xc9/0x150
[<ffffffff8020e3ab>] do_IRQ+0xcb/0x1c0
[<ffffffff8020c093>] ret_from_intr+0x0/0xa
<EOI> <4>---[ end trace f6435a98e2a38c0e ]---
The driver developer can find the driver and the device including a stacktrace
of the DMA-API call which caused this warning.
Per default only the first error will result in a warning message. All other
errors will only silently counted. This limitation exist to prevent the code
from flooding your kernel log. To support debugging a device driver this can
be disabled via debugfs. See the debugfs interface documentation below for
details.
The debugfs directory for the DMA-API debugging code is called dma-api/. In
this directory the following files can currently be found:
dma-api/all_errors This file contains a numeric value. If this
value is not equal to zero the debugging code
will print a warning for every error it finds
into the kernel log. Be carefull with this
option. It can easily flood your logs.
dma-api/disabled This read-only file contains the character 'Y'
if the debugging code is disabled. This can
happen when it runs out of memory or if it was
disabled at boot time
dma-api/error_count This file is read-only and shows the total
numbers of errors found.
dma-api/num_errors The number in this file shows how many
warnings will be printed to the kernel log
before it stops. This number is initialized to
one at system boot and be set by writing into
this file
dma-api/min_free_entries
This read-only file can be read to get the
minimum number of free dma_debug_entries the
allocator has ever seen. If this value goes
down to zero the code will disable itself
because it is not longer reliable.
dma-api/num_free_entries
The current number of free dma_debug_entries
in the allocator.
If you have this code compiled into your kernel it will be enabled by default.
If you want to boot without the bookkeeping anyway you can provide
'dma_debug=off' as a boot parameter. This will disable DMA-API debugging.
Notice that you can not enable it again at runtime. You have to reboot to do
so.
When the code disables itself at runtime this is most likely because it ran
out of dma_debug_entries. These entries are preallocated at boot. The number
of preallocated entries is defined per architecture. If it is too low for you
boot with 'dma_debug_entries=<your_desired_number>' to overwrite the
architectural default.

10
Documentation/kernel-parameters.txt
View File

@ -491,6 +491,16 @@ and is between 256 and 4096 characters. It is defined in the file
Range: 0 - 8192
Default: 64
dma_debug=off If the kernel is compiled with DMA_API_DEBUG support
this option disables the debugging code at boot.
dma_debug_entries=<number>
This option allows to tune the number of preallocated
entries for DMA-API debugging code. One entry is
required per DMA-API allocation. Use this if the
DMA-API debugging code disables itself because the
architectural default is too low.
hpet= [X86-32,HPET] option to control HPET usage
Format: { enable (default) | disable | force }
disable: disable HPET and use PIT instead

2
arch/Kconfig
View File

@ -106,3 +106,5 @@ config HAVE_CLK
The <linux/clk.h> calls support software clock gating and
thus are a key power management tool on many systems.
config HAVE_DMA_API_DEBUG
bool

1
arch/x86/Kconfig
View File

@ -40,6 +40,7 @@ config X86
select HAVE_GENERIC_DMA_COHERENT if X86_32
select HAVE_EFFICIENT_UNALIGNED_ACCESS
select USER_STACKTRACE_SUPPORT
select HAVE_DMA_API_DEBUG
config ARCH_DEFCONFIG
string

45
arch/x86/include/asm/dma-mapping.h
View File

@ -7,6 +7,7 @@
*/
#include <linux/scatterlist.h>
#include <linux/dma-debug.h>
#include <linux/dma-attrs.h>
#include <asm/io.h>
#include <asm/swiotlb.h>
@ -56,11 +57,16 @@ dma_map_single(struct device *hwdev, void *ptr, size_t size,
enum dma_data_direction dir)
{
struct dma_map_ops *ops = get_dma_ops(hwdev);
dma_addr_t addr;
BUG_ON(!valid_dma_direction(dir));
return ops->map_page(hwdev, virt_to_page(ptr),
addr = ops->map_page(hwdev, virt_to_page(ptr),
(unsigned long)ptr & ~PAGE_MASK, size,
dir, NULL);
debug_dma_map_page(hwdev, virt_to_page(ptr),
(unsigned long)ptr & ~PAGE_MASK, size,
dir, addr, true);
return addr;
}
static inline void
@ -72,6 +78,7 @@ dma_unmap_single(struct device *dev, dma_addr_t addr, size_t size,
BUG_ON(!valid_dma_direction(dir));
if (ops->unmap_page)
ops->unmap_page(dev, addr, size, dir, NULL);
debug_dma_unmap_page(dev, addr, size, dir, true);
}
static inline int
@ -79,9 +86,13 @@ dma_map_sg(struct device *hwdev, struct scatterlist *sg,
int nents, enum dma_data_direction dir)
{
struct dma_map_ops *ops = get_dma_ops(hwdev);
int ents;
BUG_ON(!valid_dma_direction(dir));
return ops->map_sg(hwdev, sg, nents, dir, NULL);
ents = ops->map_sg(hwdev, sg, nents, dir, NULL);
debug_dma_map_sg(hwdev, sg, nents, ents, dir);
return ents;
}
static inline void
@ -91,6 +102,7 @@ dma_unmap_sg(struct device *hwdev, struct scatterlist *sg, int nents,
struct dma_map_ops *ops = get_dma_ops(hwdev);
BUG_ON(!valid_dma_direction(dir));
debug_dma_unmap_sg(hwdev, sg, nents, dir);
if (ops->unmap_sg)
ops->unmap_sg(hwdev, sg, nents, dir, NULL);
}
@ -104,6 +116,7 @@ dma_sync_single_for_cpu(struct device *hwdev, dma_addr_t dma_handle,
BUG_ON(!valid_dma_direction(dir));
if (ops->sync_single_for_cpu)
ops->sync_single_for_cpu(hwdev, dma_handle, size, dir);
debug_dma_sync_single_for_cpu(hwdev, dma_handle, size, dir);
flush_write_buffers();
}
@ -116,6 +129,7 @@ dma_sync_single_for_device(struct device *hwdev, dma_addr_t dma_handle,
BUG_ON(!valid_dma_direction(dir));
if (ops->sync_single_for_device)
ops->sync_single_for_device(hwdev, dma_handle, size, dir);
debug_dma_sync_single_for_device(hwdev, dma_handle, size, dir);
flush_write_buffers();
}
@ -130,6 +144,8 @@ dma_sync_single_range_for_cpu(struct device *hwdev, dma_addr_t dma_handle,
if (ops->sync_single_range_for_cpu)
ops->sync_single_range_for_cpu(hwdev, dma_handle, offset,
size, dir);
debug_dma_sync_single_range_for_cpu(hwdev, dma_handle,
offset, size, dir);
flush_write_buffers();
}
@ -144,6 +160,8 @@ dma_sync_single_range_for_device(struct device *hwdev, dma_addr_t dma_handle,
if (ops->sync_single_range_for_device)
ops->sync_single_range_for_device(hwdev, dma_handle,
offset, size, dir);
debug_dma_sync_single_range_for_device(hwdev, dma_handle,
offset, size, dir);
flush_write_buffers();
}
@ -156,6 +174,7 @@ dma_sync_sg_for_cpu(struct device *hwdev, struct scatterlist *sg,
BUG_ON(!valid_dma_direction(dir));
if (ops->sync_sg_for_cpu)
ops->sync_sg_for_cpu(hwdev, sg, nelems, dir);
debug_dma_sync_sg_for_cpu(hwdev, sg, nelems, dir);
flush_write_buffers();
}
@ -168,6 +187,7 @@ dma_sync_sg_for_device(struct device *hwdev, struct scatterlist *sg,
BUG_ON(!valid_dma_direction(dir));
if (ops->sync_sg_for_device)
ops->sync_sg_for_device(hwdev, sg, nelems, dir);
debug_dma_sync_sg_for_device(hwdev, sg, nelems, dir);
flush_write_buffers();
}
@ -177,15 +197,24 @@ static inline dma_addr_t dma_map_page(struct device *dev, struct page *page,
enum dma_data_direction dir)
{
struct dma_map_ops *ops = get_dma_ops(dev);
dma_addr_t addr;
BUG_ON(!valid_dma_direction(dir));
return ops->map_page(dev, page, offset, size, dir, NULL);
addr = ops->map_page(dev, page, offset, size, dir, NULL);
debug_dma_map_page(dev, page, offset, size, dir, addr, false);
return addr;
}
static inline void dma_unmap_page(struct device *dev, dma_addr_t addr,
size_t size, enum dma_data_direction dir)
{
dma_unmap_single(dev, addr, size, dir);
struct dma_map_ops *ops = get_dma_ops(dev);
BUG_ON(!valid_dma_direction(dir));
if (ops->unmap_page)
ops->unmap_page(dev, addr, size, dir, NULL);
debug_dma_unmap_page(dev, addr, size, dir, false);
}
static inline void
@ -250,8 +279,11 @@ dma_alloc_coherent(struct device *dev, size_t size, dma_addr_t *dma_handle,
if (!ops->alloc_coherent)
return NULL;
return ops->alloc_coherent(dev, size, dma_handle,
dma_alloc_coherent_gfp_flags(dev, gfp));
memory = ops->alloc_coherent(dev, size, dma_handle,
dma_alloc_coherent_gfp_flags(dev, gfp));
debug_dma_alloc_coherent(dev, size, *dma_handle, memory);
return memory;
}
static inline void dma_free_coherent(struct device *dev, size_t size,
@ -264,6 +296,7 @@ static inline void dma_free_coherent(struct device *dev, size_t size,
if (dma_release_from_coherent(dev, get_order(size), vaddr))
return;
debug_dma_free_coherent(dev, size, vaddr, bus);
if (ops->free_coherent)
ops->free_coherent(dev, size, vaddr, bus);
}

10
arch/x86/kernel/pci-dma.c
View File

@ -1,4 +1,5 @@
#include <linux/dma-mapping.h>
#include <linux/dma-debug.h>
#include <linux/dmar.h>
#include <linux/bootmem.h>
#include <linux/pci.h>
@ -44,6 +45,9 @@ struct device x86_dma_fallback_dev = {
};
EXPORT_SYMBOL(x86_dma_fallback_dev);
/* Number of entries preallocated for DMA-API debugging */
#define PREALLOC_DMA_DEBUG_ENTRIES 32768
int dma_set_mask(struct device *dev, u64 mask)
{
if (!dev->dma_mask || !dma_supported(dev, mask))
@ -265,6 +269,12 @@ EXPORT_SYMBOL(dma_supported);
static int __init pci_iommu_init(void)
{
dma_debug_init(PREALLOC_DMA_DEBUG_ENTRIES);
#ifdef CONFIG_PCI
dma_debug_add_bus(&pci_bus_type);
#endif
calgary_iommu_init();
intel_iommu_init();

174
include/linux/dma-debug.h Normal file
View File

@ -0,0 +1,174 @@
/*
* Copyright (C) 2008 Advanced Micro Devices, Inc.
*
* Author: Joerg Roedel <joerg.roedel@amd.com>
*
* This program is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 as published
* by the Free Software Foundation.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
#ifndef __DMA_DEBUG_H
#define __DMA_DEBUG_H
#include <linux/types.h>
struct device;
struct scatterlist;
struct bus_type;
#ifdef CONFIG_DMA_API_DEBUG
extern void dma_debug_add_bus(struct bus_type *bus);
extern void dma_debug_init(u32 num_entries);
extern void debug_dma_map_page(struct device *dev, struct page *page,
size_t offset, size_t size,
int direction, dma_addr_t dma_addr,
bool map_single);
extern void debug_dma_unmap_page(struct device *dev, dma_addr_t addr,
size_t size, int direction, bool map_single);
extern void debug_dma_map_sg(struct device *dev, struct scatterlist *sg,
int nents, int mapped_ents, int direction);
extern void debug_dma_unmap_sg(struct device *dev, struct scatterlist *sglist,
int nelems, int dir);
extern void debug_dma_alloc_coherent(struct device *dev, size_t size,
dma_addr_t dma_addr, void *virt);
extern void debug_dma_free_coherent(struct device *dev, size_t size,
void *virt, dma_addr_t addr);
extern void debug_dma_sync_single_for_cpu(struct device *dev,
dma_addr_t dma_handle, size_t size,
int direction);
extern void debug_dma_sync_single_for_device(struct device *dev,
dma_addr_t dma_handle,
size_t size, int direction);
extern void debug_dma_sync_single_range_for_cpu(struct device *dev,
dma_addr_t dma_handle,
unsigned long offset,
size_t size,
int direction);
extern void debug_dma_sync_single_range_for_device(struct device *dev,
dma_addr_t dma_handle,
unsigned long offset,
size_t size, int direction);
extern void debug_dma_sync_sg_for_cpu(struct device *dev,
struct scatterlist *sg,
int nelems, int direction);
extern void debug_dma_sync_sg_for_device(struct device *dev,
struct scatterlist *sg,
int nelems, int direction);
extern void debug_dma_dump_mappings(struct device *dev);
#else /* CONFIG_DMA_API_DEBUG */
void dma_debug_add_bus(struct bus_type *bus)
{
}
static inline void dma_debug_init(u32 num_entries)
{
}
static inline void debug_dma_map_page(struct device *dev, struct page *page,
size_t offset, size_t size,
int direction, dma_addr_t dma_addr,
bool map_single)
{
}
static inline void debug_dma_unmap_page(struct device *dev, dma_addr_t addr,
size_t size, int direction,
bool map_single)
{
}
static inline void debug_dma_map_sg(struct device *dev, struct scatterlist *sg,
int nents, int mapped_ents, int direction)
{
}
static inline void debug_dma_unmap_sg(struct device *dev,
struct scatterlist *sglist,
int nelems, int dir)
{
}
static inline void debug_dma_alloc_coherent(struct device *dev, size_t size,
dma_addr_t dma_addr, void *virt)
{
}
static inline void debug_dma_free_coherent(struct device *dev, size_t size,
void *virt, dma_addr_t addr)
{
}
static inline void debug_dma_sync_single_for_cpu(struct device *dev,
dma_addr_t dma_handle,
size_t size, int direction)
{
}
static inline void debug_dma_sync_single_for_device(struct device *dev,
dma_addr_t dma_handle,
size_t size, int direction)
{
}
static inline void debug_dma_sync_single_range_for_cpu(struct device *dev,
dma_addr_t dma_handle,
unsigned long offset,
size_t size,
int direction)
{
}
static inline void debug_dma_sync_single_range_for_device(struct device *dev,
dma_addr_t dma_handle,
unsigned long offset,
size_t size,
int direction)
{
}
static inline void debug_dma_sync_sg_for_cpu(struct device *dev,
struct scatterlist *sg,
int nelems, int direction)
{
}
static inline void debug_dma_sync_sg_for_device(struct device *dev,
struct scatterlist *sg,
int nelems, int direction)
{
}
static inline void debug_dma_dump_mappings(struct device *dev)
{
}
#endif /* CONFIG_DMA_API_DEBUG */
#endif /* __DMA_DEBUG_H */

11
lib/Kconfig.debug
View File

@ -902,6 +902,17 @@ config DYNAMIC_PRINTK_DEBUG
debugging for all modules. This mode can be turned off via the above
disable command.
config DMA_API_DEBUG
bool "Enable debugging of DMA-API usage"
depends on HAVE_DMA_API_DEBUG
help
Enable this option to debug the use of the DMA API by device drivers.
With this option you will be able to detect common bugs in device
drivers like double-freeing of DMA mappings or freeing mappings that
were never allocated.
This option causes a performance degredation. Use only if you want
to debug device drivers. If unsure, say N.
source "samples/Kconfig"
source "lib/Kconfig.kgdb"

2
lib/Makefile
View File

@ -84,6 +84,8 @@ obj-$(CONFIG_HAVE_ARCH_TRACEHOOK) += syscall.o
obj-$(CONFIG_DYNAMIC_PRINTK_DEBUG) += dynamic_printk.o
obj-$(CONFIG_DMA_API_DEBUG) += dma-debug.o
hostprogs-y := gen_crc32table
clean-files := crc32table.h

949
lib/dma-debug.c Normal file
View File

@ -0,0 +1,949 @@
/*
* Copyright (C) 2008 Advanced Micro Devices, Inc.
*
* Author: Joerg Roedel <joerg.roedel@amd.com>
*
* This program is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 as published
* by the Free Software Foundation.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
#include <linux/scatterlist.h>
#include <linux/dma-mapping.h>
#include <linux/stacktrace.h>
#include <linux/dma-debug.h>
#include <linux/spinlock.h>
#include <linux/debugfs.h>
#include <linux/device.h>
#include <linux/types.h>
#include <linux/sched.h>
#include <linux/list.h>
#include <linux/slab.h>
#include <asm/sections.h>
#define HASH_SIZE 1024ULL
#define HASH_FN_SHIFT 13
#define HASH_FN_MASK (HASH_SIZE - 1)
enum {
dma_debug_single,
dma_debug_page,
dma_debug_sg,
dma_debug_coherent,
};
#define DMA_DEBUG_STACKTRACE_ENTRIES 5
struct dma_debug_entry {
struct list_head list;
struct device *dev;
int type;
phys_addr_t paddr;
u64 dev_addr;
u64 size;
int direction;
int sg_call_ents;
int sg_mapped_ents;
#ifdef CONFIG_STACKTRACE
struct stack_trace stacktrace;
unsigned long st_entries[DMA_DEBUG_STACKTRACE_ENTRIES];
#endif
};
struct hash_bucket {
struct list_head list;
spinlock_t lock;
} ____cacheline_aligned_in_smp;
/* 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;
/* 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;
/* number of preallocated entries requested by kernel cmdline */
static u32 req_entries;
/* debugfs dentry's for the stuff above */
static struct dentry *dma_debug_dent __read_mostly;
static struct dentry *global_disable_dent __read_mostly;
static struct dentry *error_count_dent __read_mostly;
static struct dentry *show_all_errors_dent __read_mostly;
static struct dentry *show_num_errors_dent __read_mostly;
static struct dentry *num_free_entries_dent __read_mostly;
static struct dentry *min_free_entries_dent __read_mostly;
static const char *type2name[4] = { "single", "page",
"scather-gather", "coherent" };
static const char *dir2name[4] = { "DMA_BIDIRECTIONAL", "DMA_TO_DEVICE",
"DMA_FROM_DEVICE", "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) {
printk(KERN_WARNING "Mapped at:\n");
print_stack_trace(&entry->stacktrace, 0);
}
#endif
}
#define err_printk(dev, entry, format, arg...) do { \
error_count += 1; \
if (show_all_errors || show_num_errors > 0) { \
WARN(1, "%s %s: " format, \
dev_driver_string(dev), \
dev_name(dev) , ## arg); \
dump_entry_trace(entry); \
} \
if (!show_all_errors && show_num_errors > 0) \
show_num_errors -= 1; \
} while (0);
/*
* Hash related functions
*
* Every DMA-API request is saved into a struct dma_debug_entry. To
* have quick access to these structs they are stored into a hash.
*/
static int hash_fn(struct dma_debug_entry *entry)
{
/*
* Hash function is based on the dma address.
* We use bits 20-27 here as the index into the hash
*/
return (entry->dev_addr >> HASH_FN_SHIFT) & HASH_FN_MASK;
}
/*
* Request exclusive access to a hash bucket for a given dma_debug_entry.
*/
static struct hash_bucket *get_hash_bucket(struct dma_debug_entry *entry,
unsigned long *flags)
{
int idx = hash_fn(entry);
unsigned long __flags;
spin_lock_irqsave(&dma_entry_hash[idx].lock, __flags);
*flags = __flags;
return &dma_entry_hash[idx];
}
/*
* Give up exclusive access to the hash bucket
*/
static void put_hash_bucket(struct hash_bucket *bucket,
unsigned long *flags)
{
unsigned long __flags = *flags;
spin_unlock_irqrestore(&bucket->lock, __flags);
}
/*
* Search a given entry in the hash bucket list
*/
static struct dma_debug_entry *hash_bucket_find(struct hash_bucket *bucket,
struct dma_debug_entry *ref)
{
struct dma_debug_entry *entry;
list_for_each_entry(entry, &bucket->list, list) {
if ((entry->dev_addr == ref->dev_addr) &&
(entry->dev == ref->dev))
return entry;
}
return NULL;
}
/*
* Add an entry to a hash bucket
*/
static void hash_bucket_add(struct hash_bucket *bucket,
struct dma_debug_entry *entry)
{
list_add_tail(&entry->list, &bucket->list);
}
/*
* Remove entry from a hash bucket list
*/
static void hash_bucket_del(struct dma_debug_entry *entry)
{
list_del(&entry->list);
}
/*
* Dump mapping entries for debugging purposes
*/
void debug_dma_dump_mappings(struct device *dev)
{
int idx;
for (idx = 0; idx < HASH_SIZE; idx++) {
struct hash_bucket *bucket = &dma_entry_hash[idx];
struct dma_debug_entry *entry;
unsigned long flags;
spin_lock_irqsave(&bucket->lock, flags);
list_for_each_entry(entry, &bucket->list, list) {
if (!dev || dev == entry->dev) {
dev_info(entry->dev,
"%s idx %d P=%Lx D=%Lx L=%Lx %s\n",
type2name[entry->type], idx,
(unsigned long long)entry->paddr,
entry->dev_addr, entry->size,
dir2name[entry->direction]);
}
}
spin_unlock_irqrestore(&bucket->lock, flags);
}
}
EXPORT_SYMBOL(debug_dma_dump_mappings);
/*
* Wrapper function for adding an entry to the hash.
* This function takes care of locking itself.
*/
static void add_dma_entry(struct dma_debug_entry *entry)
{
struct hash_bucket *bucket;
unsigned long flags;
bucket = get_hash_bucket(entry, &flags);
hash_bucket_add(bucket, entry);
put_hash_bucket(bucket, &flags);
}
/* struct dma_entry allocator
*
* The next two functions implement the allocator for
* struct dma_debug_entries.
*/
static struct dma_debug_entry *dma_entry_alloc(void)
{
struct dma_debug_entry *entry = NULL;
unsigned long flags;
spin_lock_irqsave(&free_entries_lock, flags);
if (list_empty(&free_entries)) {
printk(KERN_ERR "DMA-API: debugging out of memory "
"- disabling\n");
global_disable = true;
goto out;
}
entry = list_entry(free_entries.next, struct dma_debug_entry, list);
list_del(&entry->list);
memset(entry, 0, sizeof(*entry));
#ifdef CONFIG_STACKTRACE
entry->stacktrace.max_entries = DMA_DEBUG_STACKTRACE_ENTRIES;
entry->stacktrace.entries = entry->st_entries;
entry->stacktrace.skip = 2;
save_stack_trace(&entry->stacktrace);
#endif
num_free_entries -= 1;
if (num_free_entries < min_free_entries)
min_free_entries = num_free_entries;
out:
spin_unlock_irqrestore(&free_entries_lock, flags);
return entry;
}
static void dma_entry_free(struct dma_debug_entry *entry)
{
unsigned long flags;
/*
* add to beginning of the list - this way the entries are
* more likely cache hot when they are reallocated.
*/
spin_lock_irqsave(&free_entries_lock, flags);
list_add(&entry->list, &free_entries);
num_free_entries += 1;
spin_unlock_irqrestore(&free_entries_lock, flags);
}
/*
* DMA-API debugging init code
*
* The init code does two things:
* 1. Initialize core data structures
* 2. Preallocate a given number of dma_debug_entry structs
*/
static int prealloc_memory(u32 num_entries)
{
struct dma_debug_entry *entry, *next_entry;
int i;
for (i = 0; i < num_entries; ++i) {
entry = kzalloc(sizeof(*entry), GFP_KERNEL);
if (!entry)
goto out_err;
list_add_tail(&entry->list, &free_entries);
}
num_free_entries = num_entries;
min_free_entries = num_entries;
printk(KERN_INFO "DMA-API: preallocated %d debug entries\n",
num_entries);
return 0;
out_err:
list_for_each_entry_safe(entry, next_entry, &free_entries, list) {
list_del(&entry->list);
kfree(entry);
}
return -ENOMEM;
}
static int dma_debug_fs_init(void)
{
dma_debug_dent = debugfs_create_dir("dma-api", NULL);
if (!dma_debug_dent) {
printk(KERN_ERR "DMA-API: can not create debugfs directory\n");
return -ENOMEM;
}
global_disable_dent = debugfs_create_bool("disabled", 0444,
dma_debug_dent,
(u32 *)&global_disable);
if (!global_disable_dent)
goto out_err;
error_count_dent = debugfs_create_u32("error_count", 0444,
dma_debug_dent, &error_count);
if (!error_count_dent)
goto out_err;
show_all_errors_dent = debugfs_create_u32("all_errors", 0644,
dma_debug_dent,
&show_all_errors);
if (!show_all_errors_dent)
goto out_err;
show_num_errors_dent = debugfs_create_u32("num_errors", 0644,
dma_debug_dent,
&show_num_errors);
if (!show_num_errors_dent)
goto out_err;
num_free_entries_dent = debugfs_create_u32("num_free_entries", 0444,
dma_debug_dent,
&num_free_entries);
if (!num_free_entries_dent)
goto out_err;
min_free_entries_dent = debugfs_create_u32("min_free_entries", 0444,
dma_debug_dent,
&min_free_entries);
if (!min_free_entries_dent)
goto out_err;
return 0;
out_err:
debugfs_remove_recursive(dma_debug_dent);
return -ENOMEM;
}
static int device_dma_allocations(struct device *dev)
{
struct dma_debug_entry *entry;
unsigned long flags;
int count = 0, i;
for (i = 0; i < HASH_SIZE; ++i) {
spin_lock_irqsave(&dma_entry_hash[i].lock, flags);
list_for_each_entry(entry, &dma_entry_hash[i].list, list) {
if (entry->dev == dev)
count += 1;
}
spin_unlock_irqrestore(&dma_entry_hash[i].lock, flags);
}
return count;
}
static int dma_debug_device_change(struct notifier_block *nb,
unsigned long action, void *data)
{
struct device *dev = data;
int count;
switch (action) {
case BUS_NOTIFY_UNBIND_DRIVER:
count = device_dma_allocations(dev);
if (count == 0)
break;
err_printk(dev, NULL, "DMA-API: device driver has pending "
"DMA allocations while released from device "
"[count=%d]\n", count);
break;
default:
break;
}
return 0;
}
void dma_debug_add_bus(struct bus_type *bus)
{
struct notifier_block *nb;
nb = kzalloc(sizeof(struct notifier_block), GFP_KERNEL);
if (nb == NULL) {
printk(KERN_ERR "dma_debug_add_bus: out of memory\n");
return;
}
nb->notifier_call = dma_debug_device_change;
bus_register_notifier(bus, nb);
}
/*
* Let the architectures decide how many entries should be preallocated.
*/
void dma_debug_init(u32 num_entries)
{
int i;
if (global_disable)
return;
for (i = 0; i < HASH_SIZE; ++i) {
INIT_LIST_HEAD(&dma_entry_hash[i].list);
dma_entry_hash[i].lock = SPIN_LOCK_UNLOCKED;
}
if (dma_debug_fs_init() != 0) {
printk(KERN_ERR "DMA-API: error creating debugfs entries "
"- disabling\n");
global_disable = true;
return;
}
if (req_entries)
num_entries = req_entries;
if (prealloc_memory(num_entries) != 0) {
printk(KERN_ERR "DMA-API: debugging out of memory error "
"- disabled\n");
global_disable = true;
return;
}
printk(KERN_INFO "DMA-API: debugging enabled by kernel config\n");
}
static __init int dma_debug_cmdline(char *str)
{
if (!str)
return -EINVAL;
if (strncmp(str, "off", 3) == 0) {
printk(KERN_INFO "DMA-API: debugging disabled on kernel "
"command line\n");
global_disable = true;
}
return 0;
}
static __init int dma_debug_entries_cmdline(char *str)
{
int res;
if (!str)
return -EINVAL;
res = get_option(&str, &req_entries);
if (!res)
req_entries = 0;
return 0;
}
__setup("dma_debug=", dma_debug_cmdline);
__setup("dma_debug_entries=", dma_debug_entries_cmdline);
static void check_unmap(struct dma_debug_entry *ref)
{
struct dma_debug_entry *entry;
struct hash_bucket *bucket;
unsigned long flags;
if (dma_mapping_error(ref->dev, ref->dev_addr))
return;
bucket = get_hash_bucket(ref, &flags);
entry = hash_bucket_find(bucket, ref);
if (!entry) {
err_printk(ref->dev, NULL, "DMA-API: device driver tries "
"to free DMA memory it has not allocated "
"[device address=0x%016llx] [size=%llu bytes]\n",
ref->dev_addr, ref->size);
goto out;
}
if (ref->size != entry->size) {
err_printk(ref->dev, entry, "DMA-API: device driver frees "
"DMA memory with different size "
"[device address=0x%016llx] [map size=%llu bytes] "
"[unmap size=%llu bytes]\n",
ref->dev_addr, entry->size, ref->size);
}
if (ref->type != entry->type) {
err_printk(ref->dev, entry, "DMA-API: device driver frees "
"DMA memory with wrong function "
"[device address=0x%016llx] [size=%llu bytes] "
"[mapped as %s] [unmapped as %s]\n",
ref->dev_addr, ref->size,
type2name[entry->type], type2name[ref->type]);
} else if ((entry->type == dma_debug_coherent) &&
(ref->paddr != entry->paddr)) {
err_printk(ref->dev, entry, "DMA-API: device driver frees "
"DMA memory with different CPU address "
"[device address=0x%016llx] [size=%llu bytes] "
"[cpu alloc address=%p] [cpu free address=%p]",
ref->dev_addr, ref->size,
(void *)entry->paddr, (void *)ref->paddr);
}
if (ref->sg_call_ents && ref->type == dma_debug_sg &&
ref->sg_call_ents != entry->sg_call_ents) {
err_printk(ref->dev, entry, "DMA-API: device driver frees "
"DMA sg list with different entry count "
"[map count=%d] [unmap count=%d]\n",
entry->sg_call_ents, ref->sg_call_ents);
}
/*
* This may be no bug in reality - but most implementations of the
* DMA API don't handle this properly, so check for it here
*/
if (ref->direction != entry->direction) {
err_printk(ref->dev, entry, "DMA-API: device driver frees "
"DMA memory with different direction "
"[device address=0x%016llx] [size=%llu bytes] "
"[mapped with %s] [unmapped with %s]\n",
ref->dev_addr, ref->size,
dir2name[entry->direction],
dir2name[ref->direction]);
}
hash_bucket_del(entry);
dma_entry_free(entry);
out:
put_hash_bucket(bucket, &flags);
}
static void check_for_stack(struct device *dev, void *addr)
{
if (object_is_on_stack(addr))
err_printk(dev, NULL, "DMA-API: device driver maps memory from"
"stack [addr=%p]\n", addr);
}
static inline bool overlap(void *addr, u64 size, void *start, void *end)
{
void *addr2 = (char *)addr + size;
return ((addr >= start && addr < end) ||
(addr2 >= start && addr2 < end) ||
((addr < start) && (addr2 >= end)));
}
static void check_for_illegal_area(struct device *dev, void *addr, u64 size)
{
if (overlap(addr, size, _text, _etext) ||
overlap(addr, size, __start_rodata, __end_rodata))
err_printk(dev, NULL, "DMA-API: device driver maps "
"memory from kernel text or rodata "
"[addr=%p] [size=%llu]\n", addr, size);
}
static void check_sync(struct device *dev, dma_addr_t addr,
u64 size, u64 offset, int direction, bool to_cpu)
{
struct dma_debug_entry ref = {
.dev = dev,
.dev_addr = addr,
.size = size,
.direction = direction,
};
struct dma_debug_entry *entry;
struct hash_bucket *bucket;
unsigned long flags;
bucket = get_hash_bucket(&ref, &flags);
entry = hash_bucket_find(bucket, &ref);
if (!entry) {
err_printk(dev, NULL, "DMA-API: device driver tries "
"to sync DMA memory it has not allocated "
"[device address=0x%016llx] [size=%llu bytes]\n",
addr, size);
goto out;
}
if ((offset + size) > entry->size) {
err_printk(dev, entry, "DMA-API: device driver syncs"
" DMA memory outside allocated range "
"[device address=0x%016llx] "
"[allocation size=%llu bytes] [sync offset=%llu] "
"[sync size=%llu]\n", entry->dev_addr, entry->size,
offset, size);
}
if (direction != entry->direction) {
err_printk(dev, entry, "DMA-API: device driver syncs "
"DMA memory with different direction "
"[device address=0x%016llx] [size=%llu bytes] "
"[mapped with %s] [synced with %s]\n",
addr, entry->size,
dir2name[entry->direction],
dir2name[direction]);
}
if (entry->direction == DMA_BIDIRECTIONAL)
goto out;
if (to_cpu && !(entry->direction == DMA_FROM_DEVICE) &&
!(direction == DMA_TO_DEVICE))
err_printk(dev, entry, "DMA-API: device driver syncs "
"device read-only DMA memory for cpu "
"[device address=0x%016llx] [size=%llu bytes] "
"[mapped with %s] [synced with %s]\n",
addr, entry->size,
dir2name[entry->direction],
dir2name[direction]);
if (!to_cpu && !(entry->direction == DMA_TO_DEVICE) &&
!(direction == DMA_FROM_DEVICE))
err_printk(dev, entry, "DMA-API: device driver syncs "
"device write-only DMA memory to device "
"[device address=0x%016llx] [size=%llu bytes] "
"[mapped with %s] [synced with %s]\n",
addr, entry->size,
dir2name[entry->direction],
dir2name[direction]);
out:
put_hash_bucket(bucket, &flags);
}
void debug_dma_map_page(struct device *dev, struct page *page, size_t offset,
size_t size, int direction, dma_addr_t dma_addr,
bool map_single)
{
struct dma_debug_entry *entry;
if (unlikely(global_disable))
return;
if (unlikely(dma_mapping_error(dev, dma_addr)))
return;
entry = dma_entry_alloc();
if (!entry)
return;
entry->dev = dev;
entry->type = dma_debug_page;
entry->paddr = page_to_phys(page) + offset;
entry->dev_addr = dma_addr;
entry->size = size;
entry->direction = direction;
if (map_single) {
void *addr = ((char *)page_address(page)) + offset;
entry->type = dma_debug_single;
check_for_stack(dev, addr);
check_for_illegal_area(dev, addr, size);
}
add_dma_entry(entry);
}
EXPORT_SYMBOL(debug_dma_map_page);
void debug_dma_unmap_page(struct device *dev, dma_addr_t addr,
size_t size, int direction, bool map_single)
{
struct dma_debug_entry ref = {
.type = dma_debug_page,
.dev = dev,
.dev_addr = addr,
.size = size,
.direction = direction,
};
if (unlikely(global_disable))
return;
if (map_single)
ref.type = dma_debug_single;
check_unmap(&ref);
}
EXPORT_SYMBOL(debug_dma_unmap_page);
void debug_dma_map_sg(struct device *dev, struct scatterlist *sg,
int nents, int mapped_ents, int direction)
{
struct dma_debug_entry *entry;
struct scatterlist *s;
int i;
if (unlikely(global_disable))
return;
for_each_sg(sg, s, mapped_ents, i) {
entry = dma_entry_alloc();
if (!entry)
return;
entry->type = dma_debug_sg;
entry->dev = dev;
entry->paddr = sg_phys(s);
entry->size = s->length;
entry->dev_addr = s->dma_address;
entry->direction = direction;
entry->sg_call_ents = nents;
entry->sg_mapped_ents = mapped_ents;
check_for_stack(dev, sg_virt(s));
check_for_illegal_area(dev, sg_virt(s), s->length);
add_dma_entry(entry);
}
}
EXPORT_SYMBOL(debug_dma_map_sg);
void debug_dma_unmap_sg(struct device *dev, struct scatterlist *sglist,
int nelems, int dir)
{
struct dma_debug_entry *entry;
struct scatterlist *s;
int mapped_ents = 0, i;
unsigned long flags;
if (unlikely(global_disable))
return;
for_each_sg(sglist, s, nelems, i) {
struct dma_debug_entry ref = {
.type = dma_debug_sg,
.dev = dev,
.paddr = sg_phys(s),
.dev_addr = s->dma_address,
.size = s->length,
.direction = dir,
.sg_call_ents = 0,
};
if (mapped_ents && i >= mapped_ents)
break;
if (mapped_ents == 0) {
struct hash_bucket *bucket;
ref.sg_call_ents = nelems;
bucket = get_hash_bucket(&ref, &flags);
entry = hash_bucket_find(bucket, &ref);
if (entry)
mapped_ents = entry->sg_mapped_ents;
put_hash_bucket(bucket, &flags);
}
check_unmap(&ref);
}
}
EXPORT_SYMBOL(debug_dma_unmap_sg);
void debug_dma_alloc_coherent(struct device *dev, size_t size,
dma_addr_t dma_addr, void *virt)
{
struct dma_debug_entry *entry;
if (unlikely(global_disable))
return;
if (unlikely(virt == NULL))
return;
entry = dma_entry_alloc();
if (!entry)
return;
entry->type = dma_debug_coherent;
entry->dev = dev;
entry->paddr = virt_to_phys(virt);
entry->size = size;
entry->dev_addr = dma_addr;
entry->direction = DMA_BIDIRECTIONAL;
add_dma_entry(entry);
}
EXPORT_SYMBOL(debug_dma_alloc_coherent);
void debug_dma_free_coherent(struct device *dev, size_t size,
void *virt, dma_addr_t addr)
{
struct dma_debug_entry ref = {
.type = dma_debug_coherent,
.dev = dev,
.paddr = virt_to_phys(virt),
.dev_addr = addr,
.size = size,
.direction = DMA_BIDIRECTIONAL,
};
if (unlikely(global_disable))
return;
check_unmap(&ref);
}
EXPORT_SYMBOL(debug_dma_free_coherent);
void debug_dma_sync_single_for_cpu(struct device *dev, dma_addr_t dma_handle,
size_t size, int direction)
{
if (unlikely(global_disable))
return;
check_sync(dev, dma_handle, size, 0, direction, true);
}
EXPORT_SYMBOL(debug_dma_sync_single_for_cpu);
void debug_dma_sync_single_for_device(struct device *dev,
dma_addr_t dma_handle, size_t size,
int direction)
{
if (unlikely(global_disable))
return;
check_sync(dev, dma_handle, size, 0, direction, false);
}
EXPORT_SYMBOL(debug_dma_sync_single_for_device);
void debug_dma_sync_single_range_for_cpu(struct device *dev,
dma_addr_t dma_handle,
unsigned long offset, size_t size,
int direction)
{
if (unlikely(global_disable))
return;
check_sync(dev, dma_handle, size, offset, direction, true);
}
EXPORT_SYMBOL(debug_dma_sync_single_range_for_cpu);
void debug_dma_sync_single_range_for_device(struct device *dev,
dma_addr_t dma_handle,
unsigned long offset,
size_t size, int direction)
{
if (unlikely(global_disable))
return;
check_sync(dev, dma_handle, size, offset, direction, false);
}
EXPORT_SYMBOL(debug_dma_sync_single_range_for_device);
void debug_dma_sync_sg_for_cpu(struct device *dev, struct scatterlist *sg,
int nelems, int direction)
{
struct scatterlist *s;
int i;
if (unlikely(global_disable))
return;
for_each_sg(sg, s, nelems, i) {
check_sync(dev, s->dma_address, s->dma_length, 0,
direction, true);
}
}
EXPORT_SYMBOL(debug_dma_sync_sg_for_cpu);
void debug_dma_sync_sg_for_device(struct device *dev, struct scatterlist *sg,
int nelems, int direction)
{
struct scatterlist *s;
int i;
if (unlikely(global_disable))
return;
for_each_sg(sg, s, nelems, i) {
check_sync(dev, s->dma_address, s->dma_length, 0,
direction, false);
}
}
EXPORT_SYMBOL(debug_dma_sync_sg_for_device);