dma_map_resource() uses pfn_valid() to ensure the range is not RAM.
However, pfn_valid() only checks for availability of the memory map for
a PFN but it does not ensure that the PFN is actually backed by RAM. On
ARM64 with SPARSEMEM (128MB section granularity), MMIO addresses that
share a section with RAM will falsely trigger the WARN_ON_ONCE and cause
dma_map_resource() to return DMA_MAPPING_ERROR.
This causes a WARNING on Raspberry Pi 4 during spi_bcm2835 probe because
the SPI FIFO register (0xfe204004) falls in the same sparsemem section
as the end of RAM (0xf8000000-0xfbffffff), both in section 31
(0xf8000000-0xffffffff).
Move the sanity check from dma_map_resource() into debug_dma_map_phys()
and replace the unreliable pfn_valid() with pfn_valid() &&
!PageReserved(), which correctly identifies actual usable RAM without
false positives for MMIO regions that happen to have struct pages.
Since dma_map_resource() is dma_map_phys(DMA_ATTR_MMIO), the check
applies equally to both APIs. Any non-reserved page represents kernel
memory to a sufficient degree that using DMA_ATTR_MMIO on it is almost
certainly wrong and risks breaking coherency on non-coherent platforms.
ZONE_DEVICE pages used for PCI P2P DMA (MEMORY_DEVICE_PCI_P2PDMA) have
PageReserved set, so they will not trigger a false positive.
The check no longer blocks the mapping and uses err_printk() to
integrate with dma-debug filtering.
Fixes: f7326196a7 ("dma-mapping: export new dma_*map_phys() interface")
Reviewed-by: Robin Murphy <robin.murphy@arm.com>
Signed-off-by: Jianpeng Chang <jianpeng.chang.cn@windriver.com>
Reviewed-by: Leon Romanovsky <leonro@nvidia.com>
Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
Link: https://lore.kernel.org/r/20260513072209.1486986-1-jianpeng.chang.cn@windriver.com
When CONFIG_DMA_API_DEBUG is enabled, the DMA debug infrastructure
tracks active mappings per cacheline and warns if two different DMA
mappings share the same cacheline ("cacheline tracking EEXIST,
overlapping mappings aren't supported").
On x86_64, ARCH_KMALLOC_MINALIGN defaults to 8, so small kmalloc
allocations (e.g. the 8-byte hub->buffer and hub->status in the USB
hub driver) frequently land in the same 64-byte cacheline. When both
are DMA-mapped, this triggers a false positive warning.
This has been reported repeatedly since v5.14 (when the EEXIST check
was added) across various USB host controllers and devices including
xhci_hcd with USB hubs, USB audio devices, and USB ethernet adapters.
The cacheline overlap is only a real concern on architectures that
require DMA buffer alignment to cacheline boundaries (i.e. where
ARCH_DMA_MINALIGN >= L1_CACHE_BYTES). On architectures like x86_64
where dma_get_cache_alignment() returns 1, the hardware is
cache-coherent and overlapping cacheline mappings are harmless.
Suppress the EEXIST warning when dma_get_cache_alignment() is less
than L1_CACHE_BYTES, indicating the architecture does not require
cacheline-aligned DMA buffers.
Verified with a kernel module reproducer that performs two kmalloc(8)
allocations back-to-back and DMA-maps both:
Before: allocations share a cacheline, EEXIST fires within ~50 pairs
After: same cacheline pair found, but no warning emitted
Fixes: 2b4bbc6231 ("dma-debug: report -EEXIST errors in add_dma_entry")
Link: https://bugzilla.kernel.org/show_bug.cgi?id=215740
Suggested-by: Harry Yoo <harry@kernel.org>
Tested-by: Mikhail Gavrilov <mikhail.v.gavrilov@gmail.com>
Signed-off-by: Mikhail Gavrilov <mikhail.v.gavrilov@gmail.com>
Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
Link: https://lore.kernel.org/r/20260327124156.24820-1-mikhail.v.gavrilov@gmail.com
This was done entirely with mindless brute force, using
git grep -l '\<k[vmz]*alloc_objs*(.*, GFP_KERNEL)' |
xargs sed -i 's/\(alloc_objs*(.*\), GFP_KERNEL)/\1)/'
to convert the new alloc_obj() users that had a simple GFP_KERNEL
argument to just drop that argument.
Note that due to the extreme simplicity of the scripting, any slightly
more complex cases spread over multiple lines would not be triggered:
they definitely exist, but this covers the vast bulk of the cases, and
the resulting diff is also then easier to check automatically.
For the same reason the 'flex' versions will be done as a separate
conversion.
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This is the result of running the Coccinelle script from
scripts/coccinelle/api/kmalloc_objs.cocci. The script is designed to
avoid scalar types (which need careful case-by-case checking), and
instead replace kmalloc-family calls that allocate struct or union
object instances:
Single allocations: kmalloc(sizeof(TYPE), ...)
are replaced with: kmalloc_obj(TYPE, ...)
Array allocations: kmalloc_array(COUNT, sizeof(TYPE), ...)
are replaced with: kmalloc_objs(TYPE, COUNT, ...)
Flex array allocations: kmalloc(struct_size(PTR, FAM, COUNT), ...)
are replaced with: kmalloc_flex(*PTR, FAM, COUNT, ...)
(where TYPE may also be *VAR)
The resulting allocations no longer return "void *", instead returning
"TYPE *".
Signed-off-by: Kees Cook <kees@kernel.org>
When multiple small DMA_FROM_DEVICE or DMA_BIDIRECTIONAL buffers share a
cacheline, and DMA_API_DEBUG is enabled, we get this warning:
cacheline tracking EEXIST, overlapping mappings aren't supported.
This is because when one of the mappings is removed, while another one
is active, CPU might write into the buffer.
Add an attribute for the driver to promise not to do this, making the
overlapping safe, and suppressing the warning.
Message-ID: <2d5d091f9d84b68ea96abd545b365dd1d00bbf48.1767601130.git.mst@redhat.com>
Reviewed-by: Petr Tesarik <ptesarik@suse.com>
Acked-by: Marek Szyprowski <m.szyprowski@samsung.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Commit 370645f41e ("dma-mapping: force bouncing if the kmalloc() size is
not cache-line-aligned") introduced DMA_BOUNCE_UNALIGNED_KMALLOC feature
and permitted architecture specific code configure kmalloc slabs with
sizes smaller than the value of dma_get_cache_alignment().
When that feature is enabled, the physical address of some small
kmalloc()-ed buffers might be not aligned to the CPU cachelines, thus not
really suitable for typical DMA. To properly handle that case a SWIOTLB
buffer bouncing is used, so no CPU cache corruption occurs. When that
happens, there is no point reporting a false-positive DMA-API warning that
the buffer is not properly aligned, as this is not a client driver fault.
[m.szyprowski@samsung.com: replace is_swiotlb_allocated() with is_swiotlb_active(), per Catalin]
Link: https://lkml.kernel.org/r/20251010173009.3916215-1-m.szyprowski@samsung.com
Link: https://lkml.kernel.org/r/20251009141508.2342138-1-m.szyprowski@samsung.com
Fixes: 370645f41e ("dma-mapping: force bouncing if the kmalloc() size is not cache-line-aligned")
Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Inki Dae <m.szyprowski@samsung.com>
Cc: Robin Murohy <robin.murphy@arm.com>
Cc: "Isaac J. Manjarres" <isaacmanjarres@google.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Introduce new DMA mapping functions dma_map_phys() and dma_unmap_phys()
that operate directly on physical addresses instead of page+offset
parameters. This provides a more efficient interface for drivers that
already have physical addresses available.
The new functions are implemented as the primary mapping layer, with
the existing dma_map_page_attrs()/dma_map_resource() and
dma_unmap_page_attrs()/dma_unmap_resource() functions converted to simple
wrappers around the phys-based implementations.
In case dma_map_page_attrs(), the struct page is converted to physical
address with help of page_to_phys() function and dma_map_resource()
provides physical address as is together with addition of DMA_ATTR_MMIO
attribute.
The old page-based API is preserved in mapping.c to ensure that existing
code won't be affected by changing EXPORT_SYMBOL to EXPORT_SYMBOL_GPL
variant for dma_*map_phys().
Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Reviewed-by: Keith Busch <kbusch@kernel.org>
Signed-off-by: Leon Romanovsky <leonro@nvidia.com>
Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
Link: https://lore.kernel.org/r/54cc52af91777906bbe4a386113437ba0bcfba9c.1757423202.git.leonro@nvidia.com
Convert the DMA debug infrastructure from page-based to physical address-based
mapping as a preparation to rely on physical address for DMA mapping routines.
The refactoring renames debug_dma_map_page() to debug_dma_map_phys() and
changes its signature to accept a phys_addr_t parameter instead of struct page
and offset. Similarly, debug_dma_unmap_page() becomes debug_dma_unmap_phys().
A new dma_debug_phy type is introduced to distinguish physical address mappings
from other debug entry types. All callers throughout the codebase are updated
to pass physical addresses directly, eliminating the need for page-to-physical
conversion in the debug layer.
This refactoring eliminates the need to convert between page pointers and
physical addresses in the debug layer, making the code more efficient and
consistent with the DMA mapping API's physical address focus.
Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Signed-off-by: Leon Romanovsky <leonro@nvidia.com>
[mszyprow: added a fixup]
Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
Link: https://lore.kernel.org/r/56d1a6769b68dfcbf8b26a75a7329aeb8e3c3b6a.1757423202.git.leonro@nvidia.com
Link: https://lore.kernel.org/all/20250910052618.GH341237@unreal/
Offset into the page should also be considered while calculating a physical
address for struct dma_debug_entry. page_to_phys() just shifts the value
PAGE_SHIFT bits to the left so offset part is zero-filled.
An example (wrong) debug assertion failure with CONFIG_DMA_API_DEBUG
enabled which is observed during systemd boot process after recent
dma-debug changes:
DMA-API: e1000 0000:00:03.0: cacheline tracking EEXIST, overlapping mappings aren't supported
WARNING: CPU: 4 PID: 941 at kernel/dma/debug.c:596 add_dma_entry
CPU: 4 UID: 0 PID: 941 Comm: ip Not tainted 6.12.0+ #288
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.2-debian-1.16.2-1 04/01/2014
RIP: 0010:add_dma_entry kernel/dma/debug.c:596
Call Trace:
<TASK>
debug_dma_map_page kernel/dma/debug.c:1236
dma_map_page_attrs kernel/dma/mapping.c:179
e1000_alloc_rx_buffers drivers/net/ethernet/intel/e1000/e1000_main.c:4616
...
Found by Linux Verification Center (linuxtesting.org).
Fixes: 9d4f645a1f ("dma-debug: store a phys_addr_t in struct dma_debug_entry")
Signed-off-by: Fedor Pchelkin <pchelkin@ispras.ru>
[hch: added a little helper to clean up the code]
Signed-off-by: Christoph Hellwig <hch@lst.de>
dma-debug goes to great length to split incoming physical addresses into
a PFN and offset to store them in struct dma_debug_entry, just to
recombine those for all meaningful uses. Just store a phys_addr_t
instead.
Signed-off-by: Christoph Hellwig <hch@lst.de>
radix_lock() shouldn't be held while holding dma_hash_entry[idx].lock
otherwise, there's a possible deadlock scenario when
dma debug API is called holding rq_lock():
CPU0 CPU1 CPU2
dma_free_attrs()
check_unmap() add_dma_entry() __schedule() //out
(A) rq_lock()
get_hash_bucket()
(A) dma_entry_hash
check_sync()
(A) radix_lock() (W) dma_entry_hash
dma_entry_free()
(W) radix_lock()
// CPU2's one
(W) rq_lock()
CPU1 situation can happen when it extending radix tree and
it tries to wake up kswapd via wake_all_kswapd().
CPU2 situation can happen while perf_event_task_sched_out()
(i.e. dma sync operation is called while deleting perf_event using
etm and etr tmc which are Arm Coresight hwtracing driver backends).
To remove this possible situation, call dma_entry_free() after
put_hash_bucket() in check_unmap().
Reported-by: Denis Nikitin <denik@chromium.org>
Closes: https://lists.linaro.org/archives/list/coresight@lists.linaro.org/thread/2WMS7BBSF5OZYB63VT44U5YWLFP5HL6U/#RWM6MLQX5ANBTEQ2PRM7OXCBGCE6NPWU
Signed-off-by: Levi Yun <yeoreum.yun@arm.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Currently the dma debugging code can end up indirectly calling printk
under the radix_lock. This happens when a radix tree node allocation
fails.
This is a problem because the printk code, when used together with
netconsole, can end up inside the dma debugging code while trying to
transmit a message over netcons.
This creates the possibility of either a circular deadlock on the same
CPU, with that CPU trying to grab the radix_lock twice, or an ABBA
deadlock between different CPUs, where one CPU grabs the console lock
first and then waits for the radix_lock, while the other CPU is holding
the radix_lock and is waiting for the console lock.
The trace captured by lockdep is of the ABBA variant.
-> #2 (&dma_entry_hash[i].lock){-.-.}-{2:2}:
_raw_spin_lock_irqsave+0x5a/0x90
debug_dma_map_page+0x79/0x180
dma_map_page_attrs+0x1d2/0x2f0
bnxt_start_xmit+0x8c6/0x1540
netpoll_start_xmit+0x13f/0x180
netpoll_send_skb+0x20d/0x320
netpoll_send_udp+0x453/0x4a0
write_ext_msg+0x1b9/0x460
console_flush_all+0x2ff/0x5a0
console_unlock+0x55/0x180
vprintk_emit+0x2e3/0x3c0
devkmsg_emit+0x5a/0x80
devkmsg_write+0xfd/0x180
do_iter_readv_writev+0x164/0x1b0
vfs_writev+0xf9/0x2b0
do_writev+0x6d/0x110
do_syscall_64+0x80/0x150
entry_SYSCALL_64_after_hwframe+0x4b/0x53
-> #0 (console_owner){-.-.}-{0:0}:
__lock_acquire+0x15d1/0x31a0
lock_acquire+0xe8/0x290
console_flush_all+0x2ea/0x5a0
console_unlock+0x55/0x180
vprintk_emit+0x2e3/0x3c0
_printk+0x59/0x80
warn_alloc+0x122/0x1b0
__alloc_pages_slowpath+0x1101/0x1120
__alloc_pages+0x1eb/0x2c0
alloc_slab_page+0x5f/0x150
new_slab+0x2dc/0x4e0
___slab_alloc+0xdcb/0x1390
kmem_cache_alloc+0x23d/0x360
radix_tree_node_alloc+0x3c/0xf0
radix_tree_insert+0xf5/0x230
add_dma_entry+0xe9/0x360
dma_map_page_attrs+0x1d2/0x2f0
__bnxt_alloc_rx_frag+0x147/0x180
bnxt_alloc_rx_data+0x79/0x160
bnxt_rx_skb+0x29/0xc0
bnxt_rx_pkt+0xe22/0x1570
__bnxt_poll_work+0x101/0x390
bnxt_poll+0x7e/0x320
__napi_poll+0x29/0x160
net_rx_action+0x1e0/0x3e0
handle_softirqs+0x190/0x510
run_ksoftirqd+0x4e/0x90
smpboot_thread_fn+0x1a8/0x270
kthread+0x102/0x120
ret_from_fork+0x2f/0x40
ret_from_fork_asm+0x11/0x20
This bug is more likely than it seems, because when one CPU has run out
of memory, chances are the other has too.
The good news is, this bug is hidden behind the CONFIG_DMA_API_DEBUG, so
not many users are likely to trigger it.
Signed-off-by: Rik van Riel <riel@surriel.com>
Reported-by: Konstantin Ovsepian <ovs@meta.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Pull dma-mapping fixes from Christoph Hellwig:
- fix kerneldoc warnings (Randy Dunlap)
- better bounds checking in swiotlb (ZhangPeng)
* tag 'dma-mapping-6.8-2024-01-18' of git://git.infradead.org/users/hch/dma-mapping:
dma-debug: fix kernel-doc warnings
swiotlb: check alloc_size before the allocation of a new memory pool
Update the kernel-doc comments to catch up with the code changes and
fix the kernel-doc warnings:
debug.c:83: warning: Excess struct member 'stacktrace' description in 'dma_debug_entry'
debug.c:83: warning: Function parameter or struct member 'stack_len' not described in 'dma_debug_entry'
debug.c:83: warning: Function parameter or struct member 'stack_entries' not described in 'dma_debug_entry'
Fixes: 746017ed8d ("dma/debug: Simplify stracktrace retrieval")
Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Marek Szyprowski <m.szyprowski@samsung.com>
Cc: Robin Murphy <robin.murphy@arm.com>
Cc: iommu@lists.linux.dev
Signed-off-by: Christoph Hellwig <hch@lst.de>
On 32-bit without LPAE:
kernel/dma/debug.c: In function ‘debug_dma_dump_mappings’:
kernel/dma/debug.c:537:7: warning: format ‘%llx’ expects argument of type ‘long long unsigned int’, but argument 9 has type ‘phys_addr_t’ {aka ‘unsigned int’} [-Wformat=]
kernel/dma/debug.c: In function ‘dump_show’:
kernel/dma/debug.c:568:59: warning: format ‘%llx’ expects argument of type ‘long long unsigned int’, but argument 11 has type ‘phys_addr_t’ {aka ‘unsigned int’} [-Wformat=]
Fixes: bd89d69a52 ("dma-debug: add cacheline to user/kernel space dump messages")
Reported-by: kernel test robot <lkp@intel.com>
Link: https://lore.kernel.org/r/202303160548.ReyuTsGD-lkp@intel.com
Reported-by: noreply@ellerman.id.au
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Having the cacheline also printed on the debug_dma_dump_mappings() and
dump_show() is useful for debugging. Furthermore, this also standardizes
the messages shown on both dump functions.
Signed-off-by: Desnes Nunes <desnesn@redhat.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
