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2019-09-04dma-mapping: remove the dma_declare_coherent_memory exportChristoph Hellwig1-1/+0
dma_declare_coherent_memory is something that the platform setup code (which pretty much means the device tree these days) need to do so that drivers can use the memory as declared by the platform. Drivers themselves have no business calling this function. Signed-off-by: Christoph Hellwig <hch@lst.de>
2019-09-04dma-mapping: remove the dma_mmap_from_dev_coherent exportChristoph Hellwig1-1/+0
dma_mmap_from_dev_coherent is only used by dma_map_ops instances, none of which is modular. Signed-off-by: Christoph Hellwig <hch@lst.de>
2019-09-04dma-mapping: remove dma_release_declared_memoryChristoph Hellwig1-11/+0
This function is entirely unused given that declared memory is generally provided by platform setup code. Signed-off-by: Christoph Hellwig <hch@lst.de>
2019-09-04dma-mapping: remove CONFIG_ARCH_NO_COHERENT_DMA_MMAPChristoph Hellwig1-7/+5
CONFIG_ARCH_NO_COHERENT_DMA_MMAP is now functionally identical to !CONFIG_MMU, so remove the separate symbol. The only difference is that arm did not set it for !CONFIG_MMU, but arm uses a separate dma mapping implementation including its own mmap method, which is handled by moving the CONFIG_MMU check in dma_can_mmap so that is only applies to the dma-direct case, just as the other ifdefs for it. Signed-off-by: Christoph Hellwig <hch@lst.de> Acked-by: Geert Uytterhoeven <geert@linux-m68k.org> # m68k
2019-09-04dma-mapping: add a dma_can_mmap helperChristoph Hellwig1-0/+23
Add a helper to check if DMA allocations for a specific device can be mapped to userspace using dma_mmap_*. Signed-off-by: Christoph Hellwig <hch@lst.de>
2019-09-04dma-mapping: explicitly wire up ->mmap and ->get_sgtableChristoph Hellwig1-8/+12
While the default ->mmap and ->get_sgtable implementations work for the majority of our dma_map_ops impementations they are inherently safe for others that don't use the page allocator or CMA and/or use their own way of remapping not covered by the common code. So remove the defaults if these methods are not wired up, but instead wire up the default implementations for all safe instances. Fixes: e1c7e324539a ("dma-mapping: always provide the dma_map_ops based implementation") Signed-off-by: Christoph Hellwig <hch@lst.de>
2019-09-04dma-mapping: move the dma_get_sgtable API comments from arm to common codeChristoph Hellwig1-0/+11
The comments are spot on and should be near the central API, not just near a single implementation. Signed-off-by: Christoph Hellwig <hch@lst.de>
2019-09-03dma-mapping: introduce dma_get_merge_boundary()Yoshihiro Shimoda1-0/+11
This patch adds a new DMA API "dma_get_merge_boundary". This function returns the DMA merge boundary if the DMA layer can merge the segments. This patch also adds the implementation for a new dma_map_ops pointer. Signed-off-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com> Reviewed-by: Simon Horman <horms+renesas@verge.net.au> Signed-off-by: Christoph Hellwig <hch@lst.de>
2019-08-29dma-mapping: make dma_atomic_pool_init self-containedChristoph Hellwig1-3/+14
The memory allocated for the atomic pool needs to have the same mapping attributes that we use for remapping, so use pgprot_dmacoherent instead of open coding it. Also deduct a suitable zone to allocate the memory from based on the presence of the DMA zones. Signed-off-by: Christoph Hellwig <hch@lst.de>
2019-08-29dma-mapping: remove arch_dma_mmap_pgprotChristoph Hellwig2-6/+14
arch_dma_mmap_pgprot is used for two things: 1) to override the "normal" uncached page attributes for mapping memory coherent to devices that can't snoop the CPU caches 2) to provide the special DMA_ATTR_WRITE_COMBINE semantics on older arm systems and some mips platforms Replace one with the pgprot_dmacoherent macro that is already provided by arm and much simpler to use, and lift the DMA_ATTR_WRITE_COMBINE handling to common code with an explicit arch opt-in. Signed-off-by: Christoph Hellwig <hch@lst.de> Acked-by: Geert Uytterhoeven <geert@linux-m68k.org> # m68k Acked-by: Paul Burton <paul.burton@mips.com> # mips
2019-08-21dma-direct: fix zone selection after an unaddressable CMA allocationChristoph Hellwig2-7/+11
The new dma_alloc_contiguous hides if we allocate CMA or regular pages, and thus fails to retry a ZONE_NORMAL allocation if the CMA allocation succeeds but isn't addressable. That means we either fail outright or dip into a small zone that might not succeed either. Thanks to Hillf Danton for debugging this issue. Fixes: b1d2dc009dec ("dma-contiguous: add dma_{alloc,free}_contiguous() helpers") Reported-by: Tobias Klausmann <tobias.johannes.klausmann@mni.thm.de> Signed-off-by: Christoph Hellwig <hch@lst.de> Tested-by: Tobias Klausmann <tobias.johannes.klausmann@mni.thm.de>
2019-08-10dma-mapping: fix page attributes for dma_mmap_*Christoph Hellwig2-2/+19
All the way back to introducing dma_common_mmap we've defaulted to mark the pages as uncached. But this is wrong for DMA coherent devices. Later on DMA_ATTR_WRITE_COMBINE also got incorrect treatment as that flag is only treated special on the alloc side for non-coherent devices. Introduce a new dma_pgprot helper that deals with the check for coherent devices so that only the remapping cases ever reach arch_dma_mmap_pgprot and we thus ensure no aliasing of page attributes happens, which makes the powerpc version of arch_dma_mmap_pgprot obsolete and simplifies the remaining ones. Note that this means arch_dma_mmap_pgprot is a bit misnamed now, but we'll phase it out soon. Fixes: 64ccc9c033c6 ("common: dma-mapping: add support for generic dma_mmap_* calls") Reported-by: Shawn Anastasio <shawn@anastas.io> Reported-by: Gavin Li <git@thegavinli.com> Signed-off-by: Christoph Hellwig <hch@lst.de> Acked-by: Catalin Marinas <catalin.marinas@arm.com> # arm64
2019-08-10dma-direct: don't truncate dma_required_mask to bus addressing capabilitiesLucas Stach1-3/+0
The dma required_mask needs to reflect the actual addressing capabilities needed to handle the whole system RAM. When truncated down to the bus addressing capabilities dma_addressing_limited() will incorrectly signal no limitations for devices which are restricted by the bus_dma_mask. Fixes: b4ebe6063204 (dma-direct: implement complete bus_dma_mask handling) Signed-off-by: Lucas Stach <l.stach@pengutronix.de> Tested-by: Atish Patra <atish.patra@wdc.com> Signed-off-by: Christoph Hellwig <hch@lst.de>
2019-08-10dma-direct: fix DMA_ATTR_NO_KERNEL_MAPPINGChristoph Hellwig1-2/+5
The new DMA_ATTR_NO_KERNEL_MAPPING needs to actually assign a dma_addr to work. Also skip it if the architecture needs forced decryption handling, as that needs a kernel virtual address. Fixes: d98849aff879 (dma-direct: handle DMA_ATTR_NO_KERNEL_MAPPING in common code) Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Lucas Stach <l.stach@pengutronix.de>
2019-08-09dma-mapping: Remove dma_check_mask()Thiago Jung Bauermann1-8/+0
sme_active() is an x86-specific function so it's better not to call it from generic code. Christoph Hellwig mentioned that "There is no reason why we should have a special debug printk just for one specific reason why there is a requirement for a large DMA mask.", so just remove dma_check_mask(). Signed-off-by: Thiago Jung Bauermann <bauerman@linux.ibm.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Tom Lendacky <thomas.lendacky@amd.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/20190806044919.10622-4-bauerman@linux.ibm.com
2019-08-09swiotlb: Remove call to sme_active()Thiago Jung Bauermann1-2/+1
sme_active() is an x86-specific function so it's better not to call it from generic code. There's no need to mention which memory encryption feature is active, so just use a more generic message. Besides, other architectures will have different names for similar technology. Signed-off-by: Thiago Jung Bauermann <bauerman@linux.ibm.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Tom Lendacky <thomas.lendacky@amd.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/20190806044919.10622-3-bauerman@linux.ibm.com
2019-08-02Merge tag 'arm-swiotlb-5.3' of git://git.infradead.org/users/hch/dma-mappingLinus Torvalds1-2/+11
Pull arm swiotlb support from Christoph Hellwig: "This fixes a cascade of regressions that originally started with the addition of the ia64 port, but only got fatal once we removed most uses of block layer bounce buffering in Linux 4.18. The reason is that while the original i386/PAE code that was the first architecture that supported > 4GB of memory without an iommu decided to leave bounce buffering to the subsystems, which in those days just mean block and networking as no one else consumed arbitrary userspace memory. Later with ia64, x86_64 and other ports we assumed that either an iommu or something that fakes it up ("software IOTLB" in beautiful Intel speak) is present and that subsystems can rely on that for dealing with addressing limitations in devices. Except that the ARM LPAE scheme that added larger physical address to 32-bit ARM did not follow that scheme and thus only worked by chance and only for block and networking I/O directly to highmem. Long story, short fix - add swiotlb support to arm when build for LPAE platforms, which actuallys turns out to be pretty trivial with the modern dma-direct / swiotlb code to fix the Linux 4.18-ish regression" * tag 'arm-swiotlb-5.3' of git://git.infradead.org/users/hch/dma-mapping: arm: use swiotlb for bounce buffering on LPAE configs dma-mapping: check pfn validity in dma_common_{mmap,get_sgtable}
2019-07-29dma-contiguous: page-align the size in dma_free_contiguous()Nicolin Chen1-1/+2
According to the original dma_direct_alloc_pages() code: { unsigned int count = PAGE_ALIGN(size) >> PAGE_SHIFT; if (!dma_release_from_contiguous(dev, page, count)) __free_pages(page, get_order(size)); } The count parameter for dma_release_from_contiguous() was page aligned before the right-shifting operation, while the new API dma_free_contiguous() forgets to have PAGE_ALIGN() at the size. So this patch simply adds it to prevent any corner case. Fixes: fdaeec198ada ("dma-contiguous: add dma_{alloc,free}_contiguous() helpers") Signed-off-by: Nicolin Chen <nicoleotsuka@gmail.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Christoph Hellwig <hch@lst.de>
2019-07-29dma-contiguous: do not overwrite align in dma_alloc_contiguous()Nicolin Chen1-2/+3
The dma_alloc_contiguous() limits align at CONFIG_CMA_ALIGNMENT for cma_alloc() however it does not restore it for the fallback routine. This will result in a size mismatch between the allocation and free when running into the fallback routines after cma_alloc() fails, if the align is larger than CONFIG_CMA_ALIGNMENT. This patch adds a cma_align to take care of cma_alloc() and prevent the align from being overwritten. Fixes: fdaeec198ada ("dma-contiguous: add dma_{alloc,free}_contiguous() helpers") Reported-by: Dafna Hirschfeld <dafna.hirschfeld@collabora.com> Signed-off-by: Nicolin Chen <nicoleotsuka@gmail.com> Signed-off-by: Christoph Hellwig <hch@lst.de>
2019-07-24dma-mapping: check pfn validity in dma_common_{mmap,get_sgtable}Christoph Hellwig1-2/+11
Check that the pfn returned from arch_dma_coherent_to_pfn refers to a valid page and reject the mmap / get_sgtable requests otherwise. Based on the arm implementation of the mmap and get_sgtable methods. Signed-off-by: Christoph Hellwig <hch@lst.de> Tested-by: Vignesh Raghavendra <vigneshr@ti.com>
2019-07-20Merge tag 'dma-mapping-5.3-1' of git://git.infradead.org/users/hch/dma-mappingLinus Torvalds2-25/+22
Pull dma-mapping fixes from Christoph Hellwig: "Fix various regressions: - force unencrypted dma-coherent buffers if encryption bit can't fit into the dma coherent mask (Tom Lendacky) - avoid limiting request size if swiotlb is not used (me) - fix swiotlb handling in dma_direct_sync_sg_for_cpu/device (Fugang Duan)" * tag 'dma-mapping-5.3-1' of git://git.infradead.org/users/hch/dma-mapping: dma-direct: correct the physical addr in dma_direct_sync_sg_for_cpu/device dma-direct: only limit the mapping size if swiotlb could be used dma-mapping: add a dma_addressing_limited helper dma-direct: Force unencrypted DMA under SME for certain DMA masks
2019-07-19dma-direct: correct the physical addr in dma_direct_sync_sg_for_cpu/deviceFugang Duan1-7/+11
dma_map_sg() may use swiotlb buffer when the kernel command line includes "swiotlb=force" or the dma_addr is out of dev->dma_mask range. After DMA complete the memory moving from device to memory, then user call dma_sync_sg_for_cpu() to sync with DMA buffer, and copy the original virtual buffer to other space. So dma_direct_sync_sg_for_cpu() should use swiotlb physical addr, not the original physical addr from sg_phys(sg). dma_direct_sync_sg_for_device() also has the same issue, correct it as well. Fixes: 55897af63091("dma-direct: merge swiotlb_dma_ops into the dma_direct code") Signed-off-by: Fugang Duan <fugang.duan@nxp.com> Reviewed-by: Robin Murphy <robin.murphy@arm.com> Signed-off-by: Christoph Hellwig <hch@lst.de>
2019-07-18Merge branch 'for-linus-5.2' of git://git.kernel.org/pub/scm/linux/kernel/git/konrad/swiotlbLinus Torvalds1-14/+16
Pull swiotlb updates from Konrad Rzeszutek Wilk: "One compiler fix, and a bug-fix in swiotlb_nr_tbl() and swiotlb_max_segment() to check also for no_iotlb_memory" * 'for-linus-5.2' of git://git.kernel.org/pub/scm/linux/kernel/git/konrad/swiotlb: swiotlb: fix phys_addr_t overflow warning swiotlb: Return consistent SWIOTLB segments/nr_tbl swiotlb: Group identical cleanup in swiotlb_cleanup()
2019-07-17dma-direct: only limit the mapping size if swiotlb could be usedChristoph Hellwig1-6/+4
Don't just check for a swiotlb buffer, but also if buffering might be required for this particular device. Fixes: 133d624b1cee ("dma: Introduce dma_max_mapping_size()") Reported-by: Benjamin Herrenschmidt <benh@kernel.crashing.org> Signed-off-by: Christoph Hellwig <hch@lst.de> Tested-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
2019-07-16dma-direct: Force unencrypted DMA under SME for certain DMA masksTom Lendacky2-12/+7
If a device doesn't support DMA to a physical address that includes the encryption bit (currently bit 47, so 48-bit DMA), then the DMA must occur to unencrypted memory. SWIOTLB is used to satisfy that requirement if an IOMMU is not active (enabled or configured in passthrough mode). However, commit fafadcd16595 ("swiotlb: don't dip into swiotlb pool for coherent allocations") modified the coherent allocation support in SWIOTLB to use the DMA direct coherent allocation support. When an IOMMU is not active, this resulted in dma_alloc_coherent() failing for devices that didn't support DMA addresses that included the encryption bit. Addressing this requires changes to the force_dma_unencrypted() function in kernel/dma/direct.c. Since the function is now non-trivial and SME/SEV specific, update the DMA direct support to add an arch override for the force_dma_unencrypted() function. The arch override is selected when CONFIG_AMD_MEM_ENCRYPT is set. The arch override function resides in the arch/x86/mm/mem_encrypt.c file and forces unencrypted DMA when either SEV is active or SME is active and the device does not support DMA to physical addresses that include the encryption bit. Fixes: fafadcd16595 ("swiotlb: don't dip into swiotlb pool for coherent allocations") Suggested-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Tom Lendacky <thomas.lendacky@amd.com> Acked-by: Thomas Gleixner <tglx@linutronix.de> [hch: moved the force_dma_unencrypted declaration to dma-mapping.h, fold the s390 fix from Halil Pasic] Signed-off-by: Christoph Hellwig <hch@lst.de>
2019-07-12Merge tag 'dma-mapping-5.3' of git://git.infradead.org/users/hch/dma-mappingLinus Torvalds4-33/+106
Pull dma-mapping updates from Christoph Hellwig: - move the USB special case that bounced DMA through a device bar into the USB code instead of handling it in the common DMA code (Laurentiu Tudor and Fredrik Noring) - don't dip into the global CMA pool for single page allocations (Nicolin Chen) - fix a crash when allocating memory for the atomic pool failed during boot (Florian Fainelli) - move support for MIPS-style uncached segments to the common code and use that for MIPS and nios2 (me) - make support for DMA_ATTR_NON_CONSISTENT and DMA_ATTR_NO_KERNEL_MAPPING generic (me) - convert nds32 to the generic remapping allocator (me) * tag 'dma-mapping-5.3' of git://git.infradead.org/users/hch/dma-mapping: (29 commits) dma-mapping: mark dma_alloc_need_uncached as __always_inline MIPS: only select ARCH_HAS_UNCACHED_SEGMENT for non-coherent platforms usb: host: Fix excessive alignment restriction for local memory allocations lib/genalloc.c: Add algorithm, align and zeroed family of DMA allocators nios2: use the generic uncached segment support in dma-direct nds32: use the generic remapping allocator for coherent DMA allocations arc: use the generic remapping allocator for coherent DMA allocations dma-direct: handle DMA_ATTR_NO_KERNEL_MAPPING in common code dma-direct: handle DMA_ATTR_NON_CONSISTENT in common code dma-mapping: add a dma_alloc_need_uncached helper openrisc: remove the partial DMA_ATTR_NON_CONSISTENT support arc: remove the partial DMA_ATTR_NON_CONSISTENT support arm-nommu: remove the partial DMA_ATTR_NON_CONSISTENT support ARM: dma-mapping: allow larger DMA mask than supported dma-mapping: truncate dma masks to what dma_addr_t can hold iommu/dma: Apply dma_{alloc,free}_contiguous functions dma-remap: Avoid de-referencing NULL atomic_pool MIPS: use the generic uncached segment support in dma-direct dma-direct: provide generic support for uncached kernel segments au1100fb: fix DMA API abuse ...
2019-07-12Merge tag 'driver-core-5.3-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-coreLinus Torvalds1-21/+4
Pull driver core and debugfs updates from Greg KH: "Here is the "big" driver core and debugfs changes for 5.3-rc1 It's a lot of different patches, all across the tree due to some api changes and lots of debugfs cleanups. Other than the debugfs cleanups, in this set of changes we have: - bus iteration function cleanups - scripts/get_abi.pl tool to display and parse Documentation/ABI entries in a simple way - cleanups to Documenatation/ABI/ entries to make them parse easier due to typos and other minor things - default_attrs use for some ktype users - driver model documentation file conversions to .rst - compressed firmware file loading - deferred probe fixes All of these have been in linux-next for a while, with a bunch of merge issues that Stephen has been patient with me for" * tag 'driver-core-5.3-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core: (102 commits) debugfs: make error message a bit more verbose orangefs: fix build warning from debugfs cleanup patch ubifs: fix build warning after debugfs cleanup patch driver: core: Allow subsystems to continue deferring probe drivers: base: cacheinfo: Ensure cpu hotplug work is done before Intel RDT arch_topology: Remove error messages on out-of-memory conditions lib: notifier-error-inject: no need to check return value of debugfs_create functions swiotlb: no need to check return value of debugfs_create functions ceph: no need to check return value of debugfs_create functions sunrpc: no need to check return value of debugfs_create functions ubifs: no need to check return value of debugfs_create functions orangefs: no need to check return value of debugfs_create functions nfsd: no need to check return value of debugfs_create functions lib: 842: no need to check return value of debugfs_create functions debugfs: provide pr_fmt() macro debugfs: log errors when something goes wrong drivers: s390/cio: Fix compilation warning about const qualifiers drivers: Add generic helper to match by of_node driver_find_device: Unify the match function with class_find_device() bus_find_device: Unify the match callback with class_find_device ...
2019-07-03swiotlb: no need to check return value of debugfs_create functionsGreg Kroah-Hartman1-21/+4
When calling debugfs functions, there is no need to ever check the return value. The function can work or not, but the code logic should never do something different based on this. Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Cc: Christoph Hellwig <hch@lst.de> Cc: Marek Szyprowski <m.szyprowski@samsung.com> Cc: Robin Murphy <robin.murphy@arm.com> Cc: iommu@lists.linux-foundation.org Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Link: https://lore.kernel.org/r/20190612144314.GA16803@kroah.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2019-06-25dma-direct: handle DMA_ATTR_NO_KERNEL_MAPPING in common codeChristoph Hellwig2-11/+16
DMA_ATTR_NO_KERNEL_MAPPING is generally implemented by allocating normal cacheable pages or CMA memory, and then returning the page pointer as the opaque handle. Lift that code from the xtensa and generic dma remapping implementations into the generic dma-direct code so that we don't even call arch_dma_alloc for these allocations. Signed-off-by: Christoph Hellwig <hch@lst.de>
2019-06-25dma-direct: handle DMA_ATTR_NON_CONSISTENT in common codeChristoph Hellwig1-2/+2
Only call into arch_dma_alloc if we require an uncached mapping, and remove the parisc code manually doing normal cached DMA_ATTR_NON_CONSISTENT allocations. Signed-off-by: Christoph Hellwig <hch@lst.de> Acked-by: Helge Deller <deller@gmx.de> # parisc
2019-06-25dma-mapping: add a dma_alloc_need_uncached helperChristoph Hellwig1-2/+2
Check if we need to allocate uncached memory for a device given the allocation flags. Switch over the uncached segment check to this helper to deal with architectures that do not support the dma_cache_sync operation and thus should not returned cacheable memory for DMA_ATTR_NON_CONSISTENT allocations. Signed-off-by: Christoph Hellwig <hch@lst.de>
2019-06-25dma-mapping: truncate dma masks to what dma_addr_t can holdChristoph Hellwig1-0/+12
The dma masks in struct device are always 64-bits wide. But for builds using a 32-bit dma_addr_t we need to ensure we don't store an unsupportable value. Before Linux 5.0 this was handled at least by the ARM dma mapping code by never allowing to set a larger dma_mask, but these days we allow the driver to just set the largest supported value and never fall back to a smaller one. Ensure this always works by truncating the value. Fixes: 9eb9e96e97b3 ("Documentation/DMA-API-HOWTO: update dma_mask sections") Signed-off-by: Christoph Hellwig <hch@lst.de>
2019-06-19Merge branch 'stable/for-linus-5.2' into devel/for-linus-5.2Konrad Rzeszutek Wilk1-2/+2
* stable/for-linus-5.2: swiotlb: fix phys_addr_t overflow warning
2019-06-19swiotlb: fix phys_addr_t overflow warningArnd Bergmann1-2/+2
On architectures that have a larger dma_addr_t than phys_addr_t, the swiotlb_tbl_map_single() function truncates its return code in the failure path, making it impossible to identify the error later, as we compare to the original value: kernel/dma/swiotlb.c:551:9: error: implicit conversion from 'dma_addr_t' (aka 'unsigned long long') to 'phys_addr_t' (aka 'unsigned int') changes value from 18446744073709551615 to 4294967295 [-Werror,-Wconstant-conversion] return DMA_MAPPING_ERROR; Use an explicit typecast here to convert it to the narrower type, and use the same expression in the error handling later. Fixes: b907e20508d0 ("swiotlb: remove SWIOTLB_MAP_ERROR") Acked-by: Stefano Stabellini <sstabellini@kernel.org> Signed-off-by: Arnd Bergmann <arnd@arndb.de> Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
2019-06-14dma-remap: Avoid de-referencing NULL atomic_poolFlorian Fainelli1-0/+3
With architectures allowing the kernel to be placed almost arbitrarily in memory (e.g.: ARM64), it is possible to have the kernel resides at physical addresses above 4GB, resulting in neither the default CMA area, nor the atomic pool from successfully allocating. This does not prevent specific peripherals from working though, one example is XHCI, which still operates correctly. Trouble comes when the XHCI driver gets suspended and resumed, since we can now trigger the following NPD: [ 12.664170] usb usb1: root hub lost power or was reset [ 12.669387] usb usb2: root hub lost power or was reset [ 12.674662] Unable to handle kernel NULL pointer dereference at virtual address 00000008 [ 12.682896] pgd = ffffffc1365a7000 [ 12.686386] [00000008] *pgd=0000000136500003, *pud=0000000136500003, *pmd=0000000000000000 [ 12.694897] Internal error: Oops: 96000006 [#1] SMP [ 12.699843] Modules linked in: [ 12.702980] CPU: 0 PID: 1499 Comm: pml Not tainted 4.9.135-1.13pre #51 [ 12.709577] Hardware name: BCM97268DV (DT) [ 12.713736] task: ffffffc136bb6540 task.stack: ffffffc1366cc000 [ 12.719740] PC is at addr_in_gen_pool+0x4/0x48 [ 12.724253] LR is at __dma_free+0x64/0xbc [ 12.728325] pc : [<ffffff80083c0df8>] lr : [<ffffff80080979e0>] pstate: 60000145 [ 12.735825] sp : ffffffc1366cf990 [ 12.739196] x29: ffffffc1366cf990 x28: ffffffc1366cc000 [ 12.744608] x27: 0000000000000000 x26: ffffffc13a8568c8 [ 12.750020] x25: 0000000000000000 x24: ffffff80098f9000 [ 12.755433] x23: 000000013a5ff000 x22: ffffff8009c57000 [ 12.760844] x21: ffffffc13a856810 x20: 0000000000000000 [ 12.766255] x19: 0000000000001000 x18: 000000000000000a [ 12.771667] x17: 0000007f917553e0 x16: 0000000000001002 [ 12.777078] x15: 00000000000a36cb x14: ffffff80898feb77 [ 12.782490] x13: ffffffffffffffff x12: 0000000000000030 [ 12.787899] x11: 00000000fffffffe x10: ffffff80098feb7f [ 12.793311] x9 : 0000000005f5e0ff x8 : 65776f702074736f [ 12.798723] x7 : 6c2062756820746f x6 : ffffff80098febb1 [ 12.804134] x5 : ffffff800809797c x4 : 0000000000000000 [ 12.809545] x3 : 000000013a5ff000 x2 : 0000000000000fff [ 12.814955] x1 : ffffff8009c57000 x0 : 0000000000000000 [ 12.820363] [ 12.821907] Process pml (pid: 1499, stack limit = 0xffffffc1366cc020) [ 12.828421] Stack: (0xffffffc1366cf990 to 0xffffffc1366d0000) [ 12.834240] f980: ffffffc1366cf9e0 ffffff80086004d0 [ 12.842186] f9a0: ffffffc13ab08238 0000000000000010 ffffff80097c2218 ffffffc13a856810 [ 12.850131] f9c0: ffffff8009c57000 000000013a5ff000 0000000000000008 000000013a5ff000 [ 12.858076] f9e0: ffffffc1366cfa50 ffffff80085f9250 ffffffc13ab08238 0000000000000004 [ 12.866021] fa00: ffffffc13ab08000 ffffff80097b6000 ffffffc13ab08130 0000000000000001 [ 12.873966] fa20: 0000000000000008 ffffffc13a8568c8 0000000000000000 ffffffc1366cc000 [ 12.881911] fa40: ffffffc13ab08130 0000000000000001 ffffffc1366cfa90 ffffff80085e3de8 [ 12.889856] fa60: ffffffc13ab08238 0000000000000000 ffffffc136b75b00 0000000000000000 [ 12.897801] fa80: 0000000000000010 ffffff80089ccb92 ffffffc1366cfac0 ffffff80084ad040 [ 12.905746] faa0: ffffffc13a856810 0000000000000000 ffffff80084ad004 ffffff80084b91a8 [ 12.913691] fac0: ffffffc1366cfae0 ffffff80084b91b4 ffffffc13a856810 ffffff80080db5cc [ 12.921636] fae0: ffffffc1366cfb20 ffffff80084b96bc ffffffc13a856810 0000000000000010 [ 12.929581] fb00: ffffffc13a856870 0000000000000000 ffffffc13a856810 ffffff800984d2b8 [ 12.937526] fb20: ffffffc1366cfb50 ffffff80084baa70 ffffff8009932ad0 ffffff800984d260 [ 12.945471] fb40: 0000000000000010 00000002eff0a065 ffffffc1366cfbb0 ffffff80084bafbc [ 12.953415] fb60: 0000000000000010 0000000000000003 ffffff80098fe000 0000000000000000 [ 12.961360] fb80: ffffff80097b6000 ffffff80097b6dc8 ffffff80098c12b8 ffffff80098c12f8 [ 12.969306] fba0: ffffff8008842000 ffffff80097b6dc8 ffffffc1366cfbd0 ffffff80080e0d88 [ 12.977251] fbc0: 00000000fffffffb ffffff80080e10bc ffffffc1366cfc60 ffffff80080e16a8 [ 12.985196] fbe0: 0000000000000000 0000000000000003 ffffff80097b6000 ffffff80098fe9f0 [ 12.993140] fc00: ffffff80097d4000 ffffff8008983802 0000000000000123 0000000000000040 [ 13.001085] fc20: ffffff8008842000 ffffffc1366cc000 ffffff80089803c2 00000000ffffffff [ 13.009029] fc40: 0000000000000000 0000000000000000 ffffffc1366cfc60 0000000000040987 [ 13.016974] fc60: ffffffc1366cfcc0 ffffff80080dfd08 0000000000000003 0000000000000004 [ 13.024919] fc80: 0000000000000003 ffffff80098fea08 ffffffc136577ec0 ffffff80089803c2 [ 13.032864] fca0: 0000000000000123 0000000000000001 0000000500000002 0000000000040987 [ 13.040809] fcc0: ffffffc1366cfd00 ffffff80083a89d4 0000000000000004 ffffffc136577ec0 [ 13.048754] fce0: ffffffc136610cc0 ffffffffffffffea ffffffc1366cfeb0 ffffffc136610cd8 [ 13.056700] fd00: ffffffc1366cfd10 ffffff800822a614 ffffffc1366cfd40 ffffff80082295d4 [ 13.064645] fd20: 0000000000000004 ffffffc136577ec0 ffffffc136610cc0 0000000021670570 [ 13.072590] fd40: ffffffc1366cfd80 ffffff80081b5d10 ffffff80097b6000 ffffffc13aae4200 [ 13.080536] fd60: ffffffc1366cfeb0 0000000000000004 0000000021670570 0000000000000004 [ 13.088481] fd80: ffffffc1366cfe30 ffffff80081b6b20 ffffffc13aae4200 0000000000000000 [ 13.096427] fda0: 0000000000000004 0000000021670570 ffffffc1366cfeb0 ffffffc13a838200 [ 13.104371] fdc0: 0000000000000000 000000000000000a ffffff80097b6000 0000000000040987 [ 13.112316] fde0: ffffffc1366cfe20 ffffff80081b3af0 ffffffc13a838200 0000000000000000 [ 13.120261] fe00: ffffffc1366cfe30 ffffff80081b6b0c ffffffc13aae4200 0000000000000000 [ 13.128206] fe20: 0000000000000004 0000000000040987 ffffffc1366cfe70 ffffff80081b7dd8 [ 13.136151] fe40: ffffff80097b6000 ffffffc13aae4200 ffffffc13aae4200 fffffffffffffff7 [ 13.144096] fe60: 0000000021670570 ffffffc13a8c63c0 0000000000000000 ffffff8008083180 [ 13.152042] fe80: ffffffffffffff1d 0000000021670570 ffffffffffffffff 0000007f917ad9b8 [ 13.159986] fea0: 0000000020000000 0000000000000015 0000000000000000 0000000000040987 [ 13.167930] fec0: 0000000000000001 0000000021670570 0000000000000004 0000000000000000 [ 13.175874] fee0: 0000000000000888 0000440110000000 000000000000006d 0000000000000003 [ 13.183819] ff00: 0000000000000040 ffffff80ffffffc8 0000000000000000 0000000000000020 [ 13.191762] ff20: 0000000000000000 0000000000000000 0000000000000001 0000000000000000 [ 13.199707] ff40: 0000000000000000 0000007f917553e0 0000000000000000 0000000000000004 [ 13.207651] ff60: 0000000021670570 0000007f91835480 0000000000000004 0000007f91831638 [ 13.215595] ff80: 0000000000000004 00000000004b0de0 00000000004b0000 0000000000000000 [ 13.223539] ffa0: 0000000000000000 0000007fc92ac8c0 0000007f9175d178 0000007fc92ac8c0 [ 13.231483] ffc0: 0000007f917ad9b8 0000000020000000 0000000000000001 0000000000000040 [ 13.239427] ffe0: 0000000000000000 0000000000000000 0000000000000000 0000000000000000 [ 13.247360] Call trace: [ 13.249866] Exception stack(0xffffffc1366cf7a0 to 0xffffffc1366cf8d0) [ 13.256386] f7a0: 0000000000001000 0000007fffffffff ffffffc1366cf990 ffffff80083c0df8 [ 13.264331] f7c0: 0000000060000145 ffffff80089b5001 ffffffc13ab08130 0000000000000001 [ 13.272275] f7e0: 0000000000000008 ffffffc13a8568c8 0000000000000000 0000000000000000 [ 13.280220] f800: ffffffc1366cf960 ffffffc1366cf960 ffffffc1366cf930 00000000ffffffd8 [ 13.288165] f820: ffffff8009931ac0 4554535953425553 4544006273753d4d 3831633d45434956 [ 13.296110] f840: ffff003832313a39 ffffff800845926c ffffffc1366cf880 0000000000040987 [ 13.304054] f860: 0000000000000000 ffffff8009c57000 0000000000000fff 000000013a5ff000 [ 13.311999] f880: 0000000000000000 ffffff800809797c ffffff80098febb1 6c2062756820746f [ 13.319944] f8a0: 65776f702074736f 0000000005f5e0ff ffffff80098feb7f 00000000fffffffe [ 13.327884] f8c0: 0000000000000030 ffffffffffffffff [ 13.332835] [<ffffff80083c0df8>] addr_in_gen_pool+0x4/0x48 [ 13.338398] [<ffffff80086004d0>] xhci_mem_cleanup+0xc8/0x51c [ 13.344137] [<ffffff80085f9250>] xhci_resume+0x308/0x65c [ 13.349524] [<ffffff80085e3de8>] xhci_brcm_resume+0x84/0x8c [ 13.355174] [<ffffff80084ad040>] platform_pm_resume+0x3c/0x64 [ 13.360997] [<ffffff80084b91b4>] dpm_run_callback+0x5c/0x15c [ 13.366732] [<ffffff80084b96bc>] device_resume+0xc0/0x190 [ 13.372205] [<ffffff80084baa70>] dpm_resume+0x144/0x2cc [ 13.377504] [<ffffff80084bafbc>] dpm_resume_end+0x20/0x34 [ 13.382980] [<ffffff80080e0d88>] suspend_devices_and_enter+0x104/0x704 [ 13.389585] [<ffffff80080e16a8>] pm_suspend+0x320/0x53c [ 13.394881] [<ffffff80080dfd08>] state_store+0xbc/0xe0 [ 13.400094] [<ffffff80083a89d4>] kobj_attr_store+0x14/0x24 [ 13.405655] [<ffffff800822a614>] sysfs_kf_write+0x60/0x70 [ 13.411128] [<ffffff80082295d4>] kernfs_fop_write+0x130/0x194 [ 13.416954] [<ffffff80081b5d10>] __vfs_write+0x60/0x150 [ 13.422254] [<ffffff80081b6b20>] vfs_write+0xc8/0x164 [ 13.427376] [<ffffff80081b7dd8>] SyS_write+0x70/0xc8 [ 13.432412] [<ffffff8008083180>] el0_svc_naked+0x34/0x38 [ 13.437800] Code: 92800173 97f6fb9e 17fffff5 d1000442 (f8408c03) [ 13.444033] ---[ end trace 2effe12f909ce205 ]--- The call path leading to this problem is xhci_mem_cleanup() -> dma_free_coherent() -> dma_free_from_pool() -> addr_in_gen_pool. If the atomic_pool is NULL, we can't possibly have the address in the atomic pool anyway, so guard against that. Signed-off-by: Florian Fainelli <f.fainelli@gmail.com> Signed-off-by: Christoph Hellwig <hch@lst.de>
2019-06-11swiotlb: Return consistent SWIOTLB segments/nr_tblFlorian Fainelli1-4/+4
With a specifically contrived memory layout where there is no physical memory available to the kernel below the 4GB boundary, we will fail to perform the initial swiotlb_init() call and set no_iotlb_memory to true. There are drivers out there that call into swiotlb_nr_tbl() to determine whether they can use the SWIOTLB. With the right DMA_BIT_MASK() value for these drivers (say 64-bit), they won't ever need to hit swiotlb_tbl_map_single() so this can go unoticed and we would be possibly lying about those drivers. Signed-off-by: Florian Fainelli <f.fainelli@gmail.com> Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
2019-06-11swiotlb: Group identical cleanup in swiotlb_cleanup()Florian Fainelli1-8/+10
Avoid repeating the zeroing of global swiotlb variables in two locations and introduce swiotlb_cleanup() to do that. Signed-off-by: Florian Fainelli <f.fainelli@gmail.com> Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
2019-06-05treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 333Thomas Gleixner1-13/+1
Based on 1 normalized pattern(s): 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 extracted by the scancode license scanner the SPDX license identifier GPL-2.0-only has been chosen to replace the boilerplate/reference in 136 file(s). Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Reviewed-by: Alexios Zavras <alexios.zavras@intel.com> Reviewed-by: Allison Randal <allison@lohutok.net> Cc: linux-spdx@vger.kernel.org Link: https://lkml.kernel.org/r/20190530000436.384967451@linutronix.de Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2019-06-03dma-direct: provide generic support for uncached kernel segmentsChristoph Hellwig1-2/+15
A few architectures support uncached kernel segments. In that case we get an uncached mapping for a given physica address by using an offset in the uncached segement. Implement support for this scheme in the generic dma-direct code instead of duplicating it in arch hooks. Signed-off-by: Christoph Hellwig <hch@lst.de>
2019-06-03dma-contiguous: use fallback alloc_pages for single pagesNicolin Chen1-1/+10
The addresses within a single page are always contiguous, so it's not so necessary to always allocate one single page from CMA area. Since the CMA area has a limited predefined size of space, it may run out of space in heavy use cases, where there might be quite a lot CMA pages being allocated for single pages. However, there is also a concern that a device might care where a page comes from -- it might expect the page from CMA area and act differently if the page doesn't. This patch tries to use the fallback alloc_pages path, instead of one-page size allocations from the global CMA area in case that a device does not have its own CMA area. This'd save resources from the CMA global area for more CMA allocations, and also reduce CMA fragmentations resulted from trivial allocations. Signed-off-by: Nicolin Chen <nicoleotsuka@gmail.com> Tested-by: dann frazier <dann.frazier@canonical.com> Signed-off-by: Christoph Hellwig <hch@lst.de>
2019-06-03dma-contiguous: add dma_{alloc,free}_contiguous() helpersNicolin Chen2-20/+51
Both dma_alloc_from_contiguous() and dma_release_from_contiguous() are very simply implemented, but requiring callers to pass certain parameters like count and align, and taking a boolean parameter to check __GFP_NOWARN in the allocation flags. So every function call duplicates similar work: unsigned long order = get_order(size); size_t count = size >> PAGE_SHIFT; page = dma_alloc_from_contiguous(dev, count, order, gfp & __GFP_NOWARN); [...] dma_release_from_contiguous(dev, page, size >> PAGE_SHIFT); Additionally, as CMA can be used only in the context which permits sleeping, most of callers do a gfpflags_allow_blocking() check and a corresponding fallback allocation of normal pages upon any false result: if (gfpflags_allow_blocking(flag)) page = dma_alloc_from_contiguous(); if (!page) page = alloc_pages(); [...] if (!dma_release_from_contiguous(dev, page, count)) __free_pages(page, get_order(size)); So this patch simplifies those function calls by abstracting these operations into the two new functions: dma_{alloc,free}_contiguous. As some callers of dma_{alloc,release}_from_contiguous() might be complicated, this patch just implements these two new functions to kernel/dma/direct.c only as an initial step. Suggested-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Nicolin Chen <nicoleotsuka@gmail.com> Tested-by: dann frazier <dann.frazier@canonical.com> Signed-off-by: Christoph Hellwig <hch@lst.de>
2019-05-21treewide: Add SPDX license identifier - Makefile/KconfigThomas Gleixner1-0/+1
Add SPDX license identifiers to all Make/Kconfig files which: - Have no license information of any form These files fall under the project license, GPL v2 only. The resulting SPDX license identifier is: GPL-2.0-only Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2019-05-21treewide: Add SPDX license identifier for missed filesThomas Gleixner1-0/+1
Add SPDX license identifiers to all files which: - Have no license information of any form - Have EXPORT_.*_SYMBOL_GPL inside which was used in the initial scan/conversion to ignore the file These files fall under the project license, GPL v2 only. The resulting SPDX license identifier is: GPL-2.0-only Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2019-05-09Merge tag 'dma-mapping-5.2' of git://git.infradead.org/users/hch/dma-mappingLinus Torvalds3-9/+6
Pull DMA mapping updates from Christoph Hellwig: - remove the already broken support for NULL dev arguments to the DMA API calls - Kconfig tidyups * tag 'dma-mapping-5.2' of git://git.infradead.org/users/hch/dma-mapping: dma-mapping: add a Kconfig symbol to indicate arch_dma_prep_coherent presence dma-mapping: remove an unnecessary NULL check x86/dma: Remove the x86_dma_fallback_dev hack dma-mapping: remove leftover NULL device support arm: use a dummy struct device for ISA DMA use of the DMA API pxa3xx-gcu: pass struct device to dma_mmap_coherent gbefb: switch to managed version of the DMA allocator da8xx-fb: pass struct device to DMA API functions parport_ip32: pass struct device to DMA API functions dma: select GENERIC_ALLOCATOR for DMA_REMAP
2019-05-07Merge branch 'stable/for-linus-5.2' of git://git.kernel.org/pub/scm/linux/kernel/git/konrad/swiotlbLinus Torvalds1-1/+5
Pull swiotlb updates from Konrad Rzeszutek Wilk: "Cleanups in the swiotlb code and extra debugfs knobs to help with the field diagnostics" * 'stable/for-linus-5.2' of git://git.kernel.org/pub/scm/linux/kernel/git/konrad/swiotlb: swiotlb-xen: ensure we have a single callsite for xen_dma_map_page swiotlb-xen: simplify the DMA sync method implementations swiotlb-xen: use ->map_page to implement ->map_sg swiotlb-xen: make instances match their method names swiotlb: save io_tlb_used to local variable before leaving critical section swiotlb: dump used and total slots when swiotlb buffer is full
2019-05-06dma-mapping: add a Kconfig symbol to indicate arch_dma_prep_coherent presenceChristoph Hellwig1-0/+3
Add a Kconfig symbol that indicates an architecture provides a arch_dma_prep_coherent implementation, and provide a stub otherwise. This will allow the generic dma-iommu code to use it while still allowing to be built for cache coherent architectures. Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Robin Murphy <robin.murphy@arm.com>
2019-04-29dma/debug: Simplify stracktrace retrievalThomas Gleixner1-8/+6
Replace the indirection through struct stack_trace with an invocation of the storage array based interface. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Reviewed-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Josh Poimboeuf <jpoimboe@redhat.com> Cc: Andy Lutomirski <luto@kernel.org> Cc: iommu@lists.linux-foundation.org Cc: Robin Murphy <robin.murphy@arm.com> Cc: Marek Szyprowski <m.szyprowski@samsung.com> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Alexander Potapenko <glider@google.com> Cc: Alexey Dobriyan <adobriyan@gmail.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Christoph Lameter <cl@linux.com> Cc: Pekka Enberg <penberg@kernel.org> Cc: linux-mm@kvack.org Cc: David Rientjes <rientjes@google.com> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Dmitry Vyukov <dvyukov@google.com> Cc: Andrey Ryabinin <aryabinin@virtuozzo.com> Cc: kasan-dev@googlegroups.com Cc: Mike Rapoport <rppt@linux.vnet.ibm.com> Cc: Akinobu Mita <akinobu.mita@gmail.com> Cc: Johannes Thumshirn <jthumshirn@suse.de> Cc: David Sterba <dsterba@suse.com> Cc: Chris Mason <clm@fb.com> Cc: Josef Bacik <josef@toxicpanda.com> Cc: linux-btrfs@vger.kernel.org Cc: dm-devel@redhat.com Cc: Mike Snitzer <snitzer@redhat.com> Cc: Alasdair Kergon <agk@redhat.com> Cc: Daniel Vetter <daniel@ffwll.ch> Cc: intel-gfx@lists.freedesktop.org Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com> Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com> Cc: dri-devel@lists.freedesktop.org Cc: David Airlie <airlied@linux.ie> Cc: Jani Nikula <jani.nikula@linux.intel.com> Cc: Rodrigo Vivi <rodrigo.vivi@intel.com> Cc: Tom Zanussi <tom.zanussi@linux.intel.com> Cc: Miroslav Benes <mbenes@suse.cz> Cc: linux-arch@vger.kernel.org Link: https://lkml.kernel.org/r/20190425094802.248658135@linutronix.de
2019-04-24dma-mapping: remove an unnecessary NULL checkDan Carpenter1-1/+1
We already dereferenced "dev" when we called get_dma_ops() so this NULL check is too late. We're not supposed to pass NULL "dev" pointers to dma_alloc_attrs(). Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com> Signed-off-by: Christoph Hellwig <hch@lst.de>
2019-04-12swiotlb: save io_tlb_used to local variable before leaving critical sectionDongli Zhang1-2/+5
When swiotlb is full, the kernel would print io_tlb_used. However, the result might be inaccurate at that time because we have left the critical section protected by spinlock. Therefore, we backup the io_tlb_used into local variable before leaving critical section. Fixes: 83ca25948940 ("swiotlb: dump used and total slots when swiotlb buffer is full") Suggested-by: Håkon Bugge <haakon.bugge@oracle.com> Signed-off-by: Dongli Zhang <dongli.zhang@oracle.com> Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
2019-04-11dma-debug: only skip one stackframe entryScott Wood1-1/+1
With skip set to 1, I get a traceback like this: [ 106.867637] DMA-API: Mapped at: [ 106.870784] afu_dma_map_region+0x2cd/0x4f0 [dfl_afu] [ 106.875839] afu_ioctl+0x258/0x380 [dfl_afu] [ 106.880108] do_vfs_ioctl+0xa9/0x720 [ 106.883688] ksys_ioctl+0x60/0x90 [ 106.887007] __x64_sys_ioctl+0x16/0x20 With the previous value of 2, afu_dma_map_region was being omitted. I suspect that the code paths have simply changed since the value of 2 was chosen a decade ago, but it's also possible that it varies based on which mapping function was used, compiler inlining choices, etc. In any case, it's best to err on the side of skipping less. Signed-off-by: Scott Wood <swood@redhat.com> Signed-off-by: Christoph Hellwig <hch@lst.de>
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