kernel/linux.git/include/linux/iosys-map.h, branch v6.19.11

iosys-map: Fix undefined behavior in iosys_map_clear()

2025-08-11T15:26:38+00:00

The current iosys_map_clear() implementation reads the potentially uninitialized 'is_iomem' boolean field to decide which union member to clear. This causes undefined behavior when called on uninitialized structures, as 'is_iomem' may contain garbage values like 0xFF. UBSAN detects this as: UBSAN: invalid-load in include/linux/iosys-map.h:267 load of value 255 is not a valid value for type '_Bool' Fix by unconditionally clearing the entire structure with memset(), eliminating the need to read uninitialized data and ensuring all fields are set to known good values. Closes: https://gitlab.freedesktop.org/drm/i915/kernel/-/issues/14639 Fixes: 01fd30da0474 ("dma-buf: Add struct dma-buf-map for storing struct dma_buf.vaddr_ptr") Signed-off-by: Nitin Gote Reviewed-by: Andi Shyti Reviewed-by: Thomas Zimmermann Signed-off-by: Thomas Zimmermann Link: https://lore.kernel.org/r/20250718105051.2709487-1-nitin.r.gote@intel.com

iosys-map: fix typo

2024-02-14T10:14:40+00:00

Correct a spello/typo in comments. Signed-off-by: Randy Dunlap Cc: Thomas Zimmermann Cc: dri-devel@lists.freedesktop.org Reviewed-by: Thomas Zimmermann Signed-off-by: Thomas Zimmermann Link: https://patchwork.freedesktop.org/patch/msgid/20240213224219.10644-1-rdunlap@infradead.org

iosys-map: Rename locals used inside macros

2023-11-14T17:09:18+00:00

Widely used variable names can be used by macro users, potentially leading to name collisions. Suffix locals used inside the macros with an underscore, to reduce the collision potential. Suggested-by: Lucas De Marchi Signed-off-by: Michał Winiarski Reviewed-by: Lucas De Marchi Signed-off-by: Lucas De Marchi Link: https://patchwork.freedesktop.org/patch/msgid/20231024110710.3039807-1-michal.winiarski@intel.com

iosys-map: fix kernel-doc typos

2023-10-12T07:58:02+00:00

Correct spelling of "beginning". Signed-off-by: Randy Dunlap Cc: Thomas Zimmermann Cc: dri-devel@lists.freedesktop.org Reviewed-by: Thomas Zimmermann Signed-off-by: Thomas Zimmermann Link: https://patchwork.freedesktop.org/patch/msgid/20230930221428.18463-2-rdunlap@infradead.org

iosys-map: Add IOSYS_MAP_INIT_VADDR_IOMEM()

2022-08-10T07:15:16+00:00

Add IOSYS_MAP_INIT_VADDR_IOMEM() for static init of variables of type struct iosys_map. Signed-off-by: Thomas Zimmermann Reviewed-by: Lucas De Marchi Reviewed-by: Sam Ravnborg Link: https://patchwork.freedesktop.org/patch/msgid/20220808125406.20752-2-tzimmermann@suse.de

iosys-map: Add per-word write

2022-06-30T00:42:28+00:00

Like was done for read, provide the equivalent for write. Even if current users are not in the hot path, this should future-proof it. v2: - Remove default from _Generic() - callers wanting to write more than u64 should use iosys_map_memcpy_to() - Add WRITE_ONCE() cases dereferencing the pointer when using system memory v3: - Fix precedence issue when casting inside WRITE_ONCE(). By not using () around vaddr__ the offset was not part of the cast, but rather added to it, producing a wrong address - Remove compiletime_assert() as WRITE_ONCE() already contains it Signed-off-by: Lucas De Marchi Reviewed-by: Reviewed-by: Christian König # v1 Reviewed-by: Thomas Zimmermann Link: https://patchwork.freedesktop.org/patch/msgid/20220628191016.3899428-2-lucas.demarchi@intel.com

iosys-map: Add per-word read

2022-06-30T00:41:32+00:00

Instead of always falling back to memcpy_fromio() for any size, prefer using read{b,w,l}(). When reading struct members it's common to read individual integer variables individually. Going through memcpy_fromio() for each of them poses a high penalty. Employ a similar trick as __seqprop() by using _Generic() to generate only the specific call based on a type-compatible variable. For a pariticular i915 workload producing GPU context switches, __get_engine_usage_record() is particularly hot since the engine usage is read from device local memory with dgfx, possibly multiple times since it's racy. Test execution time for this test shows a ~12.5% improvement with DG2: Before: nrepeats = 1000; min = 7.63243e+06; max = 1.01817e+07; median = 9.52548e+06; var = 526149; After: nrepeats = 1000; min = 7.03402e+06; max = 8.8832e+06; median = 8.33955e+06; var = 333113; Other things attempted that didn't prove very useful: 1) Change the _Generic() on x86 to just dereference the memory address 2) Change __get_engine_usage_record() to do just 1 read per loop, comparing with the previous value read 3) Change __get_engine_usage_record() to access the fields directly as it was before the conversion to iosys-map (3) did gave a small improvement (~3%), but doesn't seem to scale well to other similar cases in the driver. Additional test by Chris Wilson using gem_create from igt with some changes to track object creation time. This happens to accidentally stress this code path: Pre iosys_map conversion of engine busyness: lmem0: Creating 262144 4KiB objects took 59274.2ms Unpatched: lmem0: Creating 262144 4KiB objects took 108830.2ms With readl (this patch): lmem0: Creating 262144 4KiB objects took 61348.6ms s/readl/READ_ONCE/ lmem0: Creating 262144 4KiB objects took 61333.2ms So we do take a little bit more time than before the conversion, but that is due to other factors: bringing the READ_ONCE back would be as good as just doing this conversion. v2: - Remove default from _Generic() - callers wanting to read more than u64 should use iosys_map_memcpy_from() - Add READ_ONCE() cases dereferencing the pointer when using system memory v3: - Fix precedence issue when casting inside READ_ONCE(). By not using () around vaddr__ the offset was not part of the cast, but rather added to it, producing a wrong address - Remove compiletime_assert() as READ_ONCE() already contains it Signed-off-by: Lucas De Marchi Reviewed-by: Christian König # v1 Reviewed-by: Thomas Zimmermann Link: https://patchwork.freedesktop.org/patch/msgid/20220628191016.3899428-1-lucas.demarchi@intel.com

iosys-map: Fix typo in documentation

2022-06-16T23:44:34+00:00

It's one argument, vaddr_iomem, not 2 (vaddr and _iomem). Signed-off-by: Lucas De Marchi Reviewed-by: Christian König Link: https://patchwork.freedesktop.org/patch/msgid/20220610232130.2865479-3-lucas.demarchi@intel.com

iosys-map: Add a few more helpers

2022-02-20T03:23:53+00:00

First the simplest ones: - iosys_map_memset(): when abstracting system and I/O memory, just like the memcpy() use case, memset() also has dedicated functions to be called for using IO memory. - iosys_map_memcpy_from(): we may need to copy data from I/O memory, not only to. In certain situations it's useful to be able to read or write to an offset that is calculated by having the memory layout given by a struct declaration. Usually we are going to read/write a u8, u16, u32 or u64. As a pre-requisite for the implementation, add iosys_map_memcpy_from() to be the equivalent of iosys_map_memcpy_to(), but in the other direction. Then add 2 pairs of macros: - iosys_map_rd() / iosys_map_wr() - iosys_map_rd_field() / iosys_map_wr_field() The first pair takes the C-type and offset to read/write. The second pair uses a struct describing the layout of the mapping in order to calculate the offset and size being read/written. We could use readb, readw, readl, readq and the write* counterparts, however due to alignment issues this may not work on all architectures. If alignment needs to be checked to call the right function, it's not possible to decide at compile-time which function to call: so just leave the decision to the memcpy function that will do exactly that. Finally, in order to use the above macros with a map derived from another, add another initializer: IOSYS_MAP_INIT_OFFSET(). v2: - Rework IOSYS_MAP_INIT_OFFSET() so it doesn't rely on aliasing rules within the union - Add offset to both iosys_map_rd_field() and iosys_map_wr_field() to allow the struct itself to be at an offset from the mapping - Add documentation to iosys_map_rd_field() with example and expected memory layout v3: - Drop kernel.h include as it's not needed anymore Cc: Sumit Semwal Cc: Christian König Cc: Thomas Zimmermann Cc: Mauro Carvalho Chehab Cc: dri-devel@lists.freedesktop.org Cc: linux-kernel@vger.kernel.org Signed-off-by: Lucas De Marchi Reviewed-by: Mauro Carvalho Chehab Reviewed-by: Matt Atwood Reviewed-by: Thomas Zimmermann Link: https://patchwork.freedesktop.org/patch/msgid/20220216174147.3073235-3-lucas.demarchi@intel.com

iosys-map: Add offset to iosys_map_memcpy_to()

2022-02-20T03:23:52+00:00

In certain situations it's useful to be able to write to an offset of the mapping. Add a dst_offset to iosys_map_memcpy_to(). Cc: Sumit Semwal Cc: Christian König Cc: Thomas Zimmermann Cc: dri-devel@lists.freedesktop.org Cc: linux-kernel@vger.kernel.org Signed-off-by: Lucas De Marchi Reviewed-by: Christian König Reviewed-by: Thomas Zimmermann Link: https://patchwork.freedesktop.org/patch/msgid/20220216174147.3073235-2-lucas.demarchi@intel.com