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94ac529a99
Currently, we pick the MMIO offset based on the size of the pgoff_t type seen by the process that manipulates the FD, such that a 32-bit process can always map the user MMIO ranges. But this approach doesn't work well for emulators like FEX, where the emulator is a 64-bit binary which might be executing 32-bit code. In that case, the kernel thinks it's the 64-bit process and assumes DRM_PANTHOR_USER_MMIO_OFFSET_64BIT is in use, but the UMD library expects DRM_PANTHOR_USER_MMIO_OFFSET_32BIT, because it can't mmap() anything above the pgoff_t size. In order to solve that, we need a way to explicitly set the user MMIO offset from the UMD, such that the kernel doesn't have to guess it from the TIF_32BIT flag set on user thread. We keep the old behavior if DRM_PANTHOR_SET_USER_MMIO_OFFSET is never called. Changes in v2: - Drop the lock/immutable fields and allow SET_USER_MMIO_OFFSET requests to race with mmap() requests - Don't do the is_user_mmio_offset test twice in panthor_mmap() - Improve the uAPI docs Changes in v3: - Bump to version 1.5 instead of 1.4 after rebasing - Add R-bs - Fix/rephrase comment as suggested by Liviu Reviewed-by: Adrián Larumbe <adrian.larumbe@collabora.com> Reviewed-by: Steven Price <steven.price@arm.com> Reviewed-by: Liviu Dudau <liviu.dudau@arm.com> Link: https://lore.kernel.org/r/20250606080932.4140010-3-boris.brezillon@collabora.com Signed-off-by: Boris Brezillon <boris.brezillon@collabora.com> |
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| .. | ||
| asm-generic | ||
| cxl | ||
| drm | ||
| fwctl | ||
| linux | ||
| misc | ||
| mtd | ||
| rdma | ||
| regulator | ||
| scsi | ||
| sound | ||
| video | ||
| xen | ||
| Kbuild | ||