This patch adds definitions to support user space device mappings
that allows devices like frame buffer to be accessible from user
space in kernel mode.
The are mainly two changes:
- in `mm/`:
added vm_map_region(), vm_unmap_region() for drivers to do
device mapping easily.
- in `arch/`:
extended ARCH_SHM_NPAGES as user-space mapping region size.
decoupled ARCH_SHM_MAXREGIONS from region size calculations and
limit its usage only for SysV shm purposes.
Signed-off-by: Yanfeng Liu <yfliu2008@qq.com>
ctc E246: ["map/mm_map.c" 67/41] left side of '.' or '->' is not struct or union
ctc E260: ["map/mm_map.c" 67/25] not an lvalue
ctc E246: ["map/mm_map.c" 80/3] left side of '.' or '->' is not struct or union
ctc E260: ["map/mm_map.c" 80/3] not an lvalue
Signed-off-by: chao an <anchao@lixiang.com>
No memory map count limit that will exhaust memory and cause
the system hang. Also that fix pass LTP posix case mmap/24-1.c
Signed-off-by: fangxinyong <fangxinyong@xiaomi.com>
This way the mappings can be modified for any vm area, not only the
process that is running.
Why? This allows mapping pages to kernel dynamically, this functionality
will be presented later.
The task_group specific list can be used to store information about
mmappings.
For a driver or filesystem performing mmap can also enable munmap by
adding an item to this list using mm_map_add(). The item is then
returned in the corresponding munmap call.
Signed-off-by: Jukka Laitinen <jukkax@ssrc.tii.ae>
