um: Implement probe_kernel_read()
UML needs it's own probe_kernel_read() to handle kernel
mode faults correctly.
The implementation uses mincore() on the host side to detect
whether a page is owned by the UML kernel process.
This fixes also a possible crash when sysrq-t is used.
Starting with 3.10 sysrq-t calls probe_kernel_read() to
read details from the kernel workers. As kernel worker are
completely async pointers may turn NULL while reading them.
Cc: <[email protected]>
Cc: <[email protected]>
Cc: <[email protected]> # 3.10.x
Signed-off-by: Richard Weinberger <[email protected]>
4 files changed
