um: Implement probe_kernel_read()

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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: <stian@nixia.no>
Cc: <tj@kernel.org>
Cc: <stable@vger.kernel.org> # 3.10.x
Signed-off-by: Richard Weinberger <richard@nod.at>

...

This commit is contained in:

Richard Weinberger 2013-08-17 18:46:00 +02:00

parent 65984ff9d2

commit f75b1b1bed

4 changed files with 78 additions and 1 deletions

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1

arch/um/include/shared/os.h

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2

arch/um/kernel/Makefile

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24

arch/um/kernel/maccess.c

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52

arch/um/os-Linux/process.c

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