[PATCH] ARM: ftrace: Ensure code modifications are synchronised across all cpus
Jon Medhurst (Tixy)
tixy at linaro.org
Mon Dec 10 06:04:05 EST 2012
On Fri, 2012-12-07 at 19:02 +0000, Will Deacon wrote:
> For ARMv7, there are small subsets of instructions for ARM and Thumb which
> are guaranteed to be atomic wrt concurrent modification and execution of
> the instruction stream between different processors:
>
> Thumb: The 16-bit encodings of the B, NOP, BKPT, and SVC instructions.
> ARM: The B, BL, NOP, BKPT, SVC, HVC, and SMC instructions.
>
So this means for things like kprobes which can modify arbitrary kernel
code we are going to need to continue to always use some form of
stop_the_whole_system() function?
Also, kprobes currently uses patch_text() which only uses stop_machine
for Thumb2 instructions which straddle a word boundary, so this needs
changing?
--
Tixy
More information about the linux-arm-kernel
mailing list