On Thu, 11 Mar 2021 14:45:38 +0530, Ravi Bangoria wrote:

As per ISA 3.1, prefixed instruction should not cross 64-byte
boundary. So don't allow Uprobe on such prefixed instruction.

There are two ways probed instruction is changed in mapped pages.
First, when Uprobe is activated, it searches for all the relevant
pages and replace instruction in them. In this case, if that probe
is on the 64-byte unaligned prefixed instruction, error out
directly. Second, when Uprobe is already active and user maps a
relevant page via mmap(), instruction is replaced via mmap() code
path. But because Uprobe is invalid, entire mmap() operation can
not be stopped. In this case just print an error and continue.

Applied to powerpc/next.

[1/1] powerpc/uprobes: Validation for prefixed instruction
      https://git.kernel.org/powerpc/c/d943bc742a6aabc578b6b62a713ceedf8bf16623

cheers