android/workload: allow collection of kernel's symbols address

Created by: derkling

Kernel symbols are useful to support debugging of tasks traces and ftrace allows to inject a backtrack from code via a simple call to trace_dump_stack(). When the trace is dumped, the backtrace addresses can be translated to function names via the mapping available in: /proc/kallsyms

However, for security reasons, the content of this file reports the actual addresses only if access has not been "not restricted", which is the default configuration.

This patch disable such restriction by pocking the provided procfs configuration file (/proc/sys/kernel/kptr_restrict) every time we start a tracing using either ftrace or systrace.

Signed-off-by: Patrick Bellasi patrick.bellasi@arm.com