tracing: Show real address for trace event arguments

To help debugging kernel, show real address for trace event arguments in tracefs/trace{,pipe} instead of hashed pointer value. Since ftrace human-readable format uses vsprintf(), all %p are translated to hash values instead of pointer address. However, when debugging the kernel, raw address value gives a hint when comparing with the memory mapping in the kernel. (Those are sometimes used with crash log, which is not hashed too) So converting %p with %px when calling trace_seq_printf(). Moreover, this is not improving the security because the tracefs can be used only by root user and the raw address values are readable from tracefs/percpu/cpu*/trace_pipe_raw file. Link: https://lkml.kernel.org/r/160277370703.29307.5134475491761971203.stgit@devnote2

MHMasami Hiramatsu committed 6 years ago