On Wed, 14 Oct 2020 17:59:19 +0900 Masami Hiramatsu <mhira...@kernel.org> wrote:
> To help debugging kernel, use %px to show real addresses on > tracefs/trace file. > > 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) > > 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. > > Note that this has been done by the following script. > > #!/bin/sh > tmp=`mktemp` > for h in include/trace/events/*.h ; do > sed -e 's/\(%p\)\([^a-zA-Z]\)/\1x\2/g' $h > $tmp > cp $tmp $h > done > rm $tmp > > Signed-off-by: Masami Hiramatsu <mhira...@kernel.org> Hi Masami, I think a better approach is to inject on the output side a conversion of "%p" to "%px" before printing. That is, in the trace_raw_output_##call() function, instead of calling trace_seq_printf(s, print), we call a new function trace_event_printf(s, print), that will take the fmt parameter, and copies it to something that does your 's/\(%p\)\([^a-zA-Z]\)/\1x\2/g' inline before passing it off to trace_seq_printf(). -- Steve
