linux-kernel - Re: [RFC][PATCH] tracing, printk: Force no hashing when trace

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Message-ID: <20180403185937.5bcc66de@gandalf.local.home>
Date:   Tue, 3 Apr 2018 18:59:37 -0400
From:   Steven Rostedt <rostedt@...dmis.org>
To:     "Tobin C. Harding" <me@...in.cc>
Cc:     Kees Cook <keescook@...omium.org>,
        LKML <linux-kernel@...r.kernel.org>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        David Laight <David.Laight@...lab.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Ingo Molnar <mingo@...nel.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Sergey Senozhatsky <sergey.senozhatsky.work@...il.com>,
        Petr Mladek <pmladek@...e.com>
Subject: Re: [RFC][PATCH] tracing, printk: Force no hashing when
 trace_printk() is used

On Wed, 4 Apr 2018 07:43:49 +1000
"Tobin C. Harding" <me@...in.cc> wrote:

> >  static noinline_for_stack
> >  char *restricted_pointer(char *buf, char *end, const void *ptr,
> > @@ -1962,6 +1963,10 @@ char *pointer(const char *fmt, char *buf, char *end, void *ptr,
> >  		return pointer_string(buf, end, ptr, spec);
> >  	}
> >  
> > +	/* When the kernel is in debugging mode, show all pointers */
> > +	if (static_key_false(&trace_debug))
> > +		return restricted_pointer(buf, end, ptr, spec);
> > +
> >  	/* default is to _not_ leak addresses, hash before printing */
> >  	return ptr_to_id(buf, end, ptr, spec);
> >  }  
> 
> This uses the deprecated API Steve (I only know because I went to read
> Documentation/static-keys.txt after seeing this patch).

Hmm, I've been involved with static keys since it was introduced. I
simply copied the code for the original use case (tracepoints). I
forgot that we are changing the name (this has been an ongoing bikeshed
for some time, I can't keep up. Better than the original suggestion
"really_unlikely()" ;)

I need to update tracepoints too.

-- Steve