On Wed, Nov 29, 2017 at 03:20:58PM -0800, Andrew Morton wrote: > On Wed, 29 Nov 2017 13:05:04 +1100 "Tobin C. Harding" <m...@tobin.cc> wrote: > > > printk specifier %p now hashes all addresses before printing. Sometimes > > we need to see the actual unmodified address. This can be achieved using > > %lx but then we face the risk that if in future we want to change the > > way the Kernel handles printing of pointers we will have to grep through > > the already existent 50 000 %lx call sites. Let's add specifier %px as a > > clear, opt-in, way to print a pointer and maintain some level of > > isolation from all the other hex integer output within the Kernel. > > > > Add printk specifier %px to print the actual unmodified address. > > > > ... > > > > +Unmodified Addresses > > +==================== > > + > > +:: > > + > > + %px 01234567 or 0123456789abcdef > > + > > +For printing pointers when you _really_ want to print the address. Please > > +consider whether or not you are leaking sensitive information about the > > +Kernel layout in memory before printing pointers with %px. %px is > > +functionally equivalent to %lx. %px is preferred to %lx because it is more > > +uniquely grep'able. If, in the future, we need to modify the way the Kernel > > +handles printing pointers it will be nice to be able to find the call > > +sites. > > + > > You might want to add a checkpatch rule which emits a stern > do-you-really-want-to-do-this warning when someone uses %px. >
Oh, nice idea. It has to be a CHECK but right? By stern, you mean use stern language? thanks, Tobin.
