Messages in this thread | | | Date | Wed, 29 Nov 2017 15:20:58 -0800 | From | Andrew Morton <> | Subject | Re: [PATCH V11 4/5] vsprintf: add printk specifier %px |
| |
On Wed, 29 Nov 2017 13:05:04 +1100 "Tobin C. Harding" <me@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.
| |