Re: [PATCH] powerpc: Add rN aliases to the pt_regs_offset table.

On Mon, 2015-11-23 at 13:54 +0530, Anshuman Khandual wrote:

On 11/21/2015 11:38 AM, Rashmica Gupta wrote:

quoted

It is common practice with powerpc to use 'rN' to refer to register 'N'. However
when using the pt_regs_offset table we have to use 'gprN'.

So add aliases such that both 'rN' and 'gprN' can be used.

For example, we can currently do:
$ su -
$ echo "p:probe/sys_fchownat .sys_fchownat %gpr3:s32 +0(%gpr4):string %gpr5:s32
%gpr6:s32 %gpr7:s32" > /sys/kernel/debug/tracing/kprobe_events
$ echo 1 > /sys/kernel/debug/tracing/events/probe/sys_fchownat/enable
$ touch /tmp/foo
$ chown root /tmp/foo
$ echo 0 > /sys/kernel/debug/tracing/events/enable
$ cat /sys/kernel/debug/tracing/trace
           chown-5040  [001] d... 24800.047211: sys_fchownat:
(.SyS_fchownat+0x0/0x190) arg1=-100 arg2="foo" arg3=0 arg4=-1 arg5=0

Instead we'd like to be able to use:
$ echo "p:probe/sys_fchownat sys_fchownat %r3:s32 +0(%r4):string %r5:s32
%r6:s32 %r7:s32" > /sys/kernel/debug/tracing/kprobe_events

This makes sense and works for me on a LE guest. Just that the symbol
should not have the "." before it. 

Yeah that's probably my fault for giving Rashmica an example from a BE system.
I'll fix up the example before I commit it.

cheers