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

From: Anshuman Khandual <[email-masked]>
Date: Mon, 23 Nov 2015 13:54:34 +0530

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