powerpc: Add rN aliases to the pt_regs_offset table.

RashmicaG · mpe · commit 343c3327c12b · 2015-11-26T22:11:17.000+11:00
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 -
  $ cd /sys/kernel/debug/tracing
  $ echo "p:probe/sys_fchownat sys_fchownat %gpr3:s32 +0(%gpr4):string %gpr5:s32 %gpr6:s32 %gpr7:s32" &gt; kprobe_events
  $ echo 1 &gt; events/probe/sys_fchownat/enable
  $ touch /tmp/foo
  $ chown root /tmp/foo
  $ echo 0 &gt; events/enable
  $ cat trace
    chown-2925  [014] d...    76.160657: sys_fchownat: (SyS_fchownat+0x8/0x1a0) arg1=-100 arg2="/tmp/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" &gt; kprobe_events

Signed-off-by: Rashmica Gupta &lt;rashmicy@gmail.com&gt;
Signed-off-by: Michael Ellerman &lt;mpe@ellerman.id.au&gt;
diff --git a/arch/powerpc/kernel/ptrace.c b/arch/powerpc/kernel/ptrace.c
@@ -60,6 +60,7 @@ struct pt_regs_offset {
 #define STR(s)	#s			/* convert to string */
 #define REG_OFFSET_NAME(r) {.name = #r, .offset = offsetof(struct pt_regs, r)}
 #define GPR_OFFSET_NAME(num)	\
+	{.name = STR(r##num), .offset = offsetof(struct pt_regs, gpr[num])}, \
 	{.name = STR(gpr##num), .offset = offsetof(struct pt_regs, gpr[num])}
 #define REG_OFFSET_END {.name = NULL, .offset = 0}
 
