2 * mcount and friends -- ftrace stuff
4 * Copyright (C) 2009 Analog Devices Inc.
5 * Licensed under the GPL-2 or later.
8 #include <linux/linkage.h>
9 #include <asm/ftrace.h>
13 /* GCC will have called us before setting up the function prologue, so we
14 * can clobber the normal scratch registers, but we need to make sure to
15 * save/restore the registers used for argument passing (R0-R2) in case
16 * the profiled function is using them. With data registers, R3 is the
17 * only one we can blow away. With pointer registers, we have P0-P2.
19 * Upon entry, the RETS will point to the top of the current profiled
20 * function. And since GCC setup the frame for us, the previous function
21 * will be waiting there. mmmm pie.
24 /* save third function arg early so we can do testing below */
27 /* load the function pointer to the tracer */
28 p0.l = _ftrace_trace_function;
29 p0.h = _ftrace_trace_function;
32 /* optional micro optimization: don't call the stub tracer */
36 if ! cc jump .Ldo_trace;
43 /* save first/second function arg and the return register */
48 /* setup the tracer function */
51 /* tracer(ulong frompc, ulong selfpc):
52 * frompc: the pc that did the call to ...
53 * selfpc: ... this location
54 * the selfpc itself will need adjusting for the mcount call
58 r1 += -MCOUNT_INSN_SIZE;
63 /* restore state and get out of dodge */