Blackfin: initial support for ftrace
Mike Frysinger [Tue, 9 Jun 2009 11:25:09 +0000 (07:25 -0400)]
Just the basic ftrace support here -- mcount and the ftrace stub.

Signed-off-by: Mike Frysinger <vapier@gentoo.org>

arch/blackfin/Kconfig
arch/blackfin/include/asm/ftrace.h
arch/blackfin/kernel/Makefile
arch/blackfin/kernel/bfin_ksyms.c
arch/blackfin/kernel/ftrace-entry.S [new file with mode: 0644]

index d03fd63..ea8d92c 100644 (file)
@@ -19,6 +19,7 @@ config RWSEM_XCHGADD_ALGORITHM
 
 config BLACKFIN
        def_bool y
+       select HAVE_FUNCTION_TRACER
        select HAVE_IDE
        select HAVE_KERNEL_GZIP
        select HAVE_KERNEL_BZIP2
index 40a8c17..8643680 100644 (file)
@@ -1 +1,13 @@
-/* empty */
+/*
+ * Blackfin ftrace code
+ *
+ * Copyright 2009 Analog Devices Inc.
+ * Licensed under the GPL-2 or later.
+ */
+
+#ifndef __ASM_BFIN_FTRACE_H__
+#define __ASM_BFIN_FTRACE_H__
+
+#define MCOUNT_INSN_SIZE       8 /* sizeof mcount call: LINK + CALL */
+
+#endif
index a66dda4..d2ae285 100644 (file)
@@ -15,6 +15,7 @@ else
     obj-y += time.o
 endif
 
+obj-$(CONFIG_FUNCTION_TRACER)        += ftrace-entry.o
 obj-$(CONFIG_IPIPE)                  += ipipe.o
 obj-$(CONFIG_IPIPE_TRACE_MCOUNT)     += mcount.o
 obj-$(CONFIG_BFIN_GPTIMERS)          += gptimers.o
index 53e893f..aa05e63 100644 (file)
@@ -103,3 +103,8 @@ EXPORT_SYMBOL(__raw_smp_mark_barrier_asm);
 EXPORT_SYMBOL(__raw_smp_check_barrier_asm);
 #endif
 #endif
+
+#ifdef CONFIG_FUNCTION_TRACER
+extern void _mcount(void);
+EXPORT_SYMBOL(_mcount);
+#endif
diff --git a/arch/blackfin/kernel/ftrace-entry.S b/arch/blackfin/kernel/ftrace-entry.S
new file mode 100644 (file)
index 0000000..ce71487
--- /dev/null
@@ -0,0 +1,72 @@
+/*
+ * mcount and friends -- ftrace stuff
+ *
+ * Copyright (C) 2009 Analog Devices Inc.
+ * Licensed under the GPL-2 or later.
+ */
+
+#include <linux/linkage.h>
+#include <asm/ftrace.h>
+
+.text
+
+/* GCC will have called us before setting up the function prologue, so we
+ * can clobber the normal scratch registers, but we need to make sure to
+ * save/restore the registers used for argument passing (R0-R2) in case
+ * the profiled function is using them.  With data registers, R3 is the
+ * only one we can blow away.  With pointer registers, we have P0-P2.
+ *
+ * Upon entry, the RETS will point to the top of the current profiled
+ * function.  And since GCC setup the frame for us, the previous function
+ * will be waiting there.  mmmm pie.
+ */
+ENTRY(__mcount)
+       /* save third function arg early so we can do testing below */
+       [--sp] = r2;
+
+       /* load the function pointer to the tracer */
+       p0.l = _ftrace_trace_function;
+       p0.h = _ftrace_trace_function;
+       r3 = [p0];
+
+       /* optional micro optimization: don't call the stub tracer */
+       r2.l = _ftrace_stub;
+       r2.h = _ftrace_stub;
+       cc = r2 == r3;
+       if ! cc jump .Ldo_trace;
+
+       r2 = [sp++];
+       rts;
+
+.Ldo_trace:
+
+       /* save first/second function arg and the return register */
+       [--sp] = r0;
+       [--sp] = r1;
+       [--sp] = rets;
+
+       /* setup the tracer function */
+       p0 = r3;
+
+       /* tracer(ulong frompc, ulong selfpc):
+        *  frompc: the pc that did the call to ...
+        *  selfpc: ... this location
+        * the selfpc itself will need adjusting for the mcount call
+        */
+       r1 = rets;
+       r0 = [fp + 4];
+       r1 += -MCOUNT_INSN_SIZE;
+
+       /* call the tracer */
+       call (p0);
+
+       /* restore state and get out of dodge */
+       rets = [sp++];
+       r1 = [sp++];
+       r0 = [sp++];
+       r2 = [sp++];
+
+.globl _ftrace_stub
+_ftrace_stub:
+       rts;
+ENDPROC(__mcount)