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Subject[PATCH 24/27] Blackfin: initial support for ftrace
Date
Just the basic ftrace support here -- mcount and the ftrace stub.

Signed-off-by: Mike Frysinger <vapier@gentoo.org>
---
arch/blackfin/Kconfig | 1 +
arch/blackfin/include/asm/ftrace.h | 14 ++++++-
arch/blackfin/kernel/Makefile | 1 +
arch/blackfin/kernel/bfin_ksyms.c | 5 ++
arch/blackfin/kernel/ftrace-entry.S | 72 +++++++++++++++++++++++++++++++++++
5 files changed, 92 insertions(+), 1 deletions(-)
create mode 100644 arch/blackfin/kernel/ftrace-entry.S

diff --git a/arch/blackfin/Kconfig b/arch/blackfin/Kconfig
index d03fd63..ea8d92c 100644
--- a/arch/blackfin/Kconfig
+++ b/arch/blackfin/Kconfig
@@ -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
diff --git a/arch/blackfin/include/asm/ftrace.h b/arch/blackfin/include/asm/ftrace.h
index 40a8c17..8643680 100644
--- a/arch/blackfin/include/asm/ftrace.h
+++ b/arch/blackfin/include/asm/ftrace.h
@@ -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
diff --git a/arch/blackfin/kernel/Makefile b/arch/blackfin/kernel/Makefile
index a66dda4..d2ae285 100644
--- a/arch/blackfin/kernel/Makefile
+++ b/arch/blackfin/kernel/Makefile
@@ -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
diff --git a/arch/blackfin/kernel/bfin_ksyms.c b/arch/blackfin/kernel/bfin_ksyms.c
index 53e893f..aa05e63 100644
--- a/arch/blackfin/kernel/bfin_ksyms.c
+++ b/arch/blackfin/kernel/bfin_ksyms.c
@@ -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
index 0000000..ce71487
--- /dev/null
+++ b/arch/blackfin/kernel/ftrace-entry.S
@@ -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)
--
1.6.3.1


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