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Subject[PATCH 25/27] Blackfin: initial support for ftrace grapher
Date
Signed-off-by: Mike Frysinger <vapier@gentoo.org>
---
arch/blackfin/Kconfig | 1 +
arch/blackfin/kernel/Makefile | 3 ++
arch/blackfin/kernel/ftrace-entry.S | 68 +++++++++++++++++++++++++++++++++++
arch/blackfin/kernel/ftrace.c | 42 +++++++++++++++++++++
arch/blackfin/kernel/vmlinux.lds.S | 1 +
5 files changed, 115 insertions(+), 0 deletions(-)
create mode 100644 arch/blackfin/kernel/ftrace.c

diff --git a/arch/blackfin/Kconfig b/arch/blackfin/Kconfig
index ea8d92c..5bc1360 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_GRAPH_TRACER
select HAVE_FUNCTION_TRACER
select HAVE_IDE
select HAVE_KERNEL_GZIP
diff --git a/arch/blackfin/kernel/Makefile b/arch/blackfin/kernel/Makefile
index d2ae285..3731088 100644
--- a/arch/blackfin/kernel/Makefile
+++ b/arch/blackfin/kernel/Makefile
@@ -16,6 +16,9 @@ else
endif

obj-$(CONFIG_FUNCTION_TRACER) += ftrace-entry.o
+obj-$(CONFIG_FUNCTION_GRAPH_TRACER) += ftrace.o
+CFLAGS_REMOVE_ftrace.o = -pg
+
obj-$(CONFIG_IPIPE) += ipipe.o
obj-$(CONFIG_IPIPE_TRACE_MCOUNT) += mcount.o
obj-$(CONFIG_BFIN_GPTIMERS) += gptimers.o
diff --git a/arch/blackfin/kernel/ftrace-entry.S b/arch/blackfin/kernel/ftrace-entry.S
index ce71487..6980b7a 100644
--- a/arch/blackfin/kernel/ftrace-entry.S
+++ b/arch/blackfin/kernel/ftrace-entry.S
@@ -35,6 +35,28 @@ ENTRY(__mcount)
cc = r2 == r3;
if ! cc jump .Ldo_trace;

+#ifdef CONFIG_FUNCTION_GRAPH_TRACER
+ /* if the ftrace_graph_return function pointer is not set to
+ * the ftrace_stub entry, call prepare_ftrace_return().
+ */
+ p0.l = _ftrace_graph_return;
+ p0.h = _ftrace_graph_return;
+ r3 = [p0];
+ cc = r2 == r3;
+ if ! cc jump _ftrace_graph_caller;
+
+ /* similarly, if the ftrace_graph_entry function pointer is not
+ * set to the ftrace_graph_entry_stub entry, ...
+ */
+ p0.l = _ftrace_graph_entry;
+ p0.h = _ftrace_graph_entry;
+ r2.l = _ftrace_graph_entry_stub;
+ r2.h = _ftrace_graph_entry_stub;
+ r3 = [p0];
+ cc = r2 == r3;
+ if ! cc jump _ftrace_graph_caller;
+#endif
+
r2 = [sp++];
rts;

@@ -61,6 +83,7 @@ ENTRY(__mcount)
call (p0);

/* restore state and get out of dodge */
+.Lfinish_trace:
rets = [sp++];
r1 = [sp++];
r0 = [sp++];
@@ -70,3 +93,48 @@ ENTRY(__mcount)
_ftrace_stub:
rts;
ENDPROC(__mcount)
+
+#ifdef CONFIG_FUNCTION_GRAPH_TRACER
+/* The prepare_ftrace_return() function is similar to the trace function
+ * except it takes a pointer to the location of the frompc. This is so
+ * the prepare_ftrace_return() can hijack it temporarily for probing
+ * purposes.
+ */
+ENTRY(_ftrace_graph_caller)
+ /* save first/second function arg and the return register */
+ [--sp] = r0;
+ [--sp] = r1;
+ [--sp] = rets;
+
+ r0 = fp;
+ r1 = rets;
+ r0 += 4;
+ r1 += -MCOUNT_INSN_SIZE;
+ call _prepare_ftrace_return;
+
+ jump .Lfinish_trace;
+ENDPROC(_ftrace_graph_caller)
+
+/* Undo the rewrite caused by ftrace_graph_caller(). The common function
+ * ftrace_return_to_handler() will return the original rets so we can
+ * restore it and be on our way.
+ */
+ENTRY(_return_to_handler)
+ /* make sure original return values are saved */
+ [--sp] = p0;
+ [--sp] = r0;
+ [--sp] = r1;
+
+ /* get original return address */
+ call _ftrace_return_to_handler;
+ rets = r0;
+
+ /* anomaly 05000371 - make sure we have at least three instructions
+ * between rets setting and the return
+ */
+ r1 = [sp++];
+ r0 = [sp++];
+ p0 = [sp++];
+ rts;
+ENDPROC(_return_to_handler)
+#endif
diff --git a/arch/blackfin/kernel/ftrace.c b/arch/blackfin/kernel/ftrace.c
new file mode 100644
index 0000000..905bfc4
--- /dev/null
+++ b/arch/blackfin/kernel/ftrace.c
@@ -0,0 +1,42 @@
+/*
+ * ftrace graph code
+ *
+ * Copyright (C) 2009 Analog Devices Inc.
+ * Licensed under the GPL-2 or later.
+ */
+
+#include <linux/ftrace.h>
+#include <linux/kernel.h>
+#include <linux/sched.h>
+#include <asm/atomic.h>
+
+#ifdef CONFIG_FUNCTION_GRAPH_TRACER
+
+/*
+ * Hook the return address and push it in the stack of return addrs
+ * in current thread info.
+ */
+void prepare_ftrace_return(unsigned long *parent, unsigned long self_addr)
+{
+ struct ftrace_graph_ent trace;
+ unsigned long return_hooker = (unsigned long)&return_to_handler;
+
+ if (unlikely(atomic_read(&current->tracing_graph_pause)))
+ return;
+
+ if (ftrace_push_return_trace(*parent, self_addr, &trace.depth) == -EBUSY)
+ return;
+
+ trace.func = self_addr;
+
+ /* Only trace if the calling function expects to */
+ if (!ftrace_graph_entry(&trace)) {
+ current->curr_ret_stack--;
+ return;
+ }
+
+ /* all is well in the world ! hijack RETS ... */
+ *parent = return_hooker;
+}
+
+#endif
diff --git a/arch/blackfin/kernel/vmlinux.lds.S b/arch/blackfin/kernel/vmlinux.lds.S
index 119fbdb..6ac307c 100644
--- a/arch/blackfin/kernel/vmlinux.lds.S
+++ b/arch/blackfin/kernel/vmlinux.lds.S
@@ -54,6 +54,7 @@ SECTIONS
SCHED_TEXT
#endif
LOCK_TEXT
+ IRQENTRY_TEXT
KPROBES_TEXT
*(.text.*)
*(.fixup)
--
1.6.3.1


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