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Subject[PATCH 1/5] microblaze: ftrace: add static function tracer
Date
From: Michal Simek <monstr@monstr.eu>

If -pg of gcc is enabled with CONFIG_FUNCTION_TRACER=y. a calling to
_mcount will be inserted into each kernel function. so, there is a
possibility to trace the kernel functions in _mcount.

This patch add the specific _mcount support for static function
tracing. by default, ftrace_trace_function is initialized as
ftrace_stub(an empty function), so, the default _mcount will introduce
very little overhead. after enabling ftrace in user-space, it will jump
to a real tracing function and do static function tracing for us.

Commit message from Wu Zhangjin <wuzhangjin@gmail.com>

Signed-off-by: Michal Simek <monstr@monstr.eu>
---
arch/microblaze/Kconfig | 1 +
arch/microblaze/include/asm/ftrace.h | 14 ++++
arch/microblaze/kernel/Makefile | 11 +++
arch/microblaze/kernel/cpu/Makefile | 4 +
arch/microblaze/kernel/mcount.S | 105 +++++++++++++++++++++++++++++
arch/microblaze/kernel/microblaze_ksyms.c | 5 ++
6 files changed, 140 insertions(+), 0 deletions(-)
create mode 100644 arch/microblaze/kernel/mcount.S
diff --git a/arch/microblaze/Kconfig b/arch/microblaze/Kconfig
index 57eeaa6..18003ca 100644
--- a/arch/microblaze/Kconfig
+++ b/arch/microblaze/Kconfig
@@ -6,6 +6,7 @@ mainmenu "Linux/Microblaze Kernel Configuration"
config MICROBLAZE
def_bool y
select HAVE_LMB
+ select HAVE_FUNCTION_TRACER
select USB_ARCH_HAS_EHCI
select ARCH_WANT_OPTIONAL_GPIOLIB

diff --git a/arch/microblaze/include/asm/ftrace.h b/arch/microblaze/include/asm/ftrace.h
index 8b13789..22beec5 100644
--- a/arch/microblaze/include/asm/ftrace.h
+++ b/arch/microblaze/include/asm/ftrace.h
@@ -1 +1,15 @@
+#ifndef _ASM_MICROBLAZE_FTRACE
+#define _ASM_MICROBLAZE_FTRACE
+#ifdef CONFIG_FUNCTION_TRACER
+
+#define MCOUNT_ADDR ((long)(_mcount))
+#define MCOUNT_INSN_SIZE 8 /* sizeof mcount call */
+
+#ifndef __ASSEMBLY__
+extern void _mcount(void);
+extern void ftrace_call_graph(void);
+#endif
+
+#endif /* CONFIG_FUNCTION_TRACER */
+#endif /* _ASM_MICROBLAZE_FTRACE */
diff --git a/arch/microblaze/kernel/Makefile b/arch/microblaze/kernel/Makefile
index c465a5c..d5ee326 100644
--- a/arch/microblaze/kernel/Makefile
+++ b/arch/microblaze/kernel/Makefile
@@ -2,6 +2,16 @@
# Makefile
#

+ifdef CONFIG_FUNCTION_TRACER
+# Do not trace early boot code and low level code
+CFLAGS_REMOVE_timer.o = -pg
+CFLAGS_REMOVE_intc.o = -pg
+CFLAGS_REMOVE_early_printk.o = -pg
+CFLAGS_REMOVE_selfmod.o = -pg
+CFLAGS_REMOVE_heartbeat.o = -pg
+CFLAGS_REMOVE_ftrace.o = -pg
+endif
+
extra-y := head.o vmlinux.lds

obj-y += exceptions.o \
@@ -17,5 +27,6 @@ obj-$(CONFIG_HEART_BEAT) += heartbeat.o
obj-$(CONFIG_MODULES) += microblaze_ksyms.o module.o
obj-$(CONFIG_MMU) += misc.o
obj-$(CONFIG_STACKTRACE) += stacktrace.o
+obj-$(CONFIG_FUNCTION_TRACER) += mcount.o

obj-y += entry$(MMU).o
diff --git a/arch/microblaze/kernel/cpu/Makefile b/arch/microblaze/kernel/cpu/Makefile
index 20646e5..59cc7bc 100644
--- a/arch/microblaze/kernel/cpu/Makefile
+++ b/arch/microblaze/kernel/cpu/Makefile
@@ -2,6 +2,10 @@
# Build the appropriate CPU version support
#

+ifdef CONFIG_FUNCTION_TRACER
+CFLAGS_REMOVE_cache.o = -pg
+endif
+
EXTRA_CFLAGS += -DCPU_MAJOR=$(CPU_MAJOR) -DCPU_MINOR=$(CPU_MINOR) \
-DCPU_REV=$(CPU_REV)

diff --git a/arch/microblaze/kernel/mcount.S b/arch/microblaze/kernel/mcount.S
new file mode 100644
index 0000000..a257a1b
--- /dev/null
+++ b/arch/microblaze/kernel/mcount.S
@@ -0,0 +1,105 @@
+/*
+ * Low-level ftrace handling
+ *
+ * Copyright (C) 2009 Michal Simek <monstr@monstr.eu>
+ * Copyright (C) 2009 PetaLogix
+ *
+ * This file is subject to the terms and conditions of the GNU General
+ * Public License. See the file COPYING in the main directory of this
+ * archive for more details.
+ */
+
+#include <linux/linkage.h>
+
+#define NOALIGN_ENTRY(name) .globl name; name:
+
+/* FIXME MS: I think that I don't need to save all regs */
+#define SAVE_REGS \
+ addik r1, r1, -120; \
+ swi r2, r1, 4; \
+ swi r3, r1, 8; \
+ swi r4, r1, 12; \
+ swi r5, r1, 116; \
+ swi r6, r1, 16; \
+ swi r7, r1, 20; \
+ swi r8, r1, 24; \
+ swi r9, r1, 28; \
+ swi r10, r1, 32; \
+ swi r11, r1, 36; \
+ swi r12, r1, 40; \
+ swi r13, r1, 44; \
+ swi r14, r1, 48; \
+ swi r16, r1, 52; \
+ swi r17, r1, 56; \
+ swi r18, r1, 60; \
+ swi r19, r1, 64; \
+ swi r20, r1, 68; \
+ swi r21, r1, 72; \
+ swi r22, r1, 76; \
+ swi r23, r1, 80; \
+ swi r24, r1, 84; \
+ swi r25, r1, 88; \
+ swi r26, r1, 92; \
+ swi r27, r1, 96; \
+ swi r28, r1, 100; \
+ swi r29, r1, 104; \
+ swi r30, r1, 108; \
+ swi r31, r1, 112;
+
+#define RESTORE_REGS \
+ lwi r2, r1, 4; \
+ lwi r3, r1, 8; \
+ lwi r4, r1, 12; \
+ lwi r5, r1, 116; \
+ lwi r6, r1, 16; \
+ lwi r7, r1, 20; \
+ lwi r8, r1, 24; \
+ lwi r9, r1, 28; \
+ lwi r10, r1, 32; \
+ lwi r11, r1, 36; \
+ lwi r12, r1, 40; \
+ lwi r13, r1, 44; \
+ lwi r14, r1, 48; \
+ lwi r16, r1, 52; \
+ lwi r17, r1, 56; \
+ lwi r18, r1, 60; \
+ lwi r19, r1, 64; \
+ lwi r20, r1, 68; \
+ lwi r21, r1, 72; \
+ lwi r22, r1, 76; \
+ lwi r23, r1, 80; \
+ lwi r24, r1, 84; \
+ lwi r25, r1, 88; \
+ lwi r26, r1, 92; \
+ lwi r27, r1, 96; \
+ lwi r28, r1, 100; \
+ lwi r29, r1, 104; \
+ lwi r30, r1, 108; \
+ lwi r31, r1, 112; \
+ addik r1, r1, 120;
+
+ENTRY(ftrace_stub)
+ rtsd r15, 8;
+ nop;
+
+ENTRY(_mcount)
+ SAVE_REGS
+ swi r15, r1, 0;
+ /* MS: test function trace if is taken or not */
+ lwi r20, r0, ftrace_trace_function;
+ addik r6, r0, ftrace_stub;
+ cmpu r5, r20, r6; /* ftrace_trace_function != ftrace_stub */
+ beqid r5, end; /* MS: not taken -> jump over */
+ nop;
+/* static normal trace */
+ lwi r6, r1, 120; /* MS: load parent addr */
+ addik r5, r15, 0; /* MS: load current function addr */
+ /* MS: here is dependency on previous code */
+ brald r15, r20; /* MS: jump to ftrace handler */
+ nop;
+end:
+ lwi r15, r1, 0;
+ RESTORE_REGS
+
+ rtsd r15, 8; /* MS: jump back */
+ nop;
diff --git a/arch/microblaze/kernel/microblaze_ksyms.c b/arch/microblaze/kernel/microblaze_ksyms.c
index 59ff20e..bc4dcb7 100644
--- a/arch/microblaze/kernel/microblaze_ksyms.c
+++ b/arch/microblaze/kernel/microblaze_ksyms.c
@@ -18,6 +18,7 @@
#include <linux/io.h>
#include <asm/page.h>
#include <asm/system.h>
+#include <linux/ftrace.h>
#include <linux/uaccess.h>

/*
@@ -47,3 +48,7 @@ extern void __umodsi3(void);
EXPORT_SYMBOL(__umodsi3);
extern char *_ebss;
EXPORT_SYMBOL_GPL(_ebss);
+#ifdef CONFIG_FUNCTION_TRACER
+extern void _mcount(void);
+EXPORT_SYMBOL(_mcount);
+#endif
--
1.5.5.1


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