microblaze: ftrace: add static function tracer
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>
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;