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authorMichal Simek <monstr@monstr.eu>2009-12-10 08:15:44 -0500
committerMichal Simek <monstr@monstr.eu>2009-12-14 02:44:01 -0500
commit7d241ff0567b9503d79ee775c40927d09b509f83 (patch)
tree8de1af72c5643416ee427edc7e9ff2170e0d73db /arch/microblaze/kernel/ftrace.c
parent6d9e60ce30a1be35491c74df00aaa25d869f8a02 (diff)
microblaze: ftrace: Add dynamic trace support
With dynamic function tracer, by default, _mcount is defined as an "empty" function, it returns directly without any more action. When enabling it in user-space, it will jump to a real tracing function(ftrace_caller), and do the real job for us. Differ from the static function tracer, dynamic function tracer provides two functions ftrace_make_call()/ftrace_make_nop() to enable/disable the tracing of some indicated kernel functions(set_ftrace_filter). In the kernel version, there is only one "_mcount" string for every kernel function, so, we just need to match this one in mcount_regex of scripts/recordmcount.pl. For more information please look at code and Documentation/trace folder. Steven ACK that scripts/recordmcount.pl part. Acked-by: Steven Rostedt <rostedt@goodmis.org> Signed-off-by: Michal Simek <monstr@monstr.eu>
Diffstat (limited to 'arch/microblaze/kernel/ftrace.c')
-rw-r--r--arch/microblaze/kernel/ftrace.c151
1 files changed, 151 insertions, 0 deletions
diff --git a/arch/microblaze/kernel/ftrace.c b/arch/microblaze/kernel/ftrace.c
new file mode 100644
index 00000000000..c1889b101cb
--- /dev/null
+++ b/arch/microblaze/kernel/ftrace.c
@@ -0,0 +1,151 @@
1/*
2 * Ftrace support for Microblaze.
3 *
4 * Copyright (C) 2009 Michal Simek <monstr@monstr.eu>
5 * Copyright (C) 2009 PetaLogix
6 *
7 * Based on MIPS and PowerPC ftrace code
8 *
9 * This file is subject to the terms and conditions of the GNU General Public
10 * License. See the file "COPYING" in the main directory of this archive
11 * for more details.
12 */
13
14#include <asm/cacheflush.h>
15#include <linux/ftrace.h>
16
17#ifdef CONFIG_DYNAMIC_FTRACE
18/* save value to addr - it is save to do it in asm */
19static int ftrace_modify_code(unsigned long addr, unsigned int value)
20{
21 int faulted = 0;
22
23 __asm__ __volatile__(" 1: swi %2, %1, 0; \
24 addik %0, r0, 0; \
25 2: \
26 .section .fixup, \"ax\"; \
27 3: brid 2b; \
28 addik %0, r0, 1; \
29 .previous; \
30 .section __ex_table,\"a\"; \
31 .word 1b,3b; \
32 .previous;" \
33 : "=r" (faulted)
34 : "r" (addr), "r" (value)
35 );
36
37 if (unlikely(faulted))
38 return -EFAULT;
39
40 return 0;
41}
42
43#define MICROBLAZE_NOP 0x80000000
44#define MICROBLAZE_BRI 0xb800000C
45
46static unsigned int recorded; /* if save was or not */
47static unsigned int imm; /* saving whole imm instruction */
48
49/* There are two approaches howto solve ftrace_make nop function - look below */
50#undef USE_FTRACE_NOP
51
52#ifdef USE_FTRACE_NOP
53static unsigned int bralid; /* saving whole bralid instruction */
54#endif
55
56int ftrace_make_nop(struct module *mod,
57 struct dyn_ftrace *rec, unsigned long addr)
58{
59 /* we have this part of code which we are working with
60 * b000c000 imm -16384
61 * b9fc8e30 bralid r15, -29136 // c0008e30 <_mcount>
62 * 80000000 or r0, r0, r0
63 *
64 * The first solution (!USE_FTRACE_NOP-could be called branch solution)
65 * b000c000 bri 12 (0xC - jump to any other instruction)
66 * b9fc8e30 bralid r15, -29136 // c0008e30 <_mcount>
67 * 80000000 or r0, r0, r0
68 * any other instruction
69 *
70 * The second solution (USE_FTRACE_NOP) - no jump just nops
71 * 80000000 or r0, r0, r0
72 * 80000000 or r0, r0, r0
73 * 80000000 or r0, r0, r0
74 */
75 int ret = 0;
76
77 if (recorded == 0) {
78 recorded = 1;
79 imm = *(unsigned int *)rec->ip;
80 pr_debug("%s: imm:0x%x\n", __func__, imm);
81#ifdef USE_FTRACE_NOP
82 bralid = *(unsigned int *)(rec->ip + 4);
83 pr_debug("%s: bralid 0x%x\n", __func__, bralid);
84#endif /* USE_FTRACE_NOP */
85 }
86
87#ifdef USE_FTRACE_NOP
88 ret = ftrace_modify_code(rec->ip, MICROBLAZE_NOP);
89 ret += ftrace_modify_code(rec->ip + 4, MICROBLAZE_NOP);
90#else /* USE_FTRACE_NOP */
91 ret = ftrace_modify_code(rec->ip, MICROBLAZE_BRI);
92#endif /* USE_FTRACE_NOP */
93 return ret;
94}
95
96static int ret_addr; /* initialized as 0 by default */
97
98/* I believe that first is called ftrace_make_nop before this function */
99int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr)
100{
101 int ret;
102 ret_addr = addr; /* saving where the barrier jump is */
103 pr_debug("%s: addr:0x%x, rec->ip: 0x%x, imm:0x%x\n",
104 __func__, (unsigned int)addr, (unsigned int)rec->ip, imm);
105 ret = ftrace_modify_code(rec->ip, imm);
106#ifdef USE_FTRACE_NOP
107 pr_debug("%s: bralid:0x%x\n", __func__, bralid);
108 ret += ftrace_modify_code(rec->ip + 4, bralid);
109#endif /* USE_FTRACE_NOP */
110 return ret;
111}
112
113int __init ftrace_dyn_arch_init(void *data)
114{
115 /* The return code is retured via data */
116 *(unsigned long *)data = 0;
117
118 return 0;
119}
120
121int ftrace_update_ftrace_func(ftrace_func_t func)
122{
123 unsigned long ip = (unsigned long)(&ftrace_call);
124 unsigned int upper = (unsigned int)func;
125 unsigned int lower = (unsigned int)func;
126 int ret = 0;
127
128 /* create proper saving to ftrace_call poll */
129 upper = 0xb0000000 + (upper >> 16); /* imm func_upper */
130 lower = 0x32800000 + (lower & 0xFFFF); /* addik r20, r0, func_lower */
131
132 pr_debug("%s: func=0x%x, ip=0x%x, upper=0x%x, lower=0x%x\n",
133 __func__, (unsigned int)func, (unsigned int)ip, upper, lower);
134
135 /* save upper and lower code */
136 ret = ftrace_modify_code(ip, upper);
137 ret += ftrace_modify_code(ip + 4, lower);
138
139 /* We just need to remove the rtsd r15, 8 by NOP */
140 BUG_ON(!ret_addr);
141 if (ret_addr)
142 ret += ftrace_modify_code(ret_addr, MICROBLAZE_NOP);
143 else
144 ret = 1; /* fault */
145
146 /* All changes are done - lets do caches consistent */
147 flush_icache();
148 return ret;
149}
150
151#endif /* CONFIG_DYNAMIC_FTRACE */
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