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_FUNCTION_GRAPH_TRACER
18 /*
19 * Hook the return address and push it in the stack of return addrs
20 * in current thread info.
21 */
prepare_ftrace_return(unsigned long * parent,unsigned long self_addr)22 void prepare_ftrace_return(unsigned long *parent, unsigned long self_addr)
23 {
24 unsigned long old;
25 int faulted;
26 unsigned long return_hooker = (unsigned long)
27 &return_to_handler;
28
29 if (unlikely(ftrace_graph_is_dead()))
30 return;
31
32 if (unlikely(atomic_read(¤t->tracing_graph_pause)))
33 return;
34
35 /*
36 * Protect against fault, even if it shouldn't
37 * happen. This tool is too much intrusive to
38 * ignore such a protection.
39 */
40 asm volatile(" 1: lwi %0, %2, 0;" \
41 "2: swi %3, %2, 0;" \
42 " addik %1, r0, 0;" \
43 "3:" \
44 " .section .fixup, \"ax\";" \
45 "4: brid 3b;" \
46 " addik %1, r0, 1;" \
47 " .previous;" \
48 " .section __ex_table,\"a\";" \
49 " .word 1b,4b;" \
50 " .word 2b,4b;" \
51 " .previous;" \
52 : "=&r" (old), "=r" (faulted)
53 : "r" (parent), "r" (return_hooker)
54 );
55
56 flush_dcache_range((u32)parent, (u32)parent + 4);
57 flush_icache_range((u32)parent, (u32)parent + 4);
58
59 if (unlikely(faulted)) {
60 ftrace_graph_stop();
61 WARN_ON(1);
62 return;
63 }
64
65 if (function_graph_enter(old, self_addr, 0, NULL))
66 *parent = old;
67 }
68 #endif /* CONFIG_FUNCTION_GRAPH_TRACER */
69
70 #ifdef CONFIG_DYNAMIC_FTRACE
71 /* save value to addr - it is save to do it in asm */
ftrace_modify_code(unsigned long addr,unsigned int value)72 static int ftrace_modify_code(unsigned long addr, unsigned int value)
73 {
74 int faulted = 0;
75
76 __asm__ __volatile__(" 1: swi %2, %1, 0;" \
77 " addik %0, r0, 0;" \
78 "2:" \
79 " .section .fixup, \"ax\";" \
80 "3: brid 2b;" \
81 " addik %0, r0, 1;" \
82 " .previous;" \
83 " .section __ex_table,\"a\";" \
84 " .word 1b,3b;" \
85 " .previous;" \
86 : "=r" (faulted)
87 : "r" (addr), "r" (value)
88 );
89
90 if (unlikely(faulted))
91 return -EFAULT;
92
93 flush_dcache_range(addr, addr + 4);
94 flush_icache_range(addr, addr + 4);
95
96 return 0;
97 }
98
99 #define MICROBLAZE_NOP 0x80000000
100 #define MICROBLAZE_BRI 0xb800000C
101
102 static unsigned int recorded; /* if save was or not */
103 static unsigned int imm; /* saving whole imm instruction */
104
105 /* There are two approaches howto solve ftrace_make nop function - look below */
106 #undef USE_FTRACE_NOP
107
108 #ifdef USE_FTRACE_NOP
109 static unsigned int bralid; /* saving whole bralid instruction */
110 #endif
111
ftrace_make_nop(struct module * mod,struct dyn_ftrace * rec,unsigned long addr)112 int ftrace_make_nop(struct module *mod,
113 struct dyn_ftrace *rec, unsigned long addr)
114 {
115 /* we have this part of code which we are working with
116 * b000c000 imm -16384
117 * b9fc8e30 bralid r15, -29136 // c0008e30 <_mcount>
118 * 80000000 or r0, r0, r0
119 *
120 * The first solution (!USE_FTRACE_NOP-could be called branch solution)
121 * b000c000 bri 12 (0xC - jump to any other instruction)
122 * b9fc8e30 bralid r15, -29136 // c0008e30 <_mcount>
123 * 80000000 or r0, r0, r0
124 * any other instruction
125 *
126 * The second solution (USE_FTRACE_NOP) - no jump just nops
127 * 80000000 or r0, r0, r0
128 * 80000000 or r0, r0, r0
129 * 80000000 or r0, r0, r0
130 */
131 int ret = 0;
132
133 if (recorded == 0) {
134 recorded = 1;
135 imm = *(unsigned int *)rec->ip;
136 pr_debug("%s: imm:0x%x\n", __func__, imm);
137 #ifdef USE_FTRACE_NOP
138 bralid = *(unsigned int *)(rec->ip + 4);
139 pr_debug("%s: bralid 0x%x\n", __func__, bralid);
140 #endif /* USE_FTRACE_NOP */
141 }
142
143 #ifdef USE_FTRACE_NOP
144 ret = ftrace_modify_code(rec->ip, MICROBLAZE_NOP);
145 ret += ftrace_modify_code(rec->ip + 4, MICROBLAZE_NOP);
146 #else /* USE_FTRACE_NOP */
147 ret = ftrace_modify_code(rec->ip, MICROBLAZE_BRI);
148 #endif /* USE_FTRACE_NOP */
149 return ret;
150 }
151
152 /* I believe that first is called ftrace_make_nop before this function */
ftrace_make_call(struct dyn_ftrace * rec,unsigned long addr)153 int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr)
154 {
155 int ret;
156 pr_debug("%s: addr:0x%x, rec->ip: 0x%x, imm:0x%x\n",
157 __func__, (unsigned int)addr, (unsigned int)rec->ip, imm);
158 ret = ftrace_modify_code(rec->ip, imm);
159 #ifdef USE_FTRACE_NOP
160 pr_debug("%s: bralid:0x%x\n", __func__, bralid);
161 ret += ftrace_modify_code(rec->ip + 4, bralid);
162 #endif /* USE_FTRACE_NOP */
163 return ret;
164 }
165
ftrace_update_ftrace_func(ftrace_func_t func)166 int ftrace_update_ftrace_func(ftrace_func_t func)
167 {
168 unsigned long ip = (unsigned long)(&ftrace_call);
169 unsigned int upper = (unsigned int)func;
170 unsigned int lower = (unsigned int)func;
171 int ret = 0;
172
173 /* create proper saving to ftrace_call poll */
174 upper = 0xb0000000 + (upper >> 16); /* imm func_upper */
175 lower = 0x32800000 + (lower & 0xFFFF); /* addik r20, r0, func_lower */
176
177 pr_debug("%s: func=0x%x, ip=0x%x, upper=0x%x, lower=0x%x\n",
178 __func__, (unsigned int)func, (unsigned int)ip, upper, lower);
179
180 /* save upper and lower code */
181 ret = ftrace_modify_code(ip, upper);
182 ret += ftrace_modify_code(ip + 4, lower);
183
184 /* We just need to replace the rtsd r15, 8 with NOP */
185 ret += ftrace_modify_code((unsigned long)&ftrace_caller,
186 MICROBLAZE_NOP);
187
188 return ret;
189 }
190
191 #ifdef CONFIG_FUNCTION_GRAPH_TRACER
192 unsigned int old_jump; /* saving place for jump instruction */
193
ftrace_enable_ftrace_graph_caller(void)194 int ftrace_enable_ftrace_graph_caller(void)
195 {
196 unsigned int ret;
197 unsigned long ip = (unsigned long)(&ftrace_call_graph);
198
199 old_jump = *(unsigned int *)ip; /* save jump over instruction */
200 ret = ftrace_modify_code(ip, MICROBLAZE_NOP);
201
202 pr_debug("%s: Replace instruction: 0x%x\n", __func__, old_jump);
203 return ret;
204 }
205
ftrace_disable_ftrace_graph_caller(void)206 int ftrace_disable_ftrace_graph_caller(void)
207 {
208 unsigned int ret;
209 unsigned long ip = (unsigned long)(&ftrace_call_graph);
210
211 ret = ftrace_modify_code(ip, old_jump);
212
213 pr_debug("%s\n", __func__);
214 return ret;
215 }
216 #endif /* CONFIG_FUNCTION_GRAPH_TRACER */
217 #endif /* CONFIG_DYNAMIC_FTRACE */
218