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, err;
26 struct ftrace_graph_ent trace;
27 unsigned long return_hooker = (unsigned long)
28 &return_to_handler;
29
30 if (unlikely(atomic_read(¤t->tracing_graph_pause)))
31 return;
32
33 /*
34 * Protect against fault, even if it shouldn't
35 * happen. This tool is too much intrusive to
36 * ignore such a protection.
37 */
38 asm volatile(" 1: lwi %0, %2, 0; \
39 2: swi %3, %2, 0; \
40 addik %1, r0, 0; \
41 3: \
42 .section .fixup, \"ax\"; \
43 4: brid 3b; \
44 addik %1, r0, 1; \
45 .previous; \
46 .section __ex_table,\"a\"; \
47 .word 1b,4b; \
48 .word 2b,4b; \
49 .previous;" \
50 : "=&r" (old), "=r" (faulted)
51 : "r" (parent), "r" (return_hooker)
52 );
53
54 flush_dcache_range((u32)parent, (u32)parent + 4);
55 flush_icache_range((u32)parent, (u32)parent + 4);
56
57 if (unlikely(faulted)) {
58 ftrace_graph_stop();
59 WARN_ON(1);
60 return;
61 }
62
63 err = ftrace_push_return_trace(old, self_addr, &trace.depth, 0);
64 if (err == -EBUSY) {
65 *parent = old;
66 return;
67 }
68
69 trace.func = self_addr;
70 /* Only trace if the calling function expects to */
71 if (!ftrace_graph_entry(&trace)) {
72 current->curr_ret_stack--;
73 *parent = old;
74 }
75 }
76 #endif /* CONFIG_FUNCTION_GRAPH_TRACER */
77
78 #ifdef CONFIG_DYNAMIC_FTRACE
79 /* save value to addr - it is save to do it in asm */
ftrace_modify_code(unsigned long addr,unsigned int value)80 static int ftrace_modify_code(unsigned long addr, unsigned int value)
81 {
82 int faulted = 0;
83
84 __asm__ __volatile__(" 1: swi %2, %1, 0; \
85 addik %0, r0, 0; \
86 2: \
87 .section .fixup, \"ax\"; \
88 3: brid 2b; \
89 addik %0, r0, 1; \
90 .previous; \
91 .section __ex_table,\"a\"; \
92 .word 1b,3b; \
93 .previous;" \
94 : "=r" (faulted)
95 : "r" (addr), "r" (value)
96 );
97
98 if (unlikely(faulted))
99 return -EFAULT;
100
101 flush_dcache_range(addr, addr + 4);
102 flush_icache_range(addr, addr + 4);
103
104 return 0;
105 }
106
107 #define MICROBLAZE_NOP 0x80000000
108 #define MICROBLAZE_BRI 0xb800000C
109
110 static unsigned int recorded; /* if save was or not */
111 static unsigned int imm; /* saving whole imm instruction */
112
113 /* There are two approaches howto solve ftrace_make nop function - look below */
114 #undef USE_FTRACE_NOP
115
116 #ifdef USE_FTRACE_NOP
117 static unsigned int bralid; /* saving whole bralid instruction */
118 #endif
119
ftrace_make_nop(struct module * mod,struct dyn_ftrace * rec,unsigned long addr)120 int ftrace_make_nop(struct module *mod,
121 struct dyn_ftrace *rec, unsigned long addr)
122 {
123 /* we have this part of code which we are working with
124 * b000c000 imm -16384
125 * b9fc8e30 bralid r15, -29136 // c0008e30 <_mcount>
126 * 80000000 or r0, r0, r0
127 *
128 * The first solution (!USE_FTRACE_NOP-could be called branch solution)
129 * b000c000 bri 12 (0xC - jump to any other instruction)
130 * b9fc8e30 bralid r15, -29136 // c0008e30 <_mcount>
131 * 80000000 or r0, r0, r0
132 * any other instruction
133 *
134 * The second solution (USE_FTRACE_NOP) - no jump just nops
135 * 80000000 or r0, r0, r0
136 * 80000000 or r0, r0, r0
137 * 80000000 or r0, r0, r0
138 */
139 int ret = 0;
140
141 if (recorded == 0) {
142 recorded = 1;
143 imm = *(unsigned int *)rec->ip;
144 pr_debug("%s: imm:0x%x\n", __func__, imm);
145 #ifdef USE_FTRACE_NOP
146 bralid = *(unsigned int *)(rec->ip + 4);
147 pr_debug("%s: bralid 0x%x\n", __func__, bralid);
148 #endif /* USE_FTRACE_NOP */
149 }
150
151 #ifdef USE_FTRACE_NOP
152 ret = ftrace_modify_code(rec->ip, MICROBLAZE_NOP);
153 ret += ftrace_modify_code(rec->ip + 4, MICROBLAZE_NOP);
154 #else /* USE_FTRACE_NOP */
155 ret = ftrace_modify_code(rec->ip, MICROBLAZE_BRI);
156 #endif /* USE_FTRACE_NOP */
157 return ret;
158 }
159
160 /* I believe that first is called ftrace_make_nop before this function */
ftrace_make_call(struct dyn_ftrace * rec,unsigned long addr)161 int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr)
162 {
163 int ret;
164 pr_debug("%s: addr:0x%x, rec->ip: 0x%x, imm:0x%x\n",
165 __func__, (unsigned int)addr, (unsigned int)rec->ip, imm);
166 ret = ftrace_modify_code(rec->ip, imm);
167 #ifdef USE_FTRACE_NOP
168 pr_debug("%s: bralid:0x%x\n", __func__, bralid);
169 ret += ftrace_modify_code(rec->ip + 4, bralid);
170 #endif /* USE_FTRACE_NOP */
171 return ret;
172 }
173
ftrace_dyn_arch_init(void * data)174 int __init ftrace_dyn_arch_init(void *data)
175 {
176 /* The return code is retured via data */
177 *(unsigned long *)data = 0;
178
179 return 0;
180 }
181
ftrace_update_ftrace_func(ftrace_func_t func)182 int ftrace_update_ftrace_func(ftrace_func_t func)
183 {
184 unsigned long ip = (unsigned long)(&ftrace_call);
185 unsigned int upper = (unsigned int)func;
186 unsigned int lower = (unsigned int)func;
187 int ret = 0;
188
189 /* create proper saving to ftrace_call poll */
190 upper = 0xb0000000 + (upper >> 16); /* imm func_upper */
191 lower = 0x32800000 + (lower & 0xFFFF); /* addik r20, r0, func_lower */
192
193 pr_debug("%s: func=0x%x, ip=0x%x, upper=0x%x, lower=0x%x\n",
194 __func__, (unsigned int)func, (unsigned int)ip, upper, lower);
195
196 /* save upper and lower code */
197 ret = ftrace_modify_code(ip, upper);
198 ret += ftrace_modify_code(ip + 4, lower);
199
200 /* We just need to replace the rtsd r15, 8 with NOP */
201 ret += ftrace_modify_code((unsigned long)&ftrace_caller,
202 MICROBLAZE_NOP);
203
204 return ret;
205 }
206
207 #ifdef CONFIG_FUNCTION_GRAPH_TRACER
208 unsigned int old_jump; /* saving place for jump instruction */
209
ftrace_enable_ftrace_graph_caller(void)210 int ftrace_enable_ftrace_graph_caller(void)
211 {
212 unsigned int ret;
213 unsigned long ip = (unsigned long)(&ftrace_call_graph);
214
215 old_jump = *(unsigned int *)ip; /* save jump over instruction */
216 ret = ftrace_modify_code(ip, MICROBLAZE_NOP);
217
218 pr_debug("%s: Replace instruction: 0x%x\n", __func__, old_jump);
219 return ret;
220 }
221
ftrace_disable_ftrace_graph_caller(void)222 int ftrace_disable_ftrace_graph_caller(void)
223 {
224 unsigned int ret;
225 unsigned long ip = (unsigned long)(&ftrace_call_graph);
226
227 ret = ftrace_modify_code(ip, old_jump);
228
229 pr_debug("%s\n", __func__);
230 return ret;
231 }
232 #endif /* CONFIG_FUNCTION_GRAPH_TRACER */
233 #endif /* CONFIG_DYNAMIC_FTRACE */
234