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1/*
2 * Dynamic function tracing support.
3 *
4 * Copyright (C) 2008 Shaohua Li <shaohua.li@intel.com>
5 *
6 * For licencing details, see COPYING.
7 *
8 * Defines low-level handling of mcount calls when the kernel
9 * is compiled with the -pg flag. When using dynamic ftrace, the
10 * mcount call-sites get patched lazily with NOP till they are
11 * enabled. All code mutation routines here take effect atomically.
12 */
13
14#include <linux/uaccess.h>
15#include <linux/ftrace.h>
16
17#include <asm/cacheflush.h>
18#include <asm/patch.h>
19
20/* In IA64, each function will be added below two bundles with -pg option */
21static unsigned char __attribute__((aligned(8)))
22ftrace_orig_code[MCOUNT_INSN_SIZE] = {
23 0x02, 0x40, 0x31, 0x10, 0x80, 0x05, /* alloc r40=ar.pfs,12,8,0 */
24 0xb0, 0x02, 0x00, 0x00, 0x42, 0x40, /* mov r43=r0;; */
25 0x05, 0x00, 0xc4, 0x00, /* mov r42=b0 */
26 0x11, 0x48, 0x01, 0x02, 0x00, 0x21, /* mov r41=r1 */
27 0x00, 0x00, 0x00, 0x02, 0x00, 0x00, /* nop.i 0x0 */
28 0x08, 0x00, 0x00, 0x50 /* br.call.sptk.many b0 = _mcount;; */
29};
30
31struct ftrace_orig_insn {
32 u64 dummy1, dummy2, dummy3;
33 u64 dummy4:64-41+13;
34 u64 imm20:20;
35 u64 dummy5:3;
36 u64 sign:1;
37 u64 dummy6:4;
38};
39
40/* mcount stub will be converted below for nop */
41static unsigned char ftrace_nop_code[MCOUNT_INSN_SIZE] = {
42 0x00, 0x00, 0x00, 0x00, 0x01, 0x00, /* [MII] nop.m 0x0 */
43 0x30, 0x00, 0x00, 0x60, 0x00, 0x00, /* mov r3=ip */
44 0x00, 0x00, 0x04, 0x00, /* nop.i 0x0 */
45 0x05, 0x00, 0x00, 0x00, 0x01, 0x00, /* [MLX] nop.m 0x0 */
46 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, /* nop.x 0x0;; */
47 0x00, 0x00, 0x04, 0x00
48};
49
50static unsigned char *ftrace_nop_replace(void)
51{
52 return ftrace_nop_code;
53}
54
55/*
56 * mcount stub will be converted below for call
57 * Note: Just the last instruction is changed against nop
58 * */
59static unsigned char __attribute__((aligned(8)))
60ftrace_call_code[MCOUNT_INSN_SIZE] = {
61 0x00, 0x00, 0x00, 0x00, 0x01, 0x00, /* [MII] nop.m 0x0 */
62 0x30, 0x00, 0x00, 0x60, 0x00, 0x00, /* mov r3=ip */
63 0x00, 0x00, 0x04, 0x00, /* nop.i 0x0 */
64 0x05, 0x00, 0x00, 0x00, 0x01, 0x00, /* [MLX] nop.m 0x0 */
65 0xff, 0xff, 0xff, 0xff, 0x7f, 0x00, /* brl.many .;;*/
66 0xf8, 0xff, 0xff, 0xc8
67};
68
69struct ftrace_call_insn {
70 u64 dummy1, dummy2;
71 u64 dummy3:48;
72 u64 imm39_l:16;
73 u64 imm39_h:23;
74 u64 dummy4:13;
75 u64 imm20:20;
76 u64 dummy5:3;
77 u64 i:1;
78 u64 dummy6:4;
79};
80
81static unsigned char *ftrace_call_replace(unsigned long ip, unsigned long addr)
82{
83 struct ftrace_call_insn *code = (void *)ftrace_call_code;
84 unsigned long offset = addr - (ip + 0x10);
85
86 code->imm39_l = offset >> 24;
87 code->imm39_h = offset >> 40;
88 code->imm20 = offset >> 4;
89 code->i = offset >> 63;
90 return ftrace_call_code;
91}
92
93static int
94ftrace_modify_code(unsigned long ip, unsigned char *old_code,
95 unsigned char *new_code, int do_check)
96{
97 unsigned char replaced[MCOUNT_INSN_SIZE];
98
99 /*
100 * Note: Due to modules and __init, code can
101 * disappear and change, we need to protect against faulting
102 * as well as code changing. We do this by using the
103 * probe_kernel_* functions.
104 *
105 * No real locking needed, this code is run through
106 * kstop_machine, or before SMP starts.
107 */
108
109 if (!do_check)
110 goto skip_check;
111
112 /* read the text we want to modify */
113 if (probe_kernel_read(replaced, (void *)ip, MCOUNT_INSN_SIZE))
114 return -EFAULT;
115
116 /* Make sure it is what we expect it to be */
117 if (memcmp(replaced, old_code, MCOUNT_INSN_SIZE) != 0)
118 return -EINVAL;
119
120skip_check:
121 /* replace the text with the new text */
122 if (probe_kernel_write(((void *)ip), new_code, MCOUNT_INSN_SIZE))
123 return -EPERM;
124 flush_icache_range(ip, ip + MCOUNT_INSN_SIZE);
125
126 return 0;
127}
128
129static int ftrace_make_nop_check(struct dyn_ftrace *rec, unsigned long addr)
130{
131 unsigned char __attribute__((aligned(8))) replaced[MCOUNT_INSN_SIZE];
132 unsigned long ip = rec->ip;
133
134 if (probe_kernel_read(replaced, (void *)ip, MCOUNT_INSN_SIZE))
135 return -EFAULT;
136 if (rec->flags & FTRACE_FL_CONVERTED) {
137 struct ftrace_call_insn *call_insn, *tmp_call;
138
139 call_insn = (void *)ftrace_call_code;
140 tmp_call = (void *)replaced;
141 call_insn->imm39_l = tmp_call->imm39_l;
142 call_insn->imm39_h = tmp_call->imm39_h;
143 call_insn->imm20 = tmp_call->imm20;
144 call_insn->i = tmp_call->i;
145 if (memcmp(replaced, ftrace_call_code, MCOUNT_INSN_SIZE) != 0)
146 return -EINVAL;
147 return 0;
148 } else {
149 struct ftrace_orig_insn *call_insn, *tmp_call;
150
151 call_insn = (void *)ftrace_orig_code;
152 tmp_call = (void *)replaced;
153 call_insn->sign = tmp_call->sign;
154 call_insn->imm20 = tmp_call->imm20;
155 if (memcmp(replaced, ftrace_orig_code, MCOUNT_INSN_SIZE) != 0)
156 return -EINVAL;
157 return 0;
158 }
159}
160
161int ftrace_make_nop(struct module *mod,
162 struct dyn_ftrace *rec, unsigned long addr)
163{
164 int ret;
165 char *new;
166
167 ret = ftrace_make_nop_check(rec, addr);
168 if (ret)
169 return ret;
170 new = ftrace_nop_replace();
171 return ftrace_modify_code(rec->ip, NULL, new, 0);
172}
173
174int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr)
175{
176 unsigned long ip = rec->ip;
177 unsigned char *old, *new;
178
179 old= ftrace_nop_replace();
180 new = ftrace_call_replace(ip, addr);
181 return ftrace_modify_code(ip, old, new, 1);
182}
183
184/* in IA64, _mcount can't directly call ftrace_stub. Only jump is ok */
185int ftrace_update_ftrace_func(ftrace_func_t func)
186{
187 unsigned long ip;
188 unsigned long addr = ((struct fnptr *)ftrace_call)->ip;
189
190 if (func == ftrace_stub)
191 return 0;
192 ip = ((struct fnptr *)func)->ip;
193
194 ia64_patch_imm64(addr + 2, ip);
195
196 flush_icache_range(addr, addr + 16);
197 return 0;
198}
199
200/* run from kstop_machine */
201int __init ftrace_dyn_arch_init(void *data)
202{
203 *(unsigned long *)data = 0;
204
205 return 0;
206}
1/*
2 * Dynamic function tracing support.
3 *
4 * Copyright (C) 2008 Shaohua Li <shaohua.li@intel.com>
5 *
6 * For licencing details, see COPYING.
7 *
8 * Defines low-level handling of mcount calls when the kernel
9 * is compiled with the -pg flag. When using dynamic ftrace, the
10 * mcount call-sites get patched lazily with NOP till they are
11 * enabled. All code mutation routines here take effect atomically.
12 */
13
14#include <linux/uaccess.h>
15#include <linux/ftrace.h>
16
17#include <asm/cacheflush.h>
18#include <asm/patch.h>
19
20/* In IA64, each function will be added below two bundles with -pg option */
21static unsigned char __attribute__((aligned(8)))
22ftrace_orig_code[MCOUNT_INSN_SIZE] = {
23 0x02, 0x40, 0x31, 0x10, 0x80, 0x05, /* alloc r40=ar.pfs,12,8,0 */
24 0xb0, 0x02, 0x00, 0x00, 0x42, 0x40, /* mov r43=r0;; */
25 0x05, 0x00, 0xc4, 0x00, /* mov r42=b0 */
26 0x11, 0x48, 0x01, 0x02, 0x00, 0x21, /* mov r41=r1 */
27 0x00, 0x00, 0x00, 0x02, 0x00, 0x00, /* nop.i 0x0 */
28 0x08, 0x00, 0x00, 0x50 /* br.call.sptk.many b0 = _mcount;; */
29};
30
31struct ftrace_orig_insn {
32 u64 dummy1, dummy2, dummy3;
33 u64 dummy4:64-41+13;
34 u64 imm20:20;
35 u64 dummy5:3;
36 u64 sign:1;
37 u64 dummy6:4;
38};
39
40/* mcount stub will be converted below for nop */
41static unsigned char ftrace_nop_code[MCOUNT_INSN_SIZE] = {
42 0x00, 0x00, 0x00, 0x00, 0x01, 0x00, /* [MII] nop.m 0x0 */
43 0x30, 0x00, 0x00, 0x60, 0x00, 0x00, /* mov r3=ip */
44 0x00, 0x00, 0x04, 0x00, /* nop.i 0x0 */
45 0x05, 0x00, 0x00, 0x00, 0x01, 0x00, /* [MLX] nop.m 0x0 */
46 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, /* nop.x 0x0;; */
47 0x00, 0x00, 0x04, 0x00
48};
49
50static unsigned char *ftrace_nop_replace(void)
51{
52 return ftrace_nop_code;
53}
54
55/*
56 * mcount stub will be converted below for call
57 * Note: Just the last instruction is changed against nop
58 * */
59static unsigned char __attribute__((aligned(8)))
60ftrace_call_code[MCOUNT_INSN_SIZE] = {
61 0x00, 0x00, 0x00, 0x00, 0x01, 0x00, /* [MII] nop.m 0x0 */
62 0x30, 0x00, 0x00, 0x60, 0x00, 0x00, /* mov r3=ip */
63 0x00, 0x00, 0x04, 0x00, /* nop.i 0x0 */
64 0x05, 0x00, 0x00, 0x00, 0x01, 0x00, /* [MLX] nop.m 0x0 */
65 0xff, 0xff, 0xff, 0xff, 0x7f, 0x00, /* brl.many .;;*/
66 0xf8, 0xff, 0xff, 0xc8
67};
68
69struct ftrace_call_insn {
70 u64 dummy1, dummy2;
71 u64 dummy3:48;
72 u64 imm39_l:16;
73 u64 imm39_h:23;
74 u64 dummy4:13;
75 u64 imm20:20;
76 u64 dummy5:3;
77 u64 i:1;
78 u64 dummy6:4;
79};
80
81static unsigned char *ftrace_call_replace(unsigned long ip, unsigned long addr)
82{
83 struct ftrace_call_insn *code = (void *)ftrace_call_code;
84 unsigned long offset = addr - (ip + 0x10);
85
86 code->imm39_l = offset >> 24;
87 code->imm39_h = offset >> 40;
88 code->imm20 = offset >> 4;
89 code->i = offset >> 63;
90 return ftrace_call_code;
91}
92
93static int
94ftrace_modify_code(unsigned long ip, unsigned char *old_code,
95 unsigned char *new_code, int do_check)
96{
97 unsigned char replaced[MCOUNT_INSN_SIZE];
98
99 /*
100 * Note:
101 * We are paranoid about modifying text, as if a bug was to happen, it
102 * could cause us to read or write to someplace that could cause harm.
103 * Carefully read and modify the code with probe_kernel_*(), and make
104 * sure what we read is what we expected it to be before modifying it.
105 */
106
107 if (!do_check)
108 goto skip_check;
109
110 /* read the text we want to modify */
111 if (probe_kernel_read(replaced, (void *)ip, MCOUNT_INSN_SIZE))
112 return -EFAULT;
113
114 /* Make sure it is what we expect it to be */
115 if (memcmp(replaced, old_code, MCOUNT_INSN_SIZE) != 0)
116 return -EINVAL;
117
118skip_check:
119 /* replace the text with the new text */
120 if (probe_kernel_write(((void *)ip), new_code, MCOUNT_INSN_SIZE))
121 return -EPERM;
122 flush_icache_range(ip, ip + MCOUNT_INSN_SIZE);
123
124 return 0;
125}
126
127static int ftrace_make_nop_check(struct dyn_ftrace *rec, unsigned long addr)
128{
129 unsigned char __attribute__((aligned(8))) replaced[MCOUNT_INSN_SIZE];
130 unsigned long ip = rec->ip;
131
132 if (probe_kernel_read(replaced, (void *)ip, MCOUNT_INSN_SIZE))
133 return -EFAULT;
134 if (rec->flags & FTRACE_FL_CONVERTED) {
135 struct ftrace_call_insn *call_insn, *tmp_call;
136
137 call_insn = (void *)ftrace_call_code;
138 tmp_call = (void *)replaced;
139 call_insn->imm39_l = tmp_call->imm39_l;
140 call_insn->imm39_h = tmp_call->imm39_h;
141 call_insn->imm20 = tmp_call->imm20;
142 call_insn->i = tmp_call->i;
143 if (memcmp(replaced, ftrace_call_code, MCOUNT_INSN_SIZE) != 0)
144 return -EINVAL;
145 return 0;
146 } else {
147 struct ftrace_orig_insn *call_insn, *tmp_call;
148
149 call_insn = (void *)ftrace_orig_code;
150 tmp_call = (void *)replaced;
151 call_insn->sign = tmp_call->sign;
152 call_insn->imm20 = tmp_call->imm20;
153 if (memcmp(replaced, ftrace_orig_code, MCOUNT_INSN_SIZE) != 0)
154 return -EINVAL;
155 return 0;
156 }
157}
158
159int ftrace_make_nop(struct module *mod,
160 struct dyn_ftrace *rec, unsigned long addr)
161{
162 int ret;
163 char *new;
164
165 ret = ftrace_make_nop_check(rec, addr);
166 if (ret)
167 return ret;
168 new = ftrace_nop_replace();
169 return ftrace_modify_code(rec->ip, NULL, new, 0);
170}
171
172int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr)
173{
174 unsigned long ip = rec->ip;
175 unsigned char *old, *new;
176
177 old= ftrace_nop_replace();
178 new = ftrace_call_replace(ip, addr);
179 return ftrace_modify_code(ip, old, new, 1);
180}
181
182/* in IA64, _mcount can't directly call ftrace_stub. Only jump is ok */
183int ftrace_update_ftrace_func(ftrace_func_t func)
184{
185 unsigned long ip;
186 unsigned long addr = ((struct fnptr *)ftrace_call)->ip;
187
188 if (func == ftrace_stub)
189 return 0;
190 ip = ((struct fnptr *)func)->ip;
191
192 ia64_patch_imm64(addr + 2, ip);
193
194 flush_icache_range(addr, addr + 16);
195 return 0;
196}
197
198/* run from kstop_machine */
199int __init ftrace_dyn_arch_init(void)
200{
201 return 0;
202}