1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
|
// SPDX-License-Identifier: GPL-2.0
/*
* Based on arch/arm64/kernel/ftrace.c
*
* Copyright (C) 2022 Loongson Technology Corporation Limited
*/
#include <linux/ftrace.h>
#include <linux/uaccess.h>
#include <asm/inst.h>
static int ftrace_modify_code(unsigned long pc, u32 old, u32 new, bool validate)
{
u32 replaced;
if (validate) {
if (larch_insn_read((void *)pc, &replaced))
return -EFAULT;
if (replaced != old)
return -EINVAL;
}
if (larch_insn_patch_text((void *)pc, new))
return -EPERM;
return 0;
}
#ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS
int ftrace_modify_call(struct dyn_ftrace *rec, unsigned long old_addr, unsigned long addr)
{
u32 old, new;
unsigned long pc;
pc = rec->ip + LOONGARCH_INSN_SIZE;
new = larch_insn_gen_bl(pc, addr);
old = larch_insn_gen_bl(pc, old_addr);
return ftrace_modify_code(pc, old, new, true);
}
#endif /* CONFIG_DYNAMIC_FTRACE_WITH_REGS */
int ftrace_update_ftrace_func(ftrace_func_t func)
{
u32 new;
unsigned long pc;
pc = (unsigned long)&ftrace_call;
new = larch_insn_gen_bl(pc, (unsigned long)func);
return ftrace_modify_code(pc, 0, new, false);
}
/*
* The compiler has inserted 2 NOPs before the regular function prologue.
* T series registers are available and safe because of LoongArch's psABI.
*
* At runtime, we can replace nop with bl to enable ftrace call and replace bl
* with nop to disable ftrace call. The bl requires us to save the original RA
* value, so it saves RA at t0 here.
*
* Details are:
*
* | Compiled | Disabled | Enabled |
* +------------+------------------------+------------------------+
* | nop | move t0, ra | move t0, ra |
* | nop | nop | bl ftrace_caller |
* | func_body | func_body | func_body |
*
* The RA value will be recovered by ftrace_regs_entry, and restored into RA
* before returning to the regular function prologue. When a function is not
* being traced, the "move t0, ra" is not harmful.
*/
int ftrace_init_nop(struct module *mod, struct dyn_ftrace *rec)
{
u32 old, new;
unsigned long pc;
pc = rec->ip;
old = larch_insn_gen_nop();
new = larch_insn_gen_move(LOONGARCH_GPR_T0, LOONGARCH_GPR_RA);
return ftrace_modify_code(pc, old, new, true);
}
int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr)
{
u32 old, new;
unsigned long pc;
pc = rec->ip + LOONGARCH_INSN_SIZE;
old = larch_insn_gen_nop();
new = larch_insn_gen_bl(pc, addr);
return ftrace_modify_code(pc, old, new, true);
}
int ftrace_make_nop(struct module *mod, struct dyn_ftrace *rec, unsigned long addr)
{
u32 old, new;
unsigned long pc;
pc = rec->ip + LOONGARCH_INSN_SIZE;
new = larch_insn_gen_nop();
old = larch_insn_gen_bl(pc, addr);
return ftrace_modify_code(pc, old, new, true);
}
void arch_ftrace_update_code(int command)
{
command |= FTRACE_MAY_SLEEP;
ftrace_modify_all_code(command);
}
int __init ftrace_dyn_arch_init(void)
{
return 0;
}
#ifdef CONFIG_FUNCTION_GRAPH_TRACER
void prepare_ftrace_return(unsigned long self_addr, unsigned long *parent)
{
unsigned long old;
unsigned long return_hooker = (unsigned long)&return_to_handler;
if (unlikely(atomic_read(¤t->tracing_graph_pause)))
return;
old = *parent;
if (!function_graph_enter(old, self_addr, 0, NULL))
*parent = return_hooker;
}
#ifdef CONFIG_HAVE_DYNAMIC_FTRACE_WITH_ARGS
void ftrace_graph_func(unsigned long ip, unsigned long parent_ip,
struct ftrace_ops *op, struct ftrace_regs *fregs)
{
struct pt_regs *regs = &fregs->regs;
unsigned long *parent = (unsigned long *)®s->regs[1];
prepare_ftrace_return(ip, (unsigned long *)parent);
}
#else
static int ftrace_modify_graph_caller(bool enable)
{
u32 branch, nop;
unsigned long pc, func;
extern void ftrace_graph_call(void);
pc = (unsigned long)&ftrace_graph_call;
func = (unsigned long)&ftrace_graph_caller;
nop = larch_insn_gen_nop();
branch = larch_insn_gen_b(pc, func);
if (enable)
return ftrace_modify_code(pc, nop, branch, true);
else
return ftrace_modify_code(pc, branch, nop, true);
}
int ftrace_enable_ftrace_graph_caller(void)
{
return ftrace_modify_graph_caller(true);
}
int ftrace_disable_ftrace_graph_caller(void)
{
return ftrace_modify_graph_caller(false);
}
#endif /* CONFIG_HAVE_DYNAMIC_FTRACE_WITH_ARGS */
#endif /* CONFIG_FUNCTION_GRAPH_TRACER */
|
