ftrace.c (95d002e0a34cb0f238abb39987f9980f325d8332) ftrace.c (28bb030f93334495ddc64ade0bff18721bf7023d)
1// SPDX-License-Identifier: GPL-2.0
2// Copyright (C) 2018 Hangzhou C-SKY Microsystems co.,ltd.
3
4#include <linux/ftrace.h>
5#include <linux/uaccess.h>
1// SPDX-License-Identifier: GPL-2.0
2// Copyright (C) 2018 Hangzhou C-SKY Microsystems co.,ltd.
3
4#include <linux/ftrace.h>
5#include <linux/uaccess.h>
6#include <asm/cacheflush.h>
6
7
8#ifdef CONFIG_DYNAMIC_FTRACE
9
10#define NOP 0x4000
11#define NOP32_HI 0xc400
12#define NOP32_LO 0x4820
13#define PUSH_LR 0x14d0
14#define MOVIH_LINK 0xea3a
15#define ORI_LINK 0xef5a
16#define JSR_LINK 0xe8fa
17#define BSR_LINK 0xe000
18
19/*
20 * Gcc-csky with -pg will insert stub in function prologue:
21 * push lr
22 * jbsr _mcount
23 * nop32
24 * nop32
25 *
26 * If the (callee - current_pc) is less then 64MB, we'll use bsr:
27 * push lr
28 * bsr _mcount
29 * nop32
30 * nop32
31 * else we'll use (movih + ori + jsr):
32 * push lr
33 * movih r26, ...
34 * ori r26, ...
35 * jsr r26
36 *
37 * (r26 is our reserved link-reg)
38 *
39 */
40static inline void make_jbsr(unsigned long callee, unsigned long pc,
41 uint16_t *call, bool nolr)
42{
43 long offset;
44
45 call[0] = nolr ? NOP : PUSH_LR;
46
47 offset = (long) callee - (long) pc;
48
49 if (unlikely(offset < -67108864 || offset > 67108864)) {
50 call[1] = MOVIH_LINK;
51 call[2] = callee >> 16;
52 call[3] = ORI_LINK;
53 call[4] = callee & 0xffff;
54 call[5] = JSR_LINK;
55 call[6] = 0;
56 } else {
57 offset = offset >> 1;
58
59 call[1] = BSR_LINK |
60 ((uint16_t)((unsigned long) offset >> 16) & 0x3ff);
61 call[2] = (uint16_t)((unsigned long) offset & 0xffff);
62 call[3] = call[5] = NOP32_HI;
63 call[4] = call[6] = NOP32_LO;
64 }
65}
66
67static uint16_t nops[7] = {NOP, NOP32_HI, NOP32_LO, NOP32_HI, NOP32_LO,
68 NOP32_HI, NOP32_LO};
69static int ftrace_check_current_nop(unsigned long hook)
70{
71 uint16_t olds[7];
72 unsigned long hook_pos = hook - 2;
73
74 if (probe_kernel_read((void *)olds, (void *)hook_pos, sizeof(nops)))
75 return -EFAULT;
76
77 if (memcmp((void *)nops, (void *)olds, sizeof(nops))) {
78 pr_err("%p: nop but get (%04x %04x %04x %04x %04x %04x %04x)\n",
79 (void *)hook_pos,
80 olds[0], olds[1], olds[2], olds[3], olds[4], olds[5],
81 olds[6]);
82
83 return -EINVAL;
84 }
85
86 return 0;
87}
88
89static int ftrace_modify_code(unsigned long hook, unsigned long target,
90 bool enable, bool nolr)
91{
92 uint16_t call[7];
93
94 unsigned long hook_pos = hook - 2;
95 int ret = 0;
96
97 make_jbsr(target, hook, call, nolr);
98
99 ret = probe_kernel_write((void *)hook_pos, enable ? call : nops,
100 sizeof(nops));
101 if (ret)
102 return -EPERM;
103
104 flush_icache_range(hook_pos, hook_pos + MCOUNT_INSN_SIZE);
105
106 return 0;
107}
108
109int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr)
110{
111 int ret = ftrace_check_current_nop(rec->ip);
112
113 if (ret)
114 return ret;
115
116 return ftrace_modify_code(rec->ip, addr, true, false);
117}
118
119int ftrace_make_nop(struct module *mod, struct dyn_ftrace *rec,
120 unsigned long addr)
121{
122 return ftrace_modify_code(rec->ip, addr, false, false);
123}
124
125int ftrace_update_ftrace_func(ftrace_func_t func)
126{
127 int ret = ftrace_modify_code((unsigned long)&ftrace_call,
128 (unsigned long)func, true, true);
129 return ret;
130}
131
132int __init ftrace_dyn_arch_init(void)
133{
134 return 0;
135}
136#endif /* CONFIG_DYNAMIC_FTRACE */
137
7#ifdef CONFIG_FUNCTION_GRAPH_TRACER
8void prepare_ftrace_return(unsigned long *parent, unsigned long self_addr,
9 unsigned long frame_pointer)
10{
11 unsigned long return_hooker = (unsigned long)&return_to_handler;
12 unsigned long old;
13
14 if (unlikely(atomic_read(&current->tracing_graph_pause)))

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38 * because lr is resumed twice.
39 */
40 *parent = return_hooker;
41 frame_pointer += 4;
42 if (*(unsigned long *)frame_pointer == old)
43 *(unsigned long *)frame_pointer = return_hooker;
44 }
45}
138#ifdef CONFIG_FUNCTION_GRAPH_TRACER
139void prepare_ftrace_return(unsigned long *parent, unsigned long self_addr,
140 unsigned long frame_pointer)
141{
142 unsigned long return_hooker = (unsigned long)&return_to_handler;
143 unsigned long old;
144
145 if (unlikely(atomic_read(&current->tracing_graph_pause)))

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169 * because lr is resumed twice.
170 */
171 *parent = return_hooker;
172 frame_pointer += 4;
173 if (*(unsigned long *)frame_pointer == old)
174 *(unsigned long *)frame_pointer = return_hooker;
175 }
176}
46#endif
47
177
178#ifdef CONFIG_DYNAMIC_FTRACE
179int ftrace_enable_ftrace_graph_caller(void)
180{
181 return ftrace_modify_code((unsigned long)&ftrace_graph_call,
182 (unsigned long)&ftrace_graph_caller, true, true);
183}
184
185int ftrace_disable_ftrace_graph_caller(void)
186{
187 return ftrace_modify_code((unsigned long)&ftrace_graph_call,
188 (unsigned long)&ftrace_graph_caller, false, true);
189}
190#endif /* CONFIG_DYNAMIC_FTRACE */
191#endif /* CONFIG_FUNCTION_GRAPH_TRACER */
192
48/* _mcount is defined in abi's mcount.S */
193/* _mcount is defined in abi's mcount.S */
49extern void _mcount(void);
50EXPORT_SYMBOL(_mcount);
194EXPORT_SYMBOL(_mcount);