Commit | Line | Data |
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00512bdd JH |
1 | /* |
2 | * Copyright (C) 2008 Imagination Technologies Ltd. | |
3 | * Licensed under the GPL | |
4 | * | |
5 | * Dynamic ftrace support. | |
6 | */ | |
7 | ||
8 | #include <linux/ftrace.h> | |
9 | #include <linux/io.h> | |
10 | #include <linux/uaccess.h> | |
11 | ||
12 | #include <asm/cacheflush.h> | |
13 | ||
14 | #define D04_MOVT_TEMPLATE 0x02200005 | |
15 | #define D04_CALL_TEMPLATE 0xAC200005 | |
16 | #define D1RTP_MOVT_TEMPLATE 0x03200005 | |
17 | #define D1RTP_CALL_TEMPLATE 0xAC200006 | |
18 | ||
19 | static const unsigned long NOP[2] = {0xa0fffffe, 0xa0fffffe}; | |
20 | static unsigned long movt_and_call_insn[2]; | |
21 | ||
22 | static unsigned char *ftrace_nop_replace(void) | |
23 | { | |
24 | return (char *)&NOP[0]; | |
25 | } | |
26 | ||
27 | static unsigned char *ftrace_call_replace(unsigned long pc, unsigned long addr) | |
28 | { | |
29 | unsigned long hi16, low16; | |
30 | ||
31 | hi16 = (addr & 0xffff0000) >> 13; | |
32 | low16 = (addr & 0x0000ffff) << 3; | |
33 | ||
34 | /* | |
35 | * The compiler makes the call to mcount_wrapper() | |
36 | * (Meta's wrapper around mcount()) through the register | |
37 | * D0.4. So whenever we're patching one of those compiler-generated | |
38 | * calls we also need to go through D0.4. Otherwise use D1RtP. | |
39 | */ | |
40 | if (pc == (unsigned long)&ftrace_call) { | |
41 | writel(D1RTP_MOVT_TEMPLATE | hi16, &movt_and_call_insn[0]); | |
42 | writel(D1RTP_CALL_TEMPLATE | low16, &movt_and_call_insn[1]); | |
43 | } else { | |
44 | writel(D04_MOVT_TEMPLATE | hi16, &movt_and_call_insn[0]); | |
45 | writel(D04_CALL_TEMPLATE | low16, &movt_and_call_insn[1]); | |
46 | } | |
47 | ||
48 | return (unsigned char *)&movt_and_call_insn[0]; | |
49 | } | |
50 | ||
51 | static int ftrace_modify_code(unsigned long pc, unsigned char *old_code, | |
52 | unsigned char *new_code) | |
53 | { | |
54 | unsigned char replaced[MCOUNT_INSN_SIZE]; | |
55 | ||
56 | /* | |
57 | * Note: Due to modules and __init, code can | |
58 | * disappear and change, we need to protect against faulting | |
59 | * as well as code changing. | |
60 | * | |
61 | * No real locking needed, this code is run through | |
62 | * kstop_machine. | |
63 | */ | |
64 | ||
65 | /* read the text we want to modify */ | |
66 | if (probe_kernel_read(replaced, (void *)pc, MCOUNT_INSN_SIZE)) | |
67 | return -EFAULT; | |
68 | ||
69 | /* Make sure it is what we expect it to be */ | |
70 | if (memcmp(replaced, old_code, MCOUNT_INSN_SIZE) != 0) | |
71 | return -EINVAL; | |
72 | ||
73 | /* replace the text with the new text */ | |
74 | if (probe_kernel_write((void *)pc, new_code, MCOUNT_INSN_SIZE)) | |
75 | return -EPERM; | |
76 | ||
77 | flush_icache_range(pc, pc + MCOUNT_INSN_SIZE); | |
78 | ||
79 | return 0; | |
80 | } | |
81 | ||
82 | int ftrace_update_ftrace_func(ftrace_func_t func) | |
83 | { | |
84 | int ret; | |
85 | unsigned long pc; | |
86 | unsigned char old[MCOUNT_INSN_SIZE], *new; | |
87 | ||
88 | pc = (unsigned long)&ftrace_call; | |
89 | memcpy(old, &ftrace_call, MCOUNT_INSN_SIZE); | |
90 | new = ftrace_call_replace(pc, (unsigned long)func); | |
91 | ret = ftrace_modify_code(pc, old, new); | |
92 | ||
93 | return ret; | |
94 | } | |
95 | ||
96 | int ftrace_make_nop(struct module *mod, | |
97 | struct dyn_ftrace *rec, unsigned long addr) | |
98 | { | |
99 | unsigned char *new, *old; | |
100 | unsigned long ip = rec->ip; | |
101 | ||
102 | old = ftrace_call_replace(ip, addr); | |
103 | new = ftrace_nop_replace(); | |
104 | ||
105 | return ftrace_modify_code(ip, old, new); | |
106 | } | |
107 | ||
108 | int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr) | |
109 | { | |
110 | unsigned char *new, *old; | |
111 | unsigned long ip = rec->ip; | |
112 | ||
113 | old = ftrace_nop_replace(); | |
114 | new = ftrace_call_replace(ip, addr); | |
115 | ||
116 | return ftrace_modify_code(ip, old, new); | |
117 | } | |
118 | ||
119 | /* run from kstop_machine */ | |
3a36cb11 | 120 | int __init ftrace_dyn_arch_init(void) |
00512bdd | 121 | { |
00512bdd JH |
122 | return 0; |
123 | } |