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Commit | Line | Data |
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1ee76d7e MF |
1 | /* |
2 | * ftrace graph code | |
3 | * | |
f5074429 | 4 | * Copyright (C) 2009-2010 Analog Devices Inc. |
1ee76d7e MF |
5 | * Licensed under the GPL-2 or later. |
6 | */ | |
7 | ||
8 | #include <linux/ftrace.h> | |
9 | #include <linux/kernel.h> | |
10 | #include <linux/sched.h> | |
f5074429 | 11 | #include <linux/uaccess.h> |
60063497 | 12 | #include <linux/atomic.h> |
f5074429 MF |
13 | #include <asm/cacheflush.h> |
14 | ||
15 | #ifdef CONFIG_DYNAMIC_FTRACE | |
16 | ||
17 | static const unsigned char mnop[] = { | |
18 | 0x03, 0xc0, 0x00, 0x18, /* MNOP; */ | |
19 | 0x03, 0xc0, 0x00, 0x18, /* MNOP; */ | |
20 | }; | |
21 | ||
22 | static void bfin_make_pcrel24(unsigned char *insn, unsigned long src, | |
23 | unsigned long dst) | |
24 | { | |
25 | uint32_t pcrel = (dst - src) >> 1; | |
26 | insn[0] = pcrel >> 16; | |
27 | insn[1] = 0xe3; | |
28 | insn[2] = pcrel; | |
29 | insn[3] = pcrel >> 8; | |
30 | } | |
31 | #define bfin_make_pcrel24(insn, src, dst) bfin_make_pcrel24(insn, src, (unsigned long)(dst)) | |
32 | ||
33 | static int ftrace_modify_code(unsigned long ip, const unsigned char *code, | |
34 | unsigned long len) | |
35 | { | |
36 | int ret = probe_kernel_write((void *)ip, (void *)code, len); | |
37 | flush_icache_range(ip, ip + len); | |
38 | return ret; | |
39 | } | |
40 | ||
41 | int ftrace_make_nop(struct module *mod, struct dyn_ftrace *rec, | |
42 | unsigned long addr) | |
43 | { | |
44 | /* Turn the mcount call site into two MNOPs as those are 32bit insns */ | |
45 | return ftrace_modify_code(rec->ip, mnop, sizeof(mnop)); | |
46 | } | |
47 | ||
48 | int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr) | |
49 | { | |
50 | /* Restore the mcount call site */ | |
51 | unsigned char call[8]; | |
52 | call[0] = 0x67; /* [--SP] = RETS; */ | |
53 | call[1] = 0x01; | |
54 | bfin_make_pcrel24(&call[2], rec->ip + 2, addr); | |
55 | call[6] = 0x27; /* RETS = [SP++]; */ | |
56 | call[7] = 0x01; | |
57 | return ftrace_modify_code(rec->ip, call, sizeof(call)); | |
58 | } | |
59 | ||
60 | int ftrace_update_ftrace_func(ftrace_func_t func) | |
61 | { | |
62 | unsigned char call[4]; | |
63 | unsigned long ip = (unsigned long)&ftrace_call; | |
64 | bfin_make_pcrel24(call, ip, func); | |
65 | return ftrace_modify_code(ip, call, sizeof(call)); | |
66 | } | |
67 | ||
68 | int __init ftrace_dyn_arch_init(void *data) | |
69 | { | |
70 | /* return value is done indirectly via data */ | |
71 | *(unsigned long *)data = 0; | |
72 | ||
73 | return 0; | |
74 | } | |
75 | ||
76 | #endif | |
1ee76d7e MF |
77 | |
78 | #ifdef CONFIG_FUNCTION_GRAPH_TRACER | |
79 | ||
f5074429 MF |
80 | # ifdef CONFIG_DYNAMIC_FTRACE |
81 | ||
82 | extern void ftrace_graph_call(void); | |
83 | ||
84 | int ftrace_enable_ftrace_graph_caller(void) | |
85 | { | |
86 | unsigned long ip = (unsigned long)&ftrace_graph_call; | |
87 | uint16_t jump_pcrel12 = ((unsigned long)&ftrace_graph_caller - ip) >> 1; | |
88 | jump_pcrel12 |= 0x2000; | |
89 | return ftrace_modify_code(ip, (void *)&jump_pcrel12, sizeof(jump_pcrel12)); | |
90 | } | |
91 | ||
92 | int ftrace_disable_ftrace_graph_caller(void) | |
93 | { | |
94 | return ftrace_modify_code((unsigned long)&ftrace_graph_call, empty_zero_page, 2); | |
95 | } | |
96 | ||
97 | # endif | |
98 | ||
1ee76d7e MF |
99 | /* |
100 | * Hook the return address and push it in the stack of return addrs | |
101 | * in current thread info. | |
102 | */ | |
b73faf74 MF |
103 | void prepare_ftrace_return(unsigned long *parent, unsigned long self_addr, |
104 | unsigned long frame_pointer) | |
1ee76d7e MF |
105 | { |
106 | struct ftrace_graph_ent trace; | |
107 | unsigned long return_hooker = (unsigned long)&return_to_handler; | |
108 | ||
109 | if (unlikely(atomic_read(¤t->tracing_graph_pause))) | |
110 | return; | |
111 | ||
b73faf74 MF |
112 | if (ftrace_push_return_trace(*parent, self_addr, &trace.depth, |
113 | frame_pointer) == -EBUSY) | |
1ee76d7e MF |
114 | return; |
115 | ||
116 | trace.func = self_addr; | |
117 | ||
118 | /* Only trace if the calling function expects to */ | |
119 | if (!ftrace_graph_entry(&trace)) { | |
120 | current->curr_ret_stack--; | |
121 | return; | |
122 | } | |
123 | ||
124 | /* all is well in the world ! hijack RETS ... */ | |
125 | *parent = return_hooker; | |
126 | } | |
127 | ||
128 | #endif |