1 #include <linux/spinlock.h>
2 #include <linux/hardirq.h>
3 #include <linux/ftrace.h>
4 #include <linux/percpu.h>
5 #include <linux/init.h>
6 #include <linux/list.h>
7 #include <trace/syscall.h>
8
9 #include <asm/ftrace.h>
10
11 #ifdef CONFIG_DYNAMIC_FTRACE
12 static const u32 ftrace_nop = 0x01000000;
13
ftrace_call_replace(unsigned long ip,unsigned long addr)14 static u32 ftrace_call_replace(unsigned long ip, unsigned long addr)
15 {
16 u32 call;
17 s32 off;
18
19 off = ((s32)addr - (s32)ip);
20 call = 0x40000000 | ((u32)off >> 2);
21
22 return call;
23 }
24
ftrace_modify_code(unsigned long ip,u32 old,u32 new)25 static int ftrace_modify_code(unsigned long ip, u32 old, u32 new)
26 {
27 u32 replaced;
28 int faulted;
29
30 __asm__ __volatile__(
31 "1: cas [%[ip]], %[old], %[new]\n"
32 " flush %[ip]\n"
33 " mov 0, %[faulted]\n"
34 "2:\n"
35 " .section .fixup,#alloc,#execinstr\n"
36 " .align 4\n"
37 "3: sethi %%hi(2b), %[faulted]\n"
38 " jmpl %[faulted] + %%lo(2b), %%g0\n"
39 " mov 1, %[faulted]\n"
40 " .previous\n"
41 " .section __ex_table,\"a\"\n"
42 " .align 4\n"
43 " .word 1b, 3b\n"
44 " .previous\n"
45 : "=r" (replaced), [faulted] "=r" (faulted)
46 : [new] "0" (new), [old] "r" (old), [ip] "r" (ip)
47 : "memory");
48
49 if (replaced != old && replaced != new)
50 faulted = 2;
51
52 return faulted;
53 }
54
ftrace_make_nop(struct module * mod,struct dyn_ftrace * rec,unsigned long addr)55 int ftrace_make_nop(struct module *mod, struct dyn_ftrace *rec, unsigned long addr)
56 {
57 unsigned long ip = rec->ip;
58 u32 old, new;
59
60 old = ftrace_call_replace(ip, addr);
61 new = ftrace_nop;
62 return ftrace_modify_code(ip, old, new);
63 }
64
ftrace_make_call(struct dyn_ftrace * rec,unsigned long addr)65 int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr)
66 {
67 unsigned long ip = rec->ip;
68 u32 old, new;
69
70 old = ftrace_nop;
71 new = ftrace_call_replace(ip, addr);
72 return ftrace_modify_code(ip, old, new);
73 }
74
ftrace_update_ftrace_func(ftrace_func_t func)75 int ftrace_update_ftrace_func(ftrace_func_t func)
76 {
77 unsigned long ip = (unsigned long)(&ftrace_call);
78 u32 old, new;
79
80 old = *(u32 *) &ftrace_call;
81 new = ftrace_call_replace(ip, (unsigned long)func);
82 return ftrace_modify_code(ip, old, new);
83 }
84
ftrace_dyn_arch_init(void)85 int __init ftrace_dyn_arch_init(void)
86 {
87 return 0;
88 }
89 #endif
90
91 #ifdef CONFIG_FUNCTION_GRAPH_TRACER
92
93 #ifdef CONFIG_DYNAMIC_FTRACE
94 extern void ftrace_graph_call(void);
95
ftrace_enable_ftrace_graph_caller(void)96 int ftrace_enable_ftrace_graph_caller(void)
97 {
98 unsigned long ip = (unsigned long)(&ftrace_graph_call);
99 u32 old, new;
100
101 old = *(u32 *) &ftrace_graph_call;
102 new = ftrace_call_replace(ip, (unsigned long) &ftrace_graph_caller);
103 return ftrace_modify_code(ip, old, new);
104 }
105
ftrace_disable_ftrace_graph_caller(void)106 int ftrace_disable_ftrace_graph_caller(void)
107 {
108 unsigned long ip = (unsigned long)(&ftrace_graph_call);
109 u32 old, new;
110
111 old = *(u32 *) &ftrace_graph_call;
112 new = ftrace_call_replace(ip, (unsigned long) &ftrace_stub);
113
114 return ftrace_modify_code(ip, old, new);
115 }
116
117 #endif /* !CONFIG_DYNAMIC_FTRACE */
118
119 /*
120 * Hook the return address and push it in the stack of return addrs
121 * in current thread info.
122 */
prepare_ftrace_return(unsigned long parent,unsigned long self_addr,unsigned long frame_pointer)123 unsigned long prepare_ftrace_return(unsigned long parent,
124 unsigned long self_addr,
125 unsigned long frame_pointer)
126 {
127 unsigned long return_hooker = (unsigned long) &return_to_handler;
128 struct ftrace_graph_ent trace;
129
130 if (unlikely(atomic_read(¤t->tracing_graph_pause)))
131 return parent + 8UL;
132
133 if (ftrace_push_return_trace(parent, self_addr, &trace.depth,
134 frame_pointer) == -EBUSY)
135 return parent + 8UL;
136
137 trace.func = self_addr;
138
139 /* Only trace if the calling function expects to */
140 if (!ftrace_graph_entry(&trace)) {
141 current->curr_ret_stack--;
142 return parent + 8UL;
143 }
144
145 return return_hooker;
146 }
147 #endif /* CONFIG_FUNCTION_GRAPH_TRACER */
148