Commit | Line | Data |
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d75f054a HD |
1 | /* |
2 | * Code for tracing calls in Linux kernel. | |
3 | * Copyright (C) 2009 Helge Deller <deller@gmx.de> | |
4 | * | |
5 | * based on code for x86 which is: | |
6 | * Copyright (C) 2007-2008 Steven Rostedt <srostedt@redhat.com> | |
7 | * | |
8 | * future possible enhancements: | |
9 | * - add CONFIG_DYNAMIC_FTRACE | |
10 | * - add CONFIG_STACK_TRACER | |
11 | */ | |
12 | ||
13 | #include <linux/init.h> | |
14 | #include <linux/ftrace.h> | |
15 | ||
16 | #include <asm/sections.h> | |
17 | #include <asm/ftrace.h> | |
18 | ||
19 | ||
20 | ||
21 | #ifdef CONFIG_FUNCTION_GRAPH_TRACER | |
22 | ||
23 | /* Add a function return address to the trace stack on thread info.*/ | |
24 | static int push_return_trace(unsigned long ret, unsigned long long time, | |
25 | unsigned long func, int *depth) | |
26 | { | |
27 | int index; | |
28 | ||
29 | if (!current->ret_stack) | |
30 | return -EBUSY; | |
31 | ||
32 | /* The return trace stack is full */ | |
33 | if (current->curr_ret_stack == FTRACE_RETFUNC_DEPTH - 1) { | |
34 | atomic_inc(¤t->trace_overrun); | |
35 | return -EBUSY; | |
36 | } | |
37 | ||
38 | index = ++current->curr_ret_stack; | |
39 | barrier(); | |
40 | current->ret_stack[index].ret = ret; | |
41 | current->ret_stack[index].func = func; | |
42 | current->ret_stack[index].calltime = time; | |
43 | *depth = index; | |
44 | ||
45 | return 0; | |
46 | } | |
47 | ||
48 | /* Retrieve a function return address to the trace stack on thread info.*/ | |
49 | static void pop_return_trace(struct ftrace_graph_ret *trace, unsigned long *ret) | |
50 | { | |
51 | int index; | |
52 | ||
53 | index = current->curr_ret_stack; | |
54 | ||
55 | if (unlikely(index < 0)) { | |
56 | ftrace_graph_stop(); | |
57 | WARN_ON(1); | |
58 | /* Might as well panic, otherwise we have no where to go */ | |
59 | *ret = (unsigned long) | |
60 | dereference_function_descriptor(&panic); | |
61 | return; | |
62 | } | |
63 | ||
64 | *ret = current->ret_stack[index].ret; | |
65 | trace->func = current->ret_stack[index].func; | |
66 | trace->calltime = current->ret_stack[index].calltime; | |
67 | trace->overrun = atomic_read(¤t->trace_overrun); | |
68 | trace->depth = index; | |
69 | barrier(); | |
70 | current->curr_ret_stack--; | |
71 | ||
72 | } | |
73 | ||
74 | /* | |
75 | * Send the trace to the ring-buffer. | |
76 | * @return the original return address. | |
77 | */ | |
78 | unsigned long ftrace_return_to_handler(unsigned long retval0, | |
79 | unsigned long retval1) | |
80 | { | |
81 | struct ftrace_graph_ret trace; | |
82 | unsigned long ret; | |
83 | ||
84 | pop_return_trace(&trace, &ret); | |
c676329a | 85 | trace.rettime = local_clock(); |
d75f054a HD |
86 | ftrace_graph_return(&trace); |
87 | ||
88 | if (unlikely(!ret)) { | |
89 | ftrace_graph_stop(); | |
90 | WARN_ON(1); | |
91 | /* Might as well panic. What else to do? */ | |
92 | ret = (unsigned long) | |
93 | dereference_function_descriptor(&panic); | |
94 | } | |
95 | ||
96 | /* HACK: we hand over the old functions' return values | |
97 | in %r23 and %r24. Assembly in entry.S will take care | |
98 | and move those to their final registers %ret0 and %ret1 */ | |
99 | asm( "copy %0, %%r23 \n\t" | |
100 | "copy %1, %%r24 \n" : : "r" (retval0), "r" (retval1) ); | |
101 | ||
102 | return ret; | |
103 | } | |
104 | ||
105 | /* | |
106 | * Hook the return address and push it in the stack of return addrs | |
107 | * in current thread info. | |
108 | */ | |
109 | void prepare_ftrace_return(unsigned long *parent, unsigned long self_addr) | |
110 | { | |
111 | unsigned long old; | |
112 | unsigned long long calltime; | |
113 | struct ftrace_graph_ent trace; | |
114 | ||
3a46588e SRRH |
115 | if (unlikely(ftrace_graph_is_dead())) |
116 | return; | |
117 | ||
d75f054a HD |
118 | if (unlikely(atomic_read(¤t->tracing_graph_pause))) |
119 | return; | |
120 | ||
121 | old = *parent; | |
122 | *parent = (unsigned long) | |
123 | dereference_function_descriptor(&return_to_handler); | |
124 | ||
125 | if (unlikely(!__kernel_text_address(old))) { | |
126 | ftrace_graph_stop(); | |
127 | *parent = old; | |
128 | WARN_ON(1); | |
129 | return; | |
130 | } | |
131 | ||
c676329a | 132 | calltime = local_clock(); |
d75f054a HD |
133 | |
134 | if (push_return_trace(old, calltime, | |
135 | self_addr, &trace.depth) == -EBUSY) { | |
136 | *parent = old; | |
137 | return; | |
138 | } | |
139 | ||
140 | trace.func = self_addr; | |
141 | ||
142 | /* Only trace if the calling function expects to */ | |
143 | if (!ftrace_graph_entry(&trace)) { | |
144 | current->curr_ret_stack--; | |
145 | *parent = old; | |
146 | } | |
147 | } | |
148 | ||
149 | #endif /* CONFIG_FUNCTION_GRAPH_TRACER */ | |
150 | ||
151 | ||
152 | void ftrace_function_trampoline(unsigned long parent, | |
153 | unsigned long self_addr, | |
154 | unsigned long org_sp_gr3) | |
155 | { | |
156 | extern ftrace_func_t ftrace_trace_function; | |
157 | ||
d75f054a HD |
158 | if (ftrace_trace_function != ftrace_stub) { |
159 | ftrace_trace_function(parent, self_addr); | |
160 | return; | |
161 | } | |
162 | #ifdef CONFIG_FUNCTION_GRAPH_TRACER | |
163 | if (ftrace_graph_entry && ftrace_graph_return) { | |
164 | unsigned long sp; | |
165 | unsigned long *parent_rp; | |
166 | ||
167 | asm volatile ("copy %%r30, %0" : "=r"(sp)); | |
168 | /* sanity check: is stack pointer which we got from | |
169 | assembler function in entry.S in a reasonable | |
170 | range compared to current stack pointer? */ | |
171 | if ((sp - org_sp_gr3) > 0x400) | |
172 | return; | |
173 | ||
174 | /* calculate pointer to %rp in stack */ | |
175 | parent_rp = (unsigned long *) org_sp_gr3 - 0x10; | |
176 | /* sanity check: parent_rp should hold parent */ | |
177 | if (*parent_rp != parent) | |
178 | return; | |
179 | ||
180 | prepare_ftrace_return(parent_rp, self_addr); | |
181 | return; | |
182 | } | |
183 | #endif | |
184 | } | |
185 |