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8#include <inttypes.h>
9#include <dwarf.h>
10#include <elfutils/libdwfl.h>
11
12#include "util/thread.h"
13#include "util/callchain.h"
14#include "util/debug.h"
15#include "util/dso.h"
16#include "util/map.h"
17#include "util/symbol.h"
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31
32static char *debuginfo_path;
33
34static const Dwfl_Callbacks offline_callbacks = {
35 .debuginfo_path = &debuginfo_path,
36 .find_debuginfo = dwfl_standard_find_debuginfo,
37 .section_address = dwfl_offline_section_address,
38};
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44
45static int check_return_reg(int ra_regno, Dwarf_Frame *frame)
46{
47 Dwarf_Op ops_mem[2];
48 Dwarf_Op dummy;
49 Dwarf_Op *ops = &dummy;
50 size_t nops;
51 int result;
52
53 result = dwarf_frame_register(frame, ra_regno, ops_mem, &ops, &nops);
54 if (result < 0) {
55 pr_debug("dwarf_frame_register() %s\n", dwarf_errmsg(-1));
56 return -1;
57 }
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62
63
64 if ((nops != 0 || ops != NULL) &&
65 !(nops == 1 && ops[0].atom == DW_OP_regx &&
66 ops[0].number2 == 0 && ops[0].offset == 0))
67 return 0;
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73 result = dwarf_frame_cfa(frame, &ops, &nops);
74 if (result < 0) {
75 pr_debug("dwarf_frame_cfa() returns %d, %s\n", result,
76 dwarf_errmsg(-1));
77 return -1;
78 }
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82
83 if (nops == 1 && ops[0].atom == DW_OP_bregx && ops[0].number == 1 &&
84 ops[0].number2 == 0)
85 return 1;
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89
90 return 2;
91}
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95
96static Dwarf_Frame *get_eh_frame(Dwfl_Module *mod, Dwarf_Addr pc)
97{
98 int result;
99 Dwarf_Addr bias;
100 Dwarf_CFI *cfi;
101 Dwarf_Frame *frame;
102
103 cfi = dwfl_module_eh_cfi(mod, &bias);
104 if (!cfi) {
105 pr_debug("%s(): no CFI - %s\n", __func__, dwfl_errmsg(-1));
106 return NULL;
107 }
108
109 result = dwarf_cfi_addrframe(cfi, pc-bias, &frame);
110 if (result) {
111 pr_debug("%s(): %s\n", __func__, dwfl_errmsg(-1));
112 return NULL;
113 }
114
115 return frame;
116}
117
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120
121static Dwarf_Frame *get_dwarf_frame(Dwfl_Module *mod, Dwarf_Addr pc)
122{
123 Dwarf_CFI *cfi;
124 Dwarf_Addr bias;
125 Dwarf_Frame *frame;
126 int result;
127
128 cfi = dwfl_module_dwarf_cfi(mod, &bias);
129 if (!cfi) {
130 pr_debug("%s(): no CFI - %s\n", __func__, dwfl_errmsg(-1));
131 return NULL;
132 }
133
134 result = dwarf_cfi_addrframe(cfi, pc-bias, &frame);
135 if (result) {
136 pr_debug("%s(): %s\n", __func__, dwfl_errmsg(-1));
137 return NULL;
138 }
139
140 return frame;
141}
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150
151static int check_return_addr(struct dso *dso, u64 map_start, Dwarf_Addr pc)
152{
153 int rc = -1;
154 Dwfl *dwfl;
155 Dwfl_Module *mod;
156 Dwarf_Frame *frame;
157 int ra_regno;
158 Dwarf_Addr start = pc;
159 Dwarf_Addr end = pc;
160 bool signalp;
161 const char *exec_file = dso->long_name;
162
163 dwfl = dso->dwfl;
164
165 if (!dwfl) {
166 dwfl = dwfl_begin(&offline_callbacks);
167 if (!dwfl) {
168 pr_debug("dwfl_begin() failed: %s\n", dwarf_errmsg(-1));
169 return -1;
170 }
171
172 mod = dwfl_report_elf(dwfl, exec_file, exec_file, -1,
173 map_start, false);
174 if (!mod) {
175 pr_debug("dwfl_report_elf() failed %s\n",
176 dwarf_errmsg(-1));
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180
181
182 dwfl_end(dwfl);
183 goto out;
184 }
185 dso->dwfl = dwfl;
186 }
187
188 mod = dwfl_addrmodule(dwfl, pc);
189 if (!mod) {
190 pr_debug("dwfl_addrmodule() failed, %s\n", dwarf_errmsg(-1));
191 goto out;
192 }
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197
198 frame = get_eh_frame(mod, pc);
199 if (!frame) {
200 frame = get_dwarf_frame(mod, pc);
201 if (!frame)
202 goto out;
203 }
204
205 ra_regno = dwarf_frame_info(frame, &start, &end, &signalp);
206 if (ra_regno < 0) {
207 pr_debug("Return address register unavailable: %s\n",
208 dwarf_errmsg(-1));
209 goto out;
210 }
211
212 rc = check_return_reg(ra_regno, frame);
213
214out:
215 return rc;
216}
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241int arch_skip_callchain_idx(struct thread *thread, struct ip_callchain *chain)
242{
243 struct addr_location al;
244 struct dso *dso = NULL;
245 int rc;
246 u64 ip;
247 u64 skip_slot = -1;
248
249 if (!chain || chain->nr < 3)
250 return skip_slot;
251
252 ip = chain->ips[1];
253
254 thread__find_symbol(thread, PERF_RECORD_MISC_USER, ip, &al);
255
256 if (al.map)
257 dso = al.map->dso;
258
259 if (!dso) {
260 pr_debug("%" PRIx64 " dso is NULL\n", ip);
261 return skip_slot;
262 }
263
264 rc = check_return_addr(dso, al.map->start, ip);
265
266 pr_debug("[DSO %s, sym %s, ip 0x%" PRIx64 "] rc %d\n",
267 dso->long_name, al.sym->name, ip, rc);
268
269 if (rc == 0) {
270
271
272
273 skip_slot = 2;
274 } else if (rc == 2) {
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279 skip_slot = 3;
280 }
281 return skip_slot;
282}
283