1 // SPDX-License-Identifier: GPL-2.0
2 #include "dso.h"
3 #include "libdw.h"
4 #include "srcline.h"
5 #include "symbol.h"
6 #include "dwarf-aux.h"
7 #include <fcntl.h>
8 #include <unistd.h>
9 #include <elfutils/libdwfl.h>
10
11 static const Dwfl_Callbacks offline_callbacks = {
12 .find_debuginfo = dwfl_standard_find_debuginfo,
13 .section_address = dwfl_offline_section_address,
14 .find_elf = dwfl_build_id_find_elf,
15 };
16
dso__free_libdw(struct dso * dso)17 void dso__free_libdw(struct dso *dso)
18 {
19 Dwfl *dwfl = dso__libdw(dso);
20
21 if (dwfl) {
22 dwfl_end(dwfl);
23 dso__set_libdw(dso, NULL);
24 }
25 }
26
dso__libdw_dwfl(struct dso * dso)27 struct Dwfl *dso__libdw_dwfl(struct dso *dso)
28 {
29 Dwfl *dwfl = dso__libdw(dso);
30 const char *dso_name;
31 Dwfl_Module *mod;
32 int fd;
33
34 if (dwfl)
35 return dwfl;
36
37 dso_name = dso__long_name(dso);
38 /*
39 * Initialize Dwfl session.
40 * We need to open the DSO file to report it to libdw.
41 */
42 fd = open(dso_name, O_RDONLY);
43 if (fd < 0)
44 return NULL;
45
46 dwfl = dwfl_begin(&offline_callbacks);
47 if (!dwfl) {
48 close(fd);
49 return NULL;
50 }
51
52 /*
53 * If the report is successful, the file descriptor fd is consumed
54 * and closed by the Dwfl. If not, it is not closed.
55 */
56 mod = dwfl_report_offline(dwfl, dso_name, dso_name, fd);
57 if (!mod) {
58 dwfl_end(dwfl);
59 close(fd);
60 return NULL;
61 }
62
63 dwfl_report_end(dwfl, /*removed=*/NULL, /*arg=*/NULL);
64 dso__set_libdw(dso, dwfl);
65
66 return dwfl;
67 }
68
69 struct libdw_a2l_cb_args {
70 struct dso *dso;
71 struct symbol *sym;
72 struct inline_node *node;
73 char *leaf_srcline;
74 bool leaf_srcline_used;
75 };
76
libdw_a2l_cb(Dwarf_Die * die,void * _args)77 static int libdw_a2l_cb(Dwarf_Die *die, void *_args)
78 {
79 struct libdw_a2l_cb_args *args = _args;
80 struct symbol *inline_sym = new_inline_sym(args->dso, args->sym, dwarf_diename(die));
81 const char *call_fname = die_get_call_file(die);
82 char *call_srcline = srcline__unknown;
83 struct inline_list *ilist;
84
85 if (!inline_sym)
86 return -ENOMEM;
87
88 /* Assign caller information to the parent. */
89 if (call_fname)
90 call_srcline = srcline_from_fileline(call_fname, die_get_call_lineno(die));
91
92 list_for_each_entry(ilist, &args->node->val, list) {
93 if (args->leaf_srcline == ilist->srcline)
94 args->leaf_srcline_used = false;
95 else if (ilist->srcline != srcline__unknown)
96 free(ilist->srcline);
97 ilist->srcline = call_srcline;
98 call_srcline = NULL;
99 break;
100 }
101 if (call_srcline && call_srcline != srcline__unknown)
102 free(call_srcline);
103
104 /* Add this symbol to the chain as the leaf. */
105 if (!args->leaf_srcline_used) {
106 inline_list__append_tail(inline_sym, args->leaf_srcline, args->node);
107 args->leaf_srcline_used = true;
108 } else {
109 inline_list__append_tail(inline_sym, strdup(args->leaf_srcline), args->node);
110 }
111 return 0;
112 }
113
libdw__addr2line(u64 addr,char ** file,unsigned int * line_nr,struct dso * dso,bool unwind_inlines,struct inline_node * node,struct symbol * sym)114 int libdw__addr2line(u64 addr, char **file, unsigned int *line_nr,
115 struct dso *dso, bool unwind_inlines,
116 struct inline_node *node, struct symbol *sym)
117 {
118 Dwfl *dwfl = dso__libdw_dwfl(dso);
119 Dwfl_Module *mod;
120 Dwfl_Line *dwline;
121 Dwarf_Addr bias;
122 const char *src;
123 int lineno = 0;
124
125 if (!dwfl)
126 return 0;
127
128 mod = dwfl_addrmodule(dwfl, addr);
129 if (!mod)
130 return 0;
131
132 /*
133 * Get/ignore the dwarf information. Determine the bias, difference
134 * between the regular ELF addr2line addresses and those to use with
135 * libdw.
136 */
137 if (!dwfl_module_getdwarf(mod, &bias))
138 return 0;
139
140 /* Find source line information for the address. */
141 dwline = dwfl_module_getsrc(mod, addr + bias);
142 if (!dwline)
143 return 0;
144
145 /* Get line information. */
146 src = dwfl_lineinfo(dwline, /*addr=*/NULL, &lineno, /*col=*/NULL, /*mtime=*/NULL,
147 /*length=*/NULL);
148
149 if (file)
150 *file = src ? strdup(src) : NULL;
151 if (line_nr)
152 *line_nr = lineno;
153
154 /* Optionally unwind inline function call chain. */
155 if (unwind_inlines && node) {
156 Dwarf_Addr unused_bias;
157 Dwarf_Die *cudie = dwfl_module_addrdie(mod, addr + bias, &unused_bias);
158 struct libdw_a2l_cb_args args = {
159 .dso = dso,
160 .sym = sym,
161 .node = node,
162 .leaf_srcline = srcline_from_fileline(src ?: "<unknown>", lineno),
163 };
164
165 /* Walk from the parent down to the leaf. */
166 cu_walk_functions_at(cudie, addr, libdw_a2l_cb, &args);
167
168 if (!args.leaf_srcline_used)
169 free(args.leaf_srcline);
170 }
171 return 1;
172 }
173