1 /*
2  * This program is free software; you can redistribute it and/or modify
3  * it under the terms of the GNU General Public License, version 2, as
4  * published by the Free Software Foundation.
5  *
6  * Copyright (C) 2015 Naveen N. Rao, IBM Corporation
7  */
8 
9 #include "debug.h"
10 #include "symbol.h"
11 #include "map.h"
12 #include "probe-event.h"
13 #include "probe-file.h"
14 
15 #ifdef HAVE_LIBELF_SUPPORT
16 bool elf__needs_adjust_symbols(GElf_Ehdr ehdr)
17 {
18 	return ehdr.e_type == ET_EXEC ||
19 	       ehdr.e_type == ET_REL ||
20 	       ehdr.e_type == ET_DYN;
21 }
22 
23 #endif
24 
25 #if !defined(_CALL_ELF) || _CALL_ELF != 2
26 int arch__choose_best_symbol(struct symbol *syma,
27 			     struct symbol *symb __maybe_unused)
28 {
29 	char *sym = syma->name;
30 
31 	/* Skip over any initial dot */
32 	if (*sym == '.')
33 		sym++;
34 
35 	/* Avoid "SyS" kernel syscall aliases */
36 	if (strlen(sym) >= 3 && !strncmp(sym, "SyS", 3))
37 		return SYMBOL_B;
38 	if (strlen(sym) >= 10 && !strncmp(sym, "compat_SyS", 10))
39 		return SYMBOL_B;
40 
41 	return SYMBOL_A;
42 }
43 
44 /* Allow matching against dot variants */
45 int arch__compare_symbol_names(const char *namea, const char *nameb)
46 {
47 	/* Skip over initial dot */
48 	if (*namea == '.')
49 		namea++;
50 	if (*nameb == '.')
51 		nameb++;
52 
53 	return strcmp(namea, nameb);
54 }
55 
56 int arch__compare_symbol_names_n(const char *namea, const char *nameb,
57 				 unsigned int n)
58 {
59 	/* Skip over initial dot */
60 	if (*namea == '.')
61 		namea++;
62 	if (*nameb == '.')
63 		nameb++;
64 
65 	return strncmp(namea, nameb, n);
66 }
67 
68 const char *arch__normalize_symbol_name(const char *name)
69 {
70 	/* Skip over initial dot */
71 	if (name && *name == '.')
72 		name++;
73 	return name;
74 }
75 #endif
76 
77 #if defined(_CALL_ELF) && _CALL_ELF == 2
78 
79 #ifdef HAVE_LIBELF_SUPPORT
80 void arch__sym_update(struct symbol *s, GElf_Sym *sym)
81 {
82 	s->arch_sym = sym->st_other;
83 }
84 #endif
85 
86 #define PPC64LE_LEP_OFFSET	8
87 
88 void arch__fix_tev_from_maps(struct perf_probe_event *pev,
89 			     struct probe_trace_event *tev, struct map *map,
90 			     struct symbol *sym)
91 {
92 	int lep_offset;
93 
94 	/*
95 	 * When probing at a function entry point, we normally always want the
96 	 * LEP since that catches calls to the function through both the GEP and
97 	 * the LEP. Hence, we would like to probe at an offset of 8 bytes if
98 	 * the user only specified the function entry.
99 	 *
100 	 * However, if the user specifies an offset, we fall back to using the
101 	 * GEP since all userspace applications (objdump/readelf) show function
102 	 * disassembly with offsets from the GEP.
103 	 */
104 	if (pev->point.offset || !map || !sym)
105 		return;
106 
107 	/* For kretprobes, add an offset only if the kernel supports it */
108 	if (!pev->uprobes && pev->point.retprobe) {
109 #ifdef HAVE_LIBELF_SUPPORT
110 		if (!kretprobe_offset_is_supported())
111 #endif
112 			return;
113 	}
114 
115 	lep_offset = PPC64_LOCAL_ENTRY_OFFSET(sym->arch_sym);
116 
117 	if (map->dso->symtab_type == DSO_BINARY_TYPE__KALLSYMS)
118 		tev->point.offset += PPC64LE_LEP_OFFSET;
119 	else if (lep_offset) {
120 		if (pev->uprobes)
121 			tev->point.address += lep_offset;
122 		else
123 			tev->point.offset += lep_offset;
124 	}
125 }
126 
127 #ifdef HAVE_LIBELF_SUPPORT
128 void arch__post_process_probe_trace_events(struct perf_probe_event *pev,
129 					   int ntevs)
130 {
131 	struct probe_trace_event *tev;
132 	struct map *map;
133 	struct symbol *sym = NULL;
134 	struct rb_node *tmp;
135 	int i = 0;
136 
137 	map = get_target_map(pev->target, pev->nsi, pev->uprobes);
138 	if (!map || map__load(map) < 0)
139 		return;
140 
141 	for (i = 0; i < ntevs; i++) {
142 		tev = &pev->tevs[i];
143 		map__for_each_symbol(map, sym, tmp) {
144 			if (map->unmap_ip(map, sym->start) == tev->point.address) {
145 				arch__fix_tev_from_maps(pev, tev, map, sym);
146 				break;
147 			}
148 		}
149 	}
150 }
151 #endif /* HAVE_LIBELF_SUPPORT */
152 
153 #endif
154