1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  *
4  * Copyright (C) 2015 Naveen N. Rao, IBM Corporation
5  */
6 
7 #include "dso.h"
8 #include "symbol.h"
9 #include "map.h"
10 #include "probe-event.h"
11 #include "probe-file.h"
12 
13 int arch__choose_best_symbol(struct symbol *syma,
14 			     struct symbol *symb __maybe_unused)
15 {
16 	char *sym = syma->name;
17 
18 #if !defined(_CALL_ELF) || _CALL_ELF != 2
19 	/* Skip over any initial dot */
20 	if (*sym == '.')
21 		sym++;
22 #endif
23 
24 	/* Avoid "SyS" kernel syscall aliases */
25 	if (strlen(sym) >= 3 && !strncmp(sym, "SyS", 3))
26 		return SYMBOL_B;
27 	if (strlen(sym) >= 10 && !strncmp(sym, "compat_SyS", 10))
28 		return SYMBOL_B;
29 
30 	return SYMBOL_A;
31 }
32 
33 #if !defined(_CALL_ELF) || _CALL_ELF != 2
34 /* Allow matching against dot variants */
35 int arch__compare_symbol_names(const char *namea, const char *nameb)
36 {
37 	/* Skip over initial dot */
38 	if (*namea == '.')
39 		namea++;
40 	if (*nameb == '.')
41 		nameb++;
42 
43 	return strcmp(namea, nameb);
44 }
45 
46 int arch__compare_symbol_names_n(const char *namea, const char *nameb,
47 				 unsigned int n)
48 {
49 	/* Skip over initial dot */
50 	if (*namea == '.')
51 		namea++;
52 	if (*nameb == '.')
53 		nameb++;
54 
55 	return strncmp(namea, nameb, n);
56 }
57 
58 const char *arch__normalize_symbol_name(const char *name)
59 {
60 	/* Skip over initial dot */
61 	if (name && *name == '.')
62 		name++;
63 	return name;
64 }
65 #endif
66 
67 #if defined(_CALL_ELF) && _CALL_ELF == 2
68 
69 #ifdef HAVE_LIBELF_SUPPORT
70 void arch__sym_update(struct symbol *s, GElf_Sym *sym)
71 {
72 	s->arch_sym = sym->st_other;
73 }
74 #endif
75 
76 #define PPC64LE_LEP_OFFSET	8
77 
78 void arch__fix_tev_from_maps(struct perf_probe_event *pev,
79 			     struct probe_trace_event *tev, struct map *map,
80 			     struct symbol *sym)
81 {
82 	int lep_offset;
83 
84 	/*
85 	 * When probing at a function entry point, we normally always want the
86 	 * LEP since that catches calls to the function through both the GEP and
87 	 * the LEP. Hence, we would like to probe at an offset of 8 bytes if
88 	 * the user only specified the function entry.
89 	 *
90 	 * However, if the user specifies an offset, we fall back to using the
91 	 * GEP since all userspace applications (objdump/readelf) show function
92 	 * disassembly with offsets from the GEP.
93 	 */
94 	if (pev->point.offset || !map || !sym)
95 		return;
96 
97 	/* For kretprobes, add an offset only if the kernel supports it */
98 	if (!pev->uprobes && pev->point.retprobe) {
99 #ifdef HAVE_LIBELF_SUPPORT
100 		if (!kretprobe_offset_is_supported())
101 #endif
102 			return;
103 	}
104 
105 	lep_offset = PPC64_LOCAL_ENTRY_OFFSET(sym->arch_sym);
106 
107 	if (map->dso->symtab_type == DSO_BINARY_TYPE__KALLSYMS)
108 		tev->point.offset += PPC64LE_LEP_OFFSET;
109 	else if (lep_offset) {
110 		if (pev->uprobes)
111 			tev->point.address += lep_offset;
112 		else
113 			tev->point.offset += lep_offset;
114 	}
115 }
116 
117 #ifdef HAVE_LIBELF_SUPPORT
118 void arch__post_process_probe_trace_events(struct perf_probe_event *pev,
119 					   int ntevs)
120 {
121 	struct probe_trace_event *tev;
122 	struct map *map;
123 	struct symbol *sym = NULL;
124 	struct rb_node *tmp;
125 	int i = 0;
126 
127 	map = get_target_map(pev->target, pev->nsi, pev->uprobes);
128 	if (!map || map__load(map) < 0)
129 		return;
130 
131 	for (i = 0; i < ntevs; i++) {
132 		tev = &pev->tevs[i];
133 		map__for_each_symbol(map, sym, tmp) {
134 			if (map->unmap_ip(map, sym->start) == tev->point.address) {
135 				arch__fix_tev_from_maps(pev, tev, map, sym);
136 				break;
137 			}
138 		}
139 	}
140 }
141 #endif /* HAVE_LIBELF_SUPPORT */
142 
143 #endif
144