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 #endif
68 
69 #if defined(_CALL_ELF) && _CALL_ELF == 2
70 
71 #ifdef HAVE_LIBELF_SUPPORT
72 void arch__sym_update(struct symbol *s, GElf_Sym *sym)
73 {
74 	s->arch_sym = sym->st_other;
75 }
76 #endif
77 
78 #define PPC64LE_LEP_OFFSET	8
79 
80 void arch__fix_tev_from_maps(struct perf_probe_event *pev,
81 			     struct probe_trace_event *tev, struct map *map,
82 			     struct symbol *sym)
83 {
84 	int lep_offset;
85 
86 	/*
87 	 * When probing at a function entry point, we normally always want the
88 	 * LEP since that catches calls to the function through both the GEP and
89 	 * the LEP. Hence, we would like to probe at an offset of 8 bytes if
90 	 * the user only specified the function entry.
91 	 *
92 	 * However, if the user specifies an offset, we fall back to using the
93 	 * GEP since all userspace applications (objdump/readelf) show function
94 	 * disassembly with offsets from the GEP.
95 	 */
96 	if (pev->point.offset || !map || !sym)
97 		return;
98 
99 	/* For kretprobes, add an offset only if the kernel supports it */
100 	if (!pev->uprobes && pev->point.retprobe) {
101 #ifdef HAVE_LIBELF_SUPPORT
102 		if (!kretprobe_offset_is_supported())
103 #endif
104 			return;
105 	}
106 
107 	lep_offset = PPC64_LOCAL_ENTRY_OFFSET(sym->arch_sym);
108 
109 	if (map->dso->symtab_type == DSO_BINARY_TYPE__KALLSYMS)
110 		tev->point.offset += PPC64LE_LEP_OFFSET;
111 	else if (lep_offset) {
112 		if (pev->uprobes)
113 			tev->point.address += lep_offset;
114 		else
115 			tev->point.offset += lep_offset;
116 	}
117 }
118 
119 #ifdef HAVE_LIBELF_SUPPORT
120 void arch__post_process_probe_trace_events(struct perf_probe_event *pev,
121 					   int ntevs)
122 {
123 	struct probe_trace_event *tev;
124 	struct map *map;
125 	struct symbol *sym = NULL;
126 	struct rb_node *tmp;
127 	int i = 0;
128 
129 	map = get_target_map(pev->target, pev->nsi, pev->uprobes);
130 	if (!map || map__load(map) < 0)
131 		return;
132 
133 	for (i = 0; i < ntevs; i++) {
134 		tev = &pev->tevs[i];
135 		map__for_each_symbol(map, sym, tmp) {
136 			if (map->unmap_ip(map, sym->start) == tev->point.address)
137 				arch__fix_tev_from_maps(pev, tev, map, sym);
138 		}
139 	}
140 }
141 #endif /* HAVE_LIBELF_SUPPORT */
142 
143 #endif
144