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 
14 #ifdef HAVE_LIBELF_SUPPORT
15 bool elf__needs_adjust_symbols(GElf_Ehdr ehdr)
16 {
17 	return ehdr.e_type == ET_EXEC ||
18 	       ehdr.e_type == ET_REL ||
19 	       ehdr.e_type == ET_DYN;
20 }
21 
22 #endif
23 
24 #if !defined(_CALL_ELF) || _CALL_ELF != 2
25 int arch__choose_best_symbol(struct symbol *syma,
26 			     struct symbol *symb __maybe_unused)
27 {
28 	char *sym = syma->name;
29 
30 	/* Skip over any initial dot */
31 	if (*sym == '.')
32 		sym++;
33 
34 	/* Avoid "SyS" kernel syscall aliases */
35 	if (strlen(sym) >= 3 && !strncmp(sym, "SyS", 3))
36 		return SYMBOL_B;
37 	if (strlen(sym) >= 10 && !strncmp(sym, "compat_SyS", 10))
38 		return SYMBOL_B;
39 
40 	return SYMBOL_A;
41 }
42 
43 /* Allow matching against dot variants */
44 int arch__compare_symbol_names(const char *namea, const char *nameb)
45 {
46 	/* Skip over initial dot */
47 	if (*namea == '.')
48 		namea++;
49 	if (*nameb == '.')
50 		nameb++;
51 
52 	return strcmp(namea, nameb);
53 }
54 #endif
55 
56 #if defined(_CALL_ELF) && _CALL_ELF == 2
57 bool arch__prefers_symtab(void)
58 {
59 	return true;
60 }
61 
62 #ifdef HAVE_LIBELF_SUPPORT
63 void arch__sym_update(struct symbol *s, GElf_Sym *sym)
64 {
65 	s->arch_sym = sym->st_other;
66 }
67 #endif
68 
69 #define PPC64LE_LEP_OFFSET	8
70 
71 void arch__fix_tev_from_maps(struct perf_probe_event *pev,
72 			     struct probe_trace_event *tev, struct map *map,
73 			     struct symbol *sym)
74 {
75 	int lep_offset;
76 
77 	/*
78 	 * When probing at a function entry point, we normally always want the
79 	 * LEP since that catches calls to the function through both the GEP and
80 	 * the LEP. Hence, we would like to probe at an offset of 8 bytes if
81 	 * the user only specified the function entry.
82 	 *
83 	 * However, if the user specifies an offset, we fall back to using the
84 	 * GEP since all userspace applications (objdump/readelf) show function
85 	 * disassembly with offsets from the GEP.
86 	 *
87 	 * In addition, we shouldn't specify an offset for kretprobes.
88 	 */
89 	if (pev->point.offset || pev->point.retprobe || !map || !sym)
90 		return;
91 
92 	lep_offset = PPC64_LOCAL_ENTRY_OFFSET(sym->arch_sym);
93 
94 	if (map->dso->symtab_type == DSO_BINARY_TYPE__KALLSYMS)
95 		tev->point.offset += PPC64LE_LEP_OFFSET;
96 	else if (lep_offset) {
97 		if (pev->uprobes)
98 			tev->point.address += lep_offset;
99 		else
100 			tev->point.offset += lep_offset;
101 	}
102 }
103 #endif
104