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