root/tools/perf/arch/powerpc/util/sym-handling.c

DEFINITIONS

1. elf__needs_adjust_symbols
2. arch__choose_best_symbol
3. arch__compare_symbol_names
4. arch__compare_symbol_names_n
5. arch__normalize_symbol_name
6. arch__sym_update
7. arch__fix_tev_from_maps
8. arch__post_process_probe_trace_events

   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 #ifdef HAVE_LIBELF_SUPPORT
  14 bool elf__needs_adjust_symbols(GElf_Ehdr ehdr)
  15 {
  16         return ehdr.e_type == ET_EXEC ||
  17                ehdr.e_type == ET_REL ||
  18                ehdr.e_type == ET_DYN;
  19 }
  20 
  21 #endif
  22 
  23 int arch__choose_best_symbol(struct symbol *syma,
  24                              struct symbol *symb __maybe_unused)
  25 {
  26         char *sym = syma->name;
  27 
  28 #if !defined(_CALL_ELF) || _CALL_ELF != 2
  29         /* Skip over any initial dot */
  30         if (*sym == '.')
  31                 sym++;
  32 #endif
  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 #if !defined(_CALL_ELF) || _CALL_ELF != 2
  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