cachepc-linux

Fork of AMDESE/linux with modifications for CachePC side-channel attack
git clone https://git.sinitax.com/sinitax/cachepc-linux
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sym-handling.c (3278B)

      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
     13int 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 */
     35int 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
     46int 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
     58const 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
     70void 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
     78void 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
    118void 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