linux/Documentation/perf_counter/util/symbol.c

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#include "util.h"
#include "../perf.h"
#include "symbol.h"
#include <libelf.h>
#include <gelf.h>
#include <elf.h>
static struct symbol *symbol__new(uint64_t start, uint64_t len,
const char *name, unsigned int priv_size)
{
size_t namelen = strlen(name) + 1;
struct symbol *self = malloc(priv_size + sizeof(*self) + namelen);
if (self != NULL) {
if (priv_size) {
memset(self, 0, priv_size);
self = ((void *)self) + priv_size;
}
self->start = start;
self->end = start + len;
memcpy(self->name, name, namelen);
}
return self;
}
static void symbol__delete(struct symbol *self, unsigned int priv_size)
{
free(((void *)self) - priv_size);
}
static size_t symbol__fprintf(struct symbol *self, FILE *fp)
{
return fprintf(fp, " %llx-%llx %s\n",
self->start, self->end, self->name);
}
struct dso *dso__new(const char *name, unsigned int sym_priv_size)
{
struct dso *self = malloc(sizeof(*self) + strlen(name) + 1);
if (self != NULL) {
strcpy(self->name, name);
self->syms = RB_ROOT;
self->sym_priv_size = sym_priv_size;
}
return self;
}
static void dso__delete_symbols(struct dso *self)
{
struct symbol *pos;
struct rb_node *next = rb_first(&self->syms);
while (next) {
pos = rb_entry(next, struct symbol, rb_node);
next = rb_next(&pos->rb_node);
symbol__delete(pos, self->sym_priv_size);
}
}
void dso__delete(struct dso *self)
{
dso__delete_symbols(self);
free(self);
}
static void dso__insert_symbol(struct dso *self, struct symbol *sym)
{
struct rb_node **p = &self->syms.rb_node;
struct rb_node *parent = NULL;
const uint64_t ip = sym->start;
struct symbol *s;
while (*p != NULL) {
parent = *p;
s = rb_entry(parent, struct symbol, rb_node);
if (ip < s->start)
p = &(*p)->rb_left;
else
p = &(*p)->rb_right;
}
rb_link_node(&sym->rb_node, parent, p);
rb_insert_color(&sym->rb_node, &self->syms);
}
struct symbol *dso__find_symbol(struct dso *self, uint64_t ip)
{
struct rb_node *n;
if (self == NULL)
return NULL;
n = self->syms.rb_node;
while (n) {
struct symbol *s = rb_entry(n, struct symbol, rb_node);
if (ip < s->start)
n = n->rb_left;
else if (ip > s->end)
n = n->rb_right;
else
return s;
}
return NULL;
}
size_t dso__fprintf(struct dso *self, FILE *fp)
{
size_t ret = fprintf(fp, "dso: %s\n", self->name);
struct rb_node *nd;
for (nd = rb_first(&self->syms); nd; nd = rb_next(nd)) {
struct symbol *pos = rb_entry(nd, struct symbol, rb_node);
ret += symbol__fprintf(pos, fp);
}
return ret;
}
static int hex(char ch)
{
if ((ch >= '0') && (ch <= '9'))
return ch - '0';
if ((ch >= 'a') && (ch <= 'f'))
return ch - 'a' + 10;
if ((ch >= 'A') && (ch <= 'F'))
return ch - 'A' + 10;
return -1;
}
/*
* While we find nice hex chars, build a long_val.
* Return number of chars processed.
*/
static int hex2long(char *ptr, unsigned long *long_val)
{
const char *p = ptr;
*long_val = 0;
while (*p) {
const int hex_val = hex(*p);
if (hex_val < 0)
break;
*long_val = (*long_val << 4) | hex_val;
p++;
}
return p - ptr;
}
static int dso__load_kallsyms(struct dso *self)
{
struct rb_node *nd, *prevnd;
char *line = NULL;
size_t n;
FILE *file = fopen("/proc/kallsyms", "r");
if (file == NULL)
goto out_failure;
while (!feof(file)) {
unsigned long start;
struct symbol *sym;
int line_len, len;
char symbol_type;
line_len = getline(&line, &n, file);
if (line_len < 0)
break;
if (!line)
goto out_failure;
line[--line_len] = '\0'; /* \n */
len = hex2long(line, &start);
len++;
if (len + 2 >= line_len)
continue;
symbol_type = toupper(line[len]);
/*
* We're interested only in code ('T'ext)
*/
if (symbol_type != 'T' && symbol_type != 'W')
continue;
/*
* Well fix up the end later, when we have all sorted.
*/
sym = symbol__new(start, 0xdead, line + len + 2,
self->sym_priv_size);
if (sym == NULL)
goto out_delete_line;
dso__insert_symbol(self, sym);
}
/*
* Now that we have all sorted out, just set the ->end of all
* symbols
*/
prevnd = rb_first(&self->syms);
if (prevnd == NULL)
goto out_delete_line;
for (nd = rb_next(prevnd); nd; nd = rb_next(nd)) {
struct symbol *prev = rb_entry(prevnd, struct symbol, rb_node),
*curr = rb_entry(nd, struct symbol, rb_node);
prev->end = curr->start - 1;
prevnd = nd;
}
free(line);
fclose(file);
return 0;
out_delete_line:
free(line);
out_failure:
return -1;
}
/**
* elf_symtab__for_each_symbol - iterate thru all the symbols
*
* @self: struct elf_symtab instance to iterate
* @index: uint32_t index
* @sym: GElf_Sym iterator
*/
#define elf_symtab__for_each_symbol(syms, nr_syms, index, sym) \
for (index = 0, gelf_getsym(syms, index, &sym);\
index < nr_syms; \
index++, gelf_getsym(syms, index, &sym))
static inline uint8_t elf_sym__type(const GElf_Sym *sym)
{
return GELF_ST_TYPE(sym->st_info);
}
static inline int elf_sym__is_function(const GElf_Sym *sym)
{
return elf_sym__type(sym) == STT_FUNC &&
sym->st_name != 0 &&
sym->st_shndx != SHN_UNDEF &&
sym->st_size != 0;
}
static inline const char *elf_sym__name(const GElf_Sym *sym,
const Elf_Data *symstrs)
{
return symstrs->d_buf + sym->st_name;
}
static Elf_Scn *elf_section_by_name(Elf *elf, GElf_Ehdr *ep,
GElf_Shdr *shp, const char *name,
size_t *index)
{
Elf_Scn *sec = NULL;
size_t cnt = 1;
while ((sec = elf_nextscn(elf, sec)) != NULL) {
char *str;
gelf_getshdr(sec, shp);
str = elf_strptr(elf, ep->e_shstrndx, shp->sh_name);
if (!strcmp(name, str)) {
if (index)
*index = cnt;
break;
}
++cnt;
}
return sec;
}
static int dso__load_sym(struct dso *self, int fd, const char *name)
{
Elf_Data *symstrs;
uint32_t nr_syms;
int err = -1;
uint32_t index;
GElf_Ehdr ehdr;
GElf_Shdr shdr;
Elf_Data *syms;
GElf_Sym sym;
Elf_Scn *sec;
Elf *elf;
int nr = 0;
elf = elf_begin(fd, ELF_C_READ_MMAP, NULL);
if (elf == NULL) {
fprintf(stderr, "%s: cannot read %s ELF file.\n",
__func__, name);
goto out_close;
}
if (gelf_getehdr(elf, &ehdr) == NULL) {
fprintf(stderr, "%s: cannot get elf header.\n", __func__);
goto out_elf_end;
}
sec = elf_section_by_name(elf, &ehdr, &shdr, ".symtab", NULL);
if (sec == NULL)
sec = elf_section_by_name(elf, &ehdr, &shdr, ".dynsym", NULL);
if (sec == NULL)
goto out_elf_end;
syms = elf_getdata(sec, NULL);
if (syms == NULL)
goto out_elf_end;
sec = elf_getscn(elf, shdr.sh_link);
if (sec == NULL)
goto out_elf_end;
symstrs = elf_getdata(sec, NULL);
if (symstrs == NULL)
goto out_elf_end;
nr_syms = shdr.sh_size / shdr.sh_entsize;
elf_symtab__for_each_symbol(syms, nr_syms, index, sym) {
struct symbol *f;
if (!elf_sym__is_function(&sym))
continue;
sec = elf_getscn(elf, sym.st_shndx);
if (!sec)
goto out_elf_end;
gelf_getshdr(sec, &shdr);
sym.st_value -= shdr.sh_addr - shdr.sh_offset;
f = symbol__new(sym.st_value, sym.st_size,
elf_sym__name(&sym, symstrs),
self->sym_priv_size);
if (!f)
goto out_elf_end;
dso__insert_symbol(self, f);
nr++;
}
err = nr;
out_elf_end:
elf_end(elf);
out_close:
return err;
}
int dso__load(struct dso *self)
{
int size = strlen(self->name) + sizeof("/usr/lib/debug%s.debug");
char *name = malloc(size);
int variant = 0;
int ret = -1;
int fd;
if (!name)
return -1;
more:
do {
switch (variant) {
case 0: /* Fedora */
snprintf(name, size, "/usr/lib/debug%s.debug", self->name);
break;
case 1: /* Ubuntu */
snprintf(name, size, "/usr/lib/debug%s", self->name);
break;
case 2: /* Sane people */
snprintf(name, size, "%s", self->name);
break;
default:
goto out;
}
variant++;
fd = open(name, O_RDONLY);
} while (fd < 0);
ret = dso__load_sym(self, fd, name);
close(fd);
/*
* Some people seem to have debuginfo files _WITHOUT_ debug info!?!?
*/
if (!ret)
goto more;
out:
free(name);
return ret;
}
static int dso__load_vmlinux(struct dso *self, const char *vmlinux)
{
int err, fd = open(vmlinux, O_RDONLY);
if (fd < 0)
return -1;
err = dso__load_sym(self, fd, vmlinux);
close(fd);
return err;
}
int dso__load_kernel(struct dso *self, const char *vmlinux)
{
int err = -1;
if (vmlinux)
err = dso__load_vmlinux(self, vmlinux);
if (err)
err = dso__load_kallsyms(self);
return err;
}
void symbol__init(void)
{
elf_version(EV_CURRENT);
}