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#include "stddef.h"
#include <asm/vdso.h>
#include <elf.h>
#include <string.h>
#include <sys/auxv.h>
#include <time.h>
int (*__vdso_clock_gettime)(int, struct timespec *) = 0;
int (*__vdso_getcpu)(unsigned *, unsigned *, void *) = 0;
int (*__vdso_time)(long *) = 0;
struct __vdso_sym __vdso_symtab[] = {
{ "__vdso_clock_gettime", (void *)&__vdso_clock_gettime },
{ "__vdso_getcpu", (void *)&__vdso_getcpu },
{ "__vdso_time", (void *)&__vdso_time },
{ 0, 0 },
};
void __libc_init_vdso(void)
{
Elf64_Ehdr *ehdr = (Elf64_Ehdr *)getauxval(AT_SYSINFO_EHDR);
if (ehdr == NULL) {
return;
}
Elf64_Phdr *phdr = (Elf64_Phdr *)(ehdr + ehdr->e_phoff);
for (int i = 0; i < ehdr->e_phnum; i++) {
Elf64_Dyn *dyn;
Elf64_Sym *symtab;
const char *strtab;
if (phdr[i].p_type == PT_DYNAMIC) {
Elf64_Sym *sym;
dyn = (Elf64_Dyn *)((char *)ehdr + phdr[i].p_offset);
symtab = 0;
strtab = 0;
while (dyn->d_tag != DT_NULL) {
if (dyn->d_tag == DT_STRTAB) {
strtab = (const char *)(ehdr + dyn->d_un.d_ptr);
} else if (dyn->d_tag == DT_SYMTAB) {
symtab = (Elf64_Sym *)(ehdr + dyn->d_un.d_ptr);
}
if (strtab && symtab) {
break;
}
dyn++;
}
sym = symtab;
while ((char *)sym < strtab) {
if (sym->st_name != 0 && sym->st_value != 0) {
const char *name = strtab + sym->st_name;
for (int i = 0; __vdso_symtab[i].name != 0; i++) {
if (strcmp(name, __vdso_symtab[i].name) == 0) {
__vdso_symtab[i].func = (void *)(ehdr + sym->st_value);
break;
}
}
}
sym = (Elf64_Sym *)((char *)sym + sizeof(Elf64_Sym));
}
break;
}
}
}
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