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#include <elf.h>
//#include <stdio.h>
#include <string.h>
#include "sys/auxv.h"
//#include <linux/time.h>
//#include <time.h>
#include "ldso.h"
#include "generated/autoconf.h"
#ifndef ELF_BITS
# if ULONG_MAX > 0xffffffffUL
# define ELF_BITS 64
# else
# define ELF_BITS 32
# endif
#endif
#define ELF_BITS_XFORM2(bits, x) Elf##bits##_##x
#define ELF_BITS_XFORM(bits, x) ELF_BITS_XFORM2(bits, x)
#define ELF(x) ELF_BITS_XFORM(ELF_BITS, x)
#ifndef __VDSO_SUPPORT__
void load_vdso( uint32_t sys_info_ehdr, char **envp ){
#ifdef __SUPPORT_LD_DEBUG__
if ( _dl_debug_vdso != 0 ){
_dl_dprintf(2,"_dl_vdso support not enabled\n" );
}
#endif
}
#else
//typedef long (*gtod_t)(struct timeval *tv, struct timezone *tz);
void* _dl__vdso_gettimeofday = 0;
//typedef long (*clock_gettime_t)(int clk_id, struct timespec *tp);
void* _dl__vdso_clock_gettime = 0;
typedef struct{
void* base_addr;
ELF(Ehdr) *hdr;
char* section_header_strtab;
ELF(Sym) *dynsym_table;
uint32_t dynsym_table_num;
char* dynstr_table;
uint16_t *versym_table;
ELF(Verdef) *verdef_table;
uint32_t verdef_num;
ELF(Dyn) *dynamic_section;
uint32_t dynamic_section_num;
char* text_section;
char* vers_strings[10];
}elf_infos;
/*
* the raise() dummy function is needed because of divisons in this code
* but keep it hidden in this object
*
* fixes link error with gcc 12 for arm
*/
#pragma GCC visibility push(hidden)
int raise(int sig){
sig = sig;
return 0;
}
#pragma GCC visibility pop
static int vdso_check_elf_header( elf_infos* elf ){
if ( 0 != _dl_memcmp( ELFMAG, elf->base_addr, 4 ) ){
return 1;
}
if (elf->hdr->e_ident[EI_CLASS] != (ELF_BITS == 32 ? ELFCLASS32 : ELFCLASS64)) {
_dl_dprintf(2,"vdso ELF Bits check error\n");
return 1; /* Wrong ELF class -- check ELF_BITS */
}
return 0;
}
static ELF(Shdr) *vdso_get_sec_header( elf_infos* elf, int index ){
return (ELF(Shdr) *) ( elf->base_addr + elf->hdr->e_shoff + ( index * sizeof( ELF(Shdr) )) );
}
void load_vdso( uint32_t sys_info_ehdr, char **envp ){
elf_infos vdso_infos;
if ( sys_info_ehdr == 0 ){
#ifdef __SUPPORT_LD_DEBUG__
if ( _dl_debug_vdso != 0 ){
_dl_dprintf(2,"_dl_vdso no vdso provied by kernel\n" );
}
#endif
return;
}
char* _dl_vdso_disable = _dl_getenv("VDSO_DISABLE", envp);
if ( _dl_vdso_disable != 0 ){
#ifdef __SUPPORT_LD_DEBUG__
if ( _dl_debug_vdso != 0 ){
_dl_dprintf(2,"_dl_vdso vdso support disabled\n" );
}
#endif
return;
}
_dl_memset( &vdso_infos, 0 , sizeof( elf_infos ) );
vdso_infos.base_addr = (void*)sys_info_ehdr;
vdso_infos.hdr = (ELF(Ehdr)*)vdso_infos.base_addr;
//printf("base : %p\n",vdso_infos.base_addr);
if ( 0 != vdso_check_elf_header( &vdso_infos ) ){
return;
}
ELF(Shdr) *sec_header = vdso_get_sec_header( &vdso_infos, vdso_infos.hdr->e_shstrndx);
vdso_infos.section_header_strtab = ( vdso_infos.base_addr + sec_header->sh_offset );
/*
*
* load ELF section headers
*
*/
for ( int i = 0 ; i < vdso_infos.hdr->e_shnum; i++ ){
sec_header = vdso_get_sec_header( &vdso_infos, i );
char* name = vdso_infos.section_header_strtab + sec_header->sh_name;
if( ( SHT_DYNSYM == sec_header->sh_type ) && ( 0 == _dl_strcmp( ".dynsym",name ) ) ){
vdso_infos.dynsym_table = ( vdso_infos.base_addr + sec_header->sh_offset );
vdso_infos.dynsym_table_num = sec_header->sh_size / sec_header->sh_entsize ;
continue;
}
if( ( SHT_STRTAB == sec_header->sh_type ) && ( 0 == _dl_strcmp( ".dynstr",name ) ) ){
vdso_infos.dynstr_table = ( vdso_infos.base_addr + sec_header->sh_offset );
continue;
}
if( ( SHT_GNU_versym == sec_header->sh_type ) && ( 0 == _dl_strcmp( ".gnu.version",name ) ) ){
vdso_infos.versym_table = ( vdso_infos.base_addr + sec_header->sh_offset );
continue;
}
if( ( SHT_GNU_verdef == sec_header->sh_type ) && ( 0 == _dl_strcmp( ".gnu.version_d",name ) ) ){
vdso_infos.verdef_table = ( vdso_infos.base_addr + sec_header->sh_offset );
continue;
}
if( ( SHT_DYNAMIC == sec_header->sh_type ) && ( 0 == _dl_strcmp( ".dynamic",name ) ) ){
vdso_infos.dynamic_section = ( vdso_infos.base_addr + sec_header->sh_offset );
vdso_infos.dynamic_section_num = sec_header->sh_size / sec_header->sh_entsize ;
continue;
}
if( ( SHT_PROGBITS == sec_header->sh_type ) && ( 0 == _dl_strcmp( ".text",name ) ) ){
vdso_infos.text_section = ( vdso_infos.base_addr + sec_header->sh_offset );
continue;
}
}
/*
*
* check section header -> dynamic table consistence
*
*/
for( int i = 0 ; i < vdso_infos.dynamic_section_num ; i++ ){
ELF(Dyn) *dyn_sec = &vdso_infos.dynamic_section[i];
if ( dyn_sec->d_tag == 0 ) continue;
if ( dyn_sec->d_tag == DT_STRTAB ){
char* strtab = ( vdso_infos.base_addr + dyn_sec->d_un.d_ptr );
if ( strtab != (char*) vdso_infos.dynstr_table ){
_dl_dprintf(2,"vdso elf DT_STRTAB check error\n");
return;
}
continue;
}
if ( dyn_sec->d_tag == DT_SYMTAB ){
char* symtab = ( vdso_infos.base_addr + dyn_sec->d_un.d_ptr );
if ( symtab != (char*) vdso_infos.dynsym_table ){
_dl_dprintf(2,"vdso elf DT_SYMTAB check error\n");
return;
}
continue;
}
if ( dyn_sec->d_tag == DT_VERDEF ){
Elf32_Verdef* verdef = ( vdso_infos.base_addr + dyn_sec->d_un.d_ptr );
if ( verdef != (Elf32_Verdef*) vdso_infos.verdef_table ){
_dl_dprintf(2,"vdso elf DT_VERDEF check error\n");
return;
}
continue;
}
if ( dyn_sec->d_tag == DT_VERDEFNUM ){
vdso_infos.verdef_num = dyn_sec->d_un.d_val;
continue;
}
if ( dyn_sec->d_tag == DT_VERSYM ){
uint16_t* versym = ( vdso_infos.base_addr + dyn_sec->d_un.d_ptr );
if ( versym != vdso_infos.versym_table ){
_dl_dprintf(2,"vdso elf DT_VERSYM check error\n");
return;
}
continue;
}
}
/*
*
* load vdso version definition strings
*
*/
ELF(Verdef) *vd = vdso_infos.verdef_table;
for( int i = 0 ; i < vdso_infos.verdef_num ; i++ ){
ELF(Verdaux) *vd_aux = (ELF(Verdaux) *)(( ( char*)vd ) + vd->vd_aux);
vdso_infos.vers_strings[ vd->vd_ndx ] = vdso_infos.dynstr_table + vd_aux->vda_name;
vd = ( ELF(Verdef) *)(( ( char*)vd ) + vd->vd_next);
}
/*
*
* load function from the vdso
*
*/
#ifdef __SUPPORT_LD_DEBUG__
if ( _dl_debug_vdso != 0 ){
int vdso_functions = 0;
for( int i = 0 ; i < vdso_infos.dynsym_table_num ; i++ ){
ELF(Sym)* sym = &vdso_infos.dynsym_table[i];
if (ELF64_ST_TYPE(sym->st_info) != STT_FUNC)
continue;
char* name = vdso_infos.dynstr_table + sym->st_name;
if ( name[0] == 0 ){
continue;
}
vdso_functions++;
}
_dl_dprintf(2,"_dl_vdso_load functions found : %d\n", vdso_functions );
}
#endif
for( int i = 0 ; i < vdso_infos.dynsym_table_num ; i++ ){
ELF(Sym)* sym = &vdso_infos.dynsym_table[i];
if (ELF64_ST_TYPE(sym->st_info) != STT_FUNC)
continue;
char* name = vdso_infos.dynstr_table + sym->st_name;
char* vers = vdso_infos.vers_strings[ vdso_infos.versym_table[i] ];
void* func_addr = (void*)( vdso_infos.base_addr + sym->st_value );
// the function name is patched to zero if the kernel has no timer which is
// usable for the function
if ( name[0] == 0 ){
#ifdef __SUPPORT_LD_DEBUG__
if ( _dl_debug_vdso != 0 ){
_dl_dprintf(2," function at address %p disabled by the kernel\n", sym->st_value );
}
#endif
continue;
}
//printf(" %s@@%s\n", name , vers );
//print_sym( sym );
if ( 0 == _dl_strcmp( name, "__vdso_gettimeofday" ) ){
_dl__vdso_gettimeofday = func_addr;
#ifdef __SUPPORT_LD_DEBUG__
if ( _dl_debug_vdso != 0 ){
_dl_dprintf(2," %s at address %p\n", name, func_addr );
}
#endif
continue;
}
if ( 0 == _dl_strcmp( name, "__vdso_clock_gettime" ) ){
_dl__vdso_clock_gettime = func_addr;
#ifdef __SUPPORT_LD_DEBUG__
if ( _dl_debug_vdso != 0 ){
_dl_dprintf(2," %s at address %p\n", name, func_addr );
}
#endif
continue;
}
#ifdef __SUPPORT_LD_DEBUG__
if ( _dl_debug_vdso != 0 ){
_dl_dprintf(2," <%s> not handled\n", name );
}
#endif
}
}
#endif // __VDSO_SUPPORT__
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