diff options
Diffstat (limited to 'ldso/ldso/dl-vdso.c')
| -rwxr-xr-x | ldso/ldso/dl-vdso.c | 372 |
1 files changed, 372 insertions, 0 deletions
diff --git a/ldso/ldso/dl-vdso.c b/ldso/ldso/dl-vdso.c new file mode 100755 index 000000000..196cbbb3b --- /dev/null +++ b/ldso/ldso/dl-vdso.c @@ -0,0 +1,372 @@ + +#include <elf.h> +#include <string.h> +#include "sys/auxv.h" + +#define __ARCH_VDSO_GETTIMEOFDAY_NAME "__vdso_gettimeofday" +#define __ARCH_VDSO_CLOCK_GETTIME_NAME "__vdso_clock_gettime" + +#if defined(__UCLIBC_USE_TIME64__) +#define __ARCH_VDSO_CLOCK_GETTIME64_NAME "__vdso_clock_gettime64" +#endif + +/* Maybe override default vDSO functions names by arch-specific */ +#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(void *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 + +void *_dl__vdso_gettimeofday = 0; +void *_dl__vdso_clock_gettime = 0; + +#if defined(__UCLIBC_USE_TIME64__) +void *_dl__vdso_clock_gettime64 = 0; +#endif + +void *_get__dl__vdso_clock_gettime(void); +void *_get__dl__vdso_clock_gettime(void) +{ + return _dl__vdso_clock_gettime; +} + +#if defined(__UCLIBC_USE_TIME64__) +void *_get__dl__vdso_clock_gettime64(void); +void *_get__dl__vdso_clock_gettime64(void) +{ + return _dl__vdso_clock_gettime64; +} +#endif + +void *_get__dl__vdso_gettimeofday(void); +void *_get__dl__vdso_gettimeofday(void) +{ + return _dl__vdso_gettimeofday; +} + +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(void *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; + + 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; + 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; + } + + if ( 0 == _dl_strcmp( name, __ARCH_VDSO_GETTIMEOFDAY_NAME ) ){ + _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, __ARCH_VDSO_CLOCK_GETTIME_NAME ) ){ + _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; + } + +#if defined(__UCLIBC_USE_TIME64__) + if ( 0 == _dl_strcmp( name, __ARCH_VDSO_CLOCK_GETTIME64_NAME ) ){ + _dl__vdso_clock_gettime64 = func_addr; +#ifdef __SUPPORT_LD_DEBUG__ + if ( _dl_debug_vdso != 0 ){ + _dl_dprintf(2," %s at address %p\n", name, func_addr ); + } +#endif + continue; + } +#endif /* defined(__UCLIBC_USE_TIME64__) */ + +#ifdef __SUPPORT_LD_DEBUG__ + if ( _dl_debug_vdso != 0 ){ + _dl_dprintf(2," <%s> not handled\n", name ); + } +#endif + + } +} + +#endif // __VDSO_SUPPORT__ |