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-rwxr-xr-xldso/ldso/dl-vdso.c362
1 files changed, 362 insertions, 0 deletions
diff --git a/ldso/ldso/dl-vdso.c b/ldso/ldso/dl-vdso.c
new file mode 100755
index 000000000..c8d724cd0
--- /dev/null
+++ b/ldso/ldso/dl-vdso.c
@@ -0,0 +1,362 @@
+
+#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__
generated by cgit v1.2.3 (git 2.25.1) at 2024-11-22 13:40:42 +0000