| 0,0 → 1,195 |
|---|
| /* |
| * Copyright (c) 2008 Jiri Svoboda |
| * All rights reserved. |
| * |
| * Redistribution and use in source and binary forms, with or without |
| * modification, are permitted provided that the following conditions |
| * are met: |
| * |
| * - Redistributions of source code must retain the above copyright |
| * notice, this list of conditions and the following disclaimer. |
| * - Redistributions in binary form must reproduce the above copyright |
| * notice, this list of conditions and the following disclaimer in the |
| * documentation and/or other materials provided with the distribution. |
| * - The name of the author may not be used to endorse or promote products |
| * derived from this software without specific prior written permission. |
| * |
| * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR |
| * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES |
| * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. |
| * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, |
| * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT |
| * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, |
| * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY |
| * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT |
| * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF |
| * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. |
| */ |
| |
| /** @addtogroup rtld rtld |
| * @brief |
| * @{ |
| */ |
| /** |
| * @file |
| */ |
| |
| void _rtld_main(void); |
| |
| #define ELF32_R_SYM(i) ((i)>>8) |
| #define ELF32_R_TYPE(i) ((unsigned char)(i)) |
| |
| typedef struct { |
| int d_tag; |
| union { |
| unsigned d_val; |
| unsigned *d_ptr; |
| } d_un; |
| } elf32_dyn; |
| |
| typedef struct { |
| unsigned r_offset; |
| unsigned r_info; |
| } elf32_rel; |
| |
| typedef struct { |
| unsigned st_name; |
| unsigned st_value; |
| unsigned st_size; |
| unsigned char st_info; |
| unsigned char st_other; |
| unsigned short st_shndx; |
| } elf32_sym; |
| |
| static void kputint(unsigned i) |
| { |
| unsigned dummy; |
| asm volatile ( |
| "movl $30, %%eax;" |
| "int $0x30" |
| : "=d" (dummy) /* output - %edx clobbered */ |
| : "d" (i) /* input */ |
| : "%eax","%ecx" /* all scratch registers clobbered */ |
| ); |
| } |
| |
| void __bootstrap(void) |
| { |
| unsigned bias; |
| unsigned *got; |
| elf32_dyn *dynamic; |
| unsigned *dptr; |
| unsigned dval; |
| int i; |
| |
| unsigned rel_entries; |
| unsigned r_offset; |
| unsigned r_info; |
| unsigned rel_type; |
| unsigned sym_idx; |
| unsigned sym_addr; |
| |
| elf32_sym *sym_table; |
| elf32_rel *rel_table; |
| |
| asm volatile ( |
| "movl $30, %eax;" |
| "int $0x30" |
| ); |
| |
| /* Copied from libc/arch/ia32/entry.s */ |
| /*asm volatile ( |
| "mov %ss, %ax;" |
| "mov %ax, %ds;" |
| "mov %ax, %es;" |
| "mov %ax, %fs;" |
| );*/ |
| |
| |
| asm volatile ( |
| /* Calculate the bias into %0 */ |
| " call .L0;" |
| ".L0: pop %0;" |
| " subl $.L0, %0;" |
| |
| /* Calculate run-time address of _DYNAMIC into %1 */ |
| " movl $_DYNAMIC, %1;" /* Again, at link time 0-based VMA gets in */ |
| " addl %0, %1;" /* Add bias to compute run-time address */ |
| |
| : "=r" (bias), "=r" (dynamic) |
| ); |
| |
| kputint(bias); |
| kputint((unsigned)dynamic); |
| |
| /* parse DYNAMIC */ |
| got = 0; |
| sym_table = 0; |
| rel_table = 0; |
| rel_entries = 0; |
| |
| i = 0; |
| while (dynamic[i].d_tag != 0) { |
| dptr = (unsigned *)(dynamic[i].d_un.d_val + bias); |
| dval = dynamic[i].d_un.d_val; |
| |
| switch (dynamic[i].d_tag) { |
| case 3 /* DT_PLTGOT */: |
| /* GOT address */ |
| got = dptr; break; |
| case 6 /* DT_SYMTAB */ : sym_table = dptr; break; |
| case 17 /* DT_REL */ : rel_table = dptr; break; |
| case 18 /* DT_RELSZ */ : rel_entries = dval / 8; break; |
| default: break; |
| } |
| |
| ++i; |
| } |
| |
| kputint(1); |
| kputint((unsigned)sym_table); |
| kputint((unsigned)rel_table); |
| kputint((unsigned)rel_entries); |
| |
| /* Now relocate all our dynsyms */ |
| kputint(-1); |
| |
| for (i=0; i<rel_entries; i++) { |
| kputint(i); |
| r_offset = rel_table[i].r_offset; |
| r_info = rel_table[i].r_info; |
| |
| rel_type = ELF32_R_TYPE(r_info); |
| |
| kputint(rel_type); |
| kputint(r_offset); |
| |
| if (rel_type == 7 /* R_386_JUMP_SLOT */) { |
| kputint(16); |
| sym_idx = ELF32_R_SYM(r_info); |
| |
| sym_addr = sym_table[sym_idx].st_value + bias; |
| kputint(sym_idx); |
| kputint(sym_addr); |
| |
| *(unsigned *)(r_offset+bias) = sym_addr; |
| } |
| } |
| |
| kputint(-1); |
| |
| kputint(32); |
| |
| _rtld_main(); |
| |
| asm ( |
| "movl $250, %%eax;" |
| "int $0x30" |
| : /* output */ |
| : /* input */ |
| : "%eax","%ecx","%edx" /* all scratch registers clobbered */ |
| ); |
| } |
| |
| /** @} |
| */ |