/* $NetBSD: rtld_start.S,v 1.4 2001/09/26 04:06:43 mycroft Exp $ */ /*- * Copyright (C) 1998 Tsubai Masanari * All rights reserved. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * 2. 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. * 3. 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. */ #include <machine/asm.h> .extern _GLOBAL_OFFSET_TABLE_ .extern _DYNAMIC _ENTRY(_rtld_start) stdu %r1,-144(%r1) /* 16-byte aligned stack for reg saves + exit_proc & obj _rtld args + backchain & lrsave stack frame */ /* Save and restore only initial argv, because _rtld will modify * argv and envp if invoked explicitly, making it necessary to * load the (possibly) adjusted values from the stack. */ std %r4,104(%r1) /* argv */ /* std %r6,120(%r1) *//* obj (always 0) */ /* std %r7,128(%r1) *//* cleanup (always 0) */ std %r8,136(%r1) /* ps_strings */ /* * Perform initial relocation of ld-elf.so. Not as easy as it * sounds. * - perform small forward branch to put PC into link reg * - use link-time constants to determine offset to the * _DYNAMIC section and the GOT. Add these to the PC to * convert to absolute addresses. * - call reloc_non_plt_self() to fix up ld-elf.so's relocations */ bl 1f .llong _DYNAMIC-. 1: mflr %r3 /* PC value at .llong */ ld %r4,0(%r3) /* offset to _DYNAMIC */ add %r3,%r4,%r3 /* r3 = &_DYNAMIC, absolute value */ ld %r4,-0x8000(%r2) /* First TOC entry is TOC base */ subf %r4,%r4,%r2 /* Subtract from real TOC base to get base */ bl reloc_non_plt_self /* reloc_non_plt_self(&_DYNAMIC,base) */ nop /* * The _rtld() function likes to see a stack layout containing * { argc, argv[0], argv[1] ... argv[N], 0, env[0], ... , env[N] } * Since the PowerPC stack was 16-byte aligned at exec time, the * original stack layout has to be found by moving back a word * from the argv pointer. */ ld %r4,104(%r1) addi %r3,%r4,-8 /* locate argc ptr, &argv[-1] */ addi %r4,%r1,128 /* &exit_proc on stack */ addi %r5,%r1,120 /* &obj_main on stack */ bl _rtld /* &_start = _rtld(sp, &exit_proc, &obj_main)*/ nop #if !defined(_CALL_ELF) || _CALL_ELF == 1 ld %r2,8(%r3) ld %r11,16(%r3) ld %r3,0(%r3) #else mr %r12,%r3 #endif mtlr %r3 /* * Restore args, with new obj/exit proc */ ld %r4,104(%r1) /* argv */ ld %r3,-8(%r4) /* argc */ /* envp = argv + argc + 1 */ addi %r5,%r3,1 sldi %r5,%r5,3 /* x8 */ add %r5,%r4,%r5 ld %r6,120(%r1) /* obj */ ld %r7,128(%r1) /* exit proc */ ld %r8,136(%r1) /* ps_strings */ blrl /* _start(argc, argv, envp, obj, cleanup, ps_strings) */ li %r0,1 /* _exit() */ sc _END(_rtld_start) /* * _rtld_bind_start() * * Call into the MI binder. This routine is reached via the PLT call cell * * On entry, %r11 contains an object pointer and %r0 contains the PLT index. * * Save all registers, call into the binder to resolve and fixup the external * routine, and then transfer to the external routine on return. */ .globl _rtld_bind _ENTRY(_rtld_bind_start) mr %r12,%r0 # save r0 (index) immediately to r12 mflr %r0 std %r0,16(%r1) # save lr mfcr %r0 std %r0,8(%r1) # save cr stdu %r1,-48-12*8(%r1) # stack space for 8 regs + header # + 2 save regs std %r3,64+0*8(%r1) # save r3-r10 (arguments) std %r4,64+1*8(%r1) std %r5,64+2*8(%r1) std %r6,64+3*8(%r1) std %r7,64+4*8(%r1) std %r8,64+5*8(%r1) std %r9,64+6*8(%r1) std %r10,64+7*8(%r1) mr %r3,%r11 mulli %r4,%r12,24 # Multiply index by sizeof(Elf_Rela) bl _rtld_bind # target addr = _rtld_bind(obj, reloff) nop #if !defined(_CALL_ELF) || _CALL_ELF == 1 ld %r2,8(%r3) ld %r11,16(%r3) ld %r3,0(%r3) #else mr %r12,%r3 #endif mtctr %r3 # move absolute target addr into ctr ld %r3,64+0*8(%r1) # restore r3-r10 ld %r4,64+1*8(%r1) ld %r5,64+2*8(%r1) ld %r6,64+3*8(%r1) ld %r7,64+4*8(%r1) ld %r8,64+5*8(%r1) ld %r9,64+6*8(%r1) ld %r10,64+7*8(%r1) ld %r1,0(%r1) # restore stack ld %r0,8(%r1) # restore cr mtcr %r0 ld %r0,16(%r1) # restore lr mtlr %r0 bctr # jump to target _END(_rtld_bind_start) .section .note.GNU-stack,"",%progbits
