/* $NetBSD: rtld_start.S,v 1.18 2024/08/03 21:59:58 riastradh Exp $ */ /*- * Copyright (c) 2000 Eduardo Horvath. * Copyright (c) 1999, 2002, 2003 The NetBSD Foundation, Inc. * All rights reserved. * * This code is derived from software contributed to The NetBSD Foundation * by Christos Zoulas, Paul Kranenburg and by Charles M. Hannum. * * 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. * * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS * ``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 FOUNDATION OR CONTRIBUTORS * 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> #define _LOCORE #include <machine/frame.h> /* * ELF: * On startup the stack should contain 16 extended word register save area, * followed by the arg count, etc. * * _rtld() expects the stack pointer to point to two longwords for argument * return followed by argc, etc. We need to create a pointer to * &argc + 16 and pass that in. The return args will be in those locations. * * NB: We are violating the ELF spec by passing a pointer to the ps strings in * %g1 instead of a termination routine. */ .register %g2,#scratch .register %g3,#scratch /* Offset of ARGC from bottom of stack */ #define ARGC 176 .section ".text" .align 4 .global _rtld_start .type _rtld_start,@function _rtld_start: mov 0, %fp /* Erect a fence post for ourselves */ mov %g1, %l1 /* save ps_strings */ sub %sp, 48+16, %sp /* Make room for return args */ sethi %hi(_GLOBAL_OFFSET_TABLE_-4), %l7 call 0f add %l7, %lo(_GLOBAL_OFFSET_TABLE_+4), %l7 call _DYNAMIC+8 0: add %l7, %o7, %l7 /* real &_GLOBAL_OFFSET_TABLE_ */ ld [%o7+8], %o0 /* load stub call instruction */ ldx [%l7], %l0 /* base-relative &_DYNAMIC */ sll %o0, 2, %o0 /* extract PC offset */ sra %o0, 0, %o0 /* sign-extend */ add %o0, %o7, %o0 /* real &_DYNAMIC */ sub %o0, %l0, %l0 /* relocbase */ call _rtld_relocate_nonplt_self mov %l0, %o1 /* relocbase */ mov %l0, %o1 /* relocbase */ call _rtld add %sp, BIAS + ARGC, %o0 /* &argc - 16 */ ldx [%sp + BIAS + ARGC], %g3 /* arg: cleanup */ ldx [%sp + BIAS + ARGC + 8], %g2 /* arg: obj */ add %sp, 48+16, %sp /* restore stack pointer */ jmp %o0 mov %l1, %g1 /* restore ps_strings */ /* * We have two separate entry points to the runtime linker. * I'm implementing this following the SPARC v9 ABI spec. * * _rtld_bind_start_0(y, x) is called from .PLT0, and is used for * PLT entries above 32768. * * _rtld_bind_start_1(y, x) is called from .PLT1, and is used for * PLT entries below 32768. * * The first two entries of PLT2 contain the xword object pointer. * * These routines are called with two longword arguments, * x and y. To calculate the address of the entry, * _rtld_bind_start_1(y, x) does: * * n = x >> 15; * * and _rtld_bind_start_0(y, x) does: * * i = x - y + 8 - 32768*32; * n = 32768 + (i/5120)*160 + (i%5120)/24; * * Neither routine needs to issue a save since it's already been * done in the PLT entry. */ .section ".text" .align 4 .global _rtld_bind_start_0 .type _rtld_bind_start_0,@function _rtld_bind_start_0: # (y, x) /* %o0 = obj->pltgot[6] */ /* %o1 = plt[4] */ /* %o1 - %o0 + 8 == offset of plt[] from obj->pltgot[] */ /* -32768*32 to get offset from beginning of upper PLT section */ sethi %hi(32768*32-8), %l1 sub %o1, %o0, %l0 /* i = x - y */ or %l1, %lo(32768*32-8), %l1 sub %l0, %l1, %l0 /* i = x - y + 8 - 32768*32 */ ldx [%o0 + (10*4)], %o0 /* Load object pointer from PLT2 */ sethi %hi(5120), %l1 sdivx %l0, %l1, %l1 /* Calculate i/5120 */ sllx %l1, 2, %l2 add %l2, %l1, %l2 sllx %l2, 10, %l2 sub %l0, %l2, %l2 /* And i%5120 */ /* Let the division churn for a bit. */ sdivx %l2, 24, %l4 /* (i%5120)/24 */ /* 160 is (32 * 5) or (32 * (4 + 1)) */ sllx %l1, 2, %l3 /* 4 * (i/5120) */ add %l1, %l3, %l3 /* 5 * (i/5120) */ sllx %l3, 5, %l3 /* 32 * 5 * (i/5120) */ sethi %hi(32768), %l6 add %l3, %l4, %l5 /* %l5 = (i/5120)*160 + (i%5120)/24; */ call _rtld_bind /* Call _rtld_bind(obj, offset) */ add %l5, %l6, %o1 /* %o1 = 32768 + ... */ jmp %o0 /* return value == function address */ restore /* Dump our stack frame */ .section ".text" .align 4 .global _rtld_bind_start_1 .type _rtld_bind_start_1,@function _rtld_bind_start_1: # (y, x) ldx [%o0 + (2*4)], %o0 /* Load object pointer from PLT2 */ call _rtld_bind /* Call _rtld_bind(obj, offset) */ srax %o1, 15, %o1 /* %o1 is the index to our PLT slot */ jmp %o0 /* return value == function address */ restore /* Dump our stack frame */
