1/* $NetBSD: rtld_start.S,v 1.4 2001/09/26 04:06:43 mycroft Exp $ */ 2 3/*- 4 * Copyright (C) 1998 Tsubai Masanari 5 * All rights reserved. 6 * 7 * Redistribution and use in source and binary forms, with or without 8 * modification, are permitted provided that the following conditions 9 * are met: 10 * 1. Redistributions of source code must retain the above copyright 11 * notice, this list of conditions and the following disclaimer. 12 * 2. Redistributions in binary form must reproduce the above copyright 13 * notice, this list of conditions and the following disclaimer in the 14 * documentation and/or other materials provided with the distribution. 15 * 3. The name of the author may not be used to endorse or promote products 16 * derived from this software without specific prior written permission. 17 * 18 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 19 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 20 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 21 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 22 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 23 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 24 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 25 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 26 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE 27 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 28 * 29 * $FreeBSD$ 30 */ 31 32#include <machine/asm.h> 33#include <machine/spr.h> /* For SPR_SPEFSCR if needed. */ 34 35.extern _GLOBAL_OFFSET_TABLE_ 36.extern _DYNAMIC 37 38_ENTRY(.rtld_start) 39 stwu %r1,-48(%r1) /* 16-byte aligned stack for reg saves + 40 exit_proc & obj _rtld args + 41 backchain & lrsave stack frame */ 42 stw %r3,16(%r1) /* argc */ 43 stw %r4,20(%r1) /* argv */ 44 stw %r5,24(%r1) /* envp */ 45/* stw %r6,28(%r1) *//* obj (always 0) */ 46/* stw %r7,32(%r1) *//* cleanup (always 0) */ 47 stw %r8,36(%r1) /* ps_strings */ 48 49 /* 50 * Perform initial relocation of ld-elf.so. Not as easy as it 51 * sounds. 52 * - perform small forward branch to put PC into link reg 53 * - use link-time constants to determine offset to the 54 * _DYNAMIC section and the GOT. Add these to the PC to 55 * convert to absolute addresses. 56 * - read GOT[0], which is the SVR4 ABI-specified link-time 57 * value of _DYNAMIC. Subtract this value from the absolute 58 * value to determine the load address 59 * - call reloc_non_plt_self() to fix up ld-elf.so's relocations 60 */ 61 bcl 20,31,1f 621: mflr %r30 63 mr %r3,%r30 # save for _DYNAMIC 64 addis %r30,%r30,_GLOBAL_OFFSET_TABLE_-1b@ha 65 addi %r30,%r30,_GLOBAL_OFFSET_TABLE_-1b@l 66 addis %r3,%r3,_DYNAMIC-1b@ha # get _DYNAMIC actual address 67 addi %r3,%r3,_DYNAMIC-1b@l 68 lwz %r28,0(%r30) # get base-relative &_DYNAMIC 69 sub %r28,%r3,%r28 # r28 = relocbase 70 mr %r4,%r28 # r4 = relocbase 71 bl reloc_non_plt_self /* reloc_non_plt_self(&_DYNAMIC,base) */ 72 73 /* 74 * The _rtld() function likes to see a stack layout containing 75 * { argc, argv[0], argv[1] ... argv[N], 0, env[0], ... , env[N] } 76 * Since the PowerPC stack was 16-byte aligned at exec time, the 77 * original stack layout has to be found by moving back a word 78 * from the argv pointer. 79 */ 80 lwz %r4,20(%r1) /* restore argv */ 81 addi %r3,%r4,-4 /* locate argc ptr, &argv[-1] */ 82 83 addi %r4,%r1,8 /* &exit_proc on stack */ 84 addi %r5,%r1,12 /* &obj_main on stack */ 85 86 bl _rtld /* &_start = _rtld(sp, &exit_proc, &obj_main)*/ 87 mtlr %r3 88 89 /* 90 * Restore args, with new obj/exit proc 91 */ 92 lwz %r3,16(%r1) /* argc */ 93 lwz %r4,20(%r1) /* argv */ 94 lwz %r5,24(%r1) /* envp */ 95 lwz %r6,12(%r1) /* obj */ 96 lwz %r7,8(%r1) /* exit proc */ 97 lwz %r8,36(%r1) /* ps_strings */ 98 addi %r1,%r1,48 /* restore original stackptr */ 99 100 blrl /* _start(argc, argv, envp, obj, cleanup, ps_strings) */ 101 102 li %r0,1 /* _exit() */ 103 sc 104_END(.rtld_start) 105 106#ifdef __SPE__ 107/* stack space for 30 GPRs + SPEFSCR/ACC/lr/cr */ 108#define NREGS 31 109#define GPRWIDTH 8 110#define FUDGE 4 /* Fudge factor for alignment */ 111#else 112/* stack space for 30 GPRs + lr/cr */ 113#define NREGS 30 114#define GPRWIDTH 4 115#define FUDGE 4 116#endif 117/* Stack frame needs the 12-byte ABI frame plus fudge factor. */ 118#define STACK_SIZE (NREGS * GPRWIDTH + 4 * 2 + 12 + FUDGE) 119 120/* 121 * _rtld_bind_secureplt_start() 122 * 123 * Call into the MI binder (Secure-PLT stub). 124 * secure-plt expects %r11 to be the offset to the rela entry. 125 * bss-plt expects %r11 to be index of the rela entry. 126 * So for bss-plt, we multiply the index by 12 to get the offset. 127 */ 128_ENTRY(_rtld_bind_secureplt_start) 129 stwu %r1,-STACK_SIZE(%r1) 130#ifdef __SPE__ 131 evstdd %r0,24(%r1) 132#else 133 stw %r0,20(%r1) # save r0 134#endif 135 136 /* 137 * Instead of division which is costly we will use multiplicative 138 * inverse. a / n = ((a * inv(n)) >> 32) 139 * where inv(n) = (0x100000000 + n - 1) / n 140 */ 141 mr %r0,%r11 142 lis %r11,0x15555556@h # load multiplicative inverse of 12 143 ori %r11,%r11,0x15555556@l 144 mulhwu %r11,%r11,%r0 # get high half of multiplication 145 b 1f 146_END(_rtld_bind_secureplt_start) 147 148/* 149 * _rtld_bind_start() 150 * 151 * Call into the MI binder. This routine is reached via the PLT call cell, 152 * and then _rtld_powerpc_pltresolve(). 153 * On entry, %r11 contains the index of the PLT cell, and %r12 contains 154 * a pointer to the ELF object for the file. 155 * Save all registers, call into the binder to resolve and fixup the external 156 * routine, and then transfer to the external routine on return. 157 */ 158 .globl _rtld_bind 159 160_ENTRY(_rtld_bind_start) 161 stwu %r1,-STACK_SIZE(%r1) 162#ifdef __SPE__ 163 evstdd %r0,24(%r1) 164#else 165 stw %r0,20(%r1) # save r0 166#endif 1671: 168 mflr %r0 169 stw %r0,16(%r1) # save lr 170 mfcr %r0 171 stw %r0,12(%r1) # save cr 172#ifdef __SPE__ 173 evstdd %r3, 32(%r1) 174 evstdd %r4, 40(%r1) 175 evstdd %r5, 48(%r1) 176 evstdd %r6, 56(%r1) 177 evstdd %r7, 64(%r1) 178 evstdd %r8, 72(%r1) 179 evstdd %r9, 80(%r1) 180 evstdd %r10, 88(%r1) 181 evstdd %r11, 96(%r1) 182 evstdd %r12, 104(%r1) 183 evstdd %r13, 112(%r1) 184 evstdd %r14, 120(%r1) 185 evstdd %r15, 128(%r1) 186 evstdd %r16, 136(%r1) 187 evstdd %r17, 144(%r1) 188 evstdd %r18, 152(%r1) 189 evstdd %r19, 160(%r1) 190 evstdd %r20, 168(%r1) 191 evstdd %r21, 176(%r1) 192 evstdd %r22, 184(%r1) 193 evstdd %r23, 192(%r1) 194 evstdd %r24, 200(%r1) 195 evstdd %r25, 208(%r1) 196 evstdd %r26, 216(%r1) 197 evstdd %r27, 224(%r1) 198 evstdd %r28, 232(%r1) 199 evstdd %r29, 240(%r1) 200 evstdd %r30, 248(%r1) 201 li %r3, 256 202 evstddx %r31, %r1, %r3 203 evxor %r0, %r0, %r0 204 li %r3, 264 205 evmwumiaa %r0, %r0, %r0 206 evstddx %r0, %r1, %r3 207 mfspr %r3, SPR_SPEFSCR 208 stw %r3, 20(%r1) 209#else 210 stmw %r3,24(%r1) # save r3-r31 211#endif 212 213 mr %r3,%r12 # obj 214 mulli %r4,%r11,12 # rela index * sizeof(Elf_Rela) 215 bl _rtld_bind # target addr = _rtld_bind(obj, reloff) 216 mtctr %r3 # move absolute target addr into ctr 217 218#ifdef __SPE__ 219 lwz %r3, 20(%r1) 220 mtspr SPR_SPEFSCR, %r3 221 li %r3, 264 222 evlddx %r0, %r3, %r1 223 evmra %r0, %r0 224 evldd %r3, 32(%r1) 225 evldd %r4, 40(%r1) 226 evldd %r5, 48(%r1) 227 evldd %r6, 56(%r1) 228 evldd %r7, 64(%r1) 229 evldd %r8, 72(%r1) 230 evldd %r9, 80(%r1) 231 evldd %r10, 88(%r1) 232 evldd %r11, 96(%r1) 233 evldd %r12, 104(%r1) 234 evldd %r13, 112(%r1) 235 evldd %r14, 120(%r1) 236 evldd %r15, 128(%r1) 237 evldd %r16, 136(%r1) 238 evldd %r17, 144(%r1) 239 evldd %r18, 152(%r1) 240 evldd %r19, 160(%r1) 241 evldd %r20, 168(%r1) 242 evldd %r21, 176(%r1) 243 evldd %r22, 184(%r1) 244 evldd %r23, 192(%r1) 245 evldd %r24, 200(%r1) 246 evldd %r25, 208(%r1) 247 evldd %r26, 216(%r1) 248 evldd %r27, 224(%r1) 249 evldd %r28, 232(%r1) 250 evldd %r29, 240(%r1) 251 evldd %r30, 248(%r1) 252 li %r0, 256 253 evlddx %r31, %r1, %r0 254#else 255 lmw %r3,24(%r1) # restore r3-r31 256#endif 257 lwz %r0,12(%r1) # restore cr 258 mtcr %r0 259 lwz %r0,16(%r1) # restore lr 260 mtlr %r0 261#ifdef __SPE__ 262 evldd %r0,24(%r1) 263#else 264 lwz %r0,20(%r1) # restore r0 265#endif 266 267 addi %r1,%r1,STACK_SIZE # restore stack 268 bctr # jump to target 269_END(_rtld_bind_start) 270 271 272/* 273 * _rtld_powerpc_pltresolve() 274 * 275 * This routine is copied into the latter part of the 72-byte reserved 276 * area at the start of the PLT. The absolute address of the _rtld_bind_start 277 * routine, and the ELF object for the loaded file, are inserted into 278 * the code by the reloc.c:init_pltgot() routine. 279 * The first time an external routine is called, the PLT slot will 280 * set up %r11 to the offset of the slot, and will jump to this routine. 281 * The ELF object is shifted into %r11, and _rtld_bind_start is called 282 * to complete the binding. 283 */ 284_ENTRY(_rtld_powerpc_pltlongresolve) 285 lis %r12,0 # lis 12,jmptab@ha 286 addi %r12,%r12,0 # addi 12,12,jmptab@l 287 subf %r11,%r12,%r11 # reloff 288 li %r12,2 289 srw %r11,%r11,%r12 # index = reloff/sizeof(Elf_Addr) 290_END(_rtld_powerpc_pltlongresolve) 291_ENTRY(_rtld_powerpc_pltresolve) 292 lis %r12,0 # lis 12,_rtld_bind_start@ha 293 addi %r12,%r12,0 # addi 12,12,_rtld_bind_start@l 294 mtctr %r12 295 lis %r12,0 # lis 12,obj@ha 296 addi %r12,%r12,0 # addi 12,12,obj@l 297 bctr 298_END(_rtld_powerpc_pltresolve) 299 300/* 301 * _rtld_powerpc_pltcall() 302 * 303 * This routine is copied into the 72-byte reserved area at the 304 * start of the PLT. The reloc.c:init_pltgot() routine inserts 305 * the absolute address of the jumptable. 306 * Control is transferred to this routine when the binder has 307 * located the external routine, but determined that it is > 32Mb 308 * from the PLT slot. Code is inserted into the PLT slot to set up 309 * %r11 with the jumptable index, and jump to here, where the 310 * absolute address of the external routine is loaded from the 311 * jumptable and transferred to 312 */ 313_ENTRY(_rtld_powerpc_pltcall) 314 slwi %r11,%r11,2 # jmptab offset = index * 4 315 addis %r11,%r11,0 # addis 11,11,jmptab@ha 316 lwz %r11,0(%r11) # lwz 11,jmptab@l(11) 317 mtctr %r11 318 bctr # (*jmptab[index])() 319_END(_rtld_powerpc_pltcall) 320 321 .section .note.GNU-stack,"",%progbits 322