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author | grehan <grehan@FreeBSD.org> | 2002-12-04 07:32:20 +0000 |
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committer | grehan <grehan@FreeBSD.org> | 2002-12-04 07:32:20 +0000 |
commit | fdd44c57ca843e292df42853dc891a43b435fa1d (patch) | |
tree | 243254d50bad1e3bb59987f2697a66161cca6809 /libexec/rtld-elf/powerpc/rtld_start.S | |
parent | 16182748bd767da05374d4687e4976d703d39028 (diff) | |
download | FreeBSD-src-fdd44c57ca843e292df42853dc891a43b435fa1d.zip FreeBSD-src-fdd44c57ca843e292df42853dc891a43b435fa1d.tar.gz |
rtld support for PowerPC. Mostly obtained from NetBSD, with mods
for binutils 2.13
Reviewed by: benno
Approved by: re (blanket)
Diffstat (limited to 'libexec/rtld-elf/powerpc/rtld_start.S')
-rw-r--r-- | libexec/rtld-elf/powerpc/rtld_start.S | 194 |
1 files changed, 194 insertions, 0 deletions
diff --git a/libexec/rtld-elf/powerpc/rtld_start.S b/libexec/rtld-elf/powerpc/rtld_start.S new file mode 100644 index 0000000..040b663 --- /dev/null +++ b/libexec/rtld-elf/powerpc/rtld_start.S @@ -0,0 +1,194 @@ +/* $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. + * + * $FreeBSD$ + */ + +#include <machine/asm.h> + +.extern _GLOBAL_OFFSET_TABLE_ +.extern _DYNAMIC + +_ENTRY(.rtld_start) + stwu %r1,-48(%r1) /* 16-byte aligned stack for reg saves + + exit_proc & obj _rtld args + + backchain & lrsave stack frame */ + stw %r3,16(%r1) /* argc */ + stw %r4,20(%r1) /* argv */ + stw %r5,24(%r1) /* envp */ +/* stw %r6,28(%r1) *//* obj (always 0) */ +/* stw %r7,32(%r1) *//* cleanup (always 0) */ + stw %r8,36(%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. + * - sync icache to allow execution of the SVR4 ABI-specified + * blrl instruction preceding the GOT + * - Use this instruction to determine the GOT absolute address + * - read GOT[0], which is the SVR4 ABI-specified link-time + * value of _DYNAMIC. Subtract this value from the absolute + * value to determine the load address + * - call reloc_non_plt_self() to fix up ld-elf.so's relocations + */ + bl 1f + .long _DYNAMIC-. + .long _GLOBAL_OFFSET_TABLE_-. /* branch lr + 4 */ +1: + mflr %r3 /* PC value at .long */ + lwz %r4,4(%r3) + add %r4,%r4,%r3 /* &_GLOBAL_OFFSET_TABLE-4, blrl insn. */ + dcbst %r0,%r4 /* sync i-cache with d-cache */ + sync + icbi %r0,%r4 + isync + + lwz %r4,0(%r3) /* offset to _DYNAMIC */ + add %r3,%r4,%r3 /* r3 = &_DYNAMIC, absolute value */ + + bl _GLOBAL_OFFSET_TABLE_@local-4 + mflr %r4 /* &_GLOBAL_OFFSET_TABLE_, absolute value */ + lwz %r4,0(%r4) /* linker &_DYNAMIC, from got[0] */ + subf %r4,%r4,%r3 /* subtract to calculate relocbase */ + + bl reloc_non_plt_self@plt /* reloc_non_plt_self(&_DYNAMIC,base) */ + + /* + * 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. + */ + lwz %r4,20(%r1) /* restore argv */ + addi %r3,%r4,-4 /* locate argc ptr, &argv[-1] */ + + addi %r4,%r1,8 /* &exit_proc on stack */ + addi %r5,%r1,12 /* &obj_main on stack */ + + bl _rtld@plt /* &_start = _rtld(sp, &exit_proc, &obj_main)*/ + mtlr %r3 + + /* + * Restore args, with new obj/exit proc + */ + lwz %r3,16(%r1) /* argc */ + lwz %r4,20(%r1) /* argv */ + lwz %r5,24(%r1) /* envp */ + lwz %r6,12(%r1) /* obj */ + lwz %r7,8(%r1) /* exit proc */ + lwz %r8,36(%r1) /* ps_strings */ + addi %r1,%r1,48 /* restore original stackptr */ + + blrl /* _start(argc, argv, envp, obj, cleanup, ps_strings) */ + + li %r0,1 /* _exit() */ + sc + +/* + * _rtld_bind_start() + * + * Call into the MI binder. This routine is reached via the PLT call cell, + * and then _rtld_powerpc_pltresolve(). + * On entry, %r11 contains the index of the PLT cell, and %r12 contains + * a pointer to the ELF object for the file. + * 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) + stwu %r1,-160(%r1) # stack space for 29 regs + r0/lr/cr + stw %r0,20(%r1) # save r0 + mflr %r0 + stw %r0,16(%r1) # save lr + mfcr %r0 + stw %r0,12(%r1) # save cr + stmw %r3,24(%r1) # save r3-r31 + + mr %r3,%r12 # obj + mulli %r4,%r11,12 # rela index * sizeof(Elf_Rela) + bl _rtld_bind@PLT # target addr = _rtld_bind(obj, reloff) + mtctr %r3 # move absolute target addr into ctr + + lmw %r3,24(%r1) # restore r3-r31 + lwz %r0,12(%r1) # restore cr + mtcr %r0 + lwz %r0,16(%r1) # restore lr + mtlr %r0 + lwz %r0,20(%r1) # restore r0 + + addi %r1,%r1,160 # restore stack + bctr # jump to target + + +/* + * _rtld_powerpc_pltresolve() + * + * This routine is copied into the latter part of the 72-byte reserved + * area at the start of the PLT. The absolute address of the _rtld_bind_start + * routine, and the ELF object for the loaded file, are inserted into + * the code by the reloc.c:init_pltgot() routine. + * The first time an external routine is called, the PLT slot will + * set up %r11 to the offset of the slot, and will jump to this routine. + * The ELF object is shifted into %r11, and _rtld_bind_start is called + * to complete the binding. + */ +_ENTRY(_rtld_powerpc_pltresolve) + lis %r12,0 # lis 12,_rtld_bind_start@ha + addi %r12,%r12,0 # addi 12,12,_rtld_bind_start@l + mtctr %r12 + lis %r12,0 # lis 12,obj@ha + addi %r12,%r12,0 # addi 12,12,obj@l + bctr + +/* + * _rtld_powerpc_pltcall() + * + * This routine is copied into the 72-byte reserved area at the + * start of the PLT. The reloc.c:init_pltgot() routine inserts + * the absolute address of the jumptable. + * Control is transferred to this routine when the binder has + * located the external routine, but determined that it is > 32Mb + * from the PLT slot. Code is inserted into the PLT slot to set up + * %r11 with the jumptable index, and jump to here, where the + * absolute address of the external routine is loaded from the + * jumptable and transferred to + */ +_ENTRY(_rtld_powerpc_pltcall) + slwi %r11,%r11,2 # jmptab offset = index * 4 + addis %r11,%r11,0 # addis 11,11,jmptab@ha + lwz %r11,0(%r11) # lwz 11,jmptab@l(11) + mtctr %r11 + bctr # (*jmptab[index])() + + |