201 lines
7.3 KiB
ArmAsm
201 lines
7.3 KiB
ArmAsm
/* $NetBSD: rtld_start.S,v 1.4 2001/09/26 04:06:43 mycroft Exp $ */
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/*-
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* Copyright (C) 1998 Tsubai Masanari
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. The name of the author may not be used to endorse or promote products
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* derived from this software without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
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* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
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* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
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* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
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* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*
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* $FreeBSD$
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*/
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#include <machine/asm.h>
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.extern _GLOBAL_OFFSET_TABLE_
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.extern _DYNAMIC
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_ENTRY(.rtld_start)
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stwu %r1,-48(%r1) /* 16-byte aligned stack for reg saves +
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exit_proc & obj _rtld args +
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backchain & lrsave stack frame */
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stw %r3,16(%r1) /* argc */
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stw %r4,20(%r1) /* argv */
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stw %r5,24(%r1) /* envp */
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/* stw %r6,28(%r1) *//* obj (always 0) */
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/* stw %r7,32(%r1) *//* cleanup (always 0) */
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stw %r8,36(%r1) /* ps_strings */
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/*
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* Perform initial relocation of ld-elf.so. Not as easy as it
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* sounds.
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* - perform small forward branch to put PC into link reg
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* - use link-time constants to determine offset to the
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* _DYNAMIC section and the GOT. Add these to the PC to
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* convert to absolute addresses.
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* - sync icache to allow execution of the SVR4 ABI-specified
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* blrl instruction preceding the GOT
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* - Use this instruction to determine the GOT absolute address
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* - read GOT[0], which is the SVR4 ABI-specified link-time
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* value of _DYNAMIC. Subtract this value from the absolute
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* value to determine the load address
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* - call reloc_non_plt_self() to fix up ld-elf.so's relocations
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*/
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bl 1f
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.long _DYNAMIC-.
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.long _GLOBAL_OFFSET_TABLE_-. /* branch lr + 4 */
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1:
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mflr %r3 /* PC value at .long */
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lwz %r4,4(%r3)
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add %r4,%r4,%r3 /* &_GLOBAL_OFFSET_TABLE-4, blrl insn. */
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dcbst %r0,%r4 /* sync i-cache with d-cache */
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sync
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icbi %r0,%r4
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isync
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lwz %r4,0(%r3) /* offset to _DYNAMIC */
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add %r3,%r4,%r3 /* r3 = &_DYNAMIC, absolute value */
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bl _GLOBAL_OFFSET_TABLE_@local-4
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mflr %r4 /* &_GLOBAL_OFFSET_TABLE_, absolute value */
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lwz %r4,0(%r4) /* linker &_DYNAMIC, from got[0] */
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subf %r4,%r4,%r3 /* subtract to calculate relocbase */
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bl reloc_non_plt_self@plt /* reloc_non_plt_self(&_DYNAMIC,base) */
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/*
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* The _rtld() function likes to see a stack layout containing
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* { argc, argv[0], argv[1] ... argv[N], 0, env[0], ... , env[N] }
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* Since the PowerPC stack was 16-byte aligned at exec time, the
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* original stack layout has to be found by moving back a word
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* from the argv pointer.
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*/
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lwz %r4,20(%r1) /* restore argv */
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addi %r3,%r4,-4 /* locate argc ptr, &argv[-1] */
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addi %r4,%r1,8 /* &exit_proc on stack */
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addi %r5,%r1,12 /* &obj_main on stack */
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bl _rtld@plt /* &_start = _rtld(sp, &exit_proc, &obj_main)*/
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mtlr %r3
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/*
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* Restore args, with new obj/exit proc
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*/
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lwz %r3,16(%r1) /* argc */
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lwz %r4,20(%r1) /* argv */
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lwz %r5,24(%r1) /* envp */
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lwz %r6,12(%r1) /* obj */
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lwz %r7,8(%r1) /* exit proc */
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lwz %r8,36(%r1) /* ps_strings */
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addi %r1,%r1,48 /* restore original stackptr */
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blrl /* _start(argc, argv, envp, obj, cleanup, ps_strings) */
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li %r0,1 /* _exit() */
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sc
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/*
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* _rtld_bind_start()
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*
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* Call into the MI binder. This routine is reached via the PLT call cell,
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* and then _rtld_powerpc_pltresolve().
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* On entry, %r11 contains the index of the PLT cell, and %r12 contains
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* a pointer to the ELF object for the file.
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* Save all registers, call into the binder to resolve and fixup the external
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* routine, and then transfer to the external routine on return.
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*/
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.globl _rtld_bind
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_ENTRY(_rtld_bind_start)
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stwu %r1,-160(%r1) # stack space for 29 regs + r0/lr/cr
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stw %r0,20(%r1) # save r0
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mflr %r0
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stw %r0,16(%r1) # save lr
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mfcr %r0
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stw %r0,12(%r1) # save cr
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stmw %r3,24(%r1) # save r3-r31
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mr %r3,%r12 # obj
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mulli %r4,%r11,12 # rela index * sizeof(Elf_Rela)
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bl _rtld_bind@PLT # target addr = _rtld_bind(obj, reloff)
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mtctr %r3 # move absolute target addr into ctr
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lmw %r3,24(%r1) # restore r3-r31
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lwz %r0,12(%r1) # restore cr
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mtcr %r0
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lwz %r0,16(%r1) # restore lr
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mtlr %r0
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lwz %r0,20(%r1) # restore r0
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addi %r1,%r1,160 # restore stack
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bctr # jump to target
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/*
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* _rtld_powerpc_pltresolve()
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*
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* This routine is copied into the latter part of the 72-byte reserved
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* area at the start of the PLT. The absolute address of the _rtld_bind_start
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* routine, and the ELF object for the loaded file, are inserted into
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* the code by the reloc.c:init_pltgot() routine.
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* The first time an external routine is called, the PLT slot will
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* set up %r11 to the offset of the slot, and will jump to this routine.
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* The ELF object is shifted into %r11, and _rtld_bind_start is called
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* to complete the binding.
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*/
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_ENTRY(_rtld_powerpc_pltlongresolve)
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lis %r12,0 # lis 12,jmptab@ha
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addi %r12,%r12,0 # addi 12,12,jmptab@l
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subf %r11,%r12,%r11 # reloff
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li %r12,2
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srw %r11,%r11,%r12 # index = reloff/sizeof(Elf_Addr)
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_ENTRY(_rtld_powerpc_pltresolve)
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lis %r12,0 # lis 12,_rtld_bind_start@ha
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addi %r12,%r12,0 # addi 12,12,_rtld_bind_start@l
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mtctr %r12
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lis %r12,0 # lis 12,obj@ha
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addi %r12,%r12,0 # addi 12,12,obj@l
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bctr
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/*
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* _rtld_powerpc_pltcall()
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*
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* This routine is copied into the 72-byte reserved area at the
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* start of the PLT. The reloc.c:init_pltgot() routine inserts
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* the absolute address of the jumptable.
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* Control is transferred to this routine when the binder has
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* located the external routine, but determined that it is > 32Mb
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* from the PLT slot. Code is inserted into the PLT slot to set up
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* %r11 with the jumptable index, and jump to here, where the
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* absolute address of the external routine is loaded from the
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* jumptable and transferred to
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*/
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_ENTRY(_rtld_powerpc_pltcall)
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slwi %r11,%r11,2 # jmptab offset = index * 4
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addis %r11,%r11,0 # addis 11,11,jmptab@ha
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lwz %r11,0(%r11) # lwz 11,jmptab@l(11)
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mtctr %r11
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bctr # (*jmptab[index])()
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.section .note.GNU-stack,"",%progbits
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