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fedff58953
With gcc 4.8 tilegx has support for -mcmodel=large, to tolerate very large shared objects. This option changes the compiler output to not include direct jump instructions, which have a range of only 2^30, i.e +/- 512MB. Instead the compiler marshalls the target PCs into registers and then uses jump- or call-to-register instructions. For glibc, the upshot is that we need to arrange for a few functions to tolerate the possibility of a large range between the PC and the target. In particular, the crti.S and start.S code needs to be able to reach from .init to the PLT, as does gmon-start.c. The elf-init.c code has the reverse problem, needing to call from libc_nonshared.a (linked at the end of shared objects) back to the _init section at the beginning. No other functions in *_nonshared.a need to be built this way, as they only call the PLT (or potentially each other), but all of that code is linked at the very end of the shared object. We don't build the standard -static archives with this option as the performance cost is high enough and the use case is rare enough that it doesn't seem worthwhile. Instead, we would encourage developers who need the -static model with huge executables to build a private copy of glibc and configure it with -mcmodel=large. Note that libc.so et al don't need any changes; the only changes are for code that is statically linked into user code built with -mcmodel=large. For the assembly code, I just rewrote it so that it unconditionally uses the large model. To be able to pass -mcmodel=large to csu/elf-init.c and csu/gmon-start.c, I need to check to see if the compiler supports that flag, since gcc 4.7 doesn't; I added the support by creating a small Makefile fragment that just runs the compiler to check.
125 lines
3.6 KiB
ArmAsm
125 lines
3.6 KiB
ArmAsm
/* Special .init and .fini section support for tile.
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Copyright (C) 2012 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version.
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In addition to the permissions in the GNU Lesser General Public
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License, the Free Software Foundation gives you unlimited
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permission to link the compiled version of this file with other
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programs, and to distribute those programs without any restriction
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coming from the use of this file. (The GNU Lesser General Public
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License restrictions do apply in other respects; for example, they
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cover modification of the file, and distribution when not linked
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into another program.)
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Note that people who make modified versions of this file are not
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obligated to grant this special exception for their modified
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versions; it is their choice whether to do so. The GNU Lesser
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General Public License gives permission to release a modified
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version without this exception; this exception also makes it
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possible to release a modified version which carries forward this
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exception.
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The GNU C Library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with the GNU C Library; if not, see
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<http://www.gnu.org/licenses/>. */
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/* crti.S puts a function prologue at the beginning of the .init and
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.fini sections and defines global symbols for those addresses, so
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they can be called as functions. The symbols _init and _fini are
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magic and cause the linker to emit DT_INIT and DT_FINI. */
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#include <libc-symbols.h>
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#include <sysdep.h>
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#ifndef PREINIT_FUNCTION
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# define PREINIT_FUNCTION __gmon_start__
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#endif
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#ifndef PREINIT_FUNCTION_WEAK
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# define PREINIT_FUNCTION_WEAK 1
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#endif
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#if PREINIT_FUNCTION_WEAK
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weak_extern (PREINIT_FUNCTION)
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#else
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.hidden PREINIT_FUNCTION
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#endif
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.section .init,"ax",@progbits
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.align 8
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.globl _init
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.type _init, @function
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_init:
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{
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move r29, sp
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ADDI_PTR r28, sp, -REGSIZE
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ST sp, lr
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}
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ADDI_PTR sp, sp, -(2 * REGSIZE)
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ST r28, r29
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#if PREINIT_FUNCTION_WEAK
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lnk r2
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0:
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# ifdef __tilegx__
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moveli r1, hw2_last(_GLOBAL_OFFSET_TABLE_ - 0b)
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{
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shl16insli r1, r1, hw1(_GLOBAL_OFFSET_TABLE_ - 0b)
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moveli r0, hw1_last_got(PREINIT_FUNCTION)
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}
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{
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shl16insli r1, r1, hw0(_GLOBAL_OFFSET_TABLE_ - 0b)
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shl16insli r0, r0, hw0_got(PREINIT_FUNCTION)
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}
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# else
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{
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moveli r1, lo16(_GLOBAL_OFFSET_TABLE_ - 0b)
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moveli r0, got_lo16(PREINIT_FUNCTION)
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}
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{
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auli r1, r1, ha16(_GLOBAL_OFFSET_TABLE_ - 0b)
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auli r0, r0, got_ha16(PREINIT_FUNCTION)
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}
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# endif
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ADD_PTR r0, r0, r1
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ADD_PTR r0, r0, r2
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LD_PTR r0, r0
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BEQZ r0, .Lno_weak_fn
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jalr r0
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#elif defined(__tilegx__)
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/* Since we are calling from the start of the object to the PLT,
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call by loading the full address into a register. */
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lnk r2
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0:
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moveli r0, hw2_last_plt(PREINIT_FUNCTION - 0b)
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shl16insli r0, r0, hw1_plt(PREINIT_FUNCTION - 0b)
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shl16insli r0, r0, hw0_plt(PREINIT_FUNCTION - 0b)
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add r0, r0, r2
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jalr r0
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#else
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jal plt(PREINIT_FUNCTION)
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#endif
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.Lno_weak_fn:
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.section .fini,"ax",@progbits
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.align 8
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.globl _fini
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.type _fini, @function
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_fini:
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{
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move r29, sp
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ADDI_PTR r28, sp, -REGSIZE
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ST sp, lr
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}
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ADDI_PTR sp, sp, -(2 * REGSIZE)
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ST r28, r29
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