a0abb093ed
The linker scripts use to fill alignment gaps within the text section with the magic value 0x90909090, which correponds to the opcodes of four nop instructions on x86. This patch removes this value because it apparently solves no problem. If, for some reason (e.g., due to a dangling pointer) a thread executes instructions within alignment paddings, NOP instructions are not any better than any other instruction. The program will eventually execute the instructions after the padding, which is most likely fatal. It would be more reasonable to fill the padding with the opcode of an illegal instruction so that such an error can be immediately detected. That said, I cannot remember a single instance, where the fill value has helped us during debugging. Even if the mechanism served a purpose on x86, it is still better to remove it because it does not equally work on the other architectures where the linker scripts are used. I.e., on ARM, the opcode 0x90909090 is not a NOP instruction.
132 lines
2.5 KiB
Plaintext
132 lines
2.5 KiB
Plaintext
/*
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* \brief Linker script for Genode programs
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* \author Christian Helmuth
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* \date 2006-04-12
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*/
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/*
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* Copyright (C) 2006-2013 Genode Labs GmbH
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*
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* This file is part of the Genode OS framework, which is distributed
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* under the terms of the GNU General Public License version 2.
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*/
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/* values taken from Codezero's mm0 linker script */
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/*physical_base = 0x00208000;*/
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/*virtual_base = 0xe0000000;*/
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/*offset = virtual_base - physical_base;*/
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/*
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* Addresses correspond to the linker script generated by
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* the Codezero build system.
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*/
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vma_start = 0x100000;
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lma_start = 0x40000;
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offset = vma_start - lma_start;
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ENTRY(_start)
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PHDRS
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{
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ro PT_LOAD;
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rw PT_LOAD;
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}
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SECTIONS
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{
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. = vma_start;
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.text : AT (ADDR(.text) - offset) {
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/* begin of program image (link address) */
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_prog_img_beg = .;
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*(.text.crt0)
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*(.init)
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*(.text .text.* .gnu.linkonce.t.*)
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*(.fini)
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*(.rodata .rodata.* .gnu.linkonce.r.*)
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. = ALIGN(0x08);
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_ctors_start = .;
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KEEP (*(.ctors))
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KEEP (*(SORT(.ctors.*)))
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KEEP (*(.init_array)) /* list of constructors specific for ARM eabi */
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_ctors_end = .;
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_dtors_start = .;
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KEEP (*(SORT(.dtors.*)))
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KEEP (*(.dtors))
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_dtors_end = .;
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} : ro = 0x0
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/* Linux: exception section for uaccess mechanism */
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__ex_table : { *(__ex_table) }
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.eh_frame_hdr : { *(.eh_frame_hdr) }
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. = ALIGN(0x1000);
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_prog_img_data = .;
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.data : AT (ADDR(.data) - offset) {
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/*
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* Leave space for parent capability parameters at start of data
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* section. The protection domain creator is reponsible for storing
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* sane values here.
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*/
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_parent_cap = .;
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LONG(0xffffffff);
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LONG(0xffffffff);
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_vma_start = .;
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LONG(vma_start);
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_lma_start = .;
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LONG(lma_start);
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*(.data .data.* .gnu.linkonce.d.*)
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} : rw
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/* exception frames for C++ */
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.eh_frame : {
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__eh_frame_start__ = .;
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KEEP (*(.eh_frame))
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LONG(0)
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} : rw
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.init_array : {
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PROVIDE_HIDDEN (__init_array_start = .);
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KEEP (*(SORT(.init_array.*)))
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KEEP (*(.init_array))
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PROVIDE_HIDDEN (__init_array_end = .);
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}
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.gcc_except_table : { KEEP(*(.gcc_except_table)) }
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.dynamic : { *(.dynamic) }
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/* .ARM.exidx is sorted, so has to go in its own output section */
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__exidx_start = .;
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.ARM.exidx : {
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*(.ARM.exidx* .gnu.linkonce.armexidx.*)
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}
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__exidx_end = .;
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.ARM.extab : {
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*(.ARM.extab*)
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} : rw
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. = ALIGN(4);
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.bss : AT (ADDR(.bss) - offset) {
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*(.bss .bss.* .gnu.linkonce.b.* COMMON)
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}
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/* end of program image -- must be after last section */
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_prog_img_end = .;
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/DISCARD/ : {
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*(.note)
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*(.note.ABI-tag)
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*(.comment)
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}
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}
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