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// SPDX-License-Identifier: GPL-2.0+
/*******************************************************************************
* QtMips - MIPS 32-bit Architecture Subset Simulator
*
* Implemented to support following courses:
*
* B35APO - Computer Architectures
* https://cw.fel.cvut.cz/wiki/courses/b35apo
*
* B4M35PAP - Advanced Computer Architectures
* https://cw.fel.cvut.cz/wiki/courses/b4m35pap/start
*
* Copyright (c) 2017-2019 Karel Koci<cynerd@email.cz>
* Copyright (c) 2019 Pavel Pisa <pisa@cmp.felk.cvut.cz>
*
* Faculty of Electrical Engineering (http://www.fel.cvut.cz)
* Czech Technical University (http://www.cvut.cz/)
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version 2
* of the License, or (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor,
* Boston, MA 02110-1301, USA.
*
******************************************************************************/
#include "programloader.h"
#include <exception>
#include <unistd.h>
#include <fcntl.h>
#include <cerrno>
#include <cstring>
#include "qtmipsexception.h"
#ifndef O_BINARY
#define O_BINARY 0
#endif
using namespace machine;
ProgramLoader::ProgramLoader(const char *file) {
const GElf_Ehdr *elf_ehdr;
// Initialize elf library
if (elf_version(EV_CURRENT) == EV_NONE)
throw QTMIPS_EXCEPTION(Input, "Elf library initialization failed", elf_errmsg(-1));
// Open source file
if ((this->fd = open(file, O_RDONLY | O_BINARY, 0)) < 0)
throw QTMIPS_EXCEPTION(Input, QString("Can't open input elf file for reading (") + QString(file) + QString(")"), std::strerror(errno));
// Initialize elf
if (!(this->elf = elf_begin(this->fd, ELF_C_READ, NULL)))
throw QTMIPS_EXCEPTION(Input, "Elf read begin failed", elf_errmsg(-1));
// Check elf kind
if (elf_kind(this->elf) != ELF_K_ELF)
throw QTMIPS_EXCEPTION(Input, "Invalid input file elf format, plain elf file expected", "");
elf_ehdr = gelf_getehdr(this->elf, &this->hdr);
if (!elf_ehdr)
throw QTMIPS_EXCEPTION(Input, "Getting elf file header failed", elf_errmsg(-1));
executable_entry = elf_ehdr->e_entry;
// Check elf file format, executable expected, nothing else.
if (this->hdr.e_type != ET_EXEC)
throw QTMIPS_EXCEPTION(Input, "Invalid input file type", "");
// Check elf file architecture, of course only mips is supported.
// Note: This also checks that this is big endian as EM_MIPS is suppose to be: MIPS R3000 big-endian
if (this->hdr.e_machine != EM_MIPS)
throw QTMIPS_EXCEPTION(Input, "Invalid input file architecture", "");
// Check elf file class, only 32bit architecture is supported.
int elf_class;
if ((elf_class = gelf_getclass(this->elf)) == ELFCLASSNONE)
throw QTMIPS_EXCEPTION(Input, "Getting elf class failed", elf_errmsg(-1));
if (elf_class != ELFCLASS32)
throw QTMIPS_EXCEPTION(Input, "Only supported architecture is 32bit", "");
// Get number of program sections in elf file
if (elf_getphdrnum(this->elf, &this->n_secs))
throw QTMIPS_EXCEPTION(Input, "Elf program sections count query failed", elf_errmsg(-1));
// Get program sections headers
if (!(this->phdrs = elf32_getphdr(this->elf)))
throw QTMIPS_EXCEPTION(Input, "Elf program sections get failed", elf_errmsg(-1));
// We want only LOAD sections so we create map of those sections
for (unsigned i = 0; i < this->n_secs; i++) {
if (phdrs[i].p_type != PT_LOAD)
continue;
this->map.push_back(i);
}
// TODO instead of direct access should we be using sections and elf_data? And if so how to link program header and section?
}
ProgramLoader::ProgramLoader(QString file) : ProgramLoader(file.toStdString().c_str()) { }
ProgramLoader::~ProgramLoader() {
// Close elf
elf_end(this->elf);
// Close file
close(this->fd);
}
void ProgramLoader::to_memory(Memory *mem) {
// Load program to memory (just dump it byte by byte)
for (int i = 0; i < this->map.size(); i++) {
std::uint32_t base_address = this->phdrs[this->map[i]].p_vaddr;
char *f = elf_rawfile(this->elf, NULL);
size_t phdrs_i = this->map[i];
for (unsigned y = 0; y < this->phdrs[phdrs_i].p_filesz; y++) {
mem->write_byte(base_address + y, (std::uint8_t) f[this->phdrs[phdrs_i].p_offset + y]);
}
}
}
std::uint32_t ProgramLoader::end() {
std::uint32_t last = 0;
// Go trough all sections and found out last one
for (int i = 0; i < this->map.size(); i++) {
Elf32_Phdr *phdr = &(this->phdrs[this->map[i]]);
if ((phdr->p_vaddr + phdr->p_filesz) > last)
last = phdr->p_vaddr + phdr->p_filesz;
}
return last + 0x10; // We add offset so we are sure that also pipeline is empty
}
std::uint32_t ProgramLoader::get_executable_entry() {
return executable_entry;
}
SymbolTable *ProgramLoader::get_symbol_table() {
SymbolTable *p_st = new SymbolTable();
Elf_Scn *scn = NULL;
GElf_Shdr shdr;
Elf_Data *data;
int count, ii;
elf_version(EV_CURRENT);
while (1) {
if ((scn = elf_nextscn(this->elf, scn)) == NULL)
return p_st;
gelf_getshdr(scn, &shdr);
if (shdr.sh_type == SHT_SYMTAB) {
/* found a symbol table, go print it. */
break;
}
}
data = elf_getdata(scn, NULL);
count = shdr.sh_size / shdr.sh_entsize;
/* rettrieve the symbol names */
for (ii = 0; ii < count; ++ii) {
GElf_Sym sym;
gelf_getsym(data, ii, &sym);
p_st->add_symbol(elf_strptr(elf, shdr.sh_link, sym.st_name),
sym.st_value, sym.st_size, sym.st_info, sym.st_other);
}
return p_st;
}
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