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41 #include "base/loader/elf_object.hh"
46 #include <sys/types.h>
52 #include "base/bitfield.hh"
53 #include "base/loader/symtab.hh"
54 #include "base/logging.hh"
55 #include "base/trace.hh"
56 #include "debug/Loader.hh"
58 #include "sim/byteswap.hh"
64 ElfObjectFormat::load(ImageFileDataPtr ifd
)
66 // check that header matches library version
67 if (elf_version(EV_CURRENT
) == EV_NONE
)
68 panic("wrong elf version number!");
70 ObjectFile
*object
= nullptr;
72 // get a pointer to elf structure
73 // Check that we actually have a elf file
75 elf_memory((char *)const_cast<uint8_t *>(ifd
->data()), ifd
->len());
79 if (gelf_getehdr(elf
, &ehdr
) == 0)
80 DPRINTFR(Loader
, "Not ELF\n");
82 object
= new ElfObject(ifd
);
92 ElfObjectFormat elfObjectFormat
;
93 std::string interpDir
;
95 } // anonymous namespace
98 setInterpDir(const std::string
&dirname
)
100 fatal_if(!interpDir
.empty(),
101 "Error: setInterpDir has already been called once\n");
105 ElfObject::ElfObject(ImageFileDataPtr ifd
) : ObjectFile(ifd
)
107 // get a pointer to elf structure
108 elf
= elf_memory((char *)const_cast<uint8_t *>(imageData
->data()),
111 gelf_getehdr(elf
, &ehdr
);
115 determineByteOrder();
117 entry
= ehdr
.e_entry
;
118 _programHeaderCount
= ehdr
.e_phnum
;
119 _programHeaderSize
= ehdr
.e_phentsize
;
121 // Go through all the segments in the program and record them.
122 for (int i
= 0; i
< ehdr
.e_phnum
; ++i
) {
124 if (gelf_getphdr(elf
, i
, &phdr
) == 0) {
125 panic("gelf_getphdr failed for segment %d.", i
);
128 if (phdr
.p_type
== PT_LOAD
)
129 handleLoadableSegment(phdr
, i
);
130 if (phdr
.p_type
== PT_INTERP
) {
131 // Make sure the interpreter is an valid ELF file.
132 auto interp_path
= getInterpPath(phdr
);
133 ObjectFile
*obj
= createObjectFile(interp_path
);
134 interpreter
= dynamic_cast<ElfObject
*>(obj
);
135 assert(interpreter
!= nullptr);
136 _symtab
.insert(obj
->symtab());
140 // should have found at least one loadable segment
141 warn_if(image
.segments().empty(),
142 "No loadable segments in '%s'. ELF file corrupted?\n",
143 imageData
->filename());
145 for (M5_VAR_USED
auto &seg
: image
.segments())
146 DPRINTFR(Loader
, "%s\n", seg
);
148 // We will actually read the sections when we need to load them
150 // check that header matches library version
151 if (elf_version(EV_CURRENT
) == EV_NONE
)
152 panic("wrong elf version number!");
154 // Get the first section
155 int sec_idx
= 1; // there is a 0 but it is nothing, go figure
156 Elf_Scn
*section
= elf_getscn(elf
, sec_idx
);
158 // While there are no more sections
161 gelf_getshdr(section
, &shdr
);
163 if (shdr
.sh_type
== SHT_SYMTAB
) {
164 Elf_Data
*data
= elf_getdata(section
, nullptr);
165 int count
= shdr
.sh_size
/ shdr
.sh_entsize
;
166 DPRINTF(Loader
, "Found Symbol Table, %d symbols present.", count
);
168 // Loop through all the symbols.
169 for (int i
= 0; i
< count
; ++i
) {
171 gelf_getsym(data
, i
, &sym
);
173 char *sym_name
= elf_strptr(elf
, shdr
.sh_link
, sym
.st_name
);
174 if (!sym_name
|| sym_name
[0] == '$')
177 Loader::Symbol symbol
;
178 symbol
.address
= sym
.st_value
;
179 symbol
.name
= sym_name
;
181 switch (GELF_ST_BIND(sym
.st_info
)) {
183 symbol
.binding
= Loader::Symbol::Binding::Global
;
186 symbol
.binding
= Loader::Symbol::Binding::Local
;
189 symbol
.binding
= Loader::Symbol::Binding::Weak
;
195 if (_symtab
.insert(symbol
)) {
196 DPRINTF(Loader
, "Symbol: %-40s value %#x.\n",
197 symbol
.name
, symbol
.address
);
202 section
= elf_getscn(elf
, sec_idx
);
207 ElfObject::getInterpPath(const GElf_Phdr
&phdr
) const
209 // This is the interpreter path as specified in the elf file
210 const std::string elf_path
= (char *)imageData
->data() + phdr
.p_offset
;
211 if (!interpDir
.empty())
212 return interpDir
+ elf_path
;
218 ElfObject::determineArch()
220 auto &emach
= ehdr
.e_machine
;
221 auto &eclass
= ehdr
.e_ident
[EI_CLASS
];
222 auto &edata
= ehdr
.e_ident
[EI_DATA
];
224 // Detect the architecture
225 if (emach
== EM_SPARC64
|| (emach
== EM_SPARC
&& eclass
== ELFCLASS64
) ||
226 emach
== EM_SPARCV9
) {
228 } else if (emach
== EM_SPARC32PLUS
||
229 (emach
== EM_SPARC
&& eclass
== ELFCLASS32
)) {
231 } else if (emach
== EM_MIPS
&& eclass
== ELFCLASS32
) {
233 if (edata
!= ELFDATA2LSB
) {
234 fatal("The binary you're trying to load is compiled for big "
235 "endian MIPS. gem5\nonly supports little endian MIPS. "
236 "Please recompile your binary.\n");
238 } else if (emach
== EM_X86_64
&& eclass
== ELFCLASS64
) {
240 } else if (emach
== EM_386
&& eclass
== ELFCLASS32
) {
242 } else if (emach
== EM_ARM
&& eclass
== ELFCLASS32
) {
243 arch
= bits(ehdr
.e_entry
, 0) ? Thumb
: Arm
;
244 } else if (emach
== EM_AARCH64
&& eclass
== ELFCLASS64
) {
246 } else if (emach
== EM_RISCV
) {
247 arch
= (eclass
== ELFCLASS64
) ? Riscv64
: Riscv32
;
248 } else if (emach
== EM_PPC
&& eclass
== ELFCLASS32
) {
250 } else if (emach
== EM_PPC64
&& eclass
== ELFCLASS64
) {
253 warn("Unknown architecture: %d\n", emach
);
258 ElfObject::determineOpSys()
260 // For 64-bit Power, EI_OSABI and EI_ABIVERSION cannot be used to
261 // determine the ABI version used by the ELF object
262 if (ehdr
.e_machine
== EM_PPC64
) {
263 switch (ehdr
.e_flags
& 0x3) {
264 case 0x1: opSys
= LinuxPower64ABIv1
; return;
265 case 0x2: opSys
= LinuxPower64ABIv2
; return;
267 if (ehdr
.e_ident
[EI_DATA
] == ELFDATA2MSB
)
268 opSys
= LinuxPower64ABIv1
;
269 if (ehdr
.e_ident
[EI_DATA
] == ELFDATA2LSB
)
270 opSys
= LinuxPower64ABIv2
;
275 // Detect the operating system
276 switch (ehdr
.e_ident
[EI_OSABI
]) {
280 case ELFOSABI_SOLARIS
:
287 opSys
= LinuxArmOABI
;
289 case ELFOSABI_FREEBSD
:
293 opSys
= UnknownOpSys
;
296 Elf_Scn
*section
= elf_getscn(elf
, 1);
297 for (int sec_idx
= 1; section
; section
= elf_getscn(elf
, ++sec_idx
)) {
299 gelf_getshdr(section
, &shdr
);
301 char *e_str
= elf_strptr(elf
, ehdr
.e_shstrndx
, shdr
.sh_name
);
302 if (shdr
.sh_type
== SHT_NOTE
&& !strcmp(".note.ABI-tag", e_str
)) {
303 // we have found a ABI note section
304 // Check the 5th 32bit word for OS 0 == linux, 1 == hurd,
305 // 2 == solaris, 3 == freebsd
306 Elf_Data
*raw_data
= elf_rawdata(section
, nullptr);
307 assert(raw_data
&& raw_data
->d_buf
);
309 uint32_t raw_abi
= ((uint32_t *)raw_data
->d_buf
)[4];
310 bool is_le
= ehdr
.e_ident
[EI_DATA
] == ELFDATA2LSB
;
311 uint32_t os_abi
= is_le
? htole(raw_abi
) : htobe(raw_abi
);
318 fatal("gem5 does not support the HURD ABI.\n");
328 if (!strcmp(".SUNW_version", e_str
) || !strcmp(".stab.index", e_str
)) {
336 ElfObject::determineByteOrder()
338 auto edata
= ehdr
.e_ident
[EI_DATA
];
339 if (edata
== ELFDATANONE
)
340 panic("invalid ELF data encoding");
341 byteOrder
= (edata
== ELFDATA2MSB
) ? ByteOrder::big
: ByteOrder::little
;
345 ElfObject::handleLoadableSegment(GElf_Phdr phdr
, int seg_num
)
347 auto name
= std::to_string(seg_num
);
349 if (phdr
.p_memsz
== 0) {
350 warn("Ignoring empty loadable segment %s", name
);
354 image
.addSegment({ name
, phdr
.p_paddr
, imageData
,
355 phdr
.p_offset
, phdr
.p_filesz
});
356 Addr uninitialized
= phdr
.p_memsz
- phdr
.p_filesz
;
358 // There may be parts of a segment which aren't included in the
359 // file. In those cases, we need to create a new segment with no
360 // data to take up the extra space. This should be zeroed when
361 // loaded into memory.
362 image
.addSegment({ name
+ "(uninitialized)",
363 phdr
.p_paddr
+ phdr
.p_filesz
, uninitialized
});
366 const Addr file_start
= phdr
.p_offset
;
367 const Addr file_end
= file_start
+ phdr
.p_filesz
;
369 // If there is a program header table, figure out the virtual
370 // address of the header table in the final memory image. We use
371 // the program headers themselves to translate from a file offset
372 // to the address in the image.
373 if (file_start
<= ehdr
.e_phoff
&& file_end
> ehdr
.e_phoff
)
374 _programHeaderTable
= phdr
.p_vaddr
+ (ehdr
.e_phoff
- file_start
);
377 ElfObject::~ElfObject()
383 ElfObject::getSections()
385 assert(!sectionNames
.size());
387 // check that header matches library version
388 if (elf_version(EV_CURRENT
) == EV_NONE
)
389 panic("wrong elf version number!");
391 // get a pointer to elf structure
393 elf_memory((char *)const_cast<uint8_t *>(imageData
->data()),
397 // Check that we actually have a elf file
399 if (gelf_getehdr(elf
, &ehdr
) ==0) {
400 panic("Not ELF, shouldn't be here");
403 // Get the first section
404 int sec_idx
= 1; // there is a 0 but it is nothing, go figure
405 Elf_Scn
*section
= elf_getscn(elf
, sec_idx
);
407 // While there are no more sections
410 gelf_getshdr(section
, &shdr
);
411 sectionNames
.insert(elf_strptr(elf
, ehdr
.e_shstrndx
, shdr
.sh_name
));
412 section
= elf_getscn(elf
, ++sec_idx
);
419 ElfObject::sectionExists(std::string sec
)
421 if (!sectionNames
.size())
424 return sectionNames
.find(sec
) != sectionNames
.end();
429 ElfObject::updateBias(Addr bias_addr
)
434 // Patch the entry point with bias_addr.
437 // Patch segments with the bias_addr.
438 image
.offset(bias_addr
);
441 } // namespace Loader