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-rw-r--r--base/loader/elf_object.cc266
1 files changed, 100 insertions, 166 deletions
diff --git a/base/loader/elf_object.cc b/base/loader/elf_object.cc
index d43e2fe7c..93313fac6 100644
--- a/base/loader/elf_object.cc
+++ b/base/loader/elf_object.cc
@@ -28,6 +28,14 @@
#include <string>
+// Because of the -Wundef flag we have to do this
+#define __LIBELF_INTERNAL__ 0
+#define __LIBELF64_LINUX 1
+#define __LIBELF_NEED_LINK_H 0
+
+#include <libelf/libelf.h>
+#include <libelf/gelf.h>
+
#include "base/loader/elf_object.hh"
#include "mem/functional_mem/functional_memory.hh"
@@ -44,24 +52,21 @@ ElfObject::tryFile(const string &fname, int fd, size_t len, uint8_t *data)
Elf *elf;
GElf_Ehdr ehdr;
-
- /* check that header matches library version */
+ // check that header matches library version
assert(elf_version(EV_CURRENT) != EV_NONE);
- /* get a pointer to elf structure */
+ // get a pointer to elf structure
elf = elf_memory((char*)data,len);
- /* will only fail if fd is invalid */
+ // will only fail if fd is invalid
assert(elf != NULL);
- /* Check that we actually have a elf file */
- if(gelf_getehdr(elf, &ehdr) ==0)
- {
+ // Check that we actually have a elf file
+ if (gelf_getehdr(elf, &ehdr) ==0) {
DPRINTFR(Loader, "Not ELF\n");
elf_end(elf);
return NULL;
}
- else
- {
+ else {
if (ehdr.e_ident[EI_CLASS] == ELFCLASS32)
panic("32 bit ELF Binary, Not Supported");
if (ehdr.e_machine != EM_ALPHA)
@@ -81,125 +86,107 @@ ElfObject::ElfObject(const string &_filename, int _fd,
: ObjectFile(_filename, _fd, _len, _data, _arch, _opSys)
{
-
Elf *elf;
GElf_Ehdr ehdr;
- /* check that header matches library version */
+ // check that header matches library version
assert(elf_version(EV_CURRENT) != EV_NONE);
- /* get a pointer to elf structure */
+ // get a pointer to elf structure
elf = elf_memory((char*)fileData,len);
- /* will only fail if fd is invalid */
+ // will only fail if fd is invalid
assert(elf != NULL);
- /* Check that we actually have a elf file */
- if(gelf_getehdr(elf, &ehdr) ==0)
- {
+ // Check that we actually have a elf file
+ if (gelf_getehdr(elf, &ehdr) ==0) {
panic("Not ELF, shouldn't be here");
}
-
entry = ehdr.e_entry;
- elf_end(elf);
-
- /* We will actually read the sections when we need to load them*/
-}
-
-
-bool
-ElfObject::loadSections(FunctionalMemory *mem, bool loadPhys)
-{
- Elf *elf;
- int secidx = 1; /* there is a 0 but it is nothing, go figure*/
- Elf_Scn *section;
- GElf_Shdr shdr;
- GElf_Ehdr ehdr;
-
- Addr address;
- char *secname;
- /* check that header matches library version */
- assert(elf_version(EV_CURRENT) != EV_NONE);
-
-
- /* get a pointer to elf structure */
- elf = elf_memory((char*)fileData,len);
+ // initialize segment sizes to 0 in case they're not present
+ text.size = data.size = bss.size = 0;
- assert(elf != NULL);
+ for (int i = 0; i < ehdr.e_phnum; ++i) {
+ GElf_Phdr phdr;
+ if (gelf_getphdr(elf, i, &phdr) == 0) {
+ panic("gelf_getphdr failed for section %d", i);
+ }
- /* Check that we actually have a elf file */
- if(gelf_getehdr(elf, &ehdr) ==0)
- {
- panic("Not ELF, shouldn't be here");
+ // for now we don't care about non-loadable segments
+ if (!(phdr.p_type & PT_LOAD))
+ continue;
+
+ // the headers don't explicitly distinguish text from data,
+ // but empirically the text segment comes first.
+ if (text.size == 0) { // haven't seen text segment yet
+ text.baseAddr = phdr.p_vaddr;
+ text.size = phdr.p_filesz;
+ // remember where the data is for loadSections()
+ fileTextBits = fileData + phdr.p_offset;
+ // if there's any padding at the end that's not in the
+ // file, call it the bss. This happens in the "text"
+ // segment if there's only one loadable segment (as for
+ // kernel images).
+ bss.size = phdr.p_memsz - phdr.p_filesz;
+ bss.baseAddr = phdr.p_vaddr + phdr.p_filesz;
+ }
+ else if (data.size == 0) { // have text, this must be data
+ data.baseAddr = phdr.p_vaddr;
+ data.size = phdr.p_filesz;
+ // remember where the data is for loadSections()
+ fileDataBits = fileData + phdr.p_offset;
+ // if there's any padding at the end that's not in the
+ // file, call it the bss. Warn if this happens for both
+ // the text & data segments (should only have one bss).
+ if (phdr.p_memsz - phdr.p_filesz > 0 && bss.size != 0) {
+ warn("Two implied bss segments in file!\n");
+ }
+ bss.size = phdr.p_memsz - phdr.p_filesz;
+ bss.baseAddr = phdr.p_vaddr + phdr.p_filesz;
+ }
}
+ // should have found at least one loadable segment
+ assert(text.size != 0);
+ DPRINTFR(Loader, "text: 0x%x %d\ndata: 0x%x %d\nbss: 0x%x %d\n",
+ text.baseAddr, text.size, data.baseAddr, data.size,
+ bss.baseAddr, bss.size);
- /* Get the first section */
- section = elf_getscn(elf, secidx);
-
- /* While there are no more sections */
- while (section != NULL)
- {
- gelf_getshdr(section, &shdr);
+ elf_end(elf);
+ // We will actually read the sections when we need to load them
+}
- if (shdr.sh_flags & SHF_ALLOC)
- {
- /* we should load this */
- DPRINTF(Loader,"Name: %20s Address: 0x%016llx Size: 0x%08llx Offset: 0x%08llx Flags:0x%08llx %s\n",
- elf_strptr(elf, ehdr.e_shstrndx, shdr.sh_name), shdr.sh_addr,
- shdr.sh_size, shdr.sh_offset, shdr.sh_flags, shdr.sh_flags & SHF_ALLOC ? "ALLOC" : "");
- secname = elf_strptr(elf, ehdr.e_shstrndx, shdr.sh_name);
- if(secname)
- {
- if (strcmp(secname, ".text")==0)
- {
- text.baseAddr = shdr.sh_addr;
- text.size = shdr.sh_size;
- }
- if (strcmp(secname, ".data")==0)
- {
- data.baseAddr = shdr.sh_addr;
- data.size = shdr.sh_size;
- }
- if (strcmp(secname, ".bss")==0)
- {
- bss.baseAddr = shdr.sh_addr;
- bss.size = shdr.sh_size;
- }
- }
- if(shdr.sh_size != 0)
- {
- if (loadPhys)
- {
- address = shdr.sh_addr &= (ULL(1) << 40) - 1;
- mem->prot_write(address, fileData + shdr.sh_offset, shdr.sh_size);
- }
- else
- {
- mem->prot_write(shdr.sh_addr, fileData + shdr.sh_offset, shdr.sh_size);
- }
- }
- }
+bool
+ElfObject::loadSections(FunctionalMemory *mem, bool loadPhys)
+{
+ Addr textAddr = text.baseAddr;
+ Addr dataAddr = data.baseAddr;
- ++secidx;
- section = elf_getscn(elf, secidx);
+ if (loadPhys) {
+ textAddr &= (ULL(1) << 40) - 1;
+ dataAddr &= (ULL(1) << 40) - 1;
}
- elf_end(elf);
+ // Since we don't really have an MMU and all memory is
+ // zero-filled, there's no need to set up the BSS segment.
+ if (text.size != 0)
+ mem->prot_write(textAddr, fileTextBits, text.size);
+ if (data.size != 0)
+ mem->prot_write(dataAddr, fileDataBits, data.size);
return true;
}
bool
-ElfObject::loadGlobalSymbols(SymbolTable *symtab)
+ElfObject::loadSomeSymbols(SymbolTable *symtab, int binding)
{
Elf *elf;
- int secidx = 1; /* there is a 0 but it is nothing, go figure*/
+ int secidx = 1; // there is a 0 but it is nothing, go figure
Elf_Scn *section;
GElf_Shdr shdr;
Elf_Data *data;
@@ -210,38 +197,33 @@ ElfObject::loadGlobalSymbols(SymbolTable *symtab)
if (!symtab)
return false;
- /* check that header matches library version */
+ // check that header matches library version
assert(elf_version(EV_CURRENT) != EV_NONE);
- /* get a pointer to elf structure */
+ // get a pointer to elf structure
elf = elf_memory((char*)fileData,len);
assert(elf != NULL);
-
- /* Get the first section */
+ // Get the first section
section = elf_getscn(elf, secidx);
- /* While there are no more sections */
- while (section != NULL)
- {
+ // While there are no more sections
+ while (section != NULL) {
gelf_getshdr(section, &shdr);
-
- if(shdr.sh_type == SHT_SYMTAB)
- {
+ if (shdr.sh_type == SHT_SYMTAB) {
found = true;
data = elf_getdata(section, NULL);
count = shdr.sh_size / shdr.sh_entsize;
DPRINTF(Loader, "Found Symbol Table, %d symbols present\n", count);
- /* loop through all the symbols, only loading global ones*/
- for (ii = 0; ii < count; ++ii)
- {
+ // loop through all the symbols, only loading global ones
+ for (ii = 0; ii < count; ++ii) {
gelf_getsym(data, ii, &sym);
- if (GELF_ST_BIND(sym.st_info) & STB_GLOBAL)
- {
- symtab->insert(sym.st_value, elf_strptr(elf, shdr.sh_link, sym.st_name));
+ if (GELF_ST_BIND(sym.st_info) & binding) {
+ symtab->insert(sym.st_value,
+ elf_strptr(elf, shdr.sh_link, sym.st_name));
}
}
}
@@ -255,61 +237,13 @@ ElfObject::loadGlobalSymbols(SymbolTable *symtab)
}
bool
-ElfObject::loadLocalSymbols(SymbolTable *symtab)
+ElfObject::loadGlobalSymbols(SymbolTable *symtab)
{
+ return loadSomeSymbols(symtab, STB_GLOBAL);
+}
- Elf *elf;
- int secidx = 1; /* there is a 0 but it is nothing, go figure*/
- Elf_Scn *section;
- GElf_Shdr shdr;
- Elf_Data *data;
- int count, ii;
- bool found = false;
- GElf_Sym sym;
-
- if (!symtab)
- return false;
-
- /* check that header matches library version */
- assert(elf_version(EV_CURRENT) != EV_NONE);
-
- /* get a pointer to elf structure */
- elf = elf_memory((char*)fileData,len);
-
- assert(elf != NULL);
-
-
- /* Get the first section */
- section = elf_getscn(elf, secidx);
-
- /* While there are no more sections */
- while (section != NULL)
- {
- gelf_getshdr(section, &shdr);
-
-
- if(shdr.sh_type == SHT_SYMTAB)
- {
- found = true;
- data = elf_getdata(section, NULL);
- count = shdr.sh_size / shdr.sh_entsize;
- DPRINTF(Loader, "Found Symbol Table, %d symbols present\n", count);
-
- /* loop through all the symbols, only loading global ones*/
- for (ii = 0; ii < count; ++ii)
- {
- gelf_getsym(data, ii, &sym);
- if (GELF_ST_BIND(sym.st_info) & STB_LOCAL)
- {
- symtab->insert(sym.st_value, elf_strptr(elf, shdr.sh_link, sym.st_name));
- }
- }
- }
- ++secidx;
- section = elf_getscn(elf, secidx);
- }
-
- elf_end(elf);
-
- return found;
+bool
+ElfObject::loadLocalSymbols(SymbolTable *symtab)
+{
+ return loadSomeSymbols(symtab, STB_LOCAL);
}
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