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/*
* Copyright (c) 2018 Virtuozzo International GmbH
*
* This work is licensed under the terms of the GNU GPL, version 2 or later.
*
*/
#include "qemu/osdep.h"
#include "err.h"
#include "qemu_elf.h"
#define QEMU_NOTE_NAME "QEMU"
#ifndef ROUND_UP
#define ROUND_UP(n, d) (((n) + (d) - 1) & -(0 ? (n) : (d)))
#endif
#ifndef DIV_ROUND_UP
#define DIV_ROUND_UP(n, d) (((n) + (d) - 1) / (d))
#endif
#define ELF_NOTE_SIZE(hdr_size, name_size, desc_size) \
((DIV_ROUND_UP((hdr_size), 4) + \
DIV_ROUND_UP((name_size), 4) + \
DIV_ROUND_UP((desc_size), 4)) * 4)
int is_system(QEMUCPUState *s)
{
return s->gs.base >> 63;
}
static char *nhdr_get_name(Elf64_Nhdr *nhdr)
{
return (char *)nhdr + ROUND_UP(sizeof(*nhdr), 4);
}
static void *nhdr_get_desc(Elf64_Nhdr *nhdr)
{
return nhdr_get_name(nhdr) + ROUND_UP(nhdr->n_namesz, 4);
}
static Elf64_Nhdr *nhdr_get_next(Elf64_Nhdr *nhdr)
{
return (void *)((uint8_t *)nhdr + ELF_NOTE_SIZE(sizeof(*nhdr),
nhdr->n_namesz, nhdr->n_descsz));
}
Elf64_Phdr *elf64_getphdr(void *map)
{
Elf64_Ehdr *ehdr = map;
Elf64_Phdr *phdr = (void *)((uint8_t *)map + ehdr->e_phoff);
return phdr;
}
Elf64_Half elf_getphdrnum(void *map)
{
Elf64_Ehdr *ehdr = map;
return ehdr->e_phnum;
}
static bool init_states(QEMU_Elf *qe)
{
Elf64_Phdr *phdr = elf64_getphdr(qe->map);
Elf64_Nhdr *start = (void *)((uint8_t *)qe->map + phdr[0].p_offset);
Elf64_Nhdr *end = (void *)((uint8_t *)start + phdr[0].p_memsz);
Elf64_Nhdr *nhdr;
size_t cpu_nr = 0;
if (phdr[0].p_type != PT_NOTE) {
eprintf("Failed to find PT_NOTE\n");
return false;
}
qe->has_kernel_gs_base = 1;
for (nhdr = start; nhdr < end; nhdr = nhdr_get_next(nhdr)) {
if (!strcmp(nhdr_get_name(nhdr), QEMU_NOTE_NAME)) {
QEMUCPUState *state = nhdr_get_desc(nhdr);
if (state->size < sizeof(*state)) {
eprintf("CPU #%zu: QEMU CPU state size %u doesn't match\n",
cpu_nr, state->size);
/*
* We assume either every QEMU CPU state has KERNEL_GS_BASE or
* no one has.
*/
qe->has_kernel_gs_base = 0;
}
cpu_nr++;
}
}
printf("%zu CPU states has been found\n", cpu_nr);
qe->state = g_new(QEMUCPUState*, cpu_nr);
cpu_nr = 0;
for (nhdr = start; nhdr < end; nhdr = nhdr_get_next(nhdr)) {
if (!strcmp(nhdr_get_name(nhdr), QEMU_NOTE_NAME)) {
qe->state[cpu_nr] = nhdr_get_desc(nhdr);
cpu_nr++;
}
}
qe->state_nr = cpu_nr;
return true;
}
static void exit_states(QEMU_Elf *qe)
{
g_free(qe->state);
}
static bool check_ehdr(QEMU_Elf *qe)
{
Elf64_Ehdr *ehdr = qe->map;
if (sizeof(Elf64_Ehdr) > qe->size) {
eprintf("Invalid input dump file size\n");
return false;
}
if (memcmp(ehdr->e_ident, ELFMAG, SELFMAG)) {
eprintf("Invalid ELF signature, input file is not ELF\n");
return false;
}
if (ehdr->e_ident[EI_CLASS] != ELFCLASS64 ||
ehdr->e_ident[EI_DATA] != ELFDATA2LSB) {
eprintf("Invalid ELF class or byte order, must be 64-bit LE\n");
return false;
}
if (ehdr->e_ident[EI_VERSION] != EV_CURRENT) {
eprintf("Invalid ELF version\n");
return false;
}
if (ehdr->e_machine != EM_X86_64) {
eprintf("Invalid input dump architecture, only x86_64 is supported\n");
return false;
}
if (ehdr->e_type != ET_CORE) {
eprintf("Invalid ELF type, must be core file\n");
return false;
}
/*
* ELF dump file must contain one PT_NOTE and at least one PT_LOAD to
* restore physical address space.
*/
if (ehdr->e_phnum < 2) {
eprintf("Invalid number of ELF program headers\n");
return false;
}
return true;
}
static bool QEMU_Elf_map(QEMU_Elf *qe, const char *filename)
{
#ifdef CONFIG_LINUX
struct stat st;
int fd;
printf("Using Linux mmap\n");
fd = open(filename, O_RDONLY, 0);
if (fd == -1) {
eprintf("Failed to open ELF dump file \'%s\'\n", filename);
return false;
}
if (fstat(fd, &st)) {
eprintf("Failed to get size of ELF dump file\n");
close(fd);
return false;
}
qe->size = st.st_size;
qe->map = mmap(NULL, qe->size, PROT_READ | PROT_WRITE,
MAP_PRIVATE | MAP_NORESERVE, fd, 0);
if (qe->map == MAP_FAILED) {
eprintf("Failed to map ELF file\n");
close(fd);
return false;
}
close(fd);
#else
GError *gerr = NULL;
printf("Using GLib mmap\n");
qe->gmf = g_mapped_file_new(filename, TRUE, &gerr);
if (gerr) {
eprintf("Failed to map ELF dump file \'%s\'\n", filename);
g_error_free(gerr);
return false;
}
qe->map = g_mapped_file_get_contents(qe->gmf);
qe->size = g_mapped_file_get_length(qe->gmf);
#endif
return true;
}
static void QEMU_Elf_unmap(QEMU_Elf *qe)
{
#ifdef CONFIG_LINUX
munmap(qe->map, qe->size);
#else
g_mapped_file_unref(qe->gmf);
#endif
}
bool QEMU_Elf_init(QEMU_Elf *qe, const char *filename)
{
if (!QEMU_Elf_map(qe, filename)) {
return false;
}
if (!check_ehdr(qe)) {
eprintf("Input file has the wrong format\n");
QEMU_Elf_unmap(qe);
return false;
}
if (!init_states(qe)) {
eprintf("Failed to extract QEMU CPU states\n");
QEMU_Elf_unmap(qe);
return false;
}
return true;
}
void QEMU_Elf_exit(QEMU_Elf *qe)
{
exit_states(qe);
QEMU_Elf_unmap(qe);
}
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