status_t linux_init (vmi_instance_t vmi)
{
status_t ret = VMI_FAILURE;
if (vmi->cr3){
vmi->kpgd = vmi->cr3;
}
else if (VMI_SUCCESS == linux_system_map_symbol_to_address(vmi, "swapper_pg_dir", &vmi->kpgd)){
dbprint("--got vaddr for swapper_pg_dir (0x%.16llx).\n", vmi->kpgd);
if (driver_is_pv(vmi)){
vmi->kpgd = vmi_translate_kv2p(vmi, vmi->kpgd);
if (vmi_read_addr_pa(vmi, vmi->kpgd, &(vmi->kpgd)) == VMI_FAILURE){
errprint("Failed to get physical addr for kpgd.\n");
goto _exit;
}
}
else{
vmi->kpgd = vmi_translate_kv2p(vmi, vmi->kpgd);
}
}
else{
errprint("swapper_pg_dir not found and CR3 not set, exiting\n");
goto _exit;
}
vmi->kpgd = vmi->cr3;
dbprint("**set vmi->kpgd (0x%.16llx).\n", vmi->kpgd);
addr_t address = vmi_translate_ksym2v(vmi, "init_task");
address += vmi->os.linux_instance.tasks_offset;
if (VMI_FAILURE == vmi_read_addr_va(vmi, address, 0, &(vmi->init_task))){
errprint("Failed to get task list head 'init_task'.\n");
goto _exit;
}
ret = VMI_SUCCESS;
_exit:
return ret;
}
/*
* check that this vm uses a paging method that we support
* and set pm/cr3/pae/pse/lme flags optionally on the given pointers
*/
status_t probe_memory_layout_x86(vmi_instance_t vmi) {
// To get the paging layout, the following bits are needed:
// 1. CR0.PG
// 2. CR4.PAE
// 3. Either (a) IA32_EFER.LME, or (b) the guest's address width (32 or
// 64). Not all backends allow us to read an MSR; in particular, Xen's PV
// backend doessn't.
status_t ret = VMI_FAILURE;
page_mode_t pm = VMI_PM_UNKNOWN;
uint8_t dom_addr_width = 0; // domain address width (bytes)
/* pull info from registers, if we can */
reg_t cr0, cr3, cr4, efer;
int pae = 0, pse = 0, lme = 0;
uint8_t msr_efer_lme = 0; // LME bit in MSR_EFER
/* get the control register values */
if (driver_get_vcpureg(vmi, &cr0, CR0, 0) == VMI_FAILURE) {
errprint("**failed to get CR0\n");
goto _exit;
}
/* PG Flag --> CR0, bit 31 == 1 --> paging enabled */
if (!VMI_GET_BIT(cr0, 31)) {
dbprint(VMI_DEBUG_CORE, "Paging disabled for this VM, only physical addresses supported.\n");
vmi->page_mode = VMI_PM_UNKNOWN;
vmi->pae = 0;
vmi->pse = 0;
vmi->lme = 0;
ret = VMI_SUCCESS;
goto _exit;
}
//
// Paging enabled (PG==1)
//
if (driver_get_vcpureg(vmi, &cr4, CR4, 0) == VMI_FAILURE) {
errprint("**failed to get CR4\n");
goto _exit;
}
/* PSE Flag --> CR4, bit 5 */
pae = VMI_GET_BIT(cr4, 5);
dbprint(VMI_DEBUG_CORE, "**set pae = %d\n", pae);
/* PSE Flag --> CR4, bit 4 */
pse = VMI_GET_BIT(cr4, 4);
dbprint(VMI_DEBUG_CORE, "**set pse = %d\n", pse);
ret = driver_get_vcpureg(vmi, &efer, MSR_EFER, 0);
if (VMI_SUCCESS == ret) {
lme = VMI_GET_BIT(efer, 8);
dbprint(VMI_DEBUG_CORE, "**set lme = %d\n", lme);
} else {
dbprint(VMI_DEBUG_CORE, "**failed to get MSR_EFER, trying method #2\n");
// does this trick work in all cases?
ret = driver_get_address_width(vmi, &dom_addr_width);
if (VMI_FAILURE == ret) {
errprint
("Failed to get domain address width. Giving up.\n");
goto _exit;
}
lme = (8 == dom_addr_width);
dbprint
(VMI_DEBUG_CORE, "**found guest address width is %d bytes; assuming IA32_EFER.LME = %d\n",
dom_addr_width, lme);
} // if
// Get current cr3 for sanity checking
if (driver_get_vcpureg(vmi, &cr3, CR3, 0) == VMI_FAILURE) {
errprint("**failed to get CR3\n");
goto _exit;
}
// now determine addressing mode
if (0 == pae) {
dbprint(VMI_DEBUG_CORE, "**32-bit paging\n");
pm = VMI_PM_LEGACY;
cr3 &= 0xFFFFF000ull;
}
// PAE == 1; determine IA-32e or PAE
else if (lme) { // PAE == 1, LME == 1
dbprint(VMI_DEBUG_CORE, "**IA-32e paging\n");
pm = VMI_PM_IA32E;
cr3 &= 0xFFFFFFFFFFFFF000ull;
} else { // PAE == 1, LME == 0
dbprint(VMI_DEBUG_CORE, "**PAE paging\n");
pm = VMI_PM_PAE;
cr3 &= 0xFFFFFFE0;
} // if-else
dbprint(VMI_DEBUG_CORE, "**sanity checking cr3 = 0x%.16"PRIx64"\n", cr3);
/* testing to see CR3 value */
if (!driver_is_pv(vmi) && cr3 >= vmi->max_physical_address) { // sanity check on CR3
dbprint(VMI_DEBUG_CORE, "** Note cr3 value [0x%"PRIx64"] exceeds memsize [0x%"PRIx64"]\n",
cr3, vmi->size);
}
vmi->page_mode = pm;
vmi->pae = pae;
vmi->pse = pse;
vmi->lme = lme;
_exit:
return ret;
}
status_t linux_init(vmi_instance_t vmi) {
status_t ret = VMI_FAILURE;
os_interface_t os_interface = NULL;
if (vmi->config == NULL) {
errprint("VMI_ERROR: No config table found\n");
return VMI_FAILURE;
}
if (vmi->os_data != NULL) {
errprint("VMI_ERROR: os data already initialized, reinitializing\n");
free(vmi->os_data);
}
vmi->os_data = safe_malloc(sizeof(struct linux_instance));
bzero(vmi->os_data, sizeof(struct linux_instance));
g_hash_table_foreach(vmi->config, (GHFunc)linux_read_config_ghashtable_entries, vmi);
if (VMI_SUCCESS
== linux_system_map_symbol_to_address(vmi, "swapper_pg_dir", NULL,
&vmi->kpgd)) {
dbprint("--got vaddr for swapper_pg_dir (0x%.16"PRIx64").\n",
vmi->kpgd);
if (driver_is_pv(vmi)) {
vmi->kpgd = vmi_translate_kv2p(vmi, vmi->kpgd);
if (vmi_read_addr_pa(vmi, vmi->kpgd, &(vmi->kpgd)) == VMI_FAILURE) {
errprint(
"Failed to get physical addr for kpgd using swapper_pg_dir.\n");
}
}
}
if (!vmi->kpgd) {
ret = driver_get_vcpureg(vmi, &vmi->kpgd, CR3, 0);
if (ret != VMI_SUCCESS) {
errprint(
"Driver does not support cr3 read and kpgd could not be set, exiting\n");
goto _exit;
}
}
dbprint("**set vmi->kpgd (0x%.16"PRIx64").\n", vmi->kpgd);
ret = linux_system_map_symbol_to_address(vmi, "init_task", NULL,
&vmi->init_task);
if (ret != VMI_SUCCESS) {
errprint("VMI_ERROR: Could not get init_task from System.map\n");
return ret;
}
os_interface = safe_malloc(sizeof(struct os_interface));
bzero(os_interface, sizeof(struct os_interface));
os_interface->os_get_offset = linux_get_offset;
os_interface->os_pid_to_pgd = linux_pid_to_pgd;
os_interface->os_pgd_to_pid = linux_pgd_to_pid;
os_interface->os_ksym2v = linux_system_map_symbol_to_address;
os_interface->os_usym2rva = NULL;
os_interface->os_rva2sym = NULL;
os_interface->os_teardown = linux_teardown;
vmi->os_interface = os_interface;
_exit: return ret;
}
