register_t
cheritest_libcheri_userfn_getstack(void)
{
struct cheri_stack cs;
struct cheri_stack_frame *csfp;
u_int stack_depth;
int retval;
retval = sysarch(CHERI_GET_STACK, &cs);
if (retval != 0)
cheritest_failure_err("sysarch(CHERI_GET_STACK) failed");
/* Does stack layout look sensible enough to continue? */
if ((cs.cs_tsize % CHERI_FRAME_SIZE) != 0)
cheritest_failure_errx(
"stack size (%ld) not a multiple of frame size",
cs.cs_tsize);
stack_depth = cs.cs_tsize / CHERI_FRAME_SIZE;
if ((cs.cs_tsp % CHERI_FRAME_SIZE) != 0)
cheritest_failure_errx(
"stack pointer (%ld) not a multiple of frame size",
cs.cs_tsp);
/* Validate that two stack frames are found. */
if (cs.cs_tsp != cs.cs_tsize - (register_t)(2 * CHERI_FRAME_SIZE))
cheritest_failure_errx("stack contains %d frames; expected "
"2", (cs.cs_tsize - (2 * CHERI_FRAME_SIZE)) /
CHERI_FRAME_SIZE);
/* Validate that the first is a saved ambient context. */
csfp = &cs.cs_frames[stack_depth - 1];
if (cheri_getbase(csfp->csf_pcc) != cheri_getbase(cheri_getpcc()) ||
cheri_getlen(csfp->csf_pcc) != cheri_getlen(cheri_getpcc()))
cheritest_failure_errx("frame 0: not global code cap");
/* Validate that the second is cheritest_objectp. */
csfp = &cs.cs_frames[stack_depth - 2];
if ((cheri_getbase(csfp->csf_pcc) != cheri_getbase(
sandbox_object_getobject(cheritest_objectp).co_codecap)) ||
cheri_getlen(csfp->csf_pcc) != cheri_getlen(
sandbox_object_getobject(cheritest_objectp).co_codecap))
cheritest_failure_errx("frame 1: not sandbox code cap");
return (0);
}
context_t act_init(context_t own_context, init_info_t* info, size_t init_base, size_t init_entry) {
KERNEL_TRACE("init", "activation init");
internel_if.message_send = kernel_seal(act_send_message_get_trampoline(), act_ref_type);
internel_if.message_reply = kernel_seal(act_send_return_get_trampoline(), act_sync_ref_type);
setup_syscall_interface(&internel_if);
kernel_next_act = 0;
// This is a dummy. Our first context has already been created
reg_frame_t frame;
bzero(&frame, sizeof(struct reg_frame));
// Register the kernel (exception) activation
act_t * kernel_act = &kernel_acts[0];
act_register(&frame, &kernel_queue.queue, "kernel", status_terminated, NULL, cheri_getbase(cheri_getpcc()));
/* The kernel context already exists and we set it here */
kernel_act->context = own_context;
// Create and register the init activation
KERNEL_TRACE("act", "Retroactively creating init activation");
/* Not a dummy here. We will subset our own c0/pcc for init. init is loaded directly after the kernel */
bzero(&frame, sizeof(struct reg_frame));
size_t length = cheri_getlen(cheri_getdefault()) - init_base;
frame.cf_c0 = cheri_setbounds(cheri_setoffset(cheri_getdefault(), init_base), length);
capability pcc = cheri_setbounds(cheri_setoffset(cheri_getpcc(), init_base), length);
KERNEL_TRACE("act", "assuming init has virtual entry point %lx", init_entry);
frame.cf_c12 = frame.cf_pcc = cheri_setoffset(pcc, init_entry);
/* provide config info to init. c3 is the conventional register */
frame.cf_c3 = info;
act_t * init_act = &kernel_acts[namespace_num_boot];
act_register_create(&frame, &init_queue.queue, "init", status_alive, NULL);
/* The boot activation should be the current activation */
sched_schedule(init_act);
return init_act->context;
}
/*
* Allocate a new cheri_fd object for an already-open file descriptor.
*/
int
cheri_fd_new(int fd, struct cheri_object *cop)
{
__capability void *codecap, *datacap;
struct cheri_fd *cfp;
cfp = calloc(1, sizeof(*cfp));
if (cfp == NULL) {
errno = ENOMEM;
return (-1);
}
CHERI_SYSTEM_OBJECT_INIT(cfp, cheri_fd_vtable);
cfp->cf_fd = fd;
/*
* Construct a sealed code capability for the class. This is just the
* ambient $pcc with the offset set to the entry address.
*
* XXXRW: For now, when invoked, we install $pcc into $c0, so this
* needs a full set of permissions rather than just LOAD/EXECUTE. In
* the future, we will want to preserve a copy of cheri_getdefault()
* in the struct cheri_fd to be reinstalled by the entry code.
*
* XXXRW: In the future, use cheri_codeptr() here?
*/
codecap = cheri_setoffset(cheri_getpcc(),
(register_t)CHERI_CLASS_ENTRY(cheri_fd));
cop->co_codecap = cheri_seal(codecap, cheri_fd_type);
/*
* Construct a sealed data capability for the class. This describes
* the 'struct cheri_fd' for the specific file descriptor. The $c0
* to reinstall later is the first field in the structure.
*
* XXXRW: Should we also do an explicit cheri_setoffset()?
*/
datacap = cheri_ptrperm(cfp, sizeof(*cfp), CHERI_PERM_GLOBAL |
CHERI_PERM_LOAD | CHERI_PERM_LOAD_CAP | CHERI_PERM_STORE |
CHERI_PERM_STORE_CAP);
cop->co_datacap = cheri_seal(datacap, cheri_fd_type);
return (0);
}
void bootloader_main(void) {
/* Init hardware */
hw_init();
/* Initialize elf-loader environment */
init_elf_loader();
/* Load the nano kernel. Doing this will install exception vectors */
boot_printf("Boot: loading nano kernel ...\n");
nano_init_t * nano_init = (nano_init_t *)load_nano(); //We have to rederive this as an executable cap
nano_init = (nano_init_t*)cheri_setoffset(cheri_getpcc(),cheri_getoffset(nano_init));
/* TODO: we could have some boot exception vectors if we want exception handling in boot. */
/* These should be in ROM as a part of the boot image (i.e. make a couple more dedicated sections */
cp0_status_bev_set(0);
boot_printf("Boot: loading kernel ...\n");
size_t entry = load_kernel();
boot_printf("Boot: loading init ...\n");
boot_info_t *bi = load_init();
size_t invalid_length = bi->init_end;
capability phy_start = cheri_setbounds(cheri_setoffset(cheri_getdefault(), MIPS_KSEG0), invalid_length);
/* Do we actually need this? */
//boot_printf("Invalidating %p length %lx:\n", phy_start, invalid_length);
//caches_invalidate(phy_start, invalid_length);
register_t mem_size = bi->init_end - bi->nano_end;
/* Jumps to the nano kernel init. This will completely destroy boot and so we can never return here.
* All registers will be cleared apart from a specified few. mem_size of memory will be left unmanaged and the
* rest will be returned as a reservation. The third argument is an extra argument to the kernel */
boot_printf("Jumping to nano kernel...\n");
BOOT_PRINT_CAP(nano_init);
nano_init(mem_size, entry, bi->init_begin - bi->kernel_begin, bi->init_entry);
}
/*
* Unwind the trusted stack by the specified number of frames (or all).
*/
int
cheri_stack_unwind(ucontext_t *uap, register_t ret, u_int op,
u_int num_frames)
{
struct cheri_frame *cfp;
struct cheri_stack cs;
struct cheri_stack_frame *csfp;
u_int stack_size, stack_frames;
register_t saved_mcreg0;
if (op != CHERI_STACK_UNWIND_OP_N &&
op != CHERI_STACK_UNWIND_OP_ALL) {
errno = EINVAL;
return (-1);
}
/*
* Request to unwind zero frames is a no-op: no state transformation
* is needed.
*/
if ((op == CHERI_STACK_UNWIND_OP_N) && (num_frames == 0))
return (0);
/*
* Retrieve trusted stack and validate before attempting to unwind.
*/
if (sysarch(CHERI_GET_STACK, &cs) != 0)
return (-1);
if ((cs.cs_tsize % CHERI_FRAME_SIZE) != 0 ||
(cs.cs_tsp > cs.cs_tsize) ||
(cs.cs_tsp % CHERI_FRAME_SIZE) != 0) {
errno = ERANGE;
return (-1);
}
/*
* See if there is room on the stack for that much unwinding.
*/
stack_size = cs.cs_tsize / CHERI_FRAME_SIZE;
stack_frames = (cs.cs_tsize - cs.cs_tsp) / CHERI_FRAME_SIZE;
if (op == CHERI_STACK_UNWIND_OP_ALL)
num_frames = stack_frames;
if ((num_frames < 0) || (stack_frames < num_frames)) {
errno = ERANGE;
return (-1);
}
/*
* Restore state from the last frame being unwound.
*/
csfp = &cs.cs_frames[stack_size - (stack_frames - num_frames) - 1];
#if 0
/* Make sure we will be returning to ambient authority. */
if (cheri_getbase(csfp->csf_pcc) != cheri_getbase(cheri_getpcc()) ||
cheri_getlen(csfp->csf_pcc) != cheri_getlen(cheri_getpcc()))
return (-1);
#endif
/*
* Pop stack desired number of frames.
*/
cs.cs_tsp += num_frames * CHERI_FRAME_SIZE;
assert(cs.cs_tsp <= cs.cs_tsize);
#ifdef __CHERI_PURE_CAPABILITY__
cfp = &uap->uc_mcontext.mc_cheriframe;
#else
cfp = (struct cheri_frame *)uap->uc_mcontext.mc_cp2state;
if (cfp == NULL || uap->uc_mcontext.mc_cp2state_len != sizeof(*cfp)) {
errno = ERANGE;
return (-1);
}
#endif
/*
* Zero the capability register file, explicitly restoring $pcc and
* $idc from the last trusted-stack frame.
*/
memset(cfp, 0, sizeof(*cfp));
cfp->cf_idc = csfp->csf_idc;
cfp->cf_pcc = csfp->csf_pcc;
/*
* Zero the general-purpose register file. restore not only $pc, but
* also the slot for $zero, which will hold a magic number across
* sigcode and sigreturn(). Also set a return value.
*
* XXXRW: The kernel unwinder sets V1 to the signal number?
*/
saved_mcreg0 = uap->uc_mcontext.mc_regs[0];
memset(uap->uc_mcontext.mc_regs, 0, sizeof(uap->uc_mcontext.mc_regs));
uap->uc_mcontext.mc_regs[0] = saved_mcreg0;
uap->uc_mcontext.mc_pc = cheri_getoffset(cfp->cf_pcc);
uap->uc_mcontext.mc_regs[V0] = ret;
/*
* Update kernel view of trusted stack.
*/
if (sysarch(CHERI_SET_STACK, &cs) != 0)
return (-1);
return (0);
}
