path: root/sys/riscv/riscv/trap.c

/*-
 * Copyright (c) 2015-2018 Ruslan Bukin <br@bsdpad.com>
 * All rights reserved.
 *
 * Portions of this software were developed by SRI International and the
 * University of Cambridge Computer Laboratory under DARPA/AFRL contract
 * FA8750-10-C-0237 ("CTSRD"), as part of the DARPA CRASH research programme.
 *
 * Portions of this software were developed by the University of Cambridge
 * Computer Laboratory as part of the CTSRD Project, with support from the
 * UK Higher Education Innovation Fund (HEIF).
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

#include <sys/cdefs.h>
#include "opt_ddb.h"

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/kernel.h>
#include <sys/ktr.h>
#include <sys/lock.h>
#include <sys/mutex.h>
#include <sys/bus.h>
#include <sys/proc.h>
#include <sys/ptrace.h>
#include <sys/syscall.h>
#include <sys/sysent.h>
#ifdef KDB
#include <sys/kdb.h>
#endif

#include <vm/vm.h>
#include <vm/pmap.h>
#include <vm/vm_kern.h>
#include <vm/vm_map.h>
#include <vm/vm_param.h>
#include <vm/vm_extern.h>

#include <machine/fpe.h>
#include <machine/frame.h>
#include <machine/pcb.h>
#include <machine/pcpu.h>

#include <machine/resource.h>
#include <machine/intr.h>

#ifdef KDTRACE_HOOKS
#include <sys/dtrace_bsd.h>
#endif

#ifdef DDB
#include <ddb/ddb.h>
#include <ddb/db_sym.h>
#endif

int (*dtrace_invop_jump_addr)(struct trapframe *);

/* Called from exception.S */
void do_trap_supervisor(struct trapframe *);
void do_trap_user(struct trapframe *);

static __inline void
call_trapsignal(struct thread *td, int sig, int code, void *addr, int trapno)
{
	ksiginfo_t ksi;

	ksiginfo_init_trap(&ksi);
	ksi.ksi_signo = sig;
	ksi.ksi_code = code;
	ksi.ksi_addr = addr;
	ksi.ksi_trapno = trapno;
	trapsignal(td, &ksi);
}

int
cpu_fetch_syscall_args(struct thread *td)
{
	struct proc *p;
	syscallarg_t *ap, *dst_ap;
	struct syscall_args *sa;

	p = td->td_proc;
	sa = &td->td_sa;
	ap = &td->td_frame->tf_a[0];
	dst_ap = &sa->args[0];

	sa->code = td->td_frame->tf_t[0];
	sa->original_code = sa->code;

	if (__predict_false(sa->code == SYS_syscall || sa->code == SYS___syscall)) {
		sa->code = *ap++;
	} else {
		*dst_ap++ = *ap++;
	}

	if (__predict_false(sa->code >= p->p_sysent->sv_size))
		sa->callp = &p->p_sysent->sv_table[0];
	else
		sa->callp = &p->p_sysent->sv_table[sa->code];

	KASSERT(sa->callp->sy_narg <= nitems(sa->args),
	    ("Syscall %d takes too many arguments", sa->code));

	memcpy(dst_ap, ap, (NARGREG - 1) * sizeof(*dst_ap));

	td->td_retval[0] = 0;
	td->td_retval[1] = 0;

	return (0);
}

#include "../../kern/subr_syscall.c"

static void
print_with_symbol(const char *name, uint64_t value)
{
#ifdef DDB
	c_db_sym_t sym;
	db_expr_t sym_value;
	db_expr_t offset;
	const char *sym_name;
#endif

	printf("%7s: 0x%016lx", name, value);

#ifdef DDB
	if (value >= VM_MIN_KERNEL_ADDRESS) {
		sym = db_search_symbol(value, DB_STGY_ANY, &offset);
		if (sym != C_DB_SYM_NULL) {
			db_symbol_values(sym, &sym_name, &sym_value);
			if (offset != 0)
				printf(" (%s + 0x%lx)", sym_name, offset);
			else
				printf(" (%s)", sym_name);
		}
	}
#endif
	printf("\n");
}

static void
dump_regs(struct trapframe *frame)
{
	char name[6];
	int i;

	for (i = 0; i < nitems(frame->tf_t); i++) {
		snprintf(name, sizeof(name), "t[%d]", i);
		print_with_symbol(name, frame->tf_t[i]);
	}

	for (i = 0; i < nitems(frame->tf_s); i++) {
		snprintf(name, sizeof(name), "s[%d]", i);
		print_with_symbol(name, frame->tf_s[i]);
	}

	for (i = 0; i < nitems(frame->tf_a); i++) {
		snprintf(name, sizeof(name), "a[%d]", i);
		print_with_symbol(name, frame->tf_a[i]);
	}

	print_with_symbol("ra", frame->tf_ra);
	print_with_symbol("sp", frame->tf_sp);
	print_with_symbol("gp", frame->tf_gp);
	print_with_symbol("tp", frame->tf_tp);
	print_with_symbol("sepc", frame->tf_sepc);
	printf("sstatus: 0x%016lx\n", frame->tf_sstatus);
	printf("stval  : 0x%016lx\n", frame->tf_stval);
}

static void
ecall_handler(void)
{
	struct thread *td;

	td = curthread;

	syscallenter(td);
	syscallret(td);
}

static void
page_fault_handler(struct trapframe *frame, int usermode)
{
	struct vm_map *map;
	uint64_t stval;
	struct thread *td;
	struct pcb *pcb;
	vm_prot_t ftype;
	vm_offset_t va;
	struct proc *p;
	int error, sig, ucode;
#ifdef KDB
	bool handled;
#endif

#ifdef KDB
	if (kdb_active) {
		kdb_reenter();
		return;
	}
#endif

	td = curthread;
	p = td->td_proc;
	pcb = td->td_pcb;
	stval = frame->tf_stval;

	if (td->td_critnest != 0 || td->td_intr_nesting_level != 0 ||
	    WITNESS_CHECK(WARN_SLEEPOK | WARN_GIANTOK, NULL,
	    "Kernel page fault") != 0)
		goto fatal;

	if (usermode) {
		if (!VIRT_IS_VALID(stval)) {
			call_trapsignal(td, SIGSEGV, SEGV_MAPERR, (void *)stval,
			    frame->tf_scause & SCAUSE_CODE);
			goto done;
		}
		map = &p->p_vmspace->vm_map;
	} else {
		/*
		 * Enable interrupts for the duration of the page fault. For
		 * user faults this was done already in do_trap_user().
		 */
		intr_enable();

		if (stval >= VM_MIN_KERNEL_ADDRESS) {
			map = kernel_map;
		} else {
			if (pcb->pcb_onfault == 0)
				goto fatal;
			map = &p->p_vmspace->vm_map;
		}
	}

	va = trunc_page(stval);

	if (frame->tf_scause == SCAUSE_STORE_PAGE_FAULT) {
		ftype = VM_PROT_WRITE;
	} else if (frame->tf_scause == SCAUSE_INST_PAGE_FAULT) {
		ftype = VM_PROT_EXECUTE;
	} else {
		ftype = VM_PROT_READ;
	}

	if (VIRT_IS_VALID(va) && pmap_fault(map->pmap, va, ftype))
		goto done;

	error = vm_fault_trap(map, va, ftype, VM_FAULT_NORMAL, &sig, &ucode);
	if (error != KERN_SUCCESS) {
		if (usermode) {
			call_trapsignal(td, sig, ucode, (void *)stval,
			    frame->tf_scause & SCAUSE_CODE);
		} else {
			if (pcb->pcb_onfault != 0) {
				frame->tf_a[0] = error;
				frame->tf_sepc = pcb->pcb_onfault;
				return;
			}
			goto fatal;
		}
	}

done:
	if (usermode)
		userret(td, frame);
	return;

fatal:
	dump_regs(frame);
#ifdef KDB
	if (debugger_on_trap) {
		kdb_why = KDB_WHY_TRAP;
		handled = kdb_trap(frame->tf_scause & SCAUSE_CODE, 0, frame);
		kdb_why = KDB_WHY_UNSET;
		if (handled)
			return;
	}
#endif
	panic("Fatal page fault at %#lx: %#016lx", frame->tf_sepc, stval);
}

void
do_trap_supervisor(struct trapframe *frame)
{
	uint64_t exception;

	/* Ensure we came from supervisor mode, interrupts disabled */
	KASSERT((csr_read(sstatus) & (SSTATUS_SPP | SSTATUS_SIE)) ==
	    SSTATUS_SPP, ("Came from S mode with interrupts enabled"));

	KASSERT((csr_read(sstatus) & (SSTATUS_SUM)) == 0,
	    ("Came from S mode with SUM enabled"));

	exception = frame->tf_scause & SCAUSE_CODE;
	if ((frame->tf_scause & SCAUSE_INTR) != 0) {
		/* Interrupt */
		riscv_cpu_intr(frame);
		return;
	}

#ifdef KDTRACE_HOOKS
	if (dtrace_trap_func != NULL && (*dtrace_trap_func)(frame, exception))
		return;
#endif

	CTR4(KTR_TRAP, "%s: exception=%lu, sepc=%lx, stval=%lx", __func__,
	    exception, frame->tf_sepc, frame->tf_stval);

	switch (exception) {
	case SCAUSE_LOAD_ACCESS_FAULT:
	case SCAUSE_STORE_ACCESS_FAULT:
	case SCAUSE_INST_ACCESS_FAULT:
		dump_regs(frame);
		panic("Memory access exception at 0x%016lx\n", frame->tf_sepc);
		break;
	case SCAUSE_LOAD_MISALIGNED:
	case SCAUSE_STORE_MISALIGNED:
	case SCAUSE_INST_MISALIGNED:
		dump_regs(frame);
		panic("Misaligned address exception at %#016lx: %#016lx\n",
		    frame->tf_sepc, frame->tf_stval);
		break;
	case SCAUSE_STORE_PAGE_FAULT:
	case SCAUSE_LOAD_PAGE_FAULT:
	case SCAUSE_INST_PAGE_FAULT:
		page_fault_handler(frame, 0);
		break;
	case SCAUSE_BREAKPOINT:
#ifdef KDTRACE_HOOKS
		if (dtrace_invop_jump_addr != NULL &&
		    dtrace_invop_jump_addr(frame) == 0)
				break;
#endif
#ifdef KDB
		kdb_trap(exception, 0, frame);
#else
		dump_regs(frame);
		panic("No debugger in kernel.\n");
#endif
		break;
	case SCAUSE_ILLEGAL_INSTRUCTION:
		dump_regs(frame);
		panic("Illegal instruction at 0x%016lx\n", frame->tf_sepc);
		break;
	default:
		dump_regs(frame);
		panic("Unknown kernel exception %lx trap value %lx\n",
		    exception, frame->tf_stval);
	}
}

void
do_trap_user(struct trapframe *frame)
{
	uint64_t exception;
	struct thread *td;
	struct pcb *pcb;

	td = curthread;
	pcb = td->td_pcb;

	KASSERT(td->td_frame == frame,
	    ("%s: td_frame %p != frame %p", __func__, td->td_frame, frame));

	/* Ensure we came from usermode, interrupts disabled */
	KASSERT((csr_read(sstatus) & (SSTATUS_SPP | SSTATUS_SIE)) == 0,
	    ("Came from U mode with interrupts enabled"));

	KASSERT((csr_read(sstatus) & (SSTATUS_SUM)) == 0,
	    ("Came from U mode with SUM enabled"));

	exception = frame->tf_scause & SCAUSE_CODE;
	if ((frame->tf_scause & SCAUSE_INTR) != 0) {
		/* Interrupt */
		riscv_cpu_intr(frame);
		return;
	}
	intr_enable();

	CTR4(KTR_TRAP, "%s: exception=%lu, sepc=%lx, stval=%lx", __func__,
	    exception, frame->tf_sepc, frame->tf_stval);

	switch (exception) {
	case SCAUSE_LOAD_ACCESS_FAULT:
	case SCAUSE_STORE_ACCESS_FAULT:
	case SCAUSE_INST_ACCESS_FAULT:
		call_trapsignal(td, SIGBUS, BUS_ADRERR, (void *)frame->tf_sepc,
		    exception);
		userret(td, frame);
		break;
	case SCAUSE_LOAD_MISALIGNED:
	case SCAUSE_STORE_MISALIGNED:
	case SCAUSE_INST_MISALIGNED:
		call_trapsignal(td, SIGBUS, BUS_ADRALN, (void *)frame->tf_sepc,
		    exception);
		userret(td, frame);
		break;
	case SCAUSE_STORE_PAGE_FAULT:
	case SCAUSE_LOAD_PAGE_FAULT:
	case SCAUSE_INST_PAGE_FAULT:
		page_fault_handler(frame, 1);
		break;
	case SCAUSE_ECALL_USER:
		frame->tf_sepc += 4;	/* Next instruction */
		ecall_handler();
		break;
	case SCAUSE_ILLEGAL_INSTRUCTION:
		if ((pcb->pcb_fpflags & PCB_FP_STARTED) == 0) {
			/*
			 * May be a FPE trap. Enable FPE usage
			 * for this thread and try again.
			 */
			fpe_state_clear();
			frame->tf_sstatus &= ~SSTATUS_FS_MASK;
			frame->tf_sstatus |= SSTATUS_FS_CLEAN;
			pcb->pcb_fpflags |= PCB_FP_STARTED;
			break;
		}
		call_trapsignal(td, SIGILL, ILL_ILLTRP, (void *)frame->tf_sepc,
		    exception);
		userret(td, frame);
		break;
	case SCAUSE_BREAKPOINT:
		call_trapsignal(td, SIGTRAP, TRAP_BRKPT, (void *)frame->tf_sepc,
		    exception);
		userret(td, frame);
		break;
	default:
		dump_regs(frame);
		panic("Unknown userland exception %lx, trap value %lx\n",
		    exception, frame->tf_stval);
	}
}