Index: head/sys/riscv/riscv/db_trace.c
===================================================================
--- head/sys/riscv/riscv/db_trace.c	(revision 357629)
+++ head/sys/riscv/riscv/db_trace.c	(revision 357630)
@@ -1,135 +1,157 @@
 /*-
  * Copyright (c) 2015 The FreeBSD Foundation
  * Copyright (c) 2016 Ruslan Bukin <br@bsdpad.com>
  * All rights reserved.
+ * Copyright (c) 2020 John Baldwin <jhb@FreeBSD.org>
  *
  * Portions of this software were developed by Semihalf under
  * the sponsorship of the FreeBSD Foundation.
  *
  * 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>
 __FBSDID("$FreeBSD$");
+
 #include <sys/param.h>
-#include <sys/proc.h>
 #include <sys/kdb.h>
-#include <machine/pcb.h>
+#include <sys/proc.h>
+
 #include <ddb/ddb.h>
 #include <ddb/db_sym.h>
 
+#include <machine/pcb.h>
 #include <machine/riscvreg.h>
 #include <machine/stack.h>
+#include <machine/vmparam.h>
 
 void
 db_md_list_watchpoints()
 {
 
 }
 
 int
 db_md_clr_watchpoint(db_expr_t addr, db_expr_t size)
 {
 
 	return (0);
 }
 
 int
 db_md_set_watchpoint(db_expr_t addr, db_expr_t size)
 {
 
 	return (0);
 }
 
 static void
 db_stack_trace_cmd(struct unwind_state *frame)
 {
 	const char *name;
 	db_expr_t offset;
 	db_expr_t value;
 	c_db_sym_t sym;
 	uint64_t pc;
 
 	while (1) {
 		pc = frame->pc;
 
-		if (unwind_frame(frame) < 0)
-			break;
-
 		sym = db_search_symbol(pc, DB_STGY_ANY, &offset);
 		if (sym == C_DB_SYM_NULL) {
 			value = 0;
 			name = "(null)";
 		} else
 			db_symbol_values(sym, &name, &value);
 
 		db_printf("%s() at ", name);
 		db_printsym(frame->pc, DB_STGY_PROC);
 		db_printf("\n");
 
-		db_printf("\t pc = 0x%016lx ra = 0x%016lx\n",
-		    pc, frame->pc);
-		db_printf("\t sp = 0x%016lx fp = 0x%016lx\n",
-		    frame->sp, frame->fp);
-		db_printf("\n");
+		if (strcmp(name, "cpu_exception_handler_supervisor") == 0 ||
+		    strcmp(name, "cpu_exception_handler_user") == 0) {
+			struct trapframe *tf;
+
+			tf = (struct trapframe *)(uintptr_t)frame->sp;
+
+			if (tf->tf_scause & EXCP_INTR)
+				db_printf("--- interrupt %ld\n",
+				    tf->tf_scause & EXCP_MASK);
+			else
+				db_printf("--- exception %ld, tval = %#lx\n",
+				    tf->tf_scause & EXCP_MASK,
+				    tf->tf_stval);
+			frame->sp = (uint64_t)tf->tf_sp;
+			frame->fp = (uint64_t)tf->tf_s[0];
+			frame->pc = (uint64_t)tf->tf_sepc;
+			if (!INKERNEL(frame->fp))
+				break;
+			continue;
+		}
+
+		if (strcmp(name, "fork_trampoline") == 0)
+			break;
+
+		if (unwind_frame(frame) < 0)
+			break;
 	}
 }
 
 int
 db_trace_thread(struct thread *thr, int count)
 {
 	struct unwind_state frame;
 	struct pcb *ctx;
 
 	if (thr != curthread) {
 		ctx = kdb_thr_ctx(thr);
 
 		frame.sp = (uint64_t)ctx->pcb_sp;
 		frame.fp = (uint64_t)ctx->pcb_s[0];
 		frame.pc = (uint64_t)ctx->pcb_ra;
 		db_stack_trace_cmd(&frame);
 	} else
 		db_trace_self();
 	return (0);
 }
 
 void
 db_trace_self(void)
 {
 	struct unwind_state frame;
 	uint64_t sp;
 
 	__asm __volatile("mv %0, sp" : "=&r" (sp));
 
 	frame.sp = sp;
 	frame.fp = (uint64_t)__builtin_frame_address(0);
 	frame.pc = (uint64_t)db_trace_self;
 	db_stack_trace_cmd(&frame);
 }