#include <sys/param.h>
#include <sys/systm.h>
#include <sys/kernel.h>
#include <sys/sysctl.h>
#include <sys/lock.h>

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

/* Just call "stacktrace();" at key points in your code.
 * decode sysctl ring buffer later in userland.
 * I lost that code.  write your own and let me know.  I cheated and
 * parsed the output of 'nm /boot/kernel/kernel' to keep it simple.
 */

#define TRACERECORD 1024

#define TRACEBACK 15

struct stackframe {
	struct stackframe *link;
	void *retval;
};

struct tracerecord {
	int nest;
	void *ra[TRACEBACK];
};	/* 32 bytes per record */

int tracenext = 0;
SYSCTL_INT(_kern, OID_AUTO, tracenext, CTLFLAG_RW, &tracenext, 0, "");

int tracesize = TRACERECORD;
SYSCTL_INT(_kern, OID_AUTO, tracesize, CTLFLAG_RW, &tracesize, 0, "");

struct tracerecord tracebuffer[TRACERECORD];

static int
sysctl_kern_tracebuf(SYSCTL_HANDLER_ARGS)
{
	int error;

	/*
	 * Unwind the buffer so that it is linear, possibly with initial
	 * nulls at the start.
	 */
	error = sysctl_handle_opaque(oidp, &tracebuffer[tracenext],
	    (tracesize - tracenext) * sizeof(struct tracerecord), req);
	if (error)
		return error;
	if (tracenext > 0) {
		error = sysctl_handle_opaque(oidp, &tracebuffer[0],
			tracenext * sizeof(struct tracerecord), req);
	}
	return error;
}
SYSCTL_PROC(_kern, OID_AUTO, tracebuf, CTLTYPE_OPAQUE | CTLFLAG_RD,
    0, 0, sysctl_kern_tracebuf, "S,tracerecord", "");

int tracecons = 0;
SYSCTL_INT(_kern, OID_AUTO, tracecons, CTLFLAG_RW, &tracecons, 0, "");

int traceactive = 0;
SYSCTL_INT(_kern, OID_AUTO, traceactive, CTLFLAG_RW, &traceactive, 0, "");

void
stacktrace(void)
{
	struct stackframe *frame;
	int i;

	if (!traceactive)
		return;

	frame = (struct stackframe *)__builtin_frame_address(0);

	if (tracecons)
		printf("TRACE:");
	for (i = 0; i < TRACEBACK; i++) {
		if (tracecons)
			printf(" %p", frame->retval);
		tracebuffer[tracenext].nest = i + 1;
		tracebuffer[tracenext].ra[i] = frame->retval;
		if (tracenext >= TRACERECORD)
			tracenext = 0;
		frame = frame->link;
		if ((u_int32_t)frame < (u_int32_t)KERNBASE)
			break;
	}
	tracenext++;
	if (tracecons)
		printf("\n");
}

#if 0
void stacktrace_set(struct tracerecord *tr);

void
stacktrace_set(struct tracerecord *tr)
{
	struct stackframe *frame;
	int i;

	frame = (struct stackframe *)__builtin_frame_address(0);
	for (i = 0; i < TRACEBACK; i++) {
		tr->nest = i + 1;
		tr->ra[i] = frame->retval;
		frame = frame->link;
		if ((u_int32_t)frame < (u_int32_t)KERNBASE)
			break;
	}
}	
#endif