#include <u.h>
#include <libc.h>
#include "../probe.h"

extern void pentrytmpl(void);
extern void pexittmpl(void);

void
trapme(void)
{
}

void
pentry(Probe *p)
{
	ulong *sp;
	int i;
	print("pentry %p\n", p);
	print("saveret %p\n", p->saveret);
	print("callerpc %p\n", getcallerpc(&p));
	print("arg0 %ud\n", *p->argp);
	sp = (ulong *)&p;
	for(i = -2; i < 16; i++)
		print("%d	0x%lux\n", i, sp[i]);
	trapme();
}

void
pexit(Probe *p)
{
	ulong *sp;
	int i;
	print("pexit %p\n", p);
	print("saveret %p\n", p->saveret);
	print("callerpc %p\n", getcallerpc(&p));
	print("rval %ud\n", p->rval);
	sp = (ulong *)&p;
	for(i = 0; i < 16; i++)
		print("%d	0x%lux\n", i, sp[i]);
}


int (*nopclone)(int);

int
nop(int)
{
	char tab[6];
	char *p;
	int r;
	r = 0;
	for(p = tab; p < &tab[6]; p++)
		r += *p = 7;
	return r;
}

Probe *
mkprobe(void *func, void (*pentry)(Probe *), void (*pexit)(Probe *))
{
	Probe *p;
	u32int *fp;
	u32int rjmp;
	fp = (u32int*)func;
	p = malloc(sizeof p[0]);
print("entrycode = %p\n", p->entrycode);
print("exitcode = %p\n", p->exitcode);
	p->entry = pentry;
	p->exit = pexit;
	p->func = func;
	p->orig[0] = fp[0];
	p->orig[1] = fp[1];
	/* 5 is size of rcall */
	rjmp = (ulong)p->entrycode - (ulong)func - 5;
	p->probe[0] = 0xe8 | (rjmp << 8);
	p->probe[1] = (rjmp >> 24);
	memmove(p->entrycode, pentrytmpl, sizeof p->entrycode);
	memmove(p->exitcode, pexittmpl, sizeof p->exitcode);
	return p;
}

void
probeinstall(Probe *p)
{
	u32int *fp;
	fp = (u32int*)p->func;
	fp[0] = p->probe[0];
	fp[1] = p->probe[1];
}

void
probeuninstall(Probe *p)
{
	u32int *fp;
	fp = (u32int*)p->func;
	fp[0] = p->orig[0];
	fp[1] = p->orig[1];
}

void
main(void)
{
	Probe *p;
	print("#define	argp		%lud\n", offsetof(Probe, argp));
	print("#define	entry	%lud\n", offsetof(Probe, entry));
	print("#define	entrycode	%lud\n", offsetof(Probe, entrycode[0]));
	print("#define	exit		%lud\n", offsetof(Probe, exit));
	print("#define	exitcode	%lud\n", offsetof(Probe, exitcode[0]));
	print("#define	func		%lud\n", offsetof(Probe, func));
	print("#define	orig1	%lud\n", offsetof(Probe, orig[0]));
	print("#define	orig2	%lud\n", offsetof(Probe, orig[1]));
	print("#define	probe1	%lud\n", offsetof(Probe, probe[0]));
	print("#define	probe2	%lud\n", offsetof(Probe, probe[1]));
	print("#define	rval		%lud\n", offsetof(Probe, rval));
	print("#define	saveret	%lud\n", offsetof(Probe, saveret));

	nopclone = malloc(256);
	memmove(nopclone, nop, 256);
print("nopclone %p\n", nopclone);
	p = mkprobe(nopclone, pentry, pexit);
	probeinstall(p);
print("&p = %p\n", &p);
	nopclone(10);
print("&p = %p\n", &p);
	probeuninstall(p);
print("hey\n");
	exits(nil);
}