xref: /plan9-contrib/sys/src/9/vt4/syscall.c (revision f80d550d5bc48502e65b5d8bc4e8aaf82d4c6b0f)

#include "u.h"
#include "../port/lib.h"
#include "mem.h"
#include "dat.h"
#include "fns.h"
#include "../port/error.h"
#include "../port/systab.h"

#include <tos.h>
#include "ureg.h"

typedef struct {
	uintptr	pc;
	Ureg*	arg0;
	char*	arg1;
	char	msg[ERRMAX];
	Ureg*	old;
	Ureg	ureg;
} NFrame;

/*
 *   Return user to state before notify()
 */
static void
noted(Ureg* cur, uintptr arg0)
{
	Ureg *nur;
	NFrame *nf;

	qlock(&up->debug);
	if(arg0 != NRSTR && !up->notified){
		qunlock(&up->debug);
		pprint("call to noted() when not notified\n");
		pexit("Suicide", 0);
	}
	up->notified = 0;
	fpunoted();

	nf = up->ureg;

	/* sanity clause */
	if(!okaddr(PTR2UINT(nf), sizeof(NFrame), 0)){
		qunlock(&up->debug);
		pprint("bad ureg in noted %#p\n", nf);
		pexit("Suicide", 0);
	}

	/* don't let user change system status */
	nur = &nf->ureg;
	nur->status = cur->status;

	memmove(cur, nur, sizeof(Ureg));

	switch((int)arg0){
	case NCONT:
	case NRSTR:
		if(!okaddr(nur->pc, BY2SE, 0) || !okaddr(nur->usp, BY2SE, 0)){
			qunlock(&up->debug);
			pprint("suicide: trap in noted\n");
			pexit("Suicide", 0);
		}
		up->ureg = nf->old;
		qunlock(&up->debug);
		break;

	case NSAVE:
		if(!okaddr(nur->pc, BY2SE, 0) || !okaddr(nur->usp, BY2SE, 0)){
			qunlock(&up->debug);
			pprint("suicide: trap in noted\n");
			pexit("Suicide", 0);
		}
		qunlock(&up->debug);

		splhi();
		nf->arg1 = nf->msg;
		nf->arg0 = &nf->ureg;
		cur->r3 = PTR2UINT(nf->arg0);
		nf->pc = 0;
		cur->sp = PTR2UINT(nf);
		break;

	default:
		pprint("unknown noted arg %#p\n", arg0);
		up->lastnote.flag = NDebug;
		/* fall through */
	case NDFLT:
		if(up->lastnote.flag == NDebug){
			qunlock(&up->debug);
			pprint("suicide: %s\n", up->lastnote.msg);
		}
		else
			qunlock(&up->debug);
		pexit(up->lastnote.msg, up->lastnote.flag != NDebug);
	}
}

/*
 *  Call user, if necessary, with note.
 *  Pass user the Ureg struct and the note on his stack.
 */
int
notify(Ureg* ureg)
{
	int l;
	Note *n;
	ulong s;
	uintptr sp;
	NFrame *nf;

	if(up->procctl)
		procctl(up);
	if(up->nnote == 0)
		return 0;

	fpunotify(ureg);

	s = spllo();
	qlock(&up->debug);
	up->notepending = 0;
	n = &up->note[0];
	if(strncmp(n->msg, "sys:", 4) == 0){
		l = strlen(n->msg);
		if(l > ERRMAX-15)	/* " pc=0x12345678\0" */
			l = ERRMAX-15;
		sprint(n->msg+l, " pc=%#.8lux", ureg->pc);
	}

	if(n->flag!=NUser && (up->notified || up->notify==0)){
		if(n->flag == NDebug)
			pprint("suicide: %s\n", n->msg);
		qunlock(&up->debug);
		pexit(n->msg, n->flag!=NDebug);
	}

	if(up->notified) {
		qunlock(&up->debug);
		splhi();
		return 0;
	}

	if(up->notify == nil){
		qunlock(&up->debug);
		pexit(n->msg, n->flag!=NDebug);
	}
	if(!okaddr(PTR2UINT(up->notify), BY2WD, 0)){
		qunlock(&up->debug);
		pprint("suicide: notify function address %#p\n", up->notify);
		pexit("Suicide", 0);
	}

	sp = ureg->usp & ~(BY2V-1);
	sp -= (sizeof(NFrame)+BY2V-1) & ~(BY2V-1);

	if(!okaddr(sp, sizeof(NFrame), 1)){
		qunlock(&up->debug);
		pprint("suicide: notify stack address %#p\n", sp);
		pexit("Suicide", 0);
	}

	nf = UINT2PTR(sp);
	memmove(&nf->ureg, ureg, sizeof(Ureg));
	nf->old = up->ureg;
	up->ureg = nf;
	memmove(nf->msg, up->note[0].msg, ERRMAX);
	nf->arg1 = nf->msg;
	nf->arg0 = up->ureg;
	ureg->r3 = PTR2UINT(up->ureg);
	nf->pc = 0;

	ureg->usp = sp;
	ureg->pc = PTR2UINT(up->notify);
	up->notified = 1;
	up->nnote--;
	memmove(&up->lastnote, &up->note[0], sizeof(Note));
	memmove(&up->note[0], &up->note[1], up->nnote*sizeof(Note));

	qunlock(&up->debug);
	splx(s);
	return 1;
}

/*
 *  system calls and 'orrible notes
 */

/* TO DO: make this trap a separate asm entry point, as on some other RISC architectures */
void
syscall(Ureg* ureg)
{
	char *e;
	u32int s;
	uintptr sp;
	long ret;
	int i, scallnr;

	cycles(&up->kentry);

	m->syscall++;
	up->insyscall = 1;
	up->pc = ureg->pc;
	up->dbgreg = ureg;

	if(up->procctl == Proc_tracesyscall){
		up->procctl = Proc_stopme;
		procctl(up);
	}

	scallnr = ureg->r3;
	up->scallnr = scallnr;
	if(scallnr == RFORK)
		fpusysrfork(ureg);
	spllo();

	sp = ureg->sp;
	up->nerrlab = 0;
	ret = -1;
	if(!waserror()){
		if(scallnr >= nsyscall){
			pprint("bad sys call number %d pc %lux\n",
				scallnr, ureg->pc);
			postnote(up, 1, "sys: bad sys call", NDebug);
			error(Ebadarg);
		}

		if(sp < (USTKTOP-BY2PG) || sp > (USTKTOP-sizeof(Sargs)-BY2WD))
			validaddr(sp, sizeof(Sargs)+BY2WD, 0);

		up->s = *((Sargs*)(sp+BY2WD));
		up->psstate = sysctab[scallnr];

		ret = systab[scallnr](up->s.args);
		poperror();
	}else{
		/* failure: save the error buffer for errstr */
		e = up->syserrstr;
		up->syserrstr = up->errstr;
		up->errstr = e;
	}
	if(up->nerrlab){
		print("bad errstack [%d]: %d extra\n", scallnr, up->nerrlab);
		for(i = 0; i < NERR; i++)
			print("sp=%#p pc=%#p\n",
				up->errlab[i].sp, up->errlab[i].pc);
		panic("error stack");
	}

	/*
	 * Put return value in frame.
	 */
	ureg->r3 = ret;

	if(up->procctl == Proc_tracesyscall){
		up->procctl = Proc_stopme;
		s = splhi();
		procctl(up);
		splx(s);
	}

	up->insyscall = 0;
	up->psstate = 0;

	if(scallnr == NOTED)
		noted(ureg, *(uintptr*)(sp+BY2SE));

	splhi();
	if(scallnr != RFORK && (up->procctl || up->nnote))
		notify(ureg);

	/* if we delayed sched because we held a lock, sched now */
	if(up->delaysched){
		sched();
		splhi();
	}
	kexit(ureg);
}

/*
 * called in syscallfmt.c, sysfile.c, sysproc.c
 */
void
validalign(uintptr addr, unsigned align)
{
	/*
	 * Plan 9 is a 32-bit O/S, and the hardware it runs on
	 * does not usually have instructions which move 64-bit
	 * quantities directly, synthesizing the operations
	 * with 32-bit move instructions. Therefore, the compiler
	 * (and hardware) usually only enforce 32-bit alignment,
	 * if at all.
	 *
	 * Take this out if the architecture warrants it.
	 */
	if(align == sizeof(vlong))
		align = sizeof(long);

	/*
	 * Check align is a power of 2, then addr alignment.
	 */
	if((align != 0 && !(align & (align-1))) && !(addr & (align-1)))
		return;
	postnote(up, 1, "sys: odd address", NDebug);
	error(Ebadarg);
	/*NOTREACHED*/
}

uintptr
sysexecstack(uintptr stack, int argc)
{
	/*
	 * Given a current bottom-of-stack and a count
	 * of pointer arguments to be pushed onto it followed
	 * by an integer argument count, return a suitably
	 * aligned new bottom-of-stack which will satisfy any
	 * hardware stack-alignment contraints.
	 * Rounding the stack down to be aligned with the
	 * natural size of a pointer variable usually suffices,
	 * but some architectures impose further restrictions,
	 * e.g. 32-bit SPARC, where the stack must be 8-byte
	 * aligned although pointers and integers are 32-bits.
	 */
	USED(argc);

	return STACKALIGN(stack);
}

long
execregs(ulong entry, ulong ssize, ulong nargs)
{
	ulong *sp;
	Ureg *ureg;

	fpusysprocsetup(up);			/* up is a guess */

	sp = (ulong*)(USTKTOP - ssize);
	*--sp = nargs;

	ureg = up->dbgreg;
//	memset(ureg, 0, 31*sizeof(ulong));
	ureg->usp = (ulong)sp;
	ureg->pc = entry;
	ureg->srr1 &= ~MSR_FP;			/* disable floating point */

	/*
	 * return the address of kernel/user shared data
	 * (e.g. clock stuff)
	 */
	return USTKTOP-sizeof(Tos);
}

void
sysprocsetup(Proc* p)
{
	fpusysprocsetup(p);
}

/*
 *  Craft a return frame which will cause the child to pop out of
 *  the scheduler in user mode with the return register zero.  Set
 *  pc to point to a l.s return function.
 */
void
forkchild(Proc *p, Ureg *ureg)
{
	Ureg *cureg;

//print("%lud setting up for forking child %lud\n", up->pid, p->pid);
	p->sched.sp = (ulong)p->kstack+KSTACK-(sizeof(Ureg)+2*BY2SE);
	p->sched.pc = (ulong)forkret;

	cureg = (Ureg*)(p->sched.sp+2*BY2SE);
	memmove(cureg, ureg, sizeof(Ureg));

	/* syscall returns 0 for child */
	cureg->r3 = 0;

	/* Things from bottom of syscall which were never executed */
	p->psstate = 0;
	p->insyscall = 0;

	fpusysrforkchild(p, cureg, up);
}