code: plan9front

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5e: implement DSB,DMB,ISB and CLREX instructions

--- a/sys/src/cmd/5e/5e.c

+++ b/sys/src/cmd/5e/5e.c

@@ -36,6 +36,7 @@

 	if(P == nil)

 		return;

+	clrex();

 	remproc(P);

 	decref(&nproc);

 	freesegs();

--- a/sys/src/cmd/5e/arm.c

+++ b/sys/src/cmd/5e/arm.c

@@ -134,6 +134,7 @@

 	addr = *Rn;

 	if((instr & fB) == 0)

 		addr = evenaddr(addr, 3);

+	clrex();

 	targ = (u32int *) vaddr(addr, 4, &seg);

 	lock(&seg->lock);

 	if(instr & fB) {

@@ -400,8 +401,10 @@

 		invalid(instr);

 	addr = evenaddr(*Rn, 3);

 	if(instr & fS) {

+		clrex();

 		targ = vaddr(addr, 4, &seg);

 		lock(&seg->lock);

+		P->excl = seg;

 		*Rd = *targ;

 		segunlock(seg);

 	} else {

@@ -410,17 +413,40 @@

 			invalid(instr);

 		targ = vaddr(addr, 4, &seg);

 		if(canlock(&seg->lock)) {

+			unlock(&seg->lock);

 			*Rd = 1;

+		} else if(P->excl != seg) {

+			*Rd = 1;

 		} else {

 			*targ = *Rm;

-			unlock(&seg->lock);

 			*Rd = 0;

 		}

 		segunlock(seg);

+		clrex();

 	}

 }

 void

+clrex(void)

+{

+	Segment *seg;

+

+	seg = P->excl;

+	P->excl = nil;

+	if(seg != nil)

+		unlock(&seg->lock);

+}

+

+static void

+barrier(void)

+{

+	static Lock l;

+

+	lock(&l);

+	unlock(&l);

+}

+

+void

 step(void)

 {

 	u32int instr;

@@ -463,7 +489,18 @@

 	case 0xC: if((P->CPSR & flZ) || !(P->CPSR & flN) != !(P->CPSR & flV)) return; break;

 	case 0xD: if(!(P->CPSR & flZ) && !(P->CPSR & flN) == !(P->CPSR & flV)) return; break;

 	case 0xE: break;

-	default: sysfatal("condition code %x not implemented", instr >> 28);

+	case 0xF:

+		switch(instr & 0xFFF000F0){

+		case 0xF5700010:	/* CLREX */

+			clrex();

+			return;

+		case 0xF5700040:	/* DSB */

+		case 0xF5700050:	/* DMB */

+		case 0xF5700060:	/* ISB */

+			barrier();

+			return;

+		}

+	default: sysfatal("condition code %x not implemented (instr %ux, ps %ux)", instr >> 28, instr, P->R[15]);

 	}

 	if((instr & 0x0FB00FF0) == 0x01000090)

 		swap(instr);

--- a/sys/src/cmd/5e/dat.h

+++ b/sys/src/cmd/5e/dat.h

@@ -31,9 +31,10 @@

 	Ref *path;		/* Ref + string data */

 	Segment *S[SEGNUM];	/* memory */

+	Segment *excl;		/* recently acquired exclusive access */

 	u32int R[16];		/* general purpose registers / PC (R15) */

 	u32int CPSR;		/* status register */

-	

+

 	u32int FPSR;

 	long double F[Nfpregs];

--- a/sys/src/cmd/5e/fns.h

+++ b/sys/src/cmd/5e/fns.h

@@ -17,6 +17,7 @@

 int iscexec(Fd *, int);

 void setcexec(Fd *, int, int);

 void cleanup(void);

+void clrex(void);

 void segunlock(Segment *);

 void *copyifnec(u32int, int, int *);

 void *bufifnec(u32int, int, int *);

--- a/sys/src/cmd/5e/proc.c

+++ b/sys/src/cmd/5e/proc.c

@@ -378,6 +378,7 @@

 	if(P->notehandler == 0)

 		exits(msg);

+	clrex();

 	uregp = P->R[13] - 18 * 4;

 	ureg = vaddrnol(uregp, 18 * 4);

 	memcpy(ureg, P->R, 15 * 4);