ensure WakeG modifies the right timer

Author: abarisani

src/runtime/sys_tamago_arm.s

@@ -176,7 +176,7 @@ TEXT runtime·WakeG(SB),NOSPLIT|NOFRAME,$0-0
 	CMP	$0, R2
 	B.EQ	done
 
-	// find longest timer offset
+	// offset to last element
 	SUB	$1, R2, R2
 	MOVW	$(timerWhen__size), R3
 	MUL	R3, R2, R2
@@ -185,8 +185,26 @@ TEXT runtime·WakeG(SB),NOSPLIT|NOFRAME,$0-0
 	CMP	$0, R0
 	B.EQ	done
 
-	// g->timer.ts.heap[last].when = 1
+	// g->timer.ts.heap[len-1]
 	ADD	R2, R0, R0
+	B	check
+
+prev:
+	SUB	$(timerWhen__size), R0
+	CMP	$0, R0
+	B.EQ	done
+
+check:
+	// find longest timer as *timers.adjust() might be pending
+	MOVW	(timerWhen_when+0)(R0), R1
+	CMP	$0xffffffff, R1 // LS word of math.MaxInt64
+	B.NE	prev
+
+	MOVW	(timerWhen_when+4)(R0), R1
+	CMP	$0x7fffffff, R1 // MS word of math.MaxInt64
+	B.NE	prev
+
+	// g->timer.ts.heap[off] = 1
 	MOVW	$1, R1
 	MOVW	R1, (timerWhen_when+0)(R0)
 	MOVW	$0, R1

src/runtime/sys_tamago_riscv64.s

@@ -92,16 +92,29 @@ TEXT runtime·WakeG(SB),NOSPLIT|NOFRAME,$0-0
 	MOV	(timers_heap+8)(T0), T2
 	BEQ	T2, ZERO, done
 
-	// find longest timer offset
+	// offset to last element
 	SUB	$1, T2, T2
 	MOV	$(timerWhen__size), T3
 	MUL	T3, T2, T2
 
 	MOV	(timers_heap)(T0), T0
 	BEQ	T0, ZERO, done
 
-	// g->timer.ts.heap[last].when = 1
+	// g->timer.ts.heap[len-1]
 	ADD	T2, T0, T0
+	JMP	check
+
+prev:
+	SUB	$(timerWhen__size), T0
+	BEQ	T0, ZERO, done
+
+check:
+	// find longest timer as *timers.adjust() might be pending
+	MOV	(timerWhen_when)(T0), T1
+	MOV	$((1 << 63) - 1), T2 // math.MaxInt64
+	BNE	T2, T1, prev
+
+	// g->timer.ts.heap[off] = 1
 	MOV	$(1 << 32), T1
 	MOV	T1, (timerWhen_when)(T0)