arch: arc: fix the bug that interrupt stack is not switched

For the old codes, if nest interrupts come out after _isr_wrapper
and before _check_nest_int_by_irq_act, then multi-bits in irq_act
will be set, this will result irq stack will not be switched in
correctly

As a fix, it's still need to use nest interrupt counter to do
interrupt stack switch as before

The difference is in the past exc_nest_count is used, but here
_kernel.nested/_kernel.cpus[cpu_id].nested is used.

Signed-off-by: Wayne Ren <wei.ren@synopsys.com>

Author: Wayne Ren

arch/arc/core/fast_irq.S

@@ -76,7 +76,8 @@ SECTION_FUNC(TEXT, _firq_enter)
 	lr r25, [_ARC_V2_LP_END]
 #endif
 
-	_check_nest_int_by_irq_act r0, r1
+	/* check whether irq stack is used */
+	_check_and_inc_int_nest_counter r0, r1
 
 	bne.d firq_nest
 	mov r0, sp
@@ -138,6 +139,7 @@ SECTION_FUNC(TEXT, _firq_exit)
 	sr r24, [_ARC_V2_LP_START]
 	sr r25, [_ARC_V2_LP_END]
 #endif
+	_dec_int_nest_counter r0, r1
 
 	_check_nest_int_by_irq_act r0, r1
 

arch/arc/core/fault_s.S

@@ -246,9 +246,9 @@ _do_non_syscall_trap:
 	st_s r0, [sp, ___isf_t_pc_OFFSET] /* eret into pc */
 
 
-	lr r0, [_ARC_V2_AUX_IRQ_ACT]
-	and r0, r0, 0xffff
-	cmp r0, 0
+	/* check whether irq stack is used */
+	_check_and_inc_int_nest_counter r0, r1
+
 	bne.d exc_nest_handle
 	mov r0, sp
 
@@ -260,6 +260,8 @@ exc_nest_handle:
 
 	pop sp
 
+	_dec_int_nest_counter r0, r1
+
 	lr  r0, [_ARC_V2_AUX_IRQ_ACT]
 	and r0, r0, 0xffff
 	cmp r0, 0

arch/arc/core/regular_irq.S

@@ -67,7 +67,8 @@ SECTION_FUNC(TEXT, _rirq_enter)
 #endif
 	clri
 
-	_check_nest_int_by_irq_act r0, r1
+	/* check whether irq stack is used */
+	_check_and_inc_int_nest_counter r0, r1
 
 	bne.d rirq_nest
 	mov r0, sp
@@ -92,6 +93,8 @@ SECTION_FUNC(TEXT, _rirq_exit)
 
 	pop sp
 
+	_dec_int_nest_counter r0, r1
+
 	_check_nest_int_by_irq_act r0, r1
 
 	jne _rirq_no_reschedule

arch/arc/include/swap_macros.h

@@ -294,6 +294,45 @@
 #endif /* CONFIG_ARC_SECURE_FIRMWARE */
 .endm
 
+/* check and increase the interrupt nest counter
+ * after increase, check whether nest counter == 1
+ * the result will be EQ bit of status32
+ */
+.macro _check_and_inc_int_nest_counter reg1 reg2
+#ifdef CONFIG_SMP
+	_get_cpu_id \reg1
+	ld.as \reg1, [@_curr_cpu, \reg1]
+	ld \reg2, [\reg1, ___cpu_t_nested_OFFSET]
+#else
+	mov \reg1, _kernel
+	ld \reg2, [\reg1, ___kernel_t_nested_OFFSET]
+#endif
+	add \reg2, \reg2, 1
+#ifdef CONFIG_SMP
+	st \reg2, [\reg1, ___cpu_t_nested_OFFSET]
+#else
+	st \reg2, [\reg1, ___kernel_t_nested_OFFSET]
+#endif
+	cmp \reg2, 1
+.endm
+
+/* decrease interrupt nest counter */
+.macro _dec_int_nest_counter reg1 reg2
+#ifdef CONFIG_SMP
+	_get_cpu_id \reg1
+	ld.as \reg1, [@_curr_cpu, \reg1]
+	ld \reg2, [\reg1, ___cpu_t_nested_OFFSET]
+#else
+	mov \reg1, _kernel
+	ld \reg2, [\reg1, ___kernel_t_nested_OFFSET]
+#endif
+	sub \reg2, \reg2, 1
+#ifdef CONFIG_SMP
+	st \reg2, [\reg1, ___cpu_t_nested_OFFSET]
+#else
+	st \reg2, [\reg1, ___kernel_t_nested_OFFSET]
+#endif
+.endm
 
 /* If multi bits in IRQ_ACT are set, i.e. last bit != fist bit, it's
  * in nest interrupt. The result will be EQ bit of status32