ARCv2: Enable LOCKDEP

- The asm helpers for calling into irq tracer were missing

- Add calls to above helpers in low level assembly entry code for ARCv2

- irq_save() uses CLRI to disable interrupts and returns the prev interrupt
state (in STATUS32) in a specific encoding (and not the raw value of
STATUS32). This is usable with SETI in irq_restore(). However
save_flags() reads the raw value of STATUS32 which doesn't pair with
irq_save/restore() and thus needs fixing.

Signed-off-by: Evgeny Voevodin <[e-mail]>
[vgupta: updated changelog and also added some comments]
Signed-off-by: Vineet Gupta <[e-mail]>

arch/arc/include/asm/irqflags-arcv2.h

···
 #define STATUS_AD_MASK		(1<<STATUS_AD_BIT)
 #define STATUS_IE_MASK		(1<<STATUS_IE_BIT)
 
+/* status32 Bits as encoded/expected by CLRI/SETI */
+#define CLRI_STATUS_IE_BIT	4
+
+#define CLRI_STATUS_E_MASK	0xF
+#define CLRI_STATUS_IE_MASK	(1 << CLRI_STATUS_IE_BIT)
+
 #define AUX_USER_SP		0x00D
 #define AUX_IRQ_CTRL		0x00E
 #define AUX_IRQ_ACT		0x043	/* Active Intr across all levels */
···
 	:
 	: "memory");
 
+	/* To be compatible with irq_save()/irq_restore()
+	 * encode the irq bits as expected by CLRI/SETI
+	 * (this was needed to make CONFIG_TRACE_IRQFLAGS work)
+	 */
+	temp = (1 << 5) |
+		((!!(temp & STATUS_IE_MASK)) << CLRI_STATUS_IE_BIT) |
+		(temp & CLRI_STATUS_E_MASK);
 	return temp;
 }
 
···
  */
 static inline int arch_irqs_disabled_flags(unsigned long flags)
 {
-	return !(flags & (STATUS_IE_MASK));
+	return !(flags & CLRI_STATUS_IE_MASK);
 }
 
 static inline int arch_irqs_disabled(void)
···
 
 #else
 
+#ifdef CONFIG_TRACE_IRQFLAGS
+
+.macro TRACE_ASM_IRQ_DISABLE
+	bl	trace_hardirqs_off
+.endm
+
+.macro TRACE_ASM_IRQ_ENABLE
+	bl	trace_hardirqs_on
+.endm
+
+#else
+
+.macro TRACE_ASM_IRQ_DISABLE
+.endm
+
+.macro TRACE_ASM_IRQ_ENABLE
+.endm
+
+#endif
 .macro IRQ_DISABLE  scratch
 	clri
+	TRACE_ASM_IRQ_DISABLE
 .endm
 
 .macro IRQ_ENABLE  scratch
+	TRACE_ASM_IRQ_ENABLE
 	seti
 .endm
 

arch/arc/kernel/entry-arcv2.S

···
 
 	clri		; To make status32.IE agree with CPU internal state
 
-	lr  r0, [ICAUSE]
+#ifdef CONFIG_TRACE_IRQFLAGS
+	TRACE_ASM_IRQ_DISABLE
+#endif
 
+	lr  r0, [ICAUSE]
 	mov   blink, ret_from_exception
 
 	b.d  arch_do_IRQ
···
 ; All 2 entry points to here already disable interrupts
 
 .Lrestore_regs:
+
+	# Interrpts are actually disabled from this point on, but will get
+	# reenabled after we return from interrupt/exception.
+	# But irq tracer needs to be told now...
+	TRACE_ASM_IRQ_ENABLE
 
 	ld	r0, [sp, PT_status32]	; U/K mode at time of entry
 	lr	r10, [AUX_IRQ_ACT]

arch/arc/kernel/entry-compact.S

···
 
 .Lrestore_regs:
 
+	# Interrpts are actually disabled from this point on, but will get
+	# reenabled after we return from interrupt/exception.
+	# But irq tracer needs to be told now...
 	TRACE_ASM_IRQ_ENABLE
 
 	lr	r10, [status32]