ARM: 8422/1: enable imprecise aborts during early kernel startup

This patch adds imprecise abort enable/disable macros and uses them to
enable imprecise aborts early when starting the kernel.

This helps in tracking down the real cause for such imprecise abort, as
they are handled as soon as they occur. Until now those aborts would
only be enabled when entering the userspace and as a consequence crash
the first userspace process if any abort had been raised during kernel
startup.
Signed-off-by: NFabrice Gasnier <fabrice.gasnier@st.com>
Signed-off-by: NLucas Stach <l.stach@pengutronix.de>
Signed-off-by: NRussell King <rmk+kernel@arm.linux.org.uk>

arch/arm/include/asm/irqflags.h

@@ -54,6 +54,14 @@ static inline void arch_local_irq_disable(void)
 
 #define local_fiq_enable()  __asm__("cpsie f	@ __stf" : : : "memory", "cc")
 #define local_fiq_disable() __asm__("cpsid f	@ __clf" : : : "memory", "cc")
+
+#ifndef CONFIG_CPU_V7M
+#define local_abt_enable()  __asm__("cpsie a	@ __sta" : : : "memory", "cc")
+#define local_abt_disable() __asm__("cpsid a	@ __cla" : : : "memory", "cc")
+#else
+#define local_abt_enable()	do { } while (0)
+#define local_abt_disable()	do { } while (0)
+#endif
 #else
 
 /*
@@ -136,6 +144,8 @@ static inline void arch_local_irq_disable(void)
 	: "memory", "cc");					\
 	})
 
+#define local_abt_enable()	do { } while (0)
+#define local_abt_disable()	do { } while (0)
 #endif
 
 /*

arch/arm/kernel/smp.c

@@ -400,6 +400,7 @@ asmlinkage void secondary_start_kernel(void)
 
 	local_irq_enable();
 	local_fiq_enable();
+	local_abt_enable();
 
 	/*
 	 * OK, it's off to the idle thread for us

arch/arm/mm/mmu.c

@@ -1363,6 +1363,9 @@ static void __init devicemaps_init(const struct machine_desc *mdesc)
 	 */
 	local_flush_tlb_all();
 	flush_cache_all();
+
+	/* Enable asynchronous aborts */
+	local_abt_enable();
 }
 
 static void __init kmap_init(void)