[PATCH] arm64: panic on synchronous external abort in kernel context

[Xie XiuQi]

We should panic even panic_on_oops is not set, when we can't recover
from synchronous external abort in kernel context.

Othervise, there are two issues:
1) fallback to do_exit() in exception context, cause this core hung up.
   do_sea()
   -> arm64_notify_die
      -> die
         -> do_exit
2) errors may propagated.

Signed-off-by: Xie XiuQi <xiexiuqi@xxxxxxxxxx>
Cc: Xiaofei Tan <tanxiaofei@xxxxxxxxxx>
---
 arch/arm64/include/asm/esr.h | 12 ++++++++++++
 arch/arm64/kernel/traps.c    |  2 ++
 2 files changed, 14 insertions(+)

diff --git a/arch/arm64/include/asm/esr.h b/arch/arm64/include/asm/esr.h
index cb29253ae86b..acfc71c6d148 100644
--- a/arch/arm64/include/asm/esr.h
+++ b/arch/arm64/include/asm/esr.h
@@ -326,6 +326,18 @@ static inline bool esr_is_data_abort(u32 esr)
 	return ec == ESR_ELx_EC_DABT_LOW || ec == ESR_ELx_EC_DABT_CUR;
 }
 
+static inline bool esr_is_inst_abort(u32 esr)
+{
+	const u32 ec = ESR_ELx_EC(esr);
+
+	return ec == ESR_ELx_EC_IABT_LOW || ec == ESR_ELx_EC_IABT_CUR;
+}
+
+static inline bool esr_is_ext_abort(u32 esr)
+{
+	return esr_is_data_abort(esr) || esr_is_inst_abort(esr);
+}
+
 const char *esr_get_class_string(u32 esr);
 #endif /* __ASSEMBLY */
 
diff --git a/arch/arm64/kernel/traps.c b/arch/arm64/kernel/traps.c
index cf402be5c573..08f7f7688d5b 100644
--- a/arch/arm64/kernel/traps.c
+++ b/arch/arm64/kernel/traps.c
@@ -202,6 +202,8 @@ void die(const char *str, struct pt_regs *regs, int err)
 		panic("Fatal exception in interrupt");
 	if (panic_on_oops)
 		panic("Fatal exception");
+	if (esr_is_ext_abort(err))
+		panic("Synchronous external abort in kernel context");
 
 	raw_spin_unlock_irqrestore(&die_lock, flags);
 
-- 
2.20.1