[PATCH 1/2] arm64: traps: Support for registering SError hooks

[Mikko Perttunen]

Add the ability for drivers to register SError hooks to be run
on a fatal SError interrupt. This allows printing of system-specific
error information to aid with debugging.

Signed-off-by: Mikko Perttunen <mperttunen at nvidia.com>
---
 arch/arm64/include/asm/traps.h |  6 ++++++
 arch/arm64/kernel/traps.c      | 20 ++++++++++++++++++++
 2 files changed, 26 insertions(+)

diff --git a/arch/arm64/include/asm/traps.h b/arch/arm64/include/asm/traps.h
index 54f32a0675df..054fecfa22f0 100644
--- a/arch/arm64/include/asm/traps.h
+++ b/arch/arm64/include/asm/traps.h
@@ -22,8 +22,14 @@ struct undef_hook {
 	int (*fn)(struct pt_regs *regs, u32 instr);
 };
 
+struct serror_hook {
+	struct list_head node;
+	void (*fn)(void);
+};
+
 void register_undef_hook(struct undef_hook *hook);
 void unregister_undef_hook(struct undef_hook *hook);
+void register_serror_hook(struct serror_hook *hook);
 void force_signal_inject(int signal, int code, unsigned long address, unsigned int err);
 void arm64_notify_segfault(unsigned long addr);
 void arm64_force_sig_fault(int signo, int code, unsigned long far, const char *str);
diff --git a/arch/arm64/kernel/traps.c b/arch/arm64/kernel/traps.c
index 273066279bb5..02dbaab71ea3 100644
--- a/arch/arm64/kernel/traps.c
+++ b/arch/arm64/kernel/traps.c
@@ -890,8 +890,23 @@ void panic_bad_stack(struct pt_regs *regs, unsigned int esr, unsigned long far)
 }
 #endif
 
+static LIST_HEAD(serror_hook);
+static DEFINE_RAW_SPINLOCK(serror_lock);
+
+void register_serror_hook(struct serror_hook *hook)
+{
+	unsigned long flags;
+
+	raw_spin_lock_irqsave(&serror_lock, flags);
+	list_add(&hook->node, &serror_hook);
+	raw_spin_unlock_irqrestore(&serror_lock, flags);
+}
+
 void __noreturn arm64_serror_panic(struct pt_regs *regs, u32 esr)
 {
+	struct serror_hook *hook;
+	unsigned long flags;
+
 	console_verbose();
 
 	pr_crit("SError Interrupt on CPU%d, code 0x%08x -- %s\n",
@@ -899,6 +914,11 @@ void __noreturn arm64_serror_panic(struct pt_regs *regs, u32 esr)
 	if (regs)
 		__show_regs(regs);
 
+	raw_spin_lock_irqsave(&serror_lock, flags);
+	list_for_each_entry(hook, &serror_hook, node)
+		hook->fn();
+	raw_spin_unlock_irqrestore(&serror_lock, flags);
+
 	nmi_panic(regs, "Asynchronous SError Interrupt");
 
 	cpu_park_loop();
-- 
2.30.1