Re: [PATCH 2/2] kdump shutdown hook support

Index: clone3/arch/powerpc/kernel/crash.c
===================================================================

--- clone3.orig/arch/powerpc/kernel/crash.c
+++ clone3/arch/powerpc/kernel/crash.c

@@ -32,6 +32,8 @@
 #include <asm/lmb.h>
 #include <asm/firmware.h>
 #include <asm/smp.h>
+#include <asm/system.h>
+#include <asm/setjmp.h>
 
 #ifdef DEBUG
 #include <asm/udbg.h>

@@ -45,6 +47,11 @@ int crashing_cpu = -1;
 static cpumask_t cpus_in_crash = CPU_MASK_NONE;
 cpumask_t cpus_in_sr = CPU_MASK_NONE;
 
+#define CRASH_HANDLER_MAX 1
+/* NULL terminated list of shutdown handles */
+static crash_shutdown_t crash_shutdown_handles[CRASH_HANDLER_MAX+1];
+static DEFINE_SPINLOCK(crash_handers_lock);

 static atomic_t enter_on_soft_reset = ATOMIC_INIT(0);
 

@@ -285,9 +292,72 @@ static inline void crash_kexec_stop_spus
 }
 #endif /* CONFIG_SPU_BASE */
 
+/*
+ * Register a function to be called on shutdown.  Only use this if you
+ * can't reset your device in the second kernel.
+ */
+int crash_shutdown_register(crash_shutdown_t handler)
+{
+	unsigned int i, rc;
+
+	spin_lock(&crash_handers_lock);
+	for (i = 0 ; i < CRASH_HANDLER_MAX; i++)
+		if (!crash_shutdown_handles[i]) {
+			/* Insert handle at first empty entry */
+			crash_shutdown_handles[i] = handler;
+			rc = 0;
+			break;
+		}
+
+	if (i == CRASH_HANDLER_MAX) {
+		printk(KERN_ERR "Crash shutdown handles full, "
+		       "not registered.\n");
+		rc = 1;
+	}
+
+	spin_unlock(&crash_handers_lock);
+	return rc;
+}
+EXPORT_SYMBOL(crash_shutdown_register);
+
+int crash_shutdown_unregister(crash_shutdown_t handler)
+{
+	unsigned int i, rc;
+
+	spin_lock(&crash_handers_lock);
+	for (i = 0 ; i < CRASH_HANDLER_MAX; i++)
+		if (crash_shutdown_handles[i] == handler)
+			break;
+
+	if (i == CRASH_HANDLER_MAX) {
+		printk(KERN_ERR "Crash shutdown handle not found\n");
+		rc = 1;
+	} else {
+		/* Shift handles down */
+		for (; crash_shutdown_handles[i]; i++)
+			crash_shutdown_handles[i] =
+				crash_shutdown_handles[i+1];
+		rc = 0;
+	}
+
+	spin_unlock(&crash_handers_lock);
+	return rc;
+}
+EXPORT_SYMBOL(crash_shutdown_unregister);
+
+static unsigned long crash_shutdown_buf[SETJMP_BUF_LEN];
+
+static int handle_fault(struct pt_regs *regs)
+{
+	longjmp(crash_shutdown_buf, 1);
+	return 0;
+}
+
 void default_machine_crash_shutdown(struct pt_regs *regs)
 {
-	unsigned int irq;
+	unsigned int i;
+	int (*old_handler)(struct pt_regs *regs);
+
 
 	/*
 	 * This function is only called after the system

@@ -301,15 +371,37 @@ void default_machine_crash_shutdown(stru
 	 */
 	hard_irq_disable();
 
-	for_each_irq(irq) {
-		struct irq_desc *desc = irq_desc + irq;
+	for_each_irq(i) {
+		struct irq_desc *desc = irq_desc + i;
 
 		if (desc->status & IRQ_INPROGRESS)
-			desc->chip->eoi(irq);
+			desc->chip->eoi(i);
 
 		if (!(desc->status & IRQ_DISABLED))
-			desc->chip->disable(irq);
+			desc->chip->disable(i);
+	}
+
+	/*
+	 * Call registered shutdown routines savely.  Swap out
+	 * __debugger_fault_handler, and replace on exit.
+	 */
+	old_handler = __debugger_fault_handler;
+	__debugger_fault_handler = handle_fault;
+	for (i = 0; crash_shutdown_handles[i]; i++) {
+		if (setjmp(crash_shutdown_buf) == 0) {
+			/*
+			 * Insert syncs and delay to ensure
+			 * instructions in the dangerous region don't
+			 * leak away from this protected region.
+			 */
+			asm volatile("sync; isync");
+			/* dangerous region */
+			crash_shutdown_handles[i]();
+			asm volatile("sync; isync");
+			__delay(SETJMP_MACHINE_CHECK_DELAY);

+		}
 	}
+	__debugger_fault_handler = old_handler;
 
 	/*
 	 * Make a note of crashing cpu. Will be used in machine_kexec
Index: clone3/include/asm-powerpc/kexec.h
===================================================================

--- clone3.orig/include/asm-powerpc/kexec.h
+++ clone3/include/asm-powerpc/kexec.h

@@ -123,6 +123,9 @@ struct pt_regs;
 extern void default_machine_kexec(struct kimage *image);
 extern int default_machine_kexec_prepare(struct kimage *image);
 extern void default_machine_crash_shutdown(struct pt_regs *regs);
+typedef void (*crash_shutdown_t)(void);
+extern int crash_shutdown_register(crash_shutdown_t handler);
+extern int crash_shutdown_unregister(crash_shutdown_t handler);
 
 extern void machine_kexec_simple(struct kimage *image);
 extern void crash_kexec_secondary(struct pt_regs *regs);

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