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Diffstat (limited to 'drivers/base/cpu.c')
-rw-r--r--drivers/base/cpu.c30
1 files changed, 30 insertions, 0 deletions
diff --git a/drivers/base/cpu.c b/drivers/base/cpu.c
index 281d26784d2..07a7f97e1de 100644
--- a/drivers/base/cpu.c
+++ b/drivers/base/cpu.c
@@ -83,6 +83,31 @@ static inline void register_cpu_control(struct cpu *cpu)
}
#endif /* CONFIG_HOTPLUG_CPU */
+#ifdef CONFIG_KEXEC
+#include <linux/kexec.h>
+
+static ssize_t show_crash_notes(struct sys_device *dev, char *buf)
+{
+ struct cpu *cpu = container_of(dev, struct cpu, sysdev);
+ ssize_t rc;
+ unsigned long long addr;
+ int cpunum;
+
+ cpunum = cpu->sysdev.id;
+
+ /*
+ * Might be reading other cpu's data based on which cpu read thread
+ * has been scheduled. But cpu data (memory) is allocated once during
+ * boot up and this data does not change there after. Hence this
+ * operation should be safe. No locking required.
+ */
+ addr = __pa(per_cpu_ptr(crash_notes, cpunum));
+ rc = sprintf(buf, "%Lx\n", addr);
+ return rc;
+}
+static SYSDEV_ATTR(crash_notes, 0400, show_crash_notes, NULL);
+#endif
+
/*
* register_cpu - Setup a driverfs device for a CPU.
* @cpu - Callers can set the cpu->no_control field to 1, to indicate not to
@@ -108,6 +133,11 @@ int __devinit register_cpu(struct cpu *cpu, int num, struct node *root)
register_cpu_control(cpu);
if (!error)
cpu_sys_devices[num] = &cpu->sysdev;
+
+#ifdef CONFIG_KEXEC
+ if (!error)
+ error = sysdev_create_file(&cpu->sysdev, &attr_crash_notes);
+#endif
return error;
}