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authorVivek Goyal <vgoyal@in.ibm.com>2006-01-09 20:51:42 -0800
committerLinus Torvalds <torvalds@g5.osdl.org>2006-01-10 08:01:26 -0800
commit51be5606d9ff9eb27ed6514f6172fbd7578a25d6 (patch)
tree8020841fc1eb4fa4603870913385eb9253de7d2e
parentcc57165874e938ef684d71ba7d36e7088b551489 (diff)
[PATCH] kdump: export per cpu crash notes pointer through sysfs
- Kexec on panic functionality allocates memory for saving cpu registers in case of system crash event. Address of this allocated memory needs to be exported to user space, which is used by kexec-tools. - Previously, a single /sys/kernel/crash_notes entry was being exported as memory allocated was a single continuous array. Now memory allocation being dyanmic and per cpu based, address of per cpu buffer is exported through "/sys/devices/system/cpu/cpuX/crash_notes" Signed-off-by: Vivek Goyal <vgoyal@in.ibm.com> Cc: Greg KH <greg@kroah.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
-rw-r--r--drivers/base/cpu.c32
-rw-r--r--kernel/ksysfs.c13
2 files changed, 32 insertions, 13 deletions
diff --git a/drivers/base/cpu.c b/drivers/base/cpu.c
index 281d26784d2..982e6583cd6 100644
--- a/drivers/base/cpu.c
+++ b/drivers/base/cpu.c
@@ -83,6 +83,33 @@ 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.
+ */
+ get_cpu();
+ addr = __pa(per_cpu_ptr(crash_notes, cpunum));
+ rc = sprintf(buf, "%Lx\n", addr);
+ put_cpu();
+ 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 +135,11 @@ 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;
}
diff --git a/kernel/ksysfs.c b/kernel/ksysfs.c
index 99af8b05eea..d5eeae0fa5b 100644
--- a/kernel/ksysfs.c
+++ b/kernel/ksysfs.c
@@ -51,16 +51,6 @@ static ssize_t uevent_helper_store(struct subsystem *subsys, const char *page, s
KERNEL_ATTR_RW(uevent_helper);
#endif
-#ifdef CONFIG_KEXEC
-#include <asm/kexec.h>
-
-static ssize_t crash_notes_show(struct subsystem *subsys, char *page)
-{
- return sprintf(page, "%p\n", (void *)crash_notes);
-}
-KERNEL_ATTR_RO(crash_notes);
-#endif
-
decl_subsys(kernel, NULL, NULL);
EXPORT_SYMBOL_GPL(kernel_subsys);
@@ -69,9 +59,6 @@ static struct attribute * kernel_attrs[] = {
&uevent_seqnum_attr.attr,
&uevent_helper_attr.attr,
#endif
-#ifdef CONFIG_KEXEC
- &crash_notes_attr.attr,
-#endif
NULL
};