[PATCH] Kdump: Export crash notes section address through sysfs

o Following patch exports kexec global variable "crash_notes" to user space
  through sysfs as kernel attribute in /sys/kernel.

Signed-off-by: Maneesh Soni <maneesh@in.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

5 files changed, 23 insertions, 5 deletions

diff --git a/arch/i386/kernel/crash.c b/arch/i386/kernel/crash.c
index 59b92d217464..3645ad7ac200 100644
--- a/arch/i386/kernel/crash.c
+++ b/arch/i386/kernel/crash.c
@@ -26,8 +26,6 @@
 #include <asm/apic.h>
 #include <mach_ipi.h>
 
-#define MAX_NOTE_BYTES 1024
-typedef u32 note_buf_t[MAX_NOTE_BYTES/4];
 
 note_buf_t crash_notes[NR_CPUS];
 
diff --git a/arch/x86_64/kernel/crash.c b/arch/x86_64/kernel/crash.c
index 7caf8a49d0cb..6183bcb85257 100644
--- a/arch/x86_64/kernel/crash.c
+++ b/arch/x86_64/kernel/crash.c
@@ -20,9 +20,6 @@
 #include <asm/nmi.h>
 #include <asm/hw_irq.h>
 
-#define MAX_NOTE_BYTES 1024
-typedef u32 note_buf_t[MAX_NOTE_BYTES/4];
-
 note_buf_t crash_notes[NR_CPUS];
 
 void machine_crash_shutdown(void)
diff --git a/include/asm-i386/kexec.h b/include/asm-i386/kexec.h
index a1599b55d62d..6ed2a03e37b3 100644
--- a/include/asm-i386/kexec.h
+++ b/include/asm-i386/kexec.h
@@ -25,4 +25,9 @@
 /* The native architecture */
 #define KEXEC_ARCH KEXEC_ARCH_386
 
+#define MAX_NOTE_BYTES 1024
+typedef u32 note_buf_t[MAX_NOTE_BYTES/4];
+
+extern note_buf_t crash_notes[];
+
 #endif /* _I386_KEXEC_H */
diff --git a/include/asm-x86_64/kexec.h b/include/asm-x86_64/kexec.h
index dc33646dc7dd..42d2ff15c592 100644
--- a/include/asm-x86_64/kexec.h
+++ b/include/asm-x86_64/kexec.h
@@ -25,4 +25,9 @@
 /* The native architecture */
 #define KEXEC_ARCH KEXEC_ARCH_X86_64
 
+#define MAX_NOTE_BYTES 1024
+typedef u32 note_buf_t[MAX_NOTE_BYTES/4];
+
+extern note_buf_t crash_notes[];
+
 #endif /* _X86_64_KEXEC_H */
diff --git a/kernel/ksysfs.c b/kernel/ksysfs.c
index 1f064a63f8cf..015fb69ad94d 100644
--- a/kernel/ksysfs.c
+++ b/kernel/ksysfs.c
@@ -30,6 +30,16 @@ static ssize_t hotplug_seqnum_show(struct subsystem *subsys, char *page)
 KERNEL_ATTR_RO(hotplug_seqnum);
 #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);
 
@@ -37,6 +47,9 @@ static struct attribute * kernel_attrs[] = {
 #ifdef CONFIG_HOTPLUG
         &hotplug_seqnum_attr.attr,
 #endif
+#ifdef CONFIG_KEXEC
+        &crash_notes_attr.attr,
+#endif
         NULL
 };