kexec: add a kexec_crash_loaded() function

Provide a wrapper function to be used by kernel code to check whether a
crash kernel is loaded.  It returns the same value that can be seen in
/sys/kernel/kexec_crash_loaded by userspace programs.

I'm exporting the function, because it will be used by Xen, and it is
possible to compile Xen modules separately to enable the use of PV
drivers with unmodified bare-metal kernels.

Link: http://lkml.kernel.org/r/20160713121955.14969.69080.stgit@hananiah.suse.cz
Signed-off-by: Petr Tesarik <ptesarik@suse.com>
Cc: Juergen Gross <jgross@suse.com>
Cc: Josh Triplett <josh@joshtriplett.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Eric Biederman <ebiederm@xmission.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Cc: Dave Young <dyoung@redhat.com>
Cc: David Vrabel <david.vrabel@citrix.com>
Cc: Vivek Goyal <vgoyal@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/include/linux/kexec.h b/include/linux/kexec.h
index 23e14a460cfb24d2d44929f9dca9897d0de8dc25..d7437777baaafe382458df9115b005f764a064f5 100644 (file)
--- a/include/linux/kexec.h
+++ b/include/linux/kexec.h
@@ -230,6 +230,7 @@ extern void *kexec_purgatory_get_symbol_addr(struct kimage *image,
 extern void __crash_kexec(struct pt_regs *);
 extern void crash_kexec(struct pt_regs *);
 int kexec_should_crash(struct task_struct *);
+int kexec_crash_loaded(void);
 void crash_save_cpu(struct pt_regs *regs, int cpu);
 void crash_save_vmcoreinfo(void);
 void arch_crash_save_vmcoreinfo(void);
@@ -364,6 +365,7 @@ struct task_struct;
 static inline void __crash_kexec(struct pt_regs *regs) { }
 static inline void crash_kexec(struct pt_regs *regs) { }
 static inline int kexec_should_crash(struct task_struct *p) { return 0; }
+static inline int kexec_crash_loaded(void) { return 0; }
 #define kexec_in_progress false
 #endif /* CONFIG_KEXEC_CORE */
 

diff --git a/kernel/kexec_core.c b/kernel/kexec_core.c
index 73d4c5f57dd8acff1fcef3c2f5cc6897792181b4..704534029a003e1edbab3e12887bb7a35e59e6ee 100644 (file)
--- a/kernel/kexec_core.c
+++ b/kernel/kexec_core.c
@@ -95,6 +95,12 @@ int kexec_should_crash(struct task_struct *p)
        return 0;
 }
 
+int kexec_crash_loaded(void)
+{
+       return !!kexec_crash_image;
+}
+EXPORT_SYMBOL_GPL(kexec_crash_loaded);
+
 /*
  * When kexec transitions to the new kernel there is a one-to-one
  * mapping between physical and virtual addresses.  On processors

diff --git a/kernel/ksysfs.c b/kernel/ksysfs.c
index 9f1920d2d0c6dfaa285039b02edcf9db2af3352f..ee1bc1bb8feb82f4873eb38106805c2823bed7b2 100644 (file)
--- a/kernel/ksysfs.c
+++ b/kernel/ksysfs.c
@@ -101,7 +101,7 @@ KERNEL_ATTR_RO(kexec_loaded);
 static ssize_t kexec_crash_loaded_show(struct kobject *kobj,
                                       struct kobj_attribute *attr, char *buf)
 {
-       return sprintf(buf, "%d\n", !!kexec_crash_image);
+       return sprintf(buf, "%d\n", kexec_crash_loaded());
 }
 KERNEL_ATTR_RO(kexec_crash_loaded);