crash_core: move crashk_*res definition into crash_core.c

Both crashk_res and crashk_low_res are used to mark the reserved
crashkernel regions in iomem_resource tree.  And later the generic
crashkernel resrvation will be added into crash_core.c.  So move
crashk_res and crashk_low_res definition into crash_core.c to avoid
compiling error if CONFIG_CRASH_CORE=on while CONFIG_KEXEC_CORE is unset.

Meanwhile include <asm/crash_core.h> in <linux/crash_core.h> if generic
reservation is needed.  In that case, <asm/crash_core.h> need be added by
ARCH.  In asm/crash_core.h, ARCH can provide its own macro definitions to
override macros in <linux/crash_core.h> if needed.  Wrap the including
into CONFIG_ARCH_HAS_GENERIC_CRASHKERNEL_RESERVATION ifdeffery scope to
avoid compiling error in other ARCH-es which don't take the generic
reservation way yet.

Link: https://lkml.kernel.org/r/20230914033142.676708-6-bhe@redhat.comSigned-off-by: Baoquan He <bhe@redhat.com>
Reviewed-by: Zhen Lei <thunder.leizhen@huawei.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Chen Jiahao <chenjiahao16@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

include/linux/crash_core.h

@@ -5,6 +5,14 @@
 #include <linux/linkage.h>
 #include <linux/elfcore.h>
 #include <linux/elf.h>
+#ifdef CONFIG_ARCH_HAS_GENERIC_CRASHKERNEL_RESERVATION
+#include <asm/crash_core.h>
+#endif
+
+/* Location of a reserved region to hold the crash kernel.
+ */
+extern struct resource crashk_res;
+extern struct resource crashk_low_res;
 
 #define CRASH_CORE_NOTE_NAME	   "CORE"
 #define CRASH_CORE_NOTE_HEAD_BYTES ALIGN(sizeof(struct elf_note), 4)

include/linux/kexec.h

@@ -22,10 +22,6 @@
 #include <uapi/linux/kexec.h>
 #include <linux/verification.h>
 
-/* Location of a reserved region to hold the crash kernel.
- */
-extern struct resource crashk_res;
-extern struct resource crashk_low_res;
 extern note_buf_t __percpu *crash_notes;
 
 #ifdef CONFIG_KEXEC_CORE

kernel/crash_core.c

@@ -35,6 +35,22 @@ u32 *vmcoreinfo_note;
 /* trusted vmcoreinfo, e.g. we can make a copy in the crash memory */
 static unsigned char *vmcoreinfo_data_safecopy;
 
+/* Location of the reserved area for the crash kernel */
+struct resource crashk_res = {
+	.name  = "Crash kernel",
+	.start = 0,
+	.end   = 0,
+	.flags = IORESOURCE_BUSY | IORESOURCE_SYSTEM_RAM,
+	.desc  = IORES_DESC_CRASH_KERNEL
+};
+struct resource crashk_low_res = {
+	.name  = "Crash kernel",
+	.start = 0,
+	.end   = 0,
+	.flags = IORESOURCE_BUSY | IORESOURCE_SYSTEM_RAM,
+	.desc  = IORES_DESC_CRASH_KERNEL
+};
+
 /*
  * parsing the "crashkernel" commandline
  *

kernel/kexec_core.c

@@ -52,23 +52,6 @@ atomic_t __kexec_lock = ATOMIC_INIT(0);
 /* Flag to indicate we are going to kexec a new kernel */
 bool kexec_in_progress = false;
 
-
-/* Location of the reserved area for the crash kernel */
-struct resource crashk_res = {
-	.name  = "Crash kernel",
-	.start = 0,
-	.end   = 0,
-	.flags = IORESOURCE_BUSY | IORESOURCE_SYSTEM_RAM,
-	.desc  = IORES_DESC_CRASH_KERNEL
-};
-struct resource crashk_low_res = {
-	.name  = "Crash kernel",
-	.start = 0,
-	.end   = 0,
-	.flags = IORESOURCE_BUSY | IORESOURCE_SYSTEM_RAM,
-	.desc  = IORES_DESC_CRASH_KERNEL
-};
-
 int kexec_should_crash(struct task_struct *p)
 {
 	/*