arch, crash: move arch_crash_save_vmcoreinfo() out to file vmcore_info.c

Nathan reported below building error:

=====
$ curl -LSso .config https://git.alpinelinux.org/aports/plain/community/linux-edge/config-edge.armv7
$ make -skj"$(nproc)" ARCH=arm CROSS_COMPILE=arm-linux-gnueabi- olddefconfig all
..
arm-linux-gnueabi-ld: arch/arm/kernel/machine_kexec.o: in function `arch_crash_save_vmcoreinfo':
machine_kexec.c:(.text+0x488): undefined reference to `vmcoreinfo_append_str'
====

On architecutres, like arm, s390, ppc, sh, function
arch_crash_save_vmcoreinfo() is located in machine_kexec.c and it can
only be compiled in when CONFIG_KEXEC_CORE=y.

That's not right because arch_crash_save_vmcoreinfo() is used to export
arch specific vmcoreinfo. CONFIG_VMCORE_INFO is supposed to control its
compiling in. However, CONFIG_VMVCORE_INFO could be independent of
CONFIG_KEXEC_CORE, e.g CONFIG_PROC_KCORE=y will select CONFIG_VMVCORE_INFO.
Or CONFIG_KEXEC/CONFIG_KEXEC_FILE is set while CONFIG_CRASH_DUMP is
not set, it will report linking error.

So, on arm, s390, ppc and sh, move arch_crash_save_vmcoreinfo out to
a new file vmcore_info.c. Let CONFIG_VMCORE_INFO decide if compiling in
arch_crash_save_vmcoreinfo().

[akpm@linux-foundation.org: remove stray newlines at eof]
Link: https://lkml.kernel.org/r/20240129135033.157195-3-bhe@redhat.com
Signed-off-by: Baoquan He <bhe@redhat.com>
Reported-by: Nathan Chancellor <nathan@kernel.org>
Closes: https://lore.kernel.org/all/20240126045551.GA126645@dev-arch.thelio-3990X/T/#u
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Eric W. Biederman <ebiederm@xmission.com>
Cc: Hari Bathini <hbathini@linux.ibm.com>
Cc: Klara Modin <klarasmodin@gmail.com>
Cc: Michael Kelley <mhklinux@outlook.com>
Cc: Pingfan Liu <piliu@redhat.com>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Cc: Yang Li <yang.lee@linux.alibaba.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

3 files changed, 22 insertions, 15 deletions

diff --git a/arch/s390/kernel/Makefile b/arch/s390/kernel/Makefile
index 7a562b4199c8..fa029d0dc28f 100644
--- a/arch/s390/kernel/Makefile
+++ b/arch/s390/kernel/Makefile
@@ -64,6 +64,7 @@ obj-$(CONFIG_FUNCTION_TRACER)	+= ftrace.o
 obj-$(CONFIG_FUNCTION_TRACER)	+= mcount.o
 obj-$(CONFIG_CRASH_DUMP)	+= crash_dump.o
 obj-$(CONFIG_KEXEC_CORE)	+= machine_kexec.o relocate_kernel.o
+obj-$(CONFIG_VMCORE_INFO)	+= vmcore_info.o
 obj-$(CONFIG_UPROBES)		+= uprobes.o
 obj-$(CONFIG_JUMP_LABEL)	+= jump_label.o
 
diff --git a/arch/s390/kernel/machine_kexec.c b/arch/s390/kernel/machine_kexec.c
index aa22ffc16bcd..10277a460204 100644
--- a/arch/s390/kernel/machine_kexec.c
+++ b/arch/s390/kernel/machine_kexec.c
@@ -209,21 +209,6 @@ void machine_kexec_cleanup(struct kimage *image)
 {
 }
 
-void arch_crash_save_vmcoreinfo(void)
-{
-	struct lowcore *abs_lc;
-
-	VMCOREINFO_SYMBOL(lowcore_ptr);
-	VMCOREINFO_SYMBOL(high_memory);
-	VMCOREINFO_LENGTH(lowcore_ptr, NR_CPUS);
-	vmcoreinfo_append_str("SAMODE31=%lx\n", (unsigned long)__samode31);
-	vmcoreinfo_append_str("EAMODE31=%lx\n", (unsigned long)__eamode31);
-	vmcoreinfo_append_str("KERNELOFFSET=%lx\n", kaslr_offset());
-	abs_lc = get_abs_lowcore();
-	abs_lc->vmcore_info = paddr_vmcoreinfo_note();
-	put_abs_lowcore(abs_lc);
-}
-
 void machine_shutdown(void)
 {
 }
diff --git a/arch/s390/kernel/vmcore_info.c b/arch/s390/kernel/vmcore_info.c
new file mode 100644
index 000000000000..d296dfc22191
--- /dev/null
+++ b/arch/s390/kernel/vmcore_info.c
@@ -0,0 +1,21 @@
+// SPDX-License-Identifier: GPL-2.0-only
+
+#include <linux/vmcore_info.h>
+#include <asm/abs_lowcore.h>
+#include <linux/mm.h>
+#include <asm/setup.h>
+
+void arch_crash_save_vmcoreinfo(void)
+{
+	struct lowcore *abs_lc;
+
+	VMCOREINFO_SYMBOL(lowcore_ptr);
+	VMCOREINFO_SYMBOL(high_memory);
+	VMCOREINFO_LENGTH(lowcore_ptr, NR_CPUS);
+	vmcoreinfo_append_str("SAMODE31=%lx\n", (unsigned long)__samode31);
+	vmcoreinfo_append_str("EAMODE31=%lx\n", (unsigned long)__eamode31);
+	vmcoreinfo_append_str("KERNELOFFSET=%lx\n", kaslr_offset());
+	abs_lc = get_abs_lowcore();
+	abs_lc->vmcore_info = paddr_vmcoreinfo_note();
+	put_abs_lowcore(abs_lc);
+}