[PATCH v2 03/14] crash: remove dependency of FA_DUMP on CRASH_DUMP

[Baoquan He <bhe@redhat.com>]

In kdump kernel, /proc/vmcore is an elf file mapping the crashed kernel's
old memory content. Its elf header is constructed in 1st kernel and passed
to kdump kernel via elfcorehdr_addr. Config CRASH_DUMP enables the code
of 1st kernel's old memory accessing in different architectures.

Currently, config FA_DUMP has dependency on CRASH_DUMP because fadump
needs access global variable 'elfcorehdr_addr' to judge if it's in
kdump kernel within function is_kdump_kernel(). In the current
kernel/crash_dump.c, variable 'elfcorehdr_addr' is defined, and function
setup_elfcorehdr() used to parse kernel parameter to fetch the passed
value of elfcorehdr_addr. Only for accessing elfcorehdr_addr, FA_DUMP
really doesn't have to depends on CRASH_DUMP.

To remove the dependency of FA_DUMP on CRASH_DUMP to avoid confusion,
rename kernel/crash_dump.c to kernel/elfcorehdr.c, and build it when
CONFIG_VMCORE_INFO is ebabled. With this, FA_DUMP doesn't need to depend
on CRASH_DUMP.

Signed-off-by: Baoquan He <bhe@redhat.com>
---
 arch/powerpc/Kconfig                  | 1 -
 kernel/Makefile                       | 3 +--
 kernel/{crash_dump.c => elfcorehdr.c} | 0
 kernel/kexec_internal.h               | 2 ++
 4 files changed, 3 insertions(+), 3 deletions(-)
 rename kernel/{crash_dump.c => elfcorehdr.c} (100%)

diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
index 1520146d7c2c..1cdb8fdd3735 100644
--- a/arch/powerpc/Kconfig
+++ b/arch/powerpc/Kconfig
@@ -692,7 +692,6 @@ config FA_DUMP
 	depends on PPC64 && (PPC_RTAS || PPC_POWERNV)
 	select VMCORE_INFO
 	select CRASH_RESERVE
-	select CRASH_DUMP
 	help
 	  A robust mechanism to get reliable kernel crash dump with
 	  assistance from firmware. This approach does not use kexec,
diff --git a/kernel/Makefile b/kernel/Makefile
index 649272a1d6b9..35abc65e1f1a 100644
--- a/kernel/Makefile
+++ b/kernel/Makefile
@@ -68,7 +68,7 @@ obj-$(CONFIG_MODULE_SIG_FORMAT) += module_signature.o
 obj-$(CONFIG_KALLSYMS) += kallsyms.o
 obj-$(CONFIG_KALLSYMS_SELFTEST) += kallsyms_selftest.o
 obj-$(CONFIG_BSD_PROCESS_ACCT) += acct.o
-obj-$(CONFIG_VMCORE_INFO) += vmcore_info.o
+obj-$(CONFIG_VMCORE_INFO) += vmcore_info.o elfcorehdr.o
 obj-$(CONFIG_CRASH_RESERVE) += crash_reserve.o
 obj-$(CONFIG_KEXEC_CORE) += kexec_core.o crash_core.o
 obj-$(CONFIG_KEXEC) += kexec.o
@@ -121,7 +121,6 @@ obj-$(CONFIG_PERF_EVENTS) += events/
 
 obj-$(CONFIG_USER_RETURN_NOTIFIER) += user-return-notifier.o
 obj-$(CONFIG_PADATA) += padata.o
-obj-$(CONFIG_CRASH_DUMP) += crash_dump.o
 obj-$(CONFIG_JUMP_LABEL) += jump_label.o
 obj-$(CONFIG_CONTEXT_TRACKING) += context_tracking.o
 obj-$(CONFIG_TORTURE_TEST) += torture.o
diff --git a/kernel/crash_dump.c b/kernel/elfcorehdr.c
similarity index 100%
rename from kernel/crash_dump.c
rename to kernel/elfcorehdr.c
diff --git a/kernel/kexec_internal.h b/kernel/kexec_internal.h
index 74da1409cd14..2595defe8c0d 100644
--- a/kernel/kexec_internal.h
+++ b/kernel/kexec_internal.h
@@ -4,6 +4,8 @@
 
 #include <linux/kexec.h>
 
+struct kexec_segment;
+
 struct kimage *do_kimage_alloc_init(void);
 int sanity_check_segment_list(struct kimage *image);
 void kimage_free_page_list(struct list_head *list);
-- 
2.41.0