crash: split crash dumping code out from kexec_core.c

Currently, KEXEC_CORE select CRASH_CORE automatically because crash codes
need be built in to avoid compiling error when building kexec code even
though the crash dumping functionality is not enabled. E.g
--------------------
CONFIG_CRASH_CORE=y
CONFIG_KEXEC_CORE=y
CONFIG_KEXEC=y
CONFIG_KEXEC_FILE=y
---------------------

After splitting out crashkernel reservation code and vmcoreinfo exporting
code, there's only crash related code left in kernel/crash_core.c. Now
move crash related codes from kexec_core.c to crash_core.c and only build it
in when CONFIG_CRASH_DUMP=y.

And also wrap up crash codes inside CONFIG_CRASH_DUMP ifdeffery scope,
or replace inappropriate CONFIG_KEXEC_CORE ifdef with CONFIG_CRASH_DUMP
ifdef in generic kernel files.

With these changes, crash_core codes are abstracted from kexec codes and
can be disabled at all if only kexec reboot feature is wanted.

Link: https://lkml.kernel.org/r/20240124051254.67105-5-bhe@redhat.com
Signed-off-by: Baoquan He <bhe@redhat.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Eric W. Biederman <ebiederm@xmission.com>
Cc: Hari Bathini <hbathini@linux.ibm.com>
Cc: Pingfan Liu <piliu@redhat.com>
Cc: Klara Modin <klarasmodin@gmail.com>
Cc: Michael Kelley <mhklinux@outlook.com>
Cc: Nathan Chancellor <nathan@kernel.org>
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>

1 files changed, 10 insertions, 3 deletions

diff --git a/kernel/kexec_file.c b/kernel/kexec_file.c
index bef2f6f2571b..ce7ce2ae27cd 100644
--- a/kernel/kexec_file.c
+++ b/kernel/kexec_file.c
@@ -285,11 +285,13 @@ kimage_file_alloc_init(struct kimage **rimage, int kernel_fd,
 	kexec_file_dbg_print = !!(flags & KEXEC_FILE_DEBUG);
 	image->file_mode = 1;
 
+#ifdef CONFIG_CRASH_DUMP
 	if (kexec_on_panic) {
 		/* Enable special crash kernel control page alloc policy. */
 		image->control_page = crashk_res.start;
 		image->type = KEXEC_TYPE_CRASH;
 	}
+#endif
 
 	ret = kimage_file_prepare_segments(image, kernel_fd, initrd_fd,
 					   cmdline_ptr, cmdline_len, flags);
@@ -349,13 +351,14 @@ SYSCALL_DEFINE5(kexec_file_load, int, kernel_fd, int, initrd_fd,
 	if (!kexec_trylock())
 		return -EBUSY;
 
+#ifdef CONFIG_CRASH_DUMP
 	if (image_type == KEXEC_TYPE_CRASH) {
 		dest_image = &kexec_crash_image;
 		if (kexec_crash_image)
 			arch_kexec_unprotect_crashkres();
-	} else {
+	} else
+#endif
 		dest_image = &kexec_image;
-	}
 
 	if (flags & KEXEC_FILE_UNLOAD)
 		goto exchange;
@@ -419,8 +422,10 @@ SYSCALL_DEFINE5(kexec_file_load, int, kernel_fd, int, initrd_fd,
 exchange:
 	image = xchg(dest_image, image);
 out:
+#ifdef CONFIG_CRASH_DUMP
 	if ((flags & KEXEC_FILE_ON_CRASH) && kexec_crash_image)
 		arch_kexec_protect_crashkres();
+#endif
 
 	kexec_unlock();
 	kimage_free(image);
@@ -595,12 +600,14 @@ static int kexec_walk_memblock(struct kexec_buf *kbuf,
 static int kexec_walk_resources(struct kexec_buf *kbuf,
 				int (*func)(struct resource *, void *))
 {
+#ifdef CONFIG_CRASH_DUMP
 	if (kbuf->image->type == KEXEC_TYPE_CRASH)
 		return walk_iomem_res_desc(crashk_res.desc,
 					   IORESOURCE_SYSTEM_RAM | IORESOURCE_BUSY,
 					   crashk_res.start, crashk_res.end,
 					   kbuf, func);
-	else if (kbuf->top_down)
+#endif
+	if (kbuf->top_down)
 		return walk_system_ram_res_rev(0, ULONG_MAX, kbuf, func);
 	else
 		return walk_system_ram_res(0, ULONG_MAX, kbuf, func);