linux-kernel - [PATCH v2 2/4] kexec: add kexec_core flag to control debug printing

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Message-Id: <20251103063440.1681657-3-maqianga@uniontech.com>
Date: Mon,  3 Nov 2025 14:34:38 +0800
From: Qiang Ma <maqianga@...ontech.com>
To: akpm@...ux-foundation.org,
	bhe@...hat.com
Cc: kexec@...ts.infradead.org,
	linux-kernel@...r.kernel.org,
	Qiang Ma <maqianga@...ontech.com>
Subject: [PATCH v2 2/4] kexec: add kexec_core flag to control debug printing

The commit a85ee18c7900 ("kexec_file: print out debugging message
if required") has added general code printing in kexec_file_load(),
but not in kexec_load().

Since kexec_load and kexec_file_load are not triggered
simultaneously, we can unify the debug flag of kexec and kexec_file
as kexec_core_dbg_print.

Next, we need to do four things:

1. rename kexec_file_dbg_print to kexec_core_dbg_print
2. Add KEXEC_DEBUG
3. Initialize kexec_core_dbg_print for kexec
4. Set the reset of kexec_file_dbg_print to kimage_free

Signed-off-by: Qiang Ma <maqianga@...ontech.com>
---
 include/linux/kexec.h      | 9 +++++----
 include/uapi/linux/kexec.h | 1 +
 kernel/kexec.c             | 1 +
 kernel/kexec_core.c        | 4 +++-
 kernel/kexec_file.c        | 4 +---
 5 files changed, 11 insertions(+), 8 deletions(-)

diff --git a/include/linux/kexec.h b/include/linux/kexec.h
index ff7e231b0485..cad8b5c362af 100644
--- a/include/linux/kexec.h
+++ b/include/linux/kexec.h
@@ -455,10 +455,11 @@ bool kexec_load_permitted(int kexec_image_type);
 
 /* List of defined/legal kexec flags */
 #ifndef CONFIG_KEXEC_JUMP
-#define KEXEC_FLAGS    (KEXEC_ON_CRASH | KEXEC_UPDATE_ELFCOREHDR | KEXEC_CRASH_HOTPLUG_SUPPORT)
+#define KEXEC_FLAGS    (KEXEC_ON_CRASH | KEXEC_UPDATE_ELFCOREHDR | KEXEC_CRASH_HOTPLUG_SUPPORT | \
+			KEXEC_DEBUG)
 #else
 #define KEXEC_FLAGS    (KEXEC_ON_CRASH | KEXEC_PRESERVE_CONTEXT | KEXEC_UPDATE_ELFCOREHDR | \
-			KEXEC_CRASH_HOTPLUG_SUPPORT)
+			KEXEC_CRASH_HOTPLUG_SUPPORT | KEXEC_DEBUG)
 #endif
 
 /* List of defined/legal kexec file flags */
@@ -525,10 +526,10 @@ static inline int arch_kexec_post_alloc_pages(void *vaddr, unsigned int pages, g
 static inline void arch_kexec_pre_free_pages(void *vaddr, unsigned int pages) { }
 #endif
 
-extern bool kexec_file_dbg_print;
+extern bool kexec_core_dbg_print;
 
 #define kexec_dprintk(fmt, arg...) \
-        do { if (kexec_file_dbg_print) pr_info(fmt, ##arg); } while (0)
+	do { if (kexec_core_dbg_print) pr_info(fmt, ##arg); } while (0)
 
 extern void *kimage_map_segment(struct kimage *image, unsigned long addr, unsigned long size);
 extern void kimage_unmap_segment(void *buffer);
diff --git a/include/uapi/linux/kexec.h b/include/uapi/linux/kexec.h
index 55749cb0b81d..819c600af125 100644
--- a/include/uapi/linux/kexec.h
+++ b/include/uapi/linux/kexec.h
@@ -14,6 +14,7 @@
 #define KEXEC_PRESERVE_CONTEXT	0x00000002
 #define KEXEC_UPDATE_ELFCOREHDR	0x00000004
 #define KEXEC_CRASH_HOTPLUG_SUPPORT 0x00000008
+#define KEXEC_DEBUG		0x00000010
 #define KEXEC_ARCH_MASK		0xffff0000
 
 /*
diff --git a/kernel/kexec.c b/kernel/kexec.c
index 9bb1f2b6b268..c7a869d32f87 100644
--- a/kernel/kexec.c
+++ b/kernel/kexec.c
@@ -42,6 +42,7 @@ static int kimage_alloc_init(struct kimage **rimage, unsigned long entry,
 	if (!image)
 		return -ENOMEM;
 
+	kexec_core_dbg_print = !!(flags & KEXEC_DEBUG);
 	image->start = entry;
 	image->nr_segments = nr_segments;
 	memcpy(image->segment, segments, nr_segments * sizeof(*segments));
diff --git a/kernel/kexec_core.c b/kernel/kexec_core.c
index fa00b239c5d9..865f2b14f23b 100644
--- a/kernel/kexec_core.c
+++ b/kernel/kexec_core.c
@@ -53,7 +53,7 @@ atomic_t __kexec_lock = ATOMIC_INIT(0);
 /* Flag to indicate we are going to kexec a new kernel */
 bool kexec_in_progress = false;
 
-bool kexec_file_dbg_print;
+bool kexec_core_dbg_print;
 
 /*
  * When kexec transitions to the new kernel there is a one-to-one
@@ -576,6 +576,8 @@ void kimage_free(struct kimage *image)
 	kimage_entry_t *ptr, entry;
 	kimage_entry_t ind = 0;
 
+	kexec_core_dbg_print = false;
+
 	if (!image)
 		return;
 
diff --git a/kernel/kexec_file.c b/kernel/kexec_file.c
index eb62a9794242..4a24aadbad02 100644
--- a/kernel/kexec_file.c
+++ b/kernel/kexec_file.c
@@ -138,8 +138,6 @@ void kimage_file_post_load_cleanup(struct kimage *image)
 	 */
 	kfree(image->image_loader_data);
 	image->image_loader_data = NULL;
-
-	kexec_file_dbg_print = false;
 }
 
 #ifdef CONFIG_KEXEC_SIG
@@ -314,7 +312,7 @@ kimage_file_alloc_init(struct kimage **rimage, int kernel_fd,
 	if (!image)
 		return -ENOMEM;
 
-	kexec_file_dbg_print = !!(flags & KEXEC_FILE_DEBUG);
+	kexec_core_dbg_print = !!(flags & KEXEC_FILE_DEBUG);
 	image->file_mode = 1;
 
 #ifdef CONFIG_CRASH_DUMP
-- 
2.20.1