[PATCH v3 2/3] kexec: add kexec flag to control debug printing

Qiang Ma
2025-11-26T08:46:21Z

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_dbg_print.

Next, we need to do four things:

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

Signed-off-by: Qiang Ma <maqianga@uniontech.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..23f10aec0b34 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_dbg_print;

#define kexec_dprintk(fmt, arg...) \
- do { if (kexec_file_dbg_print) pr_info(fmt, ##arg); } while (0)
+ do { if (kexec_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..f6c58c767eb0 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_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..7bc1cd4105fc 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_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_dbg_print = false;
+
if (!image)
return;

diff --git a/kernel/kexec_file.c b/kernel/kexec_file.c
index eb62a9794242..3f1d6c4e8ff2 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_dbg_print = !!(flags & KEXEC_FILE_DEBUG);
image->file_mode = 1;

#ifdef CONFIG_CRASH_DUMP
--
2.20.1