[PATCH 1/3] kexec: Add debug printing of kimage table entries

[Geert Uytterhoeven]

Print a list of pages to be copied if debugging is enabled.
Consecutive entries are merged to reduce screen clutter.

Signed-off-by: Geert Uytterhoeven <geert@xxxxxxxxxxxxxx>
Cc: Eric Biederman <ebiederm@xxxxxxxxxxxx>
---
 kernel/kexec.c |   76 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 76 insertions(+)

diff --git a/kernel/kexec.c b/kernel/kexec.c
index 490afc03627e..e25022ac229e 100644
--- a/kernel/kexec.c
+++ b/kernel/kexec.c
@@ -1073,6 +1073,80 @@ asmlinkage long compat_sys_kexec_load(unsigned long entry,
 }
 #endif
 
+#ifdef DEBUG
+struct kimage_block {
+	unsigned long dst, src, len;
+};
+
+static void kimage_print_block(const struct kimage_block *block)
+{
+	pr_info("Copy from 0x%lx-0x%lx to 0x%lx-0x%lx (0x%lx bytes)\n",
+		block->src, block->src + block->len - 1, block->dst,
+		block->dst + block->len - 1, block->len);
+}
+
+static void kimage_print(const struct kimage *image)
+{
+	void *control_code_page;
+	const kimage_entry_t *ptr;
+	kimage_entry_t entry;
+	struct kimage_block block;
+	unsigned long dnext = KIMAGE_NO_DEST, snext = KIMAGE_NO_DEST;
+	unsigned long total = 0;
+
+	control_code_page = page_address(image->control_code_page);
+	pr_info("Control code page 0x%p (phys 0x%lx)\n",
+		control_code_page, virt_to_phys(control_code_page));
+
+	ptr = &image->head;
+	block.dst = KIMAGE_NO_DEST;
+	block.src = KIMAGE_NO_DEST;
+	block.len = 0;
+	while ((entry = *ptr)) {
+		if (entry & IND_DONE)
+			break;
+
+		if (entry & IND_DESTINATION) {
+			if (block.len > 0) {
+				kimage_print_block(&block);
+				total += block.len;
+			}
+			dnext = block.dst = entry & PAGE_MASK;
+			block.src = KIMAGE_NO_DEST;
+			block.len = 0;
+		}
+
+		if (entry & IND_SOURCE) {
+			if (!block.len) {
+				snext = block.src = entry & PAGE_MASK;
+			} else if ((entry & PAGE_MASK) != snext) {
+				kimage_print_block(&block);
+				total += block.len;
+				block.dst = dnext;
+				snext = block.src = entry & PAGE_MASK;
+				block.len = 0;
+			}
+			dnext += PAGE_SIZE;
+			snext += PAGE_SIZE;
+			block.len += PAGE_SIZE;
+		}
+
+		if (entry & IND_INDIRECTION) {
+			pr_info("Indirection page 0x%lx\n", entry & PAGE_MASK);
+			ptr = phys_to_virt(entry & PAGE_MASK);
+		} else
+			ptr++;
+	}
+	if (block.len) {
+		kimage_print_block(&block);
+		total += block.len;
+	}
+	pr_info("Total: 0x%lx/%ld bytes\n", total, total);
+}
+#else
+static inline void kimage_print(const struct kimage *image) {}
+#endif
+
 void crash_kexec(struct pt_regs *regs)
 {
 	/* Take the kexec_mutex here to prevent sys_kexec_load
@@ -1090,6 +1164,7 @@ void crash_kexec(struct pt_regs *regs)
 			crash_setup_regs(&fixed_regs, regs);
 			crash_save_vmcoreinfo();
 			machine_crash_shutdown(&fixed_regs);
+			kimage_print(kexec_crash_image);
 			machine_kexec(kexec_crash_image);
 		}
 		mutex_unlock(&kexec_mutex);
@@ -1680,6 +1755,7 @@ int kernel_kexec(void)
 		machine_shutdown();
 	}
 
+	kimage_print(kexec_image);
 	machine_kexec(kexec_image);
 
 #ifdef CONFIG_KEXEC_JUMP
-- 
1.7.9.5

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