To aid in debugging kexec problems or when adding new functionality to kexec add
a new routine kexec_image_info() and several inline pr_debug statements.

Signed-off-by: Geoff Levand <ge...@infradead.org>
---
 arch/arm64/kernel/machine_kexec.c | 70 +++++++++++++++++++++++++++++++++++++--
 1 file changed, 68 insertions(+), 2 deletions(-)

diff --git a/arch/arm64/kernel/machine_kexec.c 
b/arch/arm64/kernel/machine_kexec.c
index 9379d31..a375268 100644
--- a/arch/arm64/kernel/machine_kexec.c
+++ b/arch/arm64/kernel/machine_kexec.c
@@ -11,6 +11,7 @@
 
 #include <linux/highmem.h>
 #include <linux/kexec.h>
+#include <linux/libfdt_env.h>
 #include <linux/of_fdt.h>
 #include <linux/slab.h>
 #include <linux/uaccess.h>
@@ -26,6 +27,50 @@ extern const unsigned long arm64_relocate_new_kernel_size;
 
 static unsigned long kimage_start;
 
+/**
+ * kexec_is_dtb - Helper routine to check the device tree header signature.
+ */
+static bool kexec_is_dtb(const void *dtb)
+{
+       __be32 magic;
+
+       if (get_user(magic, (__be32 *)dtb))
+               return false;
+
+       return fdt32_to_cpu(magic) == OF_DT_HEADER;
+}
+
+/**
+ * kexec_image_info - For debugging output.
+ */
+#define kexec_image_info(_i) _kexec_image_info(__func__, __LINE__, _i)
+static void _kexec_image_info(const char *func, int line,
+       const struct kimage *kimage)
+{
+       unsigned long i;
+
+#ifndef DEBUG
+       return;
+#endif
+       pr_debug("%s:%d:\n", func, line);
+       pr_debug("  kexec kimage info:\n");
+       pr_debug("    type:        %d\n", kimage->type);
+       pr_debug("    start:       %lx\n", kimage->start);
+       pr_debug("    head:        %lx\n", kimage->head);
+       pr_debug("    nr_segments: %lu\n", kimage->nr_segments);
+
+       for (i = 0; i < kimage->nr_segments; i++) {
+               pr_debug("      segment[%lu]: %016lx - %016lx, 0x%lx bytes, %lu 
pages%s\n",
+                       i,
+                       kimage->segment[i].mem,
+                       kimage->segment[i].mem + kimage->segment[i].memsz,
+                       kimage->segment[i].memsz,
+                       kimage->segment[i].memsz /  PAGE_SIZE,
+                       (kexec_is_dtb(kimage->segment[i].buf) ?
+                               ", dtb segment" : ""));
+       }
+}
+
 void machine_kexec_cleanup(struct kimage *kimage)
 {
        /* Empty routine needed to avoid build errors. */
@@ -39,6 +84,8 @@ void machine_kexec_cleanup(struct kimage *kimage)
 int machine_kexec_prepare(struct kimage *kimage)
 {
        kimage_start = kimage->start;
+       kexec_image_info(kimage);
+
        return 0;
 }
 
@@ -81,10 +128,10 @@ static void kexec_segment_flush(const struct kimage 
*kimage)
 {
        unsigned long i;
 
-       pr_devel("%s:\n", __func__);
+       pr_debug("%s:\n", __func__);
 
        for (i = 0; i < kimage->nr_segments; i++) {
-               pr_devel("  segment[%lu]: %016lx - %016lx, %lx bytes, %lu 
pages\n",
+               pr_debug("  segment[%lu]: %016lx - %016lx, 0x%lx bytes, %lu 
pages\n",
                        i,
                        kimage->segment[i].mem,
                        kimage->segment[i].mem + kimage->segment[i].memsz,
@@ -111,6 +158,25 @@ void machine_kexec(struct kimage *kimage)
        reboot_code_buffer_phys = page_to_phys(kimage->control_code_page);
        reboot_code_buffer = kmap(kimage->control_code_page);
 
+       kexec_image_info(kimage);
+
+       pr_debug("%s:%d: control_code_page:        %p\n", __func__, __LINE__,
+               kimage->control_code_page);
+       pr_debug("%s:%d: reboot_code_buffer_phys:  %pa\n", __func__, __LINE__,
+               &reboot_code_buffer_phys);
+       pr_debug("%s:%d: reboot_code_buffer:       %p\n", __func__, __LINE__,
+               reboot_code_buffer);
+       pr_debug("%s:%d: relocate_new_kernel:      %p\n", __func__, __LINE__,
+               arm64_relocate_new_kernel);
+       pr_debug("%s:%d: relocate_new_kernel_size: 0x%lx(%lu) bytes\n",
+               __func__, __LINE__, arm64_relocate_new_kernel_size,
+               arm64_relocate_new_kernel_size);
+
+       pr_debug("%s:%d: kimage_head:              %lx\n", __func__, __LINE__,
+               kimage->head);
+       pr_debug("%s:%d: kimage_start:             %lx\n", __func__, __LINE__,
+               kimage_start);
+
        /*
         * Copy arm64_relocate_new_kernel to the reboot_code_buffer for use
         * after the kernel is shut down.
-- 
2.5.0



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