MIPS: kexec: Use prepare method from Generic for UHI platforms

Out-of-tree platforms may not be based on Generic as shown in customer
communication. Share the prepare method with all using UHI boot protocol,
and put into machine_kexec.c.

The benefit is that, when having kexec_args related problems, developers
will naturally look into machine_kexec.c, where "CONFIG_UHI_BOOT" will be
found, prompting them to add "select UHI_BOOT" to the platform Kconfig. It
would otherwise require a lot debugging or online searching to be aware
that the solution is in Generic code.

Tested-by: Rachel Mozes <rachel.mozes@intel.com>
Reported-by: Rachel Mozes <rachel.mozes@intel.com>
Signed-off-by: Dengcheng Zhu <dzhu@wavecomp.com>
Signed-off-by: Paul Burton <paul.burton@mips.com>
Patchwork: https://patchwork.linux-mips.org/patch/20569/
Cc: pburton@wavecomp.com
Cc: ralf@linux-mips.org
Cc: linux-mips@linux-mips.org

1 files changed, 41 insertions, 1 deletions

diff --git a/arch/mips/kernel/machine_kexec.c b/arch/mips/kernel/machine_kexec.c
index 14ced77c5ef6..35175eb2e8b0 100644
--- a/arch/mips/kernel/machine_kexec.c
+++ b/arch/mips/kernel/machine_kexec.c
@@ -9,6 +9,7 @@
 #include <linux/kexec.h>
 #include <linux/mm.h>
 #include <linux/delay.h>
+#include <linux/libfdt.h>
 
 #include <asm/cacheflush.h>
 #include <asm/page.h>
@@ -28,7 +29,6 @@ atomic_t kexec_ready_to_reboot = ATOMIC_INIT(0);
 void (*_crash_smp_send_stop)(void) = NULL;
 #endif
 
-int (*_machine_kexec_prepare)(struct kimage *) = NULL;
 void (*_machine_kexec_shutdown)(void) = NULL;
 void (*_machine_crash_shutdown)(struct pt_regs *regs) = NULL;
 
@@ -52,6 +52,46 @@ static void kexec_image_info(const struct kimage *kimage)
         }
 }
 
+#ifdef CONFIG_UHI_BOOT
+
+static int uhi_machine_kexec_prepare(struct kimage *kimage)
+{
+        int i;
+
+        /*
+         * In case DTB file is not passed to the new kernel, a flat device
+         * tree will be created by kexec tool. It holds modified command
+         * line for the new kernel.
+         */
+        for (i = 0; i < kimage->nr_segments; i++) {
+                struct fdt_header fdt;
+
+                if (kimage->segment[i].memsz <= sizeof(fdt))
+                        continue;
+
+                if (copy_from_user(&fdt, kimage->segment[i].buf, sizeof(fdt)))
+                        continue;
+
+                if (fdt_check_header(&fdt))
+                        continue;
+
+                kexec_args[0] = -2;
+                kexec_args[1] = (unsigned long)
+                        phys_to_virt((unsigned long)kimage->segment[i].mem);
+                break;
+        }
+
+        return 0;
+}
+
+int (*_machine_kexec_prepare)(struct kimage *) = uhi_machine_kexec_prepare;
+
+#else
+
+int (*_machine_kexec_prepare)(struct kimage *) = NULL;
+
+#endif /* CONFIG_UHI_BOOT */
+
 int
 machine_kexec_prepare(struct kimage *kimage)
 {