[PATCH V2 2/2] riscv: kexec_file: Support loading Image binary file

[Song Shuai <songshuaishuai@tinylab.org>]

This patch creates image_kexec_ops to load Image binary file
for kexec_file_load() syscall.

Signed-off-by: Song Shuai <songshuaishuai@tinylab.org>
---
 arch/riscv/include/asm/kexec.h         |  1 +
 arch/riscv/kernel/Makefile             |  2 +-
 arch/riscv/kernel/kexec_image.c        | 98 ++++++++++++++++++++++++++
 arch/riscv/kernel/machine_kexec_file.c |  1 +
 4 files changed, 101 insertions(+), 1 deletion(-)
 create mode 100644 arch/riscv/kernel/kexec_image.c

diff --git a/arch/riscv/include/asm/kexec.h b/arch/riscv/include/asm/kexec.h
index 518825fe4160..b9ee8346cc8c 100644
--- a/arch/riscv/include/asm/kexec.h
+++ b/arch/riscv/include/asm/kexec.h
@@ -56,6 +56,7 @@ extern riscv_kexec_method riscv_kexec_norelocate;
 
 #ifdef CONFIG_KEXEC_FILE
 extern const struct kexec_file_ops elf_kexec_ops;
+extern const struct kexec_file_ops image_kexec_ops;
 
 struct purgatory_info;
 int arch_kexec_apply_relocations_add(struct purgatory_info *pi,
diff --git a/arch/riscv/kernel/Makefile b/arch/riscv/kernel/Makefile
index 1c62c639e875..9ecba3231a36 100644
--- a/arch/riscv/kernel/Makefile
+++ b/arch/riscv/kernel/Makefile
@@ -86,7 +86,7 @@ endif
 obj-$(CONFIG_HOTPLUG_CPU)	+= cpu-hotplug.o
 obj-$(CONFIG_KGDB)		+= kgdb.o
 obj-$(CONFIG_KEXEC_CORE)	+= kexec_relocate.o crash_save_regs.o machine_kexec.o
-obj-$(CONFIG_KEXEC_FILE)	+= kexec_elf.o machine_kexec_file.o
+obj-$(CONFIG_KEXEC_FILE)	+= kexec_elf.o kexec_image.o machine_kexec_file.o
 obj-$(CONFIG_CRASH_DUMP)	+= crash_dump.o
 obj-$(CONFIG_CRASH_CORE)	+= crash_core.o
 
diff --git a/arch/riscv/kernel/kexec_image.c b/arch/riscv/kernel/kexec_image.c
new file mode 100644
index 000000000000..5339c4f33ff6
--- /dev/null
+++ b/arch/riscv/kernel/kexec_image.c
@@ -0,0 +1,98 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * RISC-V Kexec image loader
+ *
+ */
+
+#define pr_fmt(fmt)	"kexec_file(Image): " fmt
+
+#include <linux/err.h>
+#include <linux/errno.h>
+#include <linux/kernel.h>
+#include <linux/kexec.h>
+#include <linux/pe.h>
+#include <linux/string.h>
+#include <asm/byteorder.h>
+#include <asm/image.h>
+#include <linux/bitfield.h>
+
+static int image_probe(const char *kernel_buf, unsigned long kernel_len)
+{
+	const struct riscv_image_header *h =
+		(const struct riscv_image_header *)(kernel_buf);
+
+	if (!h || (kernel_len < sizeof(*h)))
+		return -EINVAL;
+
+	/* According to Documentation/riscv/boot-image-header.rst,
+	 * use "magic2" field to check when version >= 0.2.
+	 */
+
+	if (h->version >= RISCV_HEADER_VERSION &&
+	    memcmp(&h->magic2, RISCV_IMAGE_MAGIC2, sizeof(h->magic2)))
+		return -EINVAL;
+
+	return 0;
+}
+
+static void *image_load(struct kimage *image,
+				char *kernel, unsigned long kernel_len,
+				char *initrd, unsigned long initrd_len,
+				char *cmdline, unsigned long cmdline_len)
+{
+	struct riscv_image_header *h;
+	u64 flags;
+	bool be_image, be_kernel;
+	struct kexec_buf kbuf;
+	int ret;
+
+	/* Check Image header */
+	h = (struct riscv_image_header *)kernel;
+	if (!h->image_size) {
+		ret = -EINVAL;
+		goto out;
+	}
+
+	/* Check endianness */
+	flags = le64_to_cpu(h->flags);
+	be_image = FIELD_GET(RISCV_IMAGE_FLAG_BE_MASK, flags);
+	be_kernel = IS_ENABLED(CONFIG_CPU_BIG_ENDIAN);
+	if (be_image != be_kernel) {
+		ret = -EINVAL;
+		goto out;
+	}
+
+	/* Load the kernel image */
+	kbuf.image = image;
+	kbuf.buf_min = 0;
+	kbuf.buf_max = ULONG_MAX;
+	kbuf.top_down = false;
+
+	kbuf.buffer = kernel;
+	kbuf.bufsz = kernel_len;
+	kbuf.mem = KEXEC_BUF_MEM_UNKNOWN;
+	kbuf.memsz = le64_to_cpu(h->image_size);
+	kbuf.buf_align = le64_to_cpu(h->text_offset);
+
+	ret = kexec_add_buffer(&kbuf);
+	if (ret) {
+		pr_err("Error add kernel image ret=%d\n", ret);
+		goto out;
+	}
+
+	image->start = kbuf.mem;
+
+	pr_info("Loaded kernel at 0x%lx bufsz=0x%lx memsz=0x%lx\n",
+				kbuf.mem, kbuf.bufsz, kbuf.memsz);
+
+	ret = load_extra_segments(image, kbuf.mem, kbuf.memsz,
+				  initrd, initrd_len, cmdline, cmdline_len);
+
+out:
+	return ret ? ERR_PTR(ret) : NULL;
+}
+
+const struct kexec_file_ops image_kexec_ops = {
+	.probe = image_probe,
+	.load = image_load,
+};
diff --git a/arch/riscv/kernel/machine_kexec_file.c b/arch/riscv/kernel/machine_kexec_file.c
index aedb8c16a283..5dc700834f1e 100644
--- a/arch/riscv/kernel/machine_kexec_file.c
+++ b/arch/riscv/kernel/machine_kexec_file.c
@@ -17,6 +17,7 @@
 
 const struct kexec_file_ops * const kexec_file_loaders[] = {
 	&elf_kexec_ops,
+	&image_kexec_ops,
 	NULL
 };
 
-- 
2.20.1