riscv: kexec_file: Support loading Image binary file

From: Song Shuai <[email protected]>

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

Signed-off-by Song Shuai <[email protected]>

Signed-off-by Björn Töpel <[email protected]>

---
 arch/riscv/include/asm/image.h         |  2 +
 arch/riscv/include/asm/kexec.h         |  1 +
 arch/riscv/kernel/Makefile             |  2 +-
 arch/riscv/kernel/kexec_image.c        | 96 ++++++++++++++++++++++++++
 arch/riscv/kernel/machine_kexec_file.c |  1 +
 5 files changed, 101 insertions(+), 1 deletion(-)
 create mode 100644 arch/riscv/kernel/kexec_image.c

arch/riscv/include/asm/image.h +2 -0

index e0b319af3681..8927a6ea1127 100644
@@ -30,6 +30,8 @@
                              RISCV_HEADER_VERSION_MINOR)
 
 #ifndef __ASSEMBLY__
+#define riscv_image_flag_field(flags, field)\
+                              (((flags) >> field##_SHIFT) & field##_MASK)
 /**
  * struct riscv_image_header - riscv kernel image header
  * @code0:             Executable code

arch/riscv/include/asm/kexec.h +1 -0

index 518825fe4160..b9ee8346cc8c 100644
@@ -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,

arch/riscv/kernel/Makefile +1 -1

index d56305c8e631..0ead29826419 100644
@@ -107,7 +107,7 @@ obj-$(CONFIG_HOTPLUG_CPU)   += cpu-hotplug.o
 obj-$(CONFIG_PARAVIRT)         += paravirt.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_VMCORE_INFO)      += vmcore_info.o
 

arch/riscv/kernel/kexec_image.c new file +63 -0

new file mode 100644
index 000000000000..26a81774a78a
@@ -0,0 +1,96 @@
+// 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>
+
+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 = riscv_image_flag_field(flags, RISCV_IMAGE_FLAG_BE);
+       be_kernel = IS_ENABLED(CONFIG_CPU_BIG_ENDIAN);
+       if (be_image != be_kernel) {
+               ret = -EINVAL;
+               goto out;
+       }
+
+       /* Load the kernel image */

arch/riscv/kernel/kexec_image.c new file +23 -0

+
+       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,
+};

arch/riscv/kernel/machine_kexec_file.c +1 -1

index 99bd5a5f4234..e36104af2e24 100644
@@ -18,6 +18,7 @@
 
 const struct kexec_file_ops * const kexec_file_loaders[] = {
        &elf_kexec_ops,
+       &image_kexec_ops,
        NULL
 };
 
--

2.45.2

Hi Björn,

On Thu, Apr 10, 2025 at 3:31 AM Björn Töpel <[email protected]> wrote:

arch/riscv/kernel/kexec_image.c line 73

Quoted 5 lines

arch/riscv/kernel/kexec_image.c new file +5 -0

+       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);

It is necessary to ensure that the kernel entry is aligned to PMD_SIZE; otherwise, BUG_ON() in setup_vm() will be triggered.