The arm64 boot protocol stipulates that the kernel must be loaded
TEXT_OFFSET bytes beyond a 2 MB aligned base address, where TEXT_OFFSET
could be any 4 KB multiple between 0 and 2 MB, and whose value can be
found in the header of the Image file.
So after attempts to load the kernel image as an ELF file or as a
U-Boot image (both of which have their own way of specifying the load
offset) have failed, try to determine the TEXT_OFFSET from the image
before proceeding with loading it as a gzipped or raw image.
Signed-off-by: Ard Biesheuvel <ard.biesheu...@linaro.org>
---
hw/arm/boot.c | 56 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 56 insertions(+)
diff --git a/hw/arm/boot.c b/hw/arm/boot.c
index ff621e4b6a4b..0824f74c697f 100644
--- a/hw/arm/boot.c
+++ b/hw/arm/boot.c
@@ -31,6 +31,11 @@
#define KERNEL_LOAD_ADDR 0x00010000
#define KERNEL64_LOAD_ADDR 0x00080000
+#define ARM64_IMAGE_HEADER_SIZE 64
+#define ARM64_TEXT_OFFSET_OFFSET 8
+#define ARM64_IMAGE_SIZE_OFFSET 16
+#define ARM64_MAGIC_OFFSET 56
+
typedef enum {
FIXUP_NONE = 0, /* do nothing */
FIXUP_TERMINATOR, /* end of insns */
@@ -768,6 +773,51 @@ static uint64_t arm_load_elf(struct arm_boot_info *info,
uint64_t *pentry,
return ret;
}
+static void aarch64_get_text_offset(struct arm_boot_info *info,
+ hwaddr *text_offset)
+{
+ uint8_t *buffer;
+ uint64_t headerval;
+ int size;
+
+ size = load_image_gzipped_buffer(info->kernel_filename,
+ LOAD_IMAGE_MAX_GUNZIP_BYTES,
+ &buffer);
+
+ if (size < 0) {
+ int fd, bytes;
+
+ fd = open(info->kernel_filename, O_RDONLY | O_BINARY);
+ if (fd < 0)
+ return;
+
+ buffer = g_malloc(ARM64_IMAGE_HEADER_SIZE);
+ bytes = read(fd, buffer, ARM64_IMAGE_HEADER_SIZE);
+ close(fd);
+
+ if (bytes < ARM64_IMAGE_HEADER_SIZE)
+ goto free_buffer;
+ }
+
+ /* check the arm64 magic header value */
+ if (memcmp(buffer + ARM64_MAGIC_OFFSET, "ARM\x64", 4) != 0)
+ goto free_buffer;
+
+ /* The arm64 Image header has text_offset and image_size fields at 8 and
+ * 16 bytes into the Image header, respectively. The text_offset field is
+ * only valid if the image_size is non-zero.
+ */
+ memcpy(&headerval, buffer + ARM64_IMAGE_SIZE_OFFSET, sizeof(headerval));
+ if (headerval == 0)
+ goto free_buffer;
+
+ memcpy(&headerval, buffer + ARM64_TEXT_OFFSET_OFFSET, sizeof(headerval));
+ *text_offset = le64_to_cpu(headerval);
+
+free_buffer:
+ g_free(buffer);
+}
+
static void arm_load_kernel_notify(Notifier *notifier, void *data)
{
CPUState *cs;
@@ -900,6 +950,12 @@ static void arm_load_kernel_notify(Notifier *notifier,
void *data)
kernel_size = load_uimage(info->kernel_filename, &entry, NULL,
&is_linux, NULL, NULL);
}
+
+ /* A bare Linux/arm64 kernel carries the load offset in the Image header */
+ if (arm_feature(&cpu->env, ARM_FEATURE_AARCH64) && kernel_size < 0) {
+ aarch64_get_text_offset(info, &kernel_load_offset);
+ }
+
/* On aarch64, it's the bootloader's job to uncompress the kernel. */
if (arm_feature(&cpu->env, ARM_FEATURE_AARCH64) && kernel_size < 0) {
entry = info->loader_start + kernel_load_offset;
--
2.7.4
