elfloader: pass DTB from bootloader to seL4 on ARM

On ARM, we expect the physical address of the dtb to be passed in r2 on
aarch32 or x0 on aarch64. RISC-V supplies a DTB in a1, but we currently
don't pass it to the kernel.

The elfloader then moves the dtb to immediately after where the
kernel is loaded in memory, and passes that address on to the kernel.

If there is no bootloader provided DTB, the elfloader will pass 0
to the kernel as the start address of the DTB.

elfloader-tool/include/arch-arm/elfloader.h

@@ -16,8 +16,8 @@
 typedef void (*init_arm_kernel_t)(paddr_t ui_p_reg_start,
                                   paddr_t ui_p_reg_end,
                                   uintptr_t pv_offset,
-                                  vaddr_t v_entry);
-
+                                  vaddr_t v_entry,
+                                  paddr_t dtb, uint32_t dtb_size);
 
 
 /* Enable the mmu. */

elfloader-tool/include/elfloader_common.h

@@ -56,6 +56,7 @@ struct image_info {
 
 extern struct image_info kernel_info;
 extern struct image_info user_info;
+extern void *dtb;
 
 /* Symbols defined in linker scripts. */
 extern char _start[];
@@ -65,7 +66,7 @@ extern char _archive_start_end[];
 
 /* Load images. */
 void load_images(struct image_info *kernel_info, struct image_info *user_info,
-                 int max_user_images, int *num_images);
+                 int max_user_images, int *num_images, void **dtb, uint32_t *dtb_size);
 
 /* Platform functions */
 void platform_init(void);

elfloader-tool/include/fdt.h

@@ -0,0 +1,15 @@
+/*
+ * Copyright 2018, Data61
+ * Commonwealth Scientific and Industrial Research Organisation (CSIRO)
+ * ABN 41 687 119 230.
+ *
+ * This software may be distributed and modified according to the terms of
+ * the GNU General Public License version 2. Note that NO WARRANTY is provided.
+ * See "LICENSE_GPLv2.txt" for details.
+ *
+ * @TAG(DATA61_GPL)
+ */
+
+#pragma once
+
+uint32_t fdt_size(void *fdt);

elfloader-tool/src/arch-arm/32/crt0.S

@@ -24,14 +24,15 @@ BEGIN_FUNC(_start)
     /* Disable Async aborts that might be pending from bootloader */
     cpsid   ifa
 
+    /* r0 contains the FDT address from the bootloader */
 #if CONFIG_MAX_NUM_NODES > 1
     /* Enable SMP */
-    mrc     ACTLR(r0)
-    orr     r0, r0, #(1 << 6)       /* enable SMP bit   */
+    mrc     ACTLR(r1)
+    orr     r1, r1, #(1 << 6)       /* enable SMP bit   */
 #ifdef CONFIG_ARM_CORTEX_A9
-    orr     r0, r0, #1              /* enable FW bit    */
+    orr     r1, r1, #1              /* enable FW bit    */
 #endif
-    mcr     ACTLR(r0)
+    mcr     ACTLR(r1)
 #endif /* CONFIG_MAX_NUM_NODES > 1 */
 
     ldr     sp, =core_stack_alloc + 0xff0

elfloader-tool/src/arch-arm/smp_boot.c

@@ -24,6 +24,9 @@ static volatile int non_boot_lock = 0;
 
 void arm_disable_dcaches(void);
 
+extern void *dtb;
+extern uint32_t dtb_size;
+
 /* Entry point for all CPUs other than the initial. */
 void non_boot_main(void)
 {
@@ -53,7 +56,7 @@ void non_boot_main(void)
     /* Jump to the kernel. */
     ((init_arm_kernel_t)kernel_info.virt_entry)(user_info.phys_region_start,
                                                 user_info.phys_region_end, user_info.phys_virt_offset,
-                                                user_info.virt_entry);
+                                                user_info.virt_entry, (paddr_t)dtb, dtb_size);
 
     printf("AP Kernel returned back to the elf-loader.\n");
     abort();

elfloader-tool/src/arch-arm/sys_boot.c

@@ -22,6 +22,9 @@
 #include <binaries/efi/efi.h>
 #include <elfloader.h>
 
+/* 0xd00dfeed in big endian */
+#define DTB_MAGIC (0xedfe0dd0)
+
 ALIGN(BIT(PAGE_BITS)) VISIBLE
 char core_stack_alloc[CONFIG_MAX_NUM_NODES][BIT(PAGE_BITS)];
 
@@ -33,15 +36,37 @@ struct image_info user_info;
  *
  * Unpack images, setup the MMU, jump to the kernel.
  */
-void main(void)
+void main(UNUSED void *arg)
 {
     int num_apps;
+    uint32_t dtb_size;
+    void *dtb;
+
+#ifdef CONFIG_IMAGE_UIMAGE
+    if (arg) {
+        uint32_t magic = *(uint32_t *)arg;
+        /*
+         * This might happen on ancient bootloaders which
+         * still think Linux wants atags instead of a
+         * device tree.
+         */
+        if (magic != DTB_MAGIC) {
+            printf("Bootloader did not supply a valid device tree!\n");
+            arg = NULL;
+        }
+    }
+    dtb = arg;
+#else
+    dtb = NULL;
+#endif
 
 #ifdef CONFIG_IMAGE_EFI
     if (efi_exit_boot_services() != EFI_SUCCESS) {
         printf("Unable to exit UEFI boot services!\n");
         abort();
     }
+
+	/* TODO: get DTB from EFI like Linux does. */
 #endif
 
     /* Print welcome message. */
@@ -51,8 +76,18 @@ void main(void)
 
     printf("  paddr=[%p..%p]\n", _start, _end - 1);
 
+    /*
+     * U-Boot will either pass us a DTB, or (if we're being booted via bootelf)
+     * pass '0' in argc.
+     */
+    if (dtb) {
+        printf("  dtb=%p\n", dtb);
+    } else {
+        printf("No DTB found!\n");
+    }
+
     /* Unpack ELF images into memory. */
-    load_images(&kernel_info, &user_info, 1, &num_apps);
+    load_images(&kernel_info, &user_info, 1, &num_apps, &dtb, &dtb_size);
     if (num_apps != 1) {
         printf("No user images loaded!\n");
         abort();
@@ -98,7 +133,7 @@ void main(void)
 
     ((init_arm_kernel_t)kernel_info.virt_entry)(user_info.phys_region_start,
                                                 user_info.phys_region_end, user_info.phys_virt_offset,
-                                                user_info.virt_entry);
+                                                user_info.virt_entry, (paddr_t)dtb, dtb_size);
 
     /* We should never get here. */
     printf("Kernel returned back to the elf-loader.\n");

elfloader-tool/src/arch-riscv/boot.c

@@ -121,13 +121,14 @@ uint64_t vm_mode = 0x9llu << 60;
 #endif
 
 int num_apps = 0;
-void main(void)
+void main(UNUSED int hardid, void *dtb)
 {
+    uint32_t dtb_size;
     printf("ELF-loader started on\n");
 
     printf("  paddr=[%p..%p]\n", _start, _end - 1);
     /* Unpack ELF images into memory. */
-    load_images(&kernel_info, &user_info, 1, &num_apps);
+    load_images(&kernel_info, &user_info, 1, &num_apps, &dtb, &dtb_size);
     if (num_apps != 1) {
         printf("No user images loaded!\n");
         abort();
@@ -146,6 +147,7 @@ void main(void)
         :
     );
 
+    /* TODO: pass DTB to kernel. */
     ((init_riscv_kernel_t)kernel_info.virt_entry)(user_info.phys_region_start,
                                                   user_info.phys_region_end, user_info.phys_virt_offset,
                                                   user_info.virt_entry);

elfloader-tool/src/common.c

@@ -20,6 +20,7 @@
 #include <cpio/cpio.h>
 
 #include <elfloader.h>
+#include <fdt.h>
 
 #ifdef CONFIG_HASH_SHA
 #include "crypt_sha256.h"
@@ -262,10 +263,11 @@ static paddr_t load_elf(const char *name, void *elf, paddr_t dest_paddr,
  *  We attempt to check for some of these, but some may go unnoticed.
  */
 void load_images(struct image_info *kernel_info, struct image_info *user_info,
-                 int max_user_images, int *num_images)
+                 int max_user_images, int *num_images, void **dtb, uint32_t *dtb_size)
 {
     int i;
     uint64_t kernel_phys_start, kernel_phys_end;
+    uintptr_t dtb_phys_start, dtb_phys_end;
     paddr_t next_phys_addr;
     const char *elf_filename;
     unsigned long unused;
@@ -283,8 +285,37 @@ void load_images(struct image_info *kernel_info, struct image_info *user_info,
     }
 
     elf_getMemoryBounds(kernel_elf, 1, &kernel_phys_start, &kernel_phys_end);
-    next_phys_addr = load_elf("kernel", kernel_elf,
-                              (paddr_t)kernel_phys_start, kernel_info, 0, unused, "kernel.bin");
+
+    /*
+     * Move the DTB out of the way, if it's present.
+     */
+    if (dtb && *dtb) {
+        /* keep it page aligned */
+        next_phys_addr = dtb_phys_start = ROUND_UP(kernel_phys_end, PAGE_BITS);
+
+        *dtb_size = fdt_size(*dtb);
+        if (!*dtb_size) {
+            printf("Invalid device tree blob supplied!\n");
+            abort();
+        }
+
+        /* Make sure this is a sane thing to do */
+        ensure_phys_range_valid(next_phys_addr, next_phys_addr + *dtb_size);
+
+        memmove((void *)next_phys_addr, *dtb, *dtb_size);
+        next_phys_addr += *dtb_size;
+        next_phys_addr = ROUND_UP(next_phys_addr, PAGE_BITS);
+        dtb_phys_end = next_phys_addr;
+
+        printf("Loaded dtb from %p\n", *dtb);
+        printf("   paddr=[%lx..%lx]\n", dtb_phys_start, dtb_phys_end - 1);
+        *dtb = (void *)dtb_phys_start;
+    } else {
+        next_phys_addr = ROUND_UP(kernel_phys_end, PAGE_BITS);
+    }
+
+    load_elf("kernel", kernel_elf,
+             (paddr_t)kernel_phys_start, kernel_info, 0, unused, "kernel.bin");
 
     /*
      * Load userspace images.

elfloader-tool/src/fdt.c

@@ -0,0 +1,50 @@
+/*
+ * Copyright 2019, Data61
+ * Commonwealth Scientific and Industrial Research Organisation (CSIRO)
+ * ABN 41 687 119 230.
+ *
+ * This software may be distributed and modified according to the terms of
+ * the GNU General Public License version 2. Note that NO WARRANTY is provided.
+ * See "LICENSE_GPLv2.txt" for details.
+ *
+ * @TAG(DATA61_GPL)
+ */
+#include <types.h>
+
+#define FDT_MAGIC (0xd00dfeed)
+/* Newest FDT version that we understand */
+#define FDT_MAX_VER 17
+
+struct fdt_header {
+    uint32_t magic;
+    uint32_t totalsize;
+    uint32_t off_dt_struct;
+    uint32_t off_dt_strings;
+    uint32_t off_mem_rsvmap;
+    uint32_t version;
+    uint32_t last_comp_version;
+    uint32_t boot_cpuid_phys;
+    uint32_t size_dt_strings;
+    uint32_t size_dt_struct;
+};
+
+uint32_t be32_to_le(uint32_t be)
+{
+    return ((be & 0xff) << 24) |
+           ((be & 0xff00) << 8) |
+           ((be & 0xff0000) >> 8) |
+           ((be & 0xff000000) >> 24);
+}
+
+uint32_t fdt_size(void *fdt)
+{
+    struct fdt_header *hdr = (struct fdt_header *)fdt;
+
+    if (be32_to_le(hdr->magic) != FDT_MAGIC ||
+        be32_to_le(hdr->last_comp_version) > FDT_MAX_VER) {
+        return 0;
+    }
+
+    return be32_to_le(hdr->totalsize);
+}
+