efi: Add grub_efi_get_ram_base() function for arm64

Since ARM platforms do not have a common memory map, add a helper
function that finds the lowest address region with the EFI_MEMORY_WB
attribute set in the UEFI memory map.

Required for the arm64 efi linux loader to restrict the initrd
location to where it will be accessible by the kernel at runtime.

Signed-off-by: Leif Lindholm <leif.lindholm@linaro.org>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>

diff --git a/grub-core/kern/efi/mm.c b/grub-core/kern/efi/mm.c
index a8e0e4a89997af46c3726a28aa23a941e9c508c1..92e9763d26f23a17ab4a31925c32d75489657457 100644 (file)
--- a/grub-core/kern/efi/mm.c
+++ b/grub-core/kern/efi/mm.c
@@ -633,3 +633,34 @@ grub_efi_mm_init (void)
   grub_efi_free_pages ((grub_addr_t) memory_map,
                       2 * BYTES_TO_PAGES (MEMORY_MAP_SIZE));
 }
+
+#if defined (__aarch64__)
+grub_err_t
+grub_efi_get_ram_base(grub_addr_t *base_addr)
+{
+  grub_efi_memory_descriptor_t *memory_map, *desc;
+  grub_efi_uintn_t memory_map_size, desc_size;
+  int ret;
+
+  memory_map_size = grub_efi_find_mmap_size();
+
+  memory_map = grub_malloc (memory_map_size);
+  if (! memory_map)
+    return GRUB_ERR_OUT_OF_MEMORY;
+  ret = grub_efi_get_memory_map (&memory_map_size, memory_map, NULL,
+                                &desc_size, NULL);
+
+  if (ret < 1)
+    return GRUB_ERR_BUG;
+
+  for (desc = memory_map, *base_addr = GRUB_UINT_MAX;
+       (grub_addr_t) desc < ((grub_addr_t) memory_map + memory_map_size);
+       desc = NEXT_MEMORY_DESCRIPTOR (desc, desc_size))
+    if (desc->attribute & GRUB_EFI_MEMORY_WB)
+      *base_addr = grub_min (*base_addr, desc->physical_start);
+
+  grub_free(memory_map);
+
+  return GRUB_ERR_NONE;
+}
+#endif

diff --git a/include/grub/efi/efi.h b/include/grub/efi/efi.h
index 1021273c1df0eec4ea58ccddf1cad2d9c159267a..57db74b57886f3974c214e1364ea50399bb00985 100644 (file)
--- a/include/grub/efi/efi.h
+++ b/include/grub/efi/efi.h
@@ -93,6 +93,9 @@ extern void (*EXPORT_VAR(grub_efi_net_config)) (grub_efi_handle_t hnd,
 #if defined(__arm__) || defined(__aarch64__)
 void *EXPORT_FUNC(grub_efi_get_firmware_fdt)(void);
 #endif
+#if defined(__aarch64__)
+grub_err_t EXPORT_FUNC(grub_efi_get_ram_base)(grub_addr_t *);
+#endif
 
 grub_addr_t grub_efi_modules_addr (void);