1 files changed, 55 insertions, 21 deletions

diff --git a/drivers/firmware/efi/efi-stub-helper.c b/drivers/firmware/efi/efi-stub-helper.c
index 333ed9c37751..361e24d8d665 100644
--- a/drivers/firmware/efi/efi-stub-helper.c
+++ b/drivers/firmware/efi/efi-stub-helper.c
@@ -485,38 +485,72 @@ fail:
 
         return status;
 }
-
-static efi_status_t relocate_kernel(struct setup_header *hdr)
+/*
+ * Relocate a kernel image, either compressed or uncompressed.
+ * In the ARM64 case, all kernel images are currently
+ * uncompressed, and as such when we relocate it we need to
+ * allocate additional space for the BSS segment. Any low
+ * memory that this function should avoid needs to be
+ * unavailable in the EFI memory map, as if the preferred
+ * address is not available the lowest available address will
+ * be used.
+ */
+static efi_status_t efi_relocate_kernel(efi_system_table_t *sys_table_arg,
+                                        unsigned long *image_addr,
+                                        unsigned long image_size,
+                                        unsigned long alloc_size,
+                                        unsigned long preferred_addr,
+                                        unsigned long alignment)
 {
-        unsigned long start, nr_pages;
+        unsigned long cur_image_addr;
+        unsigned long new_addr = 0;
         efi_status_t status;
+        unsigned long nr_pages;
+        efi_physical_addr_t efi_addr = preferred_addr;
+
+        if (!image_addr || !image_size || !alloc_size)
+                return EFI_INVALID_PARAMETER;
+        if (alloc_size < image_size)
+                return EFI_INVALID_PARAMETER;
+
+        cur_image_addr = *image_addr;
 
         /*
          * The EFI firmware loader could have placed the kernel image
-         * anywhere in memory, but the kernel has various restrictions
-         * on the max physical address it can run at. Attempt to move
-         * the kernel to boot_params.pref_address, or as low as
-         * possible.
+         * anywhere in memory, but the kernel has restrictions on the
+         * max physical address it can run at.  Some architectures
+         * also have a prefered address, so first try to relocate
+         * to the preferred address.  If that fails, allocate as low
+         * as possible while respecting the required alignment.
          */
-        start = hdr->pref_address;
-        nr_pages = round_up(hdr->init_size, EFI_PAGE_SIZE) / EFI_PAGE_SIZE;
-
-        status = efi_call_phys4(sys_table->boottime->allocate_pages,
+        nr_pages = round_up(alloc_size, EFI_PAGE_SIZE) / EFI_PAGE_SIZE;
+        status = efi_call_phys4(sys_table_arg->boottime->allocate_pages,
                                 EFI_ALLOCATE_ADDRESS, EFI_LOADER_DATA,
-                                nr_pages, &start);
+                                nr_pages, &efi_addr);
+        new_addr = efi_addr;
+        /*
+         * If preferred address allocation failed allocate as low as
+         * possible.
+         */
         if (status != EFI_SUCCESS) {
-                status = efi_low_alloc(sys_table, hdr->init_size,
-                                   hdr->kernel_alignment, &start);
-                if (status != EFI_SUCCESS)
-                        efi_printk(sys_table, "Failed to alloc mem for kernel\n");
+                status = efi_low_alloc(sys_table_arg, alloc_size, alignment,
+                                       &new_addr);
+        }
+        if (status != EFI_SUCCESS) {
+                efi_printk(sys_table_arg, "ERROR: Failed to allocate usable memory for kernel.\n");
+                return status;
         }
 
-        if (status == EFI_SUCCESS)
-                memcpy((void *)start, (void *)(unsigned long)hdr->code32_start,
-                       hdr->init_size);
+        /*
+         * We know source/dest won't overlap since both memory ranges
+         * have been allocated by UEFI, so we can safely use memcpy.
+         */
+        memcpy((void *)new_addr, (void *)cur_image_addr, image_size);
+        /* Zero any extra space we may have allocated for BSS. */
+        memset((void *)(new_addr + image_size), alloc_size - image_size, 0);
 
-        hdr->pref_address = hdr->code32_start;
-        hdr->code32_start = (__u32)start;
+        /* Return the new address of the relocated image. */
+        *image_addr = new_addr;
 
         return status;
 }