1 files changed, 150 insertions, 0 deletions
diff --git a/drivers/firmware/efi/embedded-firmware.c b/drivers/firmware/efi/embedded-firmware.c
new file mode 100644
index 000000000000..a1b199de9006
--- /dev/null
+++ b/drivers/firmware/efi/embedded-firmware.c
@@ -0,0 +1,150 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Support for extracting embedded firmware for peripherals from EFI code,
+ *
+ * Copyright (c) 2018 Hans de Goede <hdegoede@redhat.com>
+ */
+
+#include <linux/dmi.h>
+#include <linux/efi.h>
+#include <linux/efi_embedded_fw.h>
+#include <linux/io.h>
+#include <linux/slab.h>
+#include <linux/types.h>
+#include <linux/vmalloc.h>
+#include <crypto/sha.h>
+
+/* Exported for use by lib/test_firmware.c only */
+LIST_HEAD(efi_embedded_fw_list);
+EXPORT_SYMBOL_GPL(efi_embedded_fw_list);
+
+static bool checked_for_fw;
+
+static const struct dmi_system_id * const embedded_fw_table[] = {
+#ifdef CONFIG_TOUCHSCREEN_DMI
+	touchscreen_dmi_table,
+#endif
+	NULL
+};
+
+/*
+ * Note the efi_check_for_embedded_firmwares() code currently makes the
+ * following 2 assumptions. This may needs to be revisited if embedded firmware
+ * is found where this is not true:
+ * 1) The firmware is only found in EFI_BOOT_SERVICES_CODE memory segments
+ * 2) The firmware always starts at an offset which is a multiple of 8 bytes
+ */
+static int __init efi_check_md_for_embedded_firmware(
+	efi_memory_desc_t *md, const struct efi_embedded_fw_desc *desc)
+{
+	struct sha256_state sctx;
+	struct efi_embedded_fw *fw;
+	u8 sha256[32];
+	u64 i, size;
+	u8 *map;
+
+	size = md->num_pages << EFI_PAGE_SHIFT;
+	map = memremap(md->phys_addr, size, MEMREMAP_WB);
+	if (!map) {
+		pr_err("Error mapping EFI mem at %#llx\n", md->phys_addr);
+		return -ENOMEM;
+	}
+
+	for (i = 0; (i + desc->length) <= size; i += 8) {
+		if (memcmp(map + i, desc->prefix, EFI_EMBEDDED_FW_PREFIX_LEN))
+			continue;
+
+		sha256_init(&sctx);
+		sha256_update(&sctx, map + i, desc->length);
+		sha256_final(&sctx, sha256);
+		if (memcmp(sha256, desc->sha256, 32) == 0)
+			break;
+	}
+	if ((i + desc->length) > size) {
+		memunmap(map);
+		return -ENOENT;
+	}
+
+	pr_info("Found EFI embedded fw '%s'\n", desc->name);
+
+	fw = kmalloc(sizeof(*fw), GFP_KERNEL);
+	if (!fw) {
+		memunmap(map);
+		return -ENOMEM;
+	}
+
+	fw->data = kmemdup(map + i, desc->length, GFP_KERNEL);
+	memunmap(map);
+	if (!fw->data) {
+		kfree(fw);
+		return -ENOMEM;
+	}
+
+	fw->name = desc->name;
+	fw->length = desc->length;
+	list_add(&fw->list, &efi_embedded_fw_list);
+
+	return 0;
+}
+
+void __init efi_check_for_embedded_firmwares(void)
+{
+	const struct efi_embedded_fw_desc *fw_desc;
+	const struct dmi_system_id *dmi_id;
+	efi_memory_desc_t *md;
+	int i, r;
+
+	for (i = 0; embedded_fw_table[i]; i++) {
+		dmi_id = dmi_first_match(embedded_fw_table[i]);
+		if (!dmi_id)
+			continue;
+
+		fw_desc = dmi_id->driver_data;
+
+		/*
+		 * In some drivers the struct driver_data contains may contain
+		 * other driver specific data after the fw_desc struct; and
+		 * the fw_desc struct itself may be empty, skip these.
+		 */
+		if (!fw_desc->name)
+			continue;
+
+		for_each_efi_memory_desc(md) {
+			if (md->type != EFI_BOOT_SERVICES_CODE)
+				continue;
+
+			r = efi_check_md_for_embedded_firmware(md, fw_desc);
+			if (r == 0)
+				break;
+		}
+	}
+
+	checked_for_fw = true;
+}
+
+int efi_get_embedded_fw(const char *name, const u8 **data, size_t *size)
+{
+	struct efi_embedded_fw *iter, *fw = NULL;
+
+	if (!checked_for_fw) {
+		pr_warn("Warning %s called while we did not check for embedded fw\n",
+			__func__);
+		return -ENOENT;
+	}
+
+	list_for_each_entry(iter, &efi_embedded_fw_list, list) {
+		if (strcmp(name, iter->name) == 0) {
+			fw = iter;
+			break;
+		}
+	}
+
+	if (!fw)
+		return -ENOENT;
+
+	*data = fw->data;
+	*size = fw->length;
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(efi_get_embedded_fw);