1 files changed, 282 insertions, 0 deletions
diff --git a/drivers/firmware/efi/libstub/efi-stub.c b/drivers/firmware/efi/libstub/efi-stub.c
new file mode 100644
index 0000000000..f9c1e8a2bd
--- /dev/null
+++ b/drivers/firmware/efi/libstub/efi-stub.c
@@ -0,0 +1,282 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * EFI stub implementation that is shared by arm and arm64 architectures.
+ * This should be #included by the EFI stub implementation files.
+ *
+ * Copyright (C) 2013,2014 Linaro Limited
+ *     Roy Franz <roy.franz@linaro.org
+ * Copyright (C) 2013 Red Hat, Inc.
+ *     Mark Salter <msalter@redhat.com>
+ */
+
+#include <linux/efi.h>
+#include <asm/efi.h>
+
+#include "efistub.h"
+
+/*
+ * This is the base address at which to start allocating virtual memory ranges
+ * for UEFI Runtime Services.
+ *
+ * For ARM/ARM64:
+ * This is in the low TTBR0 range so that we can use
+ * any allocation we choose, and eliminate the risk of a conflict after kexec.
+ * The value chosen is the largest non-zero power of 2 suitable for this purpose
+ * both on 32-bit and 64-bit ARM CPUs, to maximize the likelihood that it can
+ * be mapped efficiently.
+ * Since 32-bit ARM could potentially execute with a 1G/3G user/kernel split,
+ * map everything below 1 GB. (512 MB is a reasonable upper bound for the
+ * entire footprint of the UEFI runtime services memory regions)
+ *
+ * For RISC-V:
+ * There is no specific reason for which, this address (512MB) can't be used
+ * EFI runtime virtual address for RISC-V. It also helps to use EFI runtime
+ * services on both RV32/RV64. Keep the same runtime virtual address for RISC-V
+ * as well to minimize the code churn.
+ */
+#define EFI_RT_VIRTUAL_BASE	SZ_512M
+
+/*
+ * Some architectures map the EFI regions into the kernel's linear map using a
+ * fixed offset.
+ */
+#ifndef EFI_RT_VIRTUAL_OFFSET
+#define EFI_RT_VIRTUAL_OFFSET	0
+#endif
+
+static u64 virtmap_base = EFI_RT_VIRTUAL_BASE;
+static bool flat_va_mapping = (EFI_RT_VIRTUAL_OFFSET != 0);
+
+void __weak free_screen_info(struct screen_info *si)
+{
+}
+
+static struct screen_info *setup_graphics(void)
+{
+	efi_guid_t gop_proto = EFI_GRAPHICS_OUTPUT_PROTOCOL_GUID;
+	efi_status_t status;
+	unsigned long size;
+	void **gop_handle = NULL;
+	struct screen_info *si = NULL;
+
+	size = 0;
+	status = efi_bs_call(locate_handle, EFI_LOCATE_BY_PROTOCOL,
+			     &gop_proto, NULL, &size, gop_handle);
+	if (status == EFI_BUFFER_TOO_SMALL) {
+		si = alloc_screen_info();
+		if (!si)
+			return NULL;
+		status = efi_setup_gop(si, &gop_proto, size);
+		if (status != EFI_SUCCESS) {
+			free_screen_info(si);
+			return NULL;
+		}
+	}
+	return si;
+}
+
+static void install_memreserve_table(void)
+{
+	struct linux_efi_memreserve *rsv;
+	efi_guid_t memreserve_table_guid = LINUX_EFI_MEMRESERVE_TABLE_GUID;
+	efi_status_t status;
+
+	status = efi_bs_call(allocate_pool, EFI_LOADER_DATA, sizeof(*rsv),
+			     (void **)&rsv);
+	if (status != EFI_SUCCESS) {
+		efi_err("Failed to allocate memreserve entry!\n");
+		return;
+	}
+
+	rsv->next = 0;
+	rsv->size = 0;
+	atomic_set(&rsv->count, 0);
+
+	status = efi_bs_call(install_configuration_table,
+			     &memreserve_table_guid, rsv);
+	if (status != EFI_SUCCESS)
+		efi_err("Failed to install memreserve config table!\n");
+}
+
+static u32 get_supported_rt_services(void)
+{
+	const efi_rt_properties_table_t *rt_prop_table;
+	u32 supported = EFI_RT_SUPPORTED_ALL;
+
+	rt_prop_table = get_efi_config_table(EFI_RT_PROPERTIES_TABLE_GUID);
+	if (rt_prop_table)
+		supported &= rt_prop_table->runtime_services_supported;
+
+	return supported;
+}
+
+efi_status_t efi_handle_cmdline(efi_loaded_image_t *image, char **cmdline_ptr)
+{
+	int cmdline_size = 0;
+	efi_status_t status;
+	char *cmdline;
+
+	/*
+	 * Get the command line from EFI, using the LOADED_IMAGE
+	 * protocol. We are going to copy the command line into the
+	 * device tree, so this can be allocated anywhere.
+	 */
+	cmdline = efi_convert_cmdline(image, &cmdline_size);
+	if (!cmdline) {
+		efi_err("getting command line via LOADED_IMAGE_PROTOCOL\n");
+		return EFI_OUT_OF_RESOURCES;
+	}
+
+	if (IS_ENABLED(CONFIG_CMDLINE_EXTEND) ||
+	    IS_ENABLED(CONFIG_CMDLINE_FORCE) ||
+	    cmdline_size == 0) {
+		status = efi_parse_options(CONFIG_CMDLINE);
+		if (status != EFI_SUCCESS) {
+			efi_err("Failed to parse options\n");
+			goto fail_free_cmdline;
+		}
+	}
+
+	if (!IS_ENABLED(CONFIG_CMDLINE_FORCE) && cmdline_size > 0) {
+		status = efi_parse_options(cmdline);
+		if (status != EFI_SUCCESS) {
+			efi_err("Failed to parse options\n");
+			goto fail_free_cmdline;
+		}
+	}
+
+	*cmdline_ptr = cmdline;
+	return EFI_SUCCESS;
+
+fail_free_cmdline:
+	efi_bs_call(free_pool, cmdline_ptr);
+	return status;
+}
+
+efi_status_t efi_stub_common(efi_handle_t handle,
+			     efi_loaded_image_t *image,
+			     unsigned long image_addr,
+			     char *cmdline_ptr)
+{
+	struct screen_info *si;
+	efi_status_t status;
+
+	status = check_platform_features();
+	if (status != EFI_SUCCESS)
+		return status;
+
+	si = setup_graphics();
+
+	efi_retrieve_tpm2_eventlog();
+
+	/* Ask the firmware to clear memory on unclean shutdown */
+	efi_enable_reset_attack_mitigation();
+
+	efi_load_initrd(image, ULONG_MAX, efi_get_max_initrd_addr(image_addr),
+			NULL);
+
+	efi_random_get_seed();
+
+	/* force efi_novamap if SetVirtualAddressMap() is unsupported */
+	efi_novamap |= !(get_supported_rt_services() &
+			 EFI_RT_SUPPORTED_SET_VIRTUAL_ADDRESS_MAP);
+
+	install_memreserve_table();
+
+	status = efi_boot_kernel(handle, image, image_addr, cmdline_ptr);
+
+	free_screen_info(si);
+	return status;
+}
+
+/*
+ * efi_allocate_virtmap() - create a pool allocation for the virtmap
+ *
+ * Create an allocation that is of sufficient size to hold all the memory
+ * descriptors that will be passed to SetVirtualAddressMap() to inform the
+ * firmware about the virtual mapping that will be used under the OS to call
+ * into the firmware.
+ */
+efi_status_t efi_alloc_virtmap(efi_memory_desc_t **virtmap,
+			       unsigned long *desc_size, u32 *desc_ver)
+{
+	unsigned long size, mmap_key;
+	efi_status_t status;
+
+	/*
+	 * Use the size of the current memory map as an upper bound for the
+	 * size of the buffer we need to pass to SetVirtualAddressMap() to
+	 * cover all EFI_MEMORY_RUNTIME regions.
+	 */
+	size = 0;
+	status = efi_bs_call(get_memory_map, &size, NULL, &mmap_key, desc_size,
+			     desc_ver);
+	if (status != EFI_BUFFER_TOO_SMALL)
+		return EFI_LOAD_ERROR;
+
+	return efi_bs_call(allocate_pool, EFI_LOADER_DATA, size,
+			   (void **)virtmap);
+}
+
+/*
+ * efi_get_virtmap() - create a virtual mapping for the EFI memory map
+ *
+ * This function populates the virt_addr fields of all memory region descriptors
+ * in @memory_map whose EFI_MEMORY_RUNTIME attribute is set. Those descriptors
+ * are also copied to @runtime_map, and their total count is returned in @count.
+ */
+void efi_get_virtmap(efi_memory_desc_t *memory_map, unsigned long map_size,
+		     unsigned long desc_size, efi_memory_desc_t *runtime_map,
+		     int *count)
+{
+	u64 efi_virt_base = virtmap_base;
+	efi_memory_desc_t *in, *out = runtime_map;
+	int l;
+
+	*count = 0;
+
+	for (l = 0; l < map_size; l += desc_size) {
+		u64 paddr, size;
+
+		in = (void *)memory_map + l;
+		if (!(in->attribute & EFI_MEMORY_RUNTIME))
+			continue;
+
+		paddr = in->phys_addr;
+		size = in->num_pages * EFI_PAGE_SIZE;
+
+		in->virt_addr = in->phys_addr + EFI_RT_VIRTUAL_OFFSET;
+		if (efi_novamap) {
+			continue;
+		}
+
+		/*
+		 * Make the mapping compatible with 64k pages: this allows
+		 * a 4k page size kernel to kexec a 64k page size kernel and
+		 * vice versa.
+		 */
+		if (!flat_va_mapping) {
+
+			paddr = round_down(in->phys_addr, SZ_64K);
+			size += in->phys_addr - paddr;
+
+			/*
+			 * Avoid wasting memory on PTEs by choosing a virtual
+			 * base that is compatible with section mappings if this
+			 * region has the appropriate size and physical
+			 * alignment. (Sections are 2 MB on 4k granule kernels)
+			 */
+			if (IS_ALIGNED(in->phys_addr, SZ_2M) && size >= SZ_2M)
+				efi_virt_base = round_up(efi_virt_base, SZ_2M);
+			else
+				efi_virt_base = round_up(efi_virt_base, SZ_64K);
+
+			in->virt_addr += efi_virt_base - paddr;
+			efi_virt_base += size;
+		}
+
+		memcpy(out, in, desc_size);
+		out = (void *)out + desc_size;
+		++*count;
+	}
+}