3 files changed, 106 insertions, 75 deletions

diff --git a/drivers/firmware/efi/libstub/Makefile b/drivers/firmware/efi/libstub/Makefile
index ea96405bfd31..5ec0635b4987 100644
--- a/drivers/firmware/efi/libstub/Makefile
+++ b/drivers/firmware/efi/libstub/Makefile
@@ -88,7 +88,7 @@ lib-$(CONFIG_EFI_GENERIC_STUB)	+= efi-stub.o string.o intrinsics.o systable.o \
 lib-$(CONFIG_ARM)		+= arm32-stub.o
 lib-$(CONFIG_ARM64)		+= arm64-stub.o arm64-entry.o
 lib-$(CONFIG_X86)		+= x86-stub.o
-lib-$(CONFIG_RISCV)		+= riscv-stub.o
+lib-$(CONFIG_RISCV)		+= riscv.o riscv-stub.o
 lib-$(CONFIG_LOONGARCH)		+= loongarch-stub.o
 
 CFLAGS_arm32-stub.o		:= -DTEXT_OFFSET=$(TEXT_OFFSET)
diff --git a/drivers/firmware/efi/libstub/riscv-stub.c b/drivers/firmware/efi/libstub/riscv-stub.c
index c5a551f69a7f..145c9f0ba217 100644
--- a/drivers/firmware/efi/libstub/riscv-stub.c
+++ b/drivers/firmware/efi/libstub/riscv-stub.c
@@ -4,7 +4,6 @@
  */
 
 #include <linux/efi.h>
-#include <linux/libfdt.h>
 
 #include <asm/efi.h>
 #include <asm/sections.h>
@@ -12,82 +11,16 @@
 
 #include "efistub.h"
 
-typedef void __noreturn (*jump_kernel_func)(unsigned long, unsigned long);
-
-static unsigned long hartid;
-
-static int get_boot_hartid_from_fdt(void)
-{
-	const void *fdt;
-	int chosen_node, len;
-	const void *prop;
-
-	fdt = get_efi_config_table(DEVICE_TREE_GUID);
-	if (!fdt)
-		return -EINVAL;
-
-	chosen_node = fdt_path_offset(fdt, "/chosen");
-	if (chosen_node < 0)
-		return -EINVAL;
-
-	prop = fdt_getprop((void *)fdt, chosen_node, "boot-hartid", &len);
-	if (!prop)
-		return -EINVAL;
-
-	if (len == sizeof(u32))
-		hartid = (unsigned long) fdt32_to_cpu(*(fdt32_t *)prop);
-	else if (len == sizeof(u64))
-		hartid = (unsigned long) fdt64_to_cpu(__get_unaligned_t(fdt64_t, prop));
-	else
-		return -EINVAL;
-
-	return 0;
-}
-
-static efi_status_t get_boot_hartid_from_efi(void)
+unsigned long stext_offset(void)
 {
-	efi_guid_t boot_protocol_guid = RISCV_EFI_BOOT_PROTOCOL_GUID;
-	struct riscv_efi_boot_protocol *boot_protocol;
-	efi_status_t status;
-
-	status = efi_bs_call(locate_protocol, &boot_protocol_guid, NULL,
-			     (void **)&boot_protocol);
-	if (status != EFI_SUCCESS)
-		return status;
-	return efi_call_proto(boot_protocol, get_boot_hartid, &hartid);
-}
-
-efi_status_t check_platform_features(void)
-{
-	efi_status_t status;
-	int ret;
-
-	status = get_boot_hartid_from_efi();
-	if (status != EFI_SUCCESS) {
-		ret = get_boot_hartid_from_fdt();
-		if (ret) {
-			efi_err("Failed to get boot hartid!\n");
-			return EFI_UNSUPPORTED;
-		}
-	}
-	return EFI_SUCCESS;
-}
-
-void __noreturn efi_enter_kernel(unsigned long entrypoint, unsigned long fdt,
-				 unsigned long fdt_size)
-{
-	unsigned long stext_offset = _start_kernel - _start;
-	unsigned long kernel_entry = entrypoint + stext_offset;
-	jump_kernel_func jump_kernel = (jump_kernel_func)kernel_entry;
-
 	/*
-	 * Jump to real kernel here with following constraints.
-	 * 1. MMU should be disabled.
-	 * 2. a0 should contain hartid
-	 * 3. a1 should DT address
+	 * When built as part of the kernel, the EFI stub cannot branch to the
+	 * kernel proper via the image header, as the PE/COFF header is
+	 * strictly not part of the in-memory presentation of the image, only
+	 * of the file representation. So instead, we need to jump to the
+	 * actual entrypoint in the .text region of the image.
 	 */
-	csr_write(CSR_SATP, 0);
-	jump_kernel(hartid, fdt);
+	return _start_kernel - _start;
 }
 
 efi_status_t handle_kernel_image(unsigned long *image_addr,
diff --git a/drivers/firmware/efi/libstub/riscv.c b/drivers/firmware/efi/libstub/riscv.c
new file mode 100644
index 000000000000..8022b104c3e6
--- /dev/null
+++ b/drivers/firmware/efi/libstub/riscv.c
@@ -0,0 +1,98 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2020 Western Digital Corporation or its affiliates.
+ */
+
+#include <linux/efi.h>
+#include <linux/libfdt.h>
+
+#include <asm/efi.h>
+#include <asm/unaligned.h>
+
+#include "efistub.h"
+
+typedef void __noreturn (*jump_kernel_func)(unsigned long, unsigned long);
+
+static unsigned long hartid;
+
+static int get_boot_hartid_from_fdt(void)
+{
+	const void *fdt;
+	int chosen_node, len;
+	const void *prop;
+
+	fdt = get_efi_config_table(DEVICE_TREE_GUID);
+	if (!fdt)
+		return -EINVAL;
+
+	chosen_node = fdt_path_offset(fdt, "/chosen");
+	if (chosen_node < 0)
+		return -EINVAL;
+
+	prop = fdt_getprop((void *)fdt, chosen_node, "boot-hartid", &len);
+	if (!prop)
+		return -EINVAL;
+
+	if (len == sizeof(u32))
+		hartid = (unsigned long) fdt32_to_cpu(*(fdt32_t *)prop);
+	else if (len == sizeof(u64))
+		hartid = (unsigned long) fdt64_to_cpu(__get_unaligned_t(fdt64_t, prop));
+	else
+		return -EINVAL;
+
+	return 0;
+}
+
+static efi_status_t get_boot_hartid_from_efi(void)
+{
+	efi_guid_t boot_protocol_guid = RISCV_EFI_BOOT_PROTOCOL_GUID;
+	struct riscv_efi_boot_protocol *boot_protocol;
+	efi_status_t status;
+
+	status = efi_bs_call(locate_protocol, &boot_protocol_guid, NULL,
+			     (void **)&boot_protocol);
+	if (status != EFI_SUCCESS)
+		return status;
+	return efi_call_proto(boot_protocol, get_boot_hartid, &hartid);
+}
+
+efi_status_t check_platform_features(void)
+{
+	efi_status_t status;
+	int ret;
+
+	status = get_boot_hartid_from_efi();
+	if (status != EFI_SUCCESS) {
+		ret = get_boot_hartid_from_fdt();
+		if (ret) {
+			efi_err("Failed to get boot hartid!\n");
+			return EFI_UNSUPPORTED;
+		}
+	}
+	return EFI_SUCCESS;
+}
+
+unsigned long __weak stext_offset(void)
+{
+	/*
+	 * This fallback definition is used by the EFI zboot stub, which loads
+	 * the entire image so it can branch via the image header at offset #0.
+	 */
+	return 0;
+}
+
+void __noreturn efi_enter_kernel(unsigned long entrypoint, unsigned long fdt,
+				 unsigned long fdt_size)
+{
+	unsigned long kernel_entry = entrypoint + stext_offset();
+	jump_kernel_func jump_kernel = (jump_kernel_func)kernel_entry;
+
+	/*
+	 * Jump to real kernel here with following constraints.
+	 * 1. MMU should be disabled.
+	 * 2. a0 should contain hartid
+	 * 3. a1 should DT address
+	 */
+	csr_write(CSR_SATP, 0);
+	jump_kernel(hartid, fdt);
+}