efi/loongarch: Directly position the loaded image file

The use of the 'kernel_offset' variable to position the image file that
has been loaded by UEFI or GRUB is unnecessary, because we can directly
position the loaded image file through using the image_base field of the
efi_loaded_image struct provided by UEFI.

Replace kernel_offset with image_base to position the image file that has
been loaded by UEFI or GRUB.
Signed-off-by: Wang Yao <wangyao@lemote.com>
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>

arch/loongarch/include/asm/efi.h

@@ -32,6 +32,4 @@ static inline unsigned long efi_get_kimg_min_align(void)
 
 #define EFI_KIMG_PREFERRED_ADDRESS	PHYSADDR(VMLINUX_LOAD_ADDRESS)
 
-unsigned long kernel_entry_address(unsigned long kernel_addr);
-
 #endif /* _ASM_LOONGARCH_EFI_H */

arch/loongarch/kernel/head.S

@@ -34,7 +34,6 @@ pe_header:
 
 SYM_DATA(kernel_asize, .long _kernel_asize);
 SYM_DATA(kernel_fsize, .long _kernel_fsize);
-SYM_DATA(kernel_offset, .long _kernel_offset);
 
 #endif
 

arch/loongarch/kernel/image-vars.h

@@ -11,7 +11,6 @@ __efistub_strcmp		= strcmp;
 __efistub_kernel_entry		= kernel_entry;
 __efistub_kernel_asize		= kernel_asize;
 __efistub_kernel_fsize		= kernel_fsize;
-__efistub_kernel_offset		= kernel_offset;
 #if defined(CONFIG_EFI_EARLYCON) || defined(CONFIG_SYSFB)
 __efistub_screen_info		= screen_info;
 #endif

arch/loongarch/kernel/vmlinux.lds.S

@@ -143,7 +143,6 @@ SECTIONS
 	_kernel_fsize = _edata - _text;
 	_kernel_vsize = _end - __initdata_begin;
 	_kernel_rsize = _edata - __initdata_begin;
-	_kernel_offset = kernel_offset - _text;
 #endif
 
 	.gptab.sdata : {

drivers/firmware/efi/libstub/loongarch-stub.c

@@ -8,10 +8,10 @@
 #include <asm/efi.h>
 #include <asm/addrspace.h>
 #include "efistub.h"
+#include "loongarch-stub.h"
 
 extern int kernel_asize;
 extern int kernel_fsize;
-extern int kernel_offset;
 extern int kernel_entry;
 
 efi_status_t handle_kernel_image(unsigned long *image_addr,
@@ -24,7 +24,7 @@ efi_status_t handle_kernel_image(unsigned long *image_addr,
 	efi_status_t status;
 	unsigned long kernel_addr = 0;
 
-	kernel_addr = (unsigned long)&kernel_offset - kernel_offset;
+	kernel_addr = (unsigned long)image->image_base;
 
 	status = efi_relocate_kernel(&kernel_addr, kernel_fsize, kernel_asize,
 		     EFI_KIMG_PREFERRED_ADDRESS, efi_get_kimg_min_align(), 0x0);
@@ -35,9 +35,10 @@ efi_status_t handle_kernel_image(unsigned long *image_addr,
 	return status;
 }
 
-unsigned long kernel_entry_address(unsigned long kernel_addr)
+unsigned long kernel_entry_address(unsigned long kernel_addr,
+		efi_loaded_image_t *image)
 {
-	unsigned long base = (unsigned long)&kernel_offset - kernel_offset;
+	unsigned long base = (unsigned long)image->image_base;
 
 	return (unsigned long)&kernel_entry - base + kernel_addr;
 }

drivers/firmware/efi/libstub/loongarch-stub.h

+/* SPDX-License-Identifier: GPL-2.0-only */
+
+unsigned long kernel_entry_address(unsigned long kernel_addr,
+		efi_loaded_image_t *image);

drivers/firmware/efi/libstub/loongarch.c

@@ -8,6 +8,7 @@
 #include <asm/efi.h>
 #include <asm/addrspace.h>
 #include "efistub.h"
+#include "loongarch-stub.h"
 
 typedef void __noreturn (*kernel_entry_t)(bool efi, unsigned long cmdline,
 					  unsigned long systab);
@@ -37,7 +38,8 @@ static efi_status_t exit_boot_func(struct efi_boot_memmap *map, void *priv)
 	return EFI_SUCCESS;
 }
 
-unsigned long __weak kernel_entry_address(unsigned long kernel_addr)
+unsigned long __weak kernel_entry_address(unsigned long kernel_addr,
+		efi_loaded_image_t *image)
 {
 	return *(unsigned long *)(kernel_addr + 8) - VMLINUX_LOAD_ADDRESS + kernel_addr;
 }
@@ -73,7 +75,7 @@ efi_status_t efi_boot_kernel(void *handle, efi_loaded_image_t *image,
 	csr_write64(CSR_DMW0_INIT, LOONGARCH_CSR_DMWIN0);
 	csr_write64(CSR_DMW1_INIT, LOONGARCH_CSR_DMWIN1);
 
-	real_kernel_entry = (void *)kernel_entry_address(kernel_addr);
+	real_kernel_entry = (void *)kernel_entry_address(kernel_addr, image);
 
 	real_kernel_entry(true, (unsigned long)cmdline_ptr,
 			  (unsigned long)efi_system_table);