efistub: LoongArch: Reimplement kernel_entry_address()

When EFI_KIMG_PREFERRED_ADDRESS is not equal to PHYS_LINK_KADDR, we
should not jump to the link address but the actual load address, so
fix the processing of kernel_entry_address().

Signed-off-by: Youling Tang <tangyouling@loongson.cn>

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(void);
-
 #endif /* _ASM_LOONGARCH_EFI_H */

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

@@ -44,10 +44,3 @@ efi_status_t handle_kernel_image(unsigned long *image_addr,
 
 	return status;
 }
-
-unsigned long kernel_entry_address(void)
-{
-	unsigned long base = (unsigned long)&kernel_offset - kernel_offset;
-
-	return (unsigned long)&kernel_entry - base + VMLINUX_LOAD_ADDRESS;
-}

drivers/firmware/efi/libstub/loongarch.c

@@ -37,9 +37,19 @@ static efi_status_t exit_boot_func(struct efi_boot_memmap *map, void *priv)
 	return EFI_SUCCESS;
 }
 
-unsigned long __weak kernel_entry_address(void)
+/*
+ * Get the offset of EFI_KIMG_PREFERRED_ADDRESS relative to the physical
+ * link address.
+ */
+static long get_kernel_offset(void)
+{
+	return EFI_KIMG_PREFERRED_ADDRESS - PHYS_LINK_KADDR;
+}
+
+unsigned long kernel_entry_address(void)
 {
-	return *(unsigned long *)(PHYSADDR(VMLINUX_LOAD_ADDRESS) + 8);
+	return *(unsigned long *)(EFI_KIMG_PREFERRED_ADDRESS + 8) +
+		get_kernel_offset();
 }
 
 efi_status_t efi_boot_kernel(void *handle, efi_loaded_image_t *image,