LoongArch: Fix entry point in kernel image header

Currently kernel entry in head.S is in DMW address range, firmware is
instructed to jump to this address after loading the kernel image.

However kernel should not make any assumption on firmware's DMW
setting, thus the entry point should be a physical address falls into
direct translation region.

Fix by converting entry address to physical and amend entry calculation
logic in libstub accordingly.

BTW, use ABSOLUTE() to calculate variables to make Clang/LLVM happy.

Cc: [email protected]
Signed-off-by: Jiaxun Yang <[email protected]>
Signed-off-by: Huacai Chen <[email protected]>

Author: FlyGoat

arch/loongarch/kernel/head.S

@@ -22,7 +22,7 @@
 _head:
 	.word	MZ_MAGIC		/* "MZ", MS-DOS header */
 	.org	0x8
-	.dword	kernel_entry		/* Kernel entry point */
+	.dword	_kernel_entry		/* Kernel entry point (physical address) */
 	.dword	_kernel_asize		/* Kernel image effective size */
 	.quad	PHYS_LINK_KADDR		/* Kernel image load offset from start of RAM */
 	.org	0x38			/* 0x20 ~ 0x37 reserved */

arch/loongarch/kernel/vmlinux.lds.S

@@ -6,6 +6,7 @@
 
 #define PAGE_SIZE _PAGE_SIZE
 #define RO_EXCEPTION_TABLE_ALIGN	4
+#define PHYSADDR_MASK			0xffffffffffff /* 48-bit */
 
 /*
  * Put .bss..swapper_pg_dir as the first thing in .bss. This will
@@ -142,10 +143,11 @@ SECTIONS
 
 #ifdef CONFIG_EFI_STUB
 	/* header symbols */
-	_kernel_asize = _end - _text;
-	_kernel_fsize = _edata - _text;
-	_kernel_vsize = _end - __initdata_begin;
-	_kernel_rsize = _edata - __initdata_begin;
+	_kernel_entry = ABSOLUTE(kernel_entry & PHYSADDR_MASK);
+	_kernel_asize = ABSOLUTE(_end - _text);
+	_kernel_fsize = ABSOLUTE(_edata - _text);
+	_kernel_vsize = ABSOLUTE(_end - __initdata_begin);
+	_kernel_rsize = ABSOLUTE(_edata - __initdata_begin);
 #endif
 
 	.gptab.sdata : {

drivers/firmware/efi/libstub/loongarch.c

@@ -41,7 +41,7 @@ static efi_status_t exit_boot_func(struct efi_boot_memmap *map, void *priv)
 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;
+	return *(unsigned long *)(kernel_addr + 8) - PHYSADDR(VMLINUX_LOAD_ADDRESS) + kernel_addr;
 }
 
 efi_status_t efi_boot_kernel(void *handle, efi_loaded_image_t *image,