1 /* SPDX-License-Identifier: GPL-2.0 */ 2 /* 3 * EFI call stub for IA32. 4 * 5 * This stub allows us to make EFI calls in physical mode with interrupts 6 * turned off. 7 */ 8 9 #include <linux/linkage.h> 10 #include <linux/init.h> 11 #include <asm/asm-offsets.h> 12 #include <asm/page_types.h> 13 14 __INIT 15 SYM_FUNC_START(efi_call_svam) 16 push %ebp 17 movl %esp, %ebp 18 push %ebx 19 20 push 16(%esp) 21 push 16(%esp) 22 push %ecx 23 push %edx 24 movl %eax, %ebx // &systab_phys->runtime 25 26 /* 27 * Switch to the flat mapped alias of this routine, by jumping to the 28 * address of label '1' after subtracting PAGE_OFFSET from it. 29 */ 30 movl $1f, %edx 31 subl $__PAGE_OFFSET, %edx 32 jmp *%edx 33 1: 34 35 /* disable paging */ 36 movl %cr0, %edx 37 andl $0x7fffffff, %edx 38 movl %edx, %cr0 39 40 /* convert the stack pointer to a flat mapped address */ 41 subl $__PAGE_OFFSET, %esp 42 43 /* call the EFI routine */ 44 movl (%eax), %eax 45 call *EFI_svam(%eax) 46 47 /* grab the virtually remapped EFI runtime services table pointer */ 48 movl (%ebx), %ecx 49 movl 36(%esp), %edx // &efi.runtime 50 movl %ecx, (%edx) 51 52 /* re-enable paging */ 53 movl %cr0, %edx 54 orl $0x80000000, %edx 55 movl %edx, %cr0 56 57 movl 16(%esp), %ebx 58 leave 59 RET 60 SYM_FUNC_END(efi_call_svam) 61