/* SPDX-License-Identifier: GPL-2.0-only *//* * Copyright (C) 2018 Linaro Ltd <ard.biesheuvel@linaro.org> */ #include <linux/linkage.h>#include <asm/assembler.h> SYM_FUNC_START(__efi_rt_asm_wrapper)	stp	x29, x30, [sp, #-112]!	mov	x29, sp 	/*	 * Register x18 is designated as the 'platform' register by the AAPCS,	 * which means firmware running at the same exception level as the OS	 * (such as UEFI) should never touch it.	 */	stp	x1, x18, [sp, #16] 	/*	 * Preserve all callee saved registers and preserve the stack pointer	 * value at the base of the EFI runtime stack so we can recover from	 * synchronous exceptions occurring while executing the firmware	 * routines.	 */	stp	x19, x20, [sp, #32]	stp	x21, x22, [sp, #48]	stp	x23, x24, [sp, #64]	stp	x25, x26, [sp, #80]	stp	x27, x28, [sp, #96] 	ldr_l	x16, efi_rt_stack_top	mov	sp, x16	stp	x18, x29, [sp, #-16]! 	/*	 * We are lucky enough that no EFI runtime services take more than	 * 5 arguments, so all are passed in registers rather than via the	 * stack.	 */	mov	x8, x0	mov	x0, x2	mov	x1, x3	mov	x2, x4	mov	x3, x5	mov	x4, x6	blr	x8 	mov	x16, sp	mov	sp, x29	str	xzr, [x16, #8]			// clear recorded task SP value 	ldp	x1, x2, [sp, #16]	cmp	x2, x18	ldp	x29, x30, [sp], #112	b.ne	0f	ret0:	/*	 * With CONFIG_SHADOW_CALL_STACK, the kernel uses x18 to store a	 * shadow stack pointer, which we need to restore before returning to	 * potentially instrumented code. This is safe because the wrapper is	 * called with preemption disabled and a separate shadow stack is used	 * for interrupts.	 */#ifdef CONFIG_SHADOW_CALL_STACK	ldr_l	x18, efi_rt_stack_top	ldr	x18, [x18, #-16]#endif 	b	efi_handle_corrupted_x18	// tail callSYM_FUNC_END(__efi_rt_asm_wrapper) SYM_CODE_START(__efi_rt_asm_recover)	mov	sp, x30 	ldr_l	x16, efi_rt_stack_top		// clear recorded task SP value	str	xzr, [x16, #-8] 	ldp	x19, x20, [sp, #32]	ldp	x21, x22, [sp, #48]	ldp	x23, x24, [sp, #64]	ldp	x25, x26, [sp, #80]	ldp	x27, x28, [sp, #96]	ldp	x29, x30, [sp], #112	retSYM_CODE_END(__efi_rt_asm_recover)