/* SPDX-License-Identifier: GPL-2.0-only *//* * relocate_kernel.S - put the kernel image in place to boot * Copyright (C) 2002-2004 Eric Biederman  <ebiederm@xmission.com> */ #include <linux/linkage.h>#include <asm/page_types.h>#include <asm/kexec.h>#include <asm/nospec-branch.h>#include <asm/processor-flags.h> /* * Must be relocatable PIC code callable as a C function, in particular * there must be a plain RET and not jump to return thunk. */ #define PTR(x) (x << 2) /* * control_page + KEXEC_CONTROL_CODE_MAX_SIZE * ~ control_page + PAGE_SIZE are used as data storage and stack for * jumping back */#define DATA(offset)		(KEXEC_CONTROL_CODE_MAX_SIZE+(offset)) /* Minimal CPU state */#define ESP			DATA(0x0)#define CR0			DATA(0x4)#define CR3			DATA(0x8)#define CR4			DATA(0xc) /* other data */#define CP_VA_CONTROL_PAGE	DATA(0x10)#define CP_PA_PGD		DATA(0x14)#define CP_PA_SWAP_PAGE		DATA(0x18)#define CP_PA_BACKUP_PAGES_MAP	DATA(0x1c) 	.textSYM_CODE_START_NOALIGN(relocate_kernel)	/* Save the CPU context, used for jumping back */ 	pushl	%ebx	pushl	%esi	pushl	%edi	pushl	%ebp	pushf 	movl	20+8(%esp), %ebp /* list of pages */	movl	PTR(VA_CONTROL_PAGE)(%ebp), %edi	movl	%esp, ESP(%edi)	movl	%cr0, %eax	movl	%eax, CR0(%edi)	movl	%cr3, %eax	movl	%eax, CR3(%edi)	movl	%cr4, %eax	movl	%eax, CR4(%edi) 	/* read the arguments and say goodbye to the stack */	movl  20+4(%esp), %ebx /* page_list */	movl  20+8(%esp), %ebp /* list of pages */	movl  20+12(%esp), %edx /* start address */	movl  20+16(%esp), %ecx /* cpu_has_pae */	movl  20+20(%esp), %esi /* preserve_context */ 	/* zero out flags, and disable interrupts */	pushl $0	popfl 	/* save some information for jumping back */	movl	PTR(VA_CONTROL_PAGE)(%ebp), %edi	movl	%edi, CP_VA_CONTROL_PAGE(%edi)	movl	PTR(PA_PGD)(%ebp), %eax	movl	%eax, CP_PA_PGD(%edi)	movl	PTR(PA_SWAP_PAGE)(%ebp), %eax	movl	%eax, CP_PA_SWAP_PAGE(%edi)	movl	%ebx, CP_PA_BACKUP_PAGES_MAP(%edi) 	/*	 * get physical address of control page now	 * this is impossible after page table switch	 */	movl	PTR(PA_CONTROL_PAGE)(%ebp), %edi 	/* switch to new set of page tables */	movl	PTR(PA_PGD)(%ebp), %eax	movl	%eax, %cr3 	/* setup a new stack at the end of the physical control page */	lea	PAGE_SIZE(%edi), %esp 	/* jump to identity mapped page */	movl    %edi, %eax	addl    $(identity_mapped - relocate_kernel), %eax	pushl   %eax	ANNOTATE_UNRET_SAFE	ret	int3SYM_CODE_END(relocate_kernel) SYM_CODE_START_LOCAL_NOALIGN(identity_mapped)	/* set return address to 0 if not preserving context */	pushl	$0	/* store the start address on the stack */	pushl   %edx 	/*	 * Set cr0 to a known state:	 *  - Paging disabled	 *  - Alignment check disabled	 *  - Write protect disabled	 *  - No task switch	 *  - Don't do FP software emulation.	 *  - Protected mode enabled	 */	movl	%cr0, %eax	andl	$~(X86_CR0_PG | X86_CR0_AM | X86_CR0_WP | X86_CR0_TS | X86_CR0_EM), %eax	orl	$(X86_CR0_PE), %eax	movl	%eax, %cr0 	/* clear cr4 if applicable */	testl	%ecx, %ecx	jz	1f	/*	 * Set cr4 to a known state:	 * Setting everything to zero seems safe.	 */	xorl	%eax, %eax	movl	%eax, %cr4 	jmp 1f1: 	/* Flush the TLB (needed?) */	xorl	%eax, %eax	movl	%eax, %cr3 	movl	CP_PA_SWAP_PAGE(%edi), %eax	pushl	%eax	pushl	%ebx	call	swap_pages	addl	$8, %esp 	/*	 * To be certain of avoiding problems with self-modifying code	 * I need to execute a serializing instruction here.	 * So I flush the TLB, it's handy, and not processor dependent.	 */	xorl	%eax, %eax	movl	%eax, %cr3 	/*	 * set all of the registers to known values	 * leave %esp alone	 */ 	testl	%esi, %esi	jnz 1f	xorl	%edi, %edi	xorl	%eax, %eax	xorl	%ebx, %ebx	xorl    %ecx, %ecx	xorl    %edx, %edx	xorl    %esi, %esi	xorl    %ebp, %ebp	ANNOTATE_UNRET_SAFE	ret	int31:	popl	%edx	movl	CP_PA_SWAP_PAGE(%edi), %esp	addl	$PAGE_SIZE, %esp2:	ANNOTATE_RETPOLINE_SAFE	call	*%edx 	/* get the re-entry point of the peer system */	movl	0(%esp), %ebp	call	1f1:	popl	%ebx	subl	$(1b - relocate_kernel), %ebx	movl	CP_VA_CONTROL_PAGE(%ebx), %edi	lea	PAGE_SIZE(%ebx), %esp	movl	CP_PA_SWAP_PAGE(%ebx), %eax	movl	CP_PA_BACKUP_PAGES_MAP(%ebx), %edx	pushl	%eax	pushl	%edx	call	swap_pages	addl	$8, %esp	movl	CP_PA_PGD(%ebx), %eax	movl	%eax, %cr3	movl	%cr0, %eax	orl	$X86_CR0_PG, %eax	movl	%eax, %cr0	lea	PAGE_SIZE(%edi), %esp	movl	%edi, %eax	addl	$(virtual_mapped - relocate_kernel), %eax	pushl	%eax	ANNOTATE_UNRET_SAFE	ret	int3SYM_CODE_END(identity_mapped) SYM_CODE_START_LOCAL_NOALIGN(virtual_mapped)	movl	CR4(%edi), %eax	movl	%eax, %cr4	movl	CR3(%edi), %eax	movl	%eax, %cr3	movl	CR0(%edi), %eax	movl	%eax, %cr0	movl	ESP(%edi), %esp	movl	%ebp, %eax 	popf	popl	%ebp	popl	%edi	popl	%esi	popl	%ebx	ANNOTATE_UNRET_SAFE	ret	int3SYM_CODE_END(virtual_mapped) 	/* Do the copies */SYM_CODE_START_LOCAL_NOALIGN(swap_pages)	movl	8(%esp), %edx	movl	4(%esp), %ecx	pushl	%ebp	pushl	%ebx	pushl	%edi	pushl	%esi	movl	%ecx, %ebx	jmp	1f 0:	/* top, read another word from the indirection page */	movl	(%ebx), %ecx	addl	$4, %ebx1:	testb	$0x1, %cl     /* is it a destination page */	jz	2f	movl	%ecx,	%edi	andl	$0xfffff000, %edi	jmp     0b2:	testb	$0x2, %cl    /* is it an indirection page */	jz	2f	movl	%ecx,	%ebx	andl	$0xfffff000, %ebx	jmp     0b2:	testb   $0x4, %cl    /* is it the done indicator */	jz      2f	jmp     3f2:	testb   $0x8, %cl    /* is it the source indicator */	jz      0b	     /* Ignore it otherwise */	movl    %ecx,   %esi /* For every source page do a copy */	andl    $0xfffff000, %esi 	movl	%edi, %eax	movl	%esi, %ebp 	movl	%edx, %edi	movl    $1024, %ecx	rep movsl 	movl	%ebp, %edi	movl	%eax, %esi	movl	$1024, %ecx	rep movsl 	movl	%eax, %edi	movl	%edx, %esi	movl	$1024, %ecx	rep movsl 	lea	PAGE_SIZE(%ebp), %esi	jmp     0b3:	popl	%esi	popl	%edi	popl	%ebx	popl	%ebp	ANNOTATE_UNRET_SAFE	ret	int3SYM_CODE_END(swap_pages) 	.globl kexec_control_code_size.set kexec_control_code_size, . - relocate_kernel