/* SPDX-License-Identifier: GPL-2.0 */
/*
 * This may not use any stack, nor any variable that is not "NoSave":
 *
 * Its rewriting one kernel image with another. What is stack in "old"
 * image could very well be data page in "new" image, and overwriting
 * your own stack under you is bad idea.
 */

#include <linux/linkage.h>
#include <asm/segment.h>
#include <asm/page_types.h>
#include <asm/asm-offsets.h>
#include <asm/processor-flags.h>
#include <asm/frame.h>

.text

SYM_FUNC_START(swsusp_arch_suspend)
        movl %esp, saved_context_esp
        movl %ebx, saved_context_ebx
        movl %ebp, saved_context_ebp
        movl %esi, saved_context_esi
        movl %edi, saved_context_edi
        pushfl
        popl saved_context_eflags

        /* save cr3 */
        movl    %cr3, %eax
        movl    %eax, restore_cr3

        FRAME_BEGIN
        call swsusp_save
        FRAME_END
        RET
SYM_FUNC_END(swsusp_arch_suspend)

SYM_CODE_START(restore_image)
        /* prepare to jump to the image kernel */
        movl    restore_jump_address, %ebx
        movl    restore_cr3, %ebp

        movl    mmu_cr4_features, %ecx

        /* jump to relocated restore code */
        movl    relocated_restore_code, %eax
        jmpl    *%eax
SYM_CODE_END(restore_image)

/* code below has been relocated to a safe page */
SYM_CODE_START(core_restore_code)
        movl    temp_pgt, %eax
        movl    %eax, %cr3

        jecxz   1f      # cr4 Pentium and higher, skip if zero
        andl    $~(X86_CR4_PGE), %ecx
        movl    %ecx, %cr4;  # turn off PGE
        movl    %cr3, %eax;  # flush TLB
        movl    %eax, %cr3
1:
        movl    restore_pblist, %edx
        .p2align 4,,7

copy_loop:
        testl   %edx, %edx
        jz      done

        movl    pbe_address(%edx), %esi
        movl    pbe_orig_address(%edx), %edi

        movl    $(PAGE_SIZE >> 2), %ecx
        rep movsl

        movl    pbe_next(%edx), %edx
        jmp     copy_loop
        .p2align 4,,7

done:
        jmpl    *%ebx
SYM_CODE_END(core_restore_code)

        /* code below belongs to the image kernel */
        .align PAGE_SIZE
SYM_FUNC_START(restore_registers)
        /* go back to the original page tables */
        movl    %ebp, %cr3
        movl    mmu_cr4_features, %ecx
        jecxz   1f      # cr4 Pentium and higher, skip if zero
        movl    %ecx, %cr4;  # turn PGE back on
1:

        movl saved_context_esp, %esp
        movl saved_context_ebp, %ebp
        movl saved_context_ebx, %ebx
        movl saved_context_esi, %esi
        movl saved_context_edi, %edi

        pushl saved_context_eflags
        popfl

        /* Saved in save_processor_state. */
        movl $saved_context, %eax
        lgdt saved_context_gdt_desc(%eax)

        xorl    %eax, %eax

        /* tell the hibernation core that we've just restored the memory */
        movl    %eax, in_suspend

        RET
SYM_FUNC_END(restore_registers)