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/* SPDX-License-Identifier: GPL-2.0-only */
/*
* Hibernate low-level support
*
* Copyright (C) 2016 ARM Ltd.
* Author: James Morse <james.morse@arm.com>
*/
#include <linux/linkage.h>
#include <linux/errno.h>
#include <asm/asm-offsets.h>
#include <asm/assembler.h>
#include <asm/cputype.h>
#include <asm/memory.h>
#include <asm/page.h>
#include <asm/virt.h>
/*
* Resume from hibernate
*
* Loads temporary page tables then restores the memory image.
* Finally branches to cpu_resume() to restore the state saved by
* swsusp_arch_suspend().
*
* Because this code has to be copied to a 'safe' page, it can't call out to
* other functions by PC-relative address. Also remember that it may be
* mid-way through over-writing other functions. For this reason it contains
* code from caches_clean_inval_pou() and uses the copy_page() macro.
*
* This 'safe' page is mapped via ttbr0, and executed from there. This function
* switches to a copy of the linear map in ttbr1, performs the restore, then
* switches ttbr1 to the original kernel's swapper_pg_dir.
*
* All of memory gets written to, including code. We need to clean the kernel
* text to the Point of Coherence (PoC) before secondary cores can be booted.
* Because the kernel modules and executable pages mapped to user space are
* also written as data, we clean all pages we touch to the Point of
* Unification (PoU).
*
* x0: physical address of temporary page tables
* x1: physical address of swapper page tables
* x2: address of cpu_resume
* x3: linear map address of restore_pblist in the current kernel
* x4: physical address of __hyp_stub_vectors, or 0
* x5: physical address of a zero page that remains zero after resume
*/
.pushsection ".hibernate_exit.text", "ax"
SYM_CODE_START(swsusp_arch_suspend_exit)
/*
* We execute from ttbr0, change ttbr1 to our copied linear map tables
* with a break-before-make via the zero page
*/
break_before_make_ttbr_switch x5, x0, x6, x8
mov x21, x1
mov x30, x2
mov x24, x4
mov x25, x5
/* walk the restore_pblist and use copy_page() to over-write memory */
mov x19, x3
1: ldr x10, [x19, #HIBERN_PBE_ORIG]
mov x0, x10
ldr x1, [x19, #HIBERN_PBE_ADDR]
copy_page x0, x1, x2, x3, x4, x5, x6, x7, x8, x9
add x1, x10, #PAGE_SIZE
/* Clean the copied page to PoU - based on caches_clean_inval_pou() */
raw_dcache_line_size x2, x3
sub x3, x2, #1
bic x4, x10, x3
2: /* clean D line / unified line */
alternative_insn "dc cvau, x4", "dc civac, x4", ARM64_WORKAROUND_CLEAN_CACHE
add x4, x4, x2
cmp x4, x1
b.lo 2b
ldr x19, [x19, #HIBERN_PBE_NEXT]
cbnz x19, 1b
dsb ish /* wait for PoU cleaning to finish */
/* switch to the restored kernels page tables */
break_before_make_ttbr_switch x25, x21, x6, x8
ic ialluis
dsb ish
isb
cbz x24, 3f /* Do we need to re-initialise EL2? */
hvc #0
3: ret
SYM_CODE_END(swsusp_arch_suspend_exit)
.popsection
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