hibernate-asm.S
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/*
* Hibernate low-level support
*
* Copyright (C) 2016 ARM Ltd.
* Author: James Morse <james.morse@arm.com>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
#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>
/*
* To prevent the possibility of old and new partial table walks being visible
* in the tlb, switch the ttbr to a zero page when we invalidate the old
* records. D4.7.1 'General TLB maintenance requirements' in ARM DDI 0487A.i
* Even switching to our copied tables will cause a changed output address at
* each stage of the walk.
*/
.macro break_before_make_ttbr_switch zero_page, page_table
msr ttbr1_el1, \zero_page
isb
tlbi vmalle1
dsb nsh
msr ttbr1_el1, \page_table
isb
.endm
/*
* 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 flush_icache_range() 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"
ENTRY(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
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 flush_icache_range() */
raw_dcache_line_size x2, x3
sub x3, x2, #1
bic x4, x10, x3
2: dc cvau, x4 /* clean D line / unified line */
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
ic ialluis
dsb ish
isb
cbz x24, 3f /* Do we need to re-initialise EL2? */
hvc #0
3: ret
.ltorg
ENDPROC(swsusp_arch_suspend_exit)
/*
* Restore the hyp stub.
* This must be done before the hibernate page is unmapped by _cpu_resume(),
* but happens before any of the hyp-stub's code is cleaned to PoC.
*
* x24: The physical address of __hyp_stub_vectors
*/
el1_sync:
msr vbar_el2, x24
eret
ENDPROC(el1_sync)
.macro invalid_vector label
\label:
b \label
ENDPROC(\label)
.endm
invalid_vector el2_sync_invalid
invalid_vector el2_irq_invalid
invalid_vector el2_fiq_invalid
invalid_vector el2_error_invalid
invalid_vector el1_sync_invalid
invalid_vector el1_irq_invalid
invalid_vector el1_fiq_invalid
invalid_vector el1_error_invalid
/* el2 vectors - switch el2 here while we restore the memory image. */
.align 11
ENTRY(hibernate_el2_vectors)
ventry el2_sync_invalid // Synchronous EL2t
ventry el2_irq_invalid // IRQ EL2t
ventry el2_fiq_invalid // FIQ EL2t
ventry el2_error_invalid // Error EL2t
ventry el2_sync_invalid // Synchronous EL2h
ventry el2_irq_invalid // IRQ EL2h
ventry el2_fiq_invalid // FIQ EL2h
ventry el2_error_invalid // Error EL2h
ventry el1_sync // Synchronous 64-bit EL1
ventry el1_irq_invalid // IRQ 64-bit EL1
ventry el1_fiq_invalid // FIQ 64-bit EL1
ventry el1_error_invalid // Error 64-bit EL1
ventry el1_sync_invalid // Synchronous 32-bit EL1
ventry el1_irq_invalid // IRQ 32-bit EL1
ventry el1_fiq_invalid // FIQ 32-bit EL1
ventry el1_error_invalid // Error 32-bit EL1
END(hibernate_el2_vectors)
.popsection