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Diffstat (limited to 'arch/arm64/kernel/hibernate-asm.S')
| -rw-r--r-- | arch/arm64/kernel/hibernate-asm.S | 178 |
1 files changed, 178 insertions, 0 deletions
diff --git a/arch/arm64/kernel/hibernate-asm.S b/arch/arm64/kernel/hibernate-asm.S new file mode 100644 index 000000000..dd14ab8c9 --- /dev/null +++ b/arch/arm64/kernel/hibernate-asm.S @@ -0,0 +1,178 @@ +/* + * 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, tmp + phys_to_ttbr \tmp, \zero_page + msr ttbr1_el1, \tmp + isb + tlbi vmalle1 + dsb nsh + phys_to_ttbr \tmp, \page_table + msr ttbr1_el1, \tmp + 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, x6 + + 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, x6 + + 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 |