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20794545c1
This reverts commit e5b8d92189
.
Pages mapped in user-space with PROT_MTE have the allocation tags either
zeroed or copied/restored to some user values. In order for the kernel
to access such pages via page_address(), resetting the tag in
page->flags was necessary. This tag resetting was deferred to
set_pte_at() -> mte_sync_page_tags() but it can race with another CPU
reading the flags (via page_to_virt()):
P0 (mte_sync_page_tags): P1 (memcpy from virt_to_page):
Rflags!=0xff
Wflags=0xff
DMB (doesn't help)
Wtags=0
Rtags=0 // fault
Since now the post_alloc_hook() function resets the page->flags tag when
unpoisoning is skipped for user pages (including the __GFP_ZEROTAGS
case), revert the arm64 commit calling page_kasan_tag_reset().
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will@kernel.org>
Cc: Vincenzo Frascino <vincenzo.frascino@arm.com>
Cc: Andrey Konovalov <andreyknvl@gmail.com>
Cc: Peter Collingbourne <pcc@google.com>
Reviewed-by: Vincenzo Frascino <vincenzo.frascino@arm.com>
Acked-by: Andrey Konovalov <andreyknvl@gmail.com>
Link: https://lore.kernel.org/r/20220610152141.2148929-5-catalin.marinas@arm.com
Signed-off-by: Will Deacon <will@kernel.org>
479 lines
11 KiB
C
479 lines
11 KiB
C
// SPDX-License-Identifier: GPL-2.0-only
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/*:
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* Hibernate support specific for ARM64
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*
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* Derived from work on ARM hibernation support by:
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*
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* Ubuntu project, hibernation support for mach-dove
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* Copyright (C) 2010 Nokia Corporation (Hiroshi Doyu)
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* Copyright (C) 2010 Texas Instruments, Inc. (Teerth Reddy et al.)
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* Copyright (C) 2006 Rafael J. Wysocki <rjw@sisk.pl>
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*/
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#define pr_fmt(x) "hibernate: " x
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#include <linux/cpu.h>
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#include <linux/kvm_host.h>
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#include <linux/pm.h>
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#include <linux/sched.h>
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#include <linux/suspend.h>
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#include <linux/utsname.h>
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#include <asm/barrier.h>
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#include <asm/cacheflush.h>
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#include <asm/cputype.h>
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#include <asm/daifflags.h>
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#include <asm/irqflags.h>
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#include <asm/kexec.h>
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#include <asm/memory.h>
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#include <asm/mmu_context.h>
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#include <asm/mte.h>
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#include <asm/sections.h>
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#include <asm/smp.h>
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#include <asm/smp_plat.h>
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#include <asm/suspend.h>
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#include <asm/sysreg.h>
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#include <asm/trans_pgd.h>
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#include <asm/virt.h>
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/*
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* Hibernate core relies on this value being 0 on resume, and marks it
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* __nosavedata assuming it will keep the resume kernel's '0' value. This
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* doesn't happen with either KASLR.
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*
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* defined as "__visible int in_suspend __nosavedata" in
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* kernel/power/hibernate.c
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*/
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extern int in_suspend;
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/* Do we need to reset el2? */
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#define el2_reset_needed() (is_hyp_nvhe())
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/* hyp-stub vectors, used to restore el2 during resume from hibernate. */
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extern char __hyp_stub_vectors[];
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/*
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* The logical cpu number we should resume on, initialised to a non-cpu
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* number.
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*/
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static int sleep_cpu = -EINVAL;
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/*
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* Values that may not change over hibernate/resume. We put the build number
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* and date in here so that we guarantee not to resume with a different
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* kernel.
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*/
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struct arch_hibernate_hdr_invariants {
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char uts_version[__NEW_UTS_LEN + 1];
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};
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/* These values need to be know across a hibernate/restore. */
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static struct arch_hibernate_hdr {
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struct arch_hibernate_hdr_invariants invariants;
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/* These are needed to find the relocated kernel if built with kaslr */
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phys_addr_t ttbr1_el1;
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void (*reenter_kernel)(void);
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/*
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* We need to know where the __hyp_stub_vectors are after restore to
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* re-configure el2.
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*/
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phys_addr_t __hyp_stub_vectors;
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u64 sleep_cpu_mpidr;
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} resume_hdr;
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static inline void arch_hdr_invariants(struct arch_hibernate_hdr_invariants *i)
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{
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memset(i, 0, sizeof(*i));
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memcpy(i->uts_version, init_utsname()->version, sizeof(i->uts_version));
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}
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int pfn_is_nosave(unsigned long pfn)
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{
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unsigned long nosave_begin_pfn = sym_to_pfn(&__nosave_begin);
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unsigned long nosave_end_pfn = sym_to_pfn(&__nosave_end - 1);
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return ((pfn >= nosave_begin_pfn) && (pfn <= nosave_end_pfn)) ||
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crash_is_nosave(pfn);
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}
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void notrace save_processor_state(void)
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{
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WARN_ON(num_online_cpus() != 1);
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}
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void notrace restore_processor_state(void)
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{
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}
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int arch_hibernation_header_save(void *addr, unsigned int max_size)
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{
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struct arch_hibernate_hdr *hdr = addr;
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if (max_size < sizeof(*hdr))
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return -EOVERFLOW;
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arch_hdr_invariants(&hdr->invariants);
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hdr->ttbr1_el1 = __pa_symbol(swapper_pg_dir);
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hdr->reenter_kernel = _cpu_resume;
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/* We can't use __hyp_get_vectors() because kvm may still be loaded */
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if (el2_reset_needed())
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hdr->__hyp_stub_vectors = __pa_symbol(__hyp_stub_vectors);
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else
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hdr->__hyp_stub_vectors = 0;
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/* Save the mpidr of the cpu we called cpu_suspend() on... */
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if (sleep_cpu < 0) {
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pr_err("Failing to hibernate on an unknown CPU.\n");
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return -ENODEV;
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}
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hdr->sleep_cpu_mpidr = cpu_logical_map(sleep_cpu);
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pr_info("Hibernating on CPU %d [mpidr:0x%llx]\n", sleep_cpu,
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hdr->sleep_cpu_mpidr);
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return 0;
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}
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EXPORT_SYMBOL(arch_hibernation_header_save);
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int arch_hibernation_header_restore(void *addr)
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{
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int ret;
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struct arch_hibernate_hdr_invariants invariants;
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struct arch_hibernate_hdr *hdr = addr;
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arch_hdr_invariants(&invariants);
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if (memcmp(&hdr->invariants, &invariants, sizeof(invariants))) {
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pr_crit("Hibernate image not generated by this kernel!\n");
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return -EINVAL;
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}
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sleep_cpu = get_logical_index(hdr->sleep_cpu_mpidr);
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pr_info("Hibernated on CPU %d [mpidr:0x%llx]\n", sleep_cpu,
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hdr->sleep_cpu_mpidr);
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if (sleep_cpu < 0) {
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pr_crit("Hibernated on a CPU not known to this kernel!\n");
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sleep_cpu = -EINVAL;
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return -EINVAL;
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}
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ret = bringup_hibernate_cpu(sleep_cpu);
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if (ret) {
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sleep_cpu = -EINVAL;
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return ret;
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}
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resume_hdr = *hdr;
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return 0;
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}
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EXPORT_SYMBOL(arch_hibernation_header_restore);
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static void *hibernate_page_alloc(void *arg)
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{
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return (void *)get_safe_page((__force gfp_t)(unsigned long)arg);
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}
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/*
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* Copies length bytes, starting at src_start into an new page,
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* perform cache maintenance, then maps it at the specified address low
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* address as executable.
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*
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* This is used by hibernate to copy the code it needs to execute when
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* overwriting the kernel text. This function generates a new set of page
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* tables, which it loads into ttbr0.
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*
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* Length is provided as we probably only want 4K of data, even on a 64K
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* page system.
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*/
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static int create_safe_exec_page(void *src_start, size_t length,
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phys_addr_t *phys_dst_addr)
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{
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struct trans_pgd_info trans_info = {
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.trans_alloc_page = hibernate_page_alloc,
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.trans_alloc_arg = (__force void *)GFP_ATOMIC,
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};
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void *page = (void *)get_safe_page(GFP_ATOMIC);
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phys_addr_t trans_ttbr0;
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unsigned long t0sz;
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int rc;
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if (!page)
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return -ENOMEM;
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memcpy(page, src_start, length);
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caches_clean_inval_pou((unsigned long)page, (unsigned long)page + length);
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rc = trans_pgd_idmap_page(&trans_info, &trans_ttbr0, &t0sz, page);
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if (rc)
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return rc;
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cpu_install_ttbr0(trans_ttbr0, t0sz);
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*phys_dst_addr = virt_to_phys(page);
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return 0;
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}
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#ifdef CONFIG_ARM64_MTE
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static DEFINE_XARRAY(mte_pages);
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static int save_tags(struct page *page, unsigned long pfn)
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{
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void *tag_storage, *ret;
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tag_storage = mte_allocate_tag_storage();
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if (!tag_storage)
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return -ENOMEM;
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mte_save_page_tags(page_address(page), tag_storage);
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ret = xa_store(&mte_pages, pfn, tag_storage, GFP_KERNEL);
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if (WARN(xa_is_err(ret), "Failed to store MTE tags")) {
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mte_free_tag_storage(tag_storage);
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return xa_err(ret);
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} else if (WARN(ret, "swsusp: %s: Duplicate entry", __func__)) {
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mte_free_tag_storage(ret);
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}
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return 0;
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}
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static void swsusp_mte_free_storage(void)
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{
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XA_STATE(xa_state, &mte_pages, 0);
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void *tags;
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xa_lock(&mte_pages);
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xas_for_each(&xa_state, tags, ULONG_MAX) {
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mte_free_tag_storage(tags);
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}
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xa_unlock(&mte_pages);
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xa_destroy(&mte_pages);
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}
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static int swsusp_mte_save_tags(void)
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{
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struct zone *zone;
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unsigned long pfn, max_zone_pfn;
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int ret = 0;
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int n = 0;
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if (!system_supports_mte())
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return 0;
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for_each_populated_zone(zone) {
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max_zone_pfn = zone_end_pfn(zone);
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for (pfn = zone->zone_start_pfn; pfn < max_zone_pfn; pfn++) {
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struct page *page = pfn_to_online_page(pfn);
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if (!page)
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continue;
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if (!test_bit(PG_mte_tagged, &page->flags))
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continue;
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ret = save_tags(page, pfn);
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if (ret) {
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swsusp_mte_free_storage();
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goto out;
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}
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n++;
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}
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}
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pr_info("Saved %d MTE pages\n", n);
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out:
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return ret;
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}
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static void swsusp_mte_restore_tags(void)
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{
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XA_STATE(xa_state, &mte_pages, 0);
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int n = 0;
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void *tags;
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xa_lock(&mte_pages);
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xas_for_each(&xa_state, tags, ULONG_MAX) {
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unsigned long pfn = xa_state.xa_index;
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struct page *page = pfn_to_online_page(pfn);
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mte_restore_page_tags(page_address(page), tags);
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mte_free_tag_storage(tags);
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n++;
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}
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xa_unlock(&mte_pages);
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pr_info("Restored %d MTE pages\n", n);
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xa_destroy(&mte_pages);
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}
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#else /* CONFIG_ARM64_MTE */
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static int swsusp_mte_save_tags(void)
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{
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return 0;
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}
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static void swsusp_mte_restore_tags(void)
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{
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}
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#endif /* CONFIG_ARM64_MTE */
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int swsusp_arch_suspend(void)
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{
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int ret = 0;
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unsigned long flags;
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struct sleep_stack_data state;
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if (cpus_are_stuck_in_kernel()) {
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pr_err("Can't hibernate: no mechanism to offline secondary CPUs.\n");
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return -EBUSY;
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}
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flags = local_daif_save();
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if (__cpu_suspend_enter(&state)) {
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/* make the crash dump kernel image visible/saveable */
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crash_prepare_suspend();
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ret = swsusp_mte_save_tags();
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if (ret)
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return ret;
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sleep_cpu = smp_processor_id();
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ret = swsusp_save();
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} else {
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/* Clean kernel core startup/idle code to PoC*/
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dcache_clean_inval_poc((unsigned long)__mmuoff_data_start,
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(unsigned long)__mmuoff_data_end);
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dcache_clean_inval_poc((unsigned long)__idmap_text_start,
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(unsigned long)__idmap_text_end);
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/* Clean kvm setup code to PoC? */
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if (el2_reset_needed()) {
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dcache_clean_inval_poc(
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(unsigned long)__hyp_idmap_text_start,
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(unsigned long)__hyp_idmap_text_end);
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dcache_clean_inval_poc((unsigned long)__hyp_text_start,
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(unsigned long)__hyp_text_end);
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}
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swsusp_mte_restore_tags();
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/* make the crash dump kernel image protected again */
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crash_post_resume();
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/*
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* Tell the hibernation core that we've just restored
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* the memory
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*/
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in_suspend = 0;
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sleep_cpu = -EINVAL;
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__cpu_suspend_exit();
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/*
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* Just in case the boot kernel did turn the SSBD
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* mitigation off behind our back, let's set the state
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* to what we expect it to be.
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*/
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spectre_v4_enable_mitigation(NULL);
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}
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local_daif_restore(flags);
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return ret;
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}
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/*
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* Setup then Resume from the hibernate image using swsusp_arch_suspend_exit().
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*
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* Memory allocated by get_safe_page() will be dealt with by the hibernate code,
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* we don't need to free it here.
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*/
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int swsusp_arch_resume(void)
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{
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int rc;
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void *zero_page;
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size_t exit_size;
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pgd_t *tmp_pg_dir;
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phys_addr_t el2_vectors;
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void __noreturn (*hibernate_exit)(phys_addr_t, phys_addr_t, void *,
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void *, phys_addr_t, phys_addr_t);
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struct trans_pgd_info trans_info = {
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.trans_alloc_page = hibernate_page_alloc,
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.trans_alloc_arg = (void *)GFP_ATOMIC,
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};
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/*
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* Restoring the memory image will overwrite the ttbr1 page tables.
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* Create a second copy of just the linear map, and use this when
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* restoring.
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*/
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rc = trans_pgd_create_copy(&trans_info, &tmp_pg_dir, PAGE_OFFSET,
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PAGE_END);
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if (rc)
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return rc;
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/*
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* We need a zero page that is zero before & after resume in order
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* to break before make on the ttbr1 page tables.
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*/
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zero_page = (void *)get_safe_page(GFP_ATOMIC);
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if (!zero_page) {
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pr_err("Failed to allocate zero page.\n");
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return -ENOMEM;
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}
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if (el2_reset_needed()) {
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rc = trans_pgd_copy_el2_vectors(&trans_info, &el2_vectors);
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if (rc) {
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pr_err("Failed to setup el2 vectors\n");
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return rc;
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}
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}
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exit_size = __hibernate_exit_text_end - __hibernate_exit_text_start;
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/*
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* Copy swsusp_arch_suspend_exit() to a safe page. This will generate
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* a new set of ttbr0 page tables and load them.
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*/
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rc = create_safe_exec_page(__hibernate_exit_text_start, exit_size,
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(phys_addr_t *)&hibernate_exit);
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if (rc) {
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pr_err("Failed to create safe executable page for hibernate_exit code.\n");
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return rc;
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}
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/*
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* KASLR will cause the el2 vectors to be in a different location in
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* the resumed kernel. Load hibernate's temporary copy into el2.
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*
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* We can skip this step if we booted at EL1, or are running with VHE.
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*/
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if (el2_reset_needed())
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__hyp_set_vectors(el2_vectors);
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hibernate_exit(virt_to_phys(tmp_pg_dir), resume_hdr.ttbr1_el1,
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resume_hdr.reenter_kernel, restore_pblist,
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resume_hdr.__hyp_stub_vectors, virt_to_phys(zero_page));
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return 0;
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}
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int hibernate_resume_nonboot_cpu_disable(void)
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{
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if (sleep_cpu < 0) {
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pr_err("Failing to resume from hibernate on an unknown CPU.\n");
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return -ENODEV;
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}
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return freeze_secondary_cpus(sleep_cpu);
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}
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