// SPDX-License-Identifier: GPL-2.0-only
/*:
 * Hibernate support specific for ARM64
 *
 * Derived from work on ARM hibernation support by:
 *
 * Ubuntu project, hibernation support for mach-dove
 * Copyright (C) 2010 Nokia Corporation (Hiroshi Doyu)
 * Copyright (C) 2010 Texas Instruments, Inc. (Teerth Reddy et al.)
 *  https://lkml.org/lkml/2010/6/18/4
 *  https://lists.linux-foundation.org/pipermail/linux-pm/2010-June/027422.html
 *  https://patchwork.kernel.org/patch/96442/
 *
 * Copyright (C) 2006 Rafael J. Wysocki <rjw@sisk.pl>
 */
#define pr_fmt(x) "hibernate: " x
#include <linux/cpu.h>
#include <linux/kvm_host.h>
#include <linux/pm.h>
#include <linux/sched.h>
#include <linux/suspend.h>
#include <linux/utsname.h>

#include <asm/barrier.h>
#include <asm/cacheflush.h>
#include <asm/cputype.h>
#include <asm/daifflags.h>
#include <asm/irqflags.h>
#include <asm/kexec.h>
#include <asm/memory.h>
#include <asm/mmu_context.h>
#include <asm/mte.h>
#include <asm/sections.h>
#include <asm/smp.h>
#include <asm/smp_plat.h>
#include <asm/suspend.h>
#include <asm/sysreg.h>
#include <asm/trans_pgd.h>
#include <asm/virt.h>

/*
 * Hibernate core relies on this value being 0 on resume, and marks it
 * __nosavedata assuming it will keep the resume kernel's '0' value. This
 * doesn't happen with either KASLR.
 *
 * defined as "__visible int in_suspend __nosavedata" in
 * kernel/power/hibernate.c
 */
extern int in_suspend;

/* Do we need to reset el2? */
#define el2_reset_needed() (is_hyp_mode_available() && !is_kernel_in_hyp_mode())

/* temporary el2 vectors in the __hibernate_exit_text section. */
extern char hibernate_el2_vectors[];

/* hyp-stub vectors, used to restore el2 during resume from hibernate. */
extern char __hyp_stub_vectors[];

/*
 * The logical cpu number we should resume on, initialised to a non-cpu
 * number.
 */
static int sleep_cpu = -EINVAL;

/*
 * Values that may not change over hibernate/resume. We put the build number
 * and date in here so that we guarantee not to resume with a different
 * kernel.
 */
struct arch_hibernate_hdr_invariants {
        char            uts_version[__NEW_UTS_LEN + 1];
};

/* These values need to be know across a hibernate/restore. */
static struct arch_hibernate_hdr {
        struct arch_hibernate_hdr_invariants invariants;

        /* These are needed to find the relocated kernel if built with kaslr */
        phys_addr_t     ttbr1_el1;
        void            (*reenter_kernel)(void);

        /*
         * We need to know where the __hyp_stub_vectors are after restore to
         * re-configure el2.
         */
        phys_addr_t     __hyp_stub_vectors;

        u64             sleep_cpu_mpidr;
} resume_hdr;

static inline void arch_hdr_invariants(struct arch_hibernate_hdr_invariants *i)
{
        memset(i, 0, sizeof(*i));
        memcpy(i->uts_version, init_utsname()->version, sizeof(i->uts_version));
}

int pfn_is_nosave(unsigned long pfn)
{
        unsigned long nosave_begin_pfn = sym_to_pfn(&__nosave_begin);
        unsigned long nosave_end_pfn = sym_to_pfn(&__nosave_end - 1);

        return ((pfn >= nosave_begin_pfn) && (pfn <= nosave_end_pfn)) ||
                crash_is_nosave(pfn);
}

void notrace save_processor_state(void)
{
        WARN_ON(num_online_cpus() != 1);
}

void notrace restore_processor_state(void)
{
}

int arch_hibernation_header_save(void *addr, unsigned int max_size)
{
        struct arch_hibernate_hdr *hdr = addr;

        if (max_size < sizeof(*hdr))
                return -EOVERFLOW;

        arch_hdr_invariants(&hdr->invariants);
        hdr->ttbr1_el1          = __pa_symbol(swapper_pg_dir);
        hdr->reenter_kernel     = _cpu_resume;

        /* We can't use __hyp_get_vectors() because kvm may still be loaded */
        if (el2_reset_needed())
                hdr->__hyp_stub_vectors = __pa_symbol(__hyp_stub_vectors);
        else
                hdr->__hyp_stub_vectors = 0;

        /* Save the mpidr of the cpu we called cpu_suspend() on... */
        if (sleep_cpu < 0) {
                pr_err("Failing to hibernate on an unknown CPU.\n");
                return -ENODEV;
        }
        hdr->sleep_cpu_mpidr = cpu_logical_map(sleep_cpu);
        pr_info("Hibernating on CPU %d [mpidr:0x%llx]\n", sleep_cpu,
                hdr->sleep_cpu_mpidr);

        return 0;
}
EXPORT_SYMBOL(arch_hibernation_header_save);

int arch_hibernation_header_restore(void *addr)
{
        int ret;
        struct arch_hibernate_hdr_invariants invariants;
        struct arch_hibernate_hdr *hdr = addr;

        arch_hdr_invariants(&invariants);
        if (memcmp(&hdr->invariants, &invariants, sizeof(invariants))) {
                pr_crit("Hibernate image not generated by this kernel!\n");
                return -EINVAL;
        }

        sleep_cpu = get_logical_index(hdr->sleep_cpu_mpidr);
        pr_info("Hibernated on CPU %d [mpidr:0x%llx]\n", sleep_cpu,
                hdr->sleep_cpu_mpidr);
        if (sleep_cpu < 0) {
                pr_crit("Hibernated on a CPU not known to this kernel!\n");
                sleep_cpu = -EINVAL;
                return -EINVAL;
        }

        ret = bringup_hibernate_cpu(sleep_cpu);
        if (ret) {
                sleep_cpu = -EINVAL;
                return ret;
        }

        resume_hdr = *hdr;

        return 0;
}
EXPORT_SYMBOL(arch_hibernation_header_restore);

static void *hibernate_page_alloc(void *arg)
{
        return (void *)get_safe_page((__force gfp_t)(unsigned long)arg);
}

/*
 * Copies length bytes, starting at src_start into an new page,
 * perform cache maintenance, then maps it at the specified address low
 * address as executable.
 *
 * This is used by hibernate to copy the code it needs to execute when
 * overwriting the kernel text. This function generates a new set of page
 * tables, which it loads into ttbr0.
 *
 * Length is provided as we probably only want 4K of data, even on a 64K
 * page system.
 */
static int create_safe_exec_page(void *src_start, size_t length,
                                 phys_addr_t *phys_dst_addr)
{
        struct trans_pgd_info trans_info = {
                .trans_alloc_page       = hibernate_page_alloc,
                .trans_alloc_arg        = (__force void *)GFP_ATOMIC,
        };

        void *page = (void *)get_safe_page(GFP_ATOMIC);
        phys_addr_t trans_ttbr0;
        unsigned long t0sz;
        int rc;

        if (!page)
                return -ENOMEM;

        memcpy(page, src_start, length);
        caches_clean_inval_pou((unsigned long)page, (unsigned long)page + length);
        rc = trans_pgd_idmap_page(&trans_info, &trans_ttbr0, &t0sz, page);
        if (rc)
                return rc;

        /*
         * Load our new page tables. A strict BBM approach requires that we
         * ensure that TLBs are free of any entries that may overlap with the
         * global mappings we are about to install.
         *
         * For a real hibernate/resume cycle TTBR0 currently points to a zero
         * page, but TLBs may contain stale ASID-tagged entries (e.g. for EFI
         * runtime services), while for a userspace-driven test_resume cycle it
         * points to userspace page tables (and we must point it at a zero page
         * ourselves).
         *
         * We change T0SZ as part of installing the idmap. This is undone by
         * cpu_uninstall_idmap() in __cpu_suspend_exit().
         */
        cpu_set_reserved_ttbr0();
        local_flush_tlb_all();
        __cpu_set_tcr_t0sz(t0sz);
        write_sysreg(trans_ttbr0, ttbr0_el1);
        isb();

        *phys_dst_addr = virt_to_phys(page);

        return 0;
}

#ifdef CONFIG_ARM64_MTE

static DEFINE_XARRAY(mte_pages);

static int save_tags(struct page *page, unsigned long pfn)
{
        void *tag_storage, *ret;

        tag_storage = mte_allocate_tag_storage();
        if (!tag_storage)
                return -ENOMEM;

        mte_save_page_tags(page_address(page), tag_storage);

        ret = xa_store(&mte_pages, pfn, tag_storage, GFP_KERNEL);
        if (WARN(xa_is_err(ret), "Failed to store MTE tags")) {
                mte_free_tag_storage(tag_storage);
                return xa_err(ret);
        } else if (WARN(ret, "swsusp: %s: Duplicate entry", __func__)) {
                mte_free_tag_storage(ret);
        }

        return 0;
}

static void swsusp_mte_free_storage(void)
{
        XA_STATE(xa_state, &mte_pages, 0);
        void *tags;

        xa_lock(&mte_pages);
        xas_for_each(&xa_state, tags, ULONG_MAX) {
                mte_free_tag_storage(tags);
        }
        xa_unlock(&mte_pages);

        xa_destroy(&mte_pages);
}

static int swsusp_mte_save_tags(void)
{
        struct zone *zone;
        unsigned long pfn, max_zone_pfn;
        int ret = 0;
        int n = 0;

        if (!system_supports_mte())
                return 0;

        for_each_populated_zone(zone) {
                max_zone_pfn = zone_end_pfn(zone);
                for (pfn = zone->zone_start_pfn; pfn < max_zone_pfn; pfn++) {
                        struct page *page = pfn_to_online_page(pfn);

                        if (!page)
                                continue;

                        if (!test_bit(PG_mte_tagged, &page->flags))
                                continue;

                        ret = save_tags(page, pfn);
                        if (ret) {
                                swsusp_mte_free_storage();
                                goto out;
                        }

                        n++;
                }
        }
        pr_info("Saved %d MTE pages\n", n);

out:
        return ret;
}

static void swsusp_mte_restore_tags(void)
{
        XA_STATE(xa_state, &mte_pages, 0);
        int n = 0;
        void *tags;

        xa_lock(&mte_pages);
        xas_for_each(&xa_state, tags, ULONG_MAX) {
                unsigned long pfn = xa_state.xa_index;
                struct page *page = pfn_to_online_page(pfn);

                /*
                 * It is not required to invoke page_kasan_tag_reset(page)
                 * at this point since the tags stored in page->flags are
                 * already restored.
                 */
                mte_restore_page_tags(page_address(page), tags);

                mte_free_tag_storage(tags);
                n++;
        }
        xa_unlock(&mte_pages);

        pr_info("Restored %d MTE pages\n", n);

        xa_destroy(&mte_pages);
}

#else   /* CONFIG_ARM64_MTE */

static int swsusp_mte_save_tags(void)
{
        return 0;
}

static void swsusp_mte_restore_tags(void)
{
}

#endif  /* CONFIG_ARM64_MTE */

int swsusp_arch_suspend(void)
{
        int ret = 0;
        unsigned long flags;
        struct sleep_stack_data state;

        if (cpus_are_stuck_in_kernel()) {
                pr_err("Can't hibernate: no mechanism to offline secondary CPUs.\n");
                return -EBUSY;
        }

        flags = local_daif_save();

        if (__cpu_suspend_enter(&state)) {
                /* make the crash dump kernel image visible/saveable */
                crash_prepare_suspend();

                ret = swsusp_mte_save_tags();
                if (ret)
                        return ret;

                sleep_cpu = smp_processor_id();
                ret = swsusp_save();
        } else {
                /* Clean kernel core startup/idle code to PoC*/
                dcache_clean_inval_poc((unsigned long)__mmuoff_data_start,
                                    (unsigned long)__mmuoff_data_end);
                dcache_clean_inval_poc((unsigned long)__idmap_text_start,
                                    (unsigned long)__idmap_text_end);

                /* Clean kvm setup code to PoC? */
                if (el2_reset_needed()) {
                        dcache_clean_inval_poc(
                                (unsigned long)__hyp_idmap_text_start,
                                (unsigned long)__hyp_idmap_text_end);
                        dcache_clean_inval_poc((unsigned long)__hyp_text_start,
                                            (unsigned long)__hyp_text_end);
                }

                swsusp_mte_restore_tags();

                /* make the crash dump kernel image protected again */
                crash_post_resume();

                /*
                 * Tell the hibernation core that we've just restored
                 * the memory
                 */
                in_suspend = 0;

                sleep_cpu = -EINVAL;
                __cpu_suspend_exit();

                /*
                 * Just in case the boot kernel did turn the SSBD
                 * mitigation off behind our back, let's set the state
                 * to what we expect it to be.
                 */
                spectre_v4_enable_mitigation(NULL);
        }

        local_daif_restore(flags);

        return ret;
}

/*
 * Setup then Resume from the hibernate image using swsusp_arch_suspend_exit().
 *
 * Memory allocated by get_safe_page() will be dealt with by the hibernate code,
 * we don't need to free it here.
 */
int swsusp_arch_resume(void)
{
        int rc;
        void *zero_page;
        size_t exit_size;
        pgd_t *tmp_pg_dir;
        void __noreturn (*hibernate_exit)(phys_addr_t, phys_addr_t, void *,
                                          void *, phys_addr_t, phys_addr_t);
        struct trans_pgd_info trans_info = {
                .trans_alloc_page       = hibernate_page_alloc,
                .trans_alloc_arg        = (void *)GFP_ATOMIC,
        };

        /*
         * Restoring the memory image will overwrite the ttbr1 page tables.
         * Create a second copy of just the linear map, and use this when
         * restoring.
         */
        rc = trans_pgd_create_copy(&trans_info, &tmp_pg_dir, PAGE_OFFSET,
                                   PAGE_END);
        if (rc)
                return rc;

        /*
         * We need a zero page that is zero before & after resume in order to
         * to break before make on the ttbr1 page tables.
         */
        zero_page = (void *)get_safe_page(GFP_ATOMIC);
        if (!zero_page) {
                pr_err("Failed to allocate zero page.\n");
                return -ENOMEM;
        }

        exit_size = __hibernate_exit_text_end - __hibernate_exit_text_start;
        /*
         * Copy swsusp_arch_suspend_exit() to a safe page. This will generate
         * a new set of ttbr0 page tables and load them.
         */
        rc = create_safe_exec_page(__hibernate_exit_text_start, exit_size,
                                   (phys_addr_t *)&hibernate_exit);
        if (rc) {
                pr_err("Failed to create safe executable page for hibernate_exit code.\n");
                return rc;
        }

        /*
         * The hibernate exit text contains a set of el2 vectors, that will
         * be executed at el2 with the mmu off in order to reload hyp-stub.
         */
        dcache_clean_inval_poc((unsigned long)hibernate_exit,
                            (unsigned long)hibernate_exit + exit_size);

        /*
         * KASLR will cause the el2 vectors to be in a different location in
         * the resumed kernel. Load hibernate's temporary copy into el2.
         *
         * We can skip this step if we booted at EL1, or are running with VHE.
         */
        if (el2_reset_needed()) {
                phys_addr_t el2_vectors = (phys_addr_t)hibernate_exit;
                el2_vectors += hibernate_el2_vectors -
                               __hibernate_exit_text_start;     /* offset */

                __hyp_set_vectors(el2_vectors);
        }

        hibernate_exit(virt_to_phys(tmp_pg_dir), resume_hdr.ttbr1_el1,
                       resume_hdr.reenter_kernel, restore_pblist,
                       resume_hdr.__hyp_stub_vectors, virt_to_phys(zero_page));

        return 0;
}

int hibernate_resume_nonboot_cpu_disable(void)
{
        if (sleep_cpu < 0) {
                pr_err("Failing to resume from hibernate on an unknown CPU.\n");
                return -ENODEV;
        }

        return freeze_secondary_cpus(sleep_cpu);
}