/* SPDX-License-Identifier: GPL-2.0-only */
/*
 * Based on arch/arm/include/asm/mmu_context.h
 *
 * Copyright (C) 1996 Russell King.
 * Copyright (C) 2012 ARM Ltd.
 */
#ifndef __ASM_MMU_CONTEXT_H
#define __ASM_MMU_CONTEXT_H

#ifndef __ASSEMBLER__

#include <linux/compiler.h>
#include <linux/sched.h>
#include <linux/sched/hotplug.h>
#include <linux/mm_types.h>
#include <linux/pgtable.h>
#include <linux/pkeys.h>

#include <asm/cacheflush.h>
#include <asm/cpufeature.h>
#include <asm/daifflags.h>
#include <asm/gcs.h>
#include <asm/proc-fns.h>
#include <asm/cputype.h>
#include <asm/sysreg.h>
#include <asm/tlbflush.h>

extern bool rodata_full;

static inline void contextidr_thread_switch(struct task_struct *next)
{
        if (!IS_ENABLED(CONFIG_PID_IN_CONTEXTIDR))
                return;

        write_sysreg(task_pid_nr(next), contextidr_el1);
        isb();
}

/*
 * Set TTBR0 to reserved_pg_dir. No translations will be possible via TTBR0.
 */
static inline void cpu_set_reserved_ttbr0_nosync(void)
{
        unsigned long ttbr = phys_to_ttbr(__pa_symbol(reserved_pg_dir));

        write_sysreg(ttbr, ttbr0_el1);
}

static inline void cpu_set_reserved_ttbr0(void)
{
        cpu_set_reserved_ttbr0_nosync();
        isb();
}

void cpu_do_switch_mm(phys_addr_t pgd_phys, struct mm_struct *mm);

static inline void cpu_switch_mm(pgd_t *pgd, struct mm_struct *mm)
{
        BUG_ON(pgd == swapper_pg_dir);
        cpu_do_switch_mm(virt_to_phys(pgd),mm);
}

/*
 * Ensure TCR.T0SZ is set to the provided value.
 */
static inline void __cpu_set_tcr_t0sz(unsigned long t0sz)
{
        unsigned long tcr = read_sysreg(tcr_el1);

        if ((tcr & TCR_EL1_T0SZ_MASK) == t0sz)
                return;

        tcr &= ~TCR_EL1_T0SZ_MASK;
        tcr |= t0sz;
        write_sysreg(tcr, tcr_el1);
        isb();
}

/*
 * Remove the idmap from TTBR0_EL1 and install the pgd of the active mm.
 *
 * The idmap lives in the same VA range as userspace, but uses global entries
 * and may use a different TCR_EL1.T0SZ. To avoid issues resulting from
 * speculative TLB fetches, we must temporarily install the reserved page
 * tables while we invalidate the TLBs and set up the correct TCR_EL1.T0SZ.
 *
 * If current is a not a user task, the mm covers the TTBR1_EL1 page tables,
 * which should not be installed in TTBR0_EL1. In this case we can leave the
 * reserved page tables in place.
 */
static inline void cpu_uninstall_idmap(void)
{
        struct mm_struct *mm = current->active_mm;

        cpu_set_reserved_ttbr0();
        local_flush_tlb_all();
        __cpu_set_tcr_t0sz(TCR_T0SZ(vabits_actual));

        if (mm != &init_mm && !system_uses_ttbr0_pan())
                cpu_switch_mm(mm->pgd, mm);
}

static inline void cpu_install_idmap(void)
{
        cpu_set_reserved_ttbr0();
        local_flush_tlb_all();
        __cpu_set_tcr_t0sz(TCR_T0SZ(IDMAP_VA_BITS));

        cpu_switch_mm(lm_alias(idmap_pg_dir), &init_mm);
}

/*
 * 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/kexec 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().
 */
static inline void cpu_install_ttbr0(phys_addr_t ttbr0, unsigned long t0sz)
{
        cpu_set_reserved_ttbr0();
        local_flush_tlb_all();
        __cpu_set_tcr_t0sz(t0sz);

        /* avoid cpu_switch_mm() and its SW-PAN and CNP interactions */
        write_sysreg(ttbr0, ttbr0_el1);
        isb();
}

void __cpu_replace_ttbr1(pgd_t *pgdp, bool cnp);

static inline void cpu_enable_swapper_cnp(void)
{
        __cpu_replace_ttbr1(lm_alias(swapper_pg_dir), true);
}

static inline void cpu_replace_ttbr1(pgd_t *pgdp)
{
        /*
         * Only for early TTBR1 replacement before cpucaps are finalized and
         * before we've decided whether to use CNP.
         */
        WARN_ON(system_capabilities_finalized());
        __cpu_replace_ttbr1(pgdp, false);
}

/*
 * It would be nice to return ASIDs back to the allocator, but unfortunately
 * that introduces a race with a generation rollover where we could erroneously
 * free an ASID allocated in a future generation. We could workaround this by
 * freeing the ASID from the context of the dying mm (e.g. in arch_exit_mmap),
 * but we'd then need to make sure that we didn't dirty any TLBs afterwards.
 * Setting a reserved TTBR0 or EPD0 would work, but it all gets ugly when you
 * take CPU migration into account.
 */
void check_and_switch_context(struct mm_struct *mm);

#define init_new_context(tsk, mm) init_new_context(tsk, mm)
static inline int
init_new_context(struct task_struct *tsk, struct mm_struct *mm)
{
        atomic64_set(&mm->context.id, 0);
        refcount_set(&mm->context.pinned, 0);

        /* pkey 0 is the default, so always reserve it. */
        mm->context.pkey_allocation_map = BIT(0);

        return 0;
}

static inline void arch_dup_pkeys(struct mm_struct *oldmm,
                                  struct mm_struct *mm)
{
        /* Duplicate the oldmm pkey state in mm: */
        mm->context.pkey_allocation_map = oldmm->context.pkey_allocation_map;
}

static inline int arch_dup_mmap(struct mm_struct *oldmm, struct mm_struct *mm)
{
        arch_dup_pkeys(oldmm, mm);

        return 0;
}

static inline void arch_exit_mmap(struct mm_struct *mm)
{
}

static inline void arch_unmap(struct mm_struct *mm,
                        unsigned long start, unsigned long end)
{
}

#ifdef CONFIG_ARM64_SW_TTBR0_PAN
static inline void update_saved_ttbr0(struct task_struct *tsk,
                                      struct mm_struct *mm)
{
        u64 ttbr;

        if (!system_uses_ttbr0_pan())
                return;

        if (mm == &init_mm)
                ttbr = phys_to_ttbr(__pa_symbol(reserved_pg_dir));
        else
                ttbr = phys_to_ttbr(virt_to_phys(mm->pgd)) | ASID(mm) << 48;

        WRITE_ONCE(task_thread_info(tsk)->ttbr0, ttbr);
}
#else
static inline void update_saved_ttbr0(struct task_struct *tsk,
                                      struct mm_struct *mm)
{
}
#endif

#define enter_lazy_tlb enter_lazy_tlb
static inline void
enter_lazy_tlb(struct mm_struct *mm, struct task_struct *tsk)
{
        /*
         * We don't actually care about the ttbr0 mapping, so point it at the
         * zero page.
         */
        update_saved_ttbr0(tsk, &init_mm);
}

static inline void __switch_mm(struct mm_struct *next)
{
        /*
         * init_mm.pgd does not contain any user mappings and it is always
         * active for kernel addresses in TTBR1. Just set the reserved TTBR0.
         */
        if (next == &init_mm) {
                cpu_set_reserved_ttbr0();
                return;
        }

        check_and_switch_context(next);
}

static inline void
switch_mm(struct mm_struct *prev, struct mm_struct *next,
          struct task_struct *tsk)
{
        if (prev != next)
                __switch_mm(next);

        /*
         * Update the saved TTBR0_EL1 of the scheduled-in task as the previous
         * value may have not been initialised yet (activate_mm caller) or the
         * ASID has changed since the last run (following the context switch
         * of another thread of the same process).
         */
        update_saved_ttbr0(tsk, next);
}

static inline const struct cpumask *
__task_cpu_possible_mask(struct task_struct *p, const struct cpumask *mask)
{
        if (!static_branch_unlikely(&arm64_mismatched_32bit_el0))
                return mask;

        if (!is_compat_thread(task_thread_info(p)))
                return mask;

        return system_32bit_el0_cpumask();
}

static inline const struct cpumask *
task_cpu_possible_mask(struct task_struct *p)
{
        return __task_cpu_possible_mask(p, cpu_possible_mask);
}
#define task_cpu_possible_mask  task_cpu_possible_mask

const struct cpumask *task_cpu_fallback_mask(struct task_struct *p);

void verify_cpu_asid_bits(void);
void post_ttbr_update_workaround(void);

unsigned long arm64_mm_context_get(struct mm_struct *mm);
void arm64_mm_context_put(struct mm_struct *mm);

#define mm_untag_mask mm_untag_mask
static inline unsigned long mm_untag_mask(struct mm_struct *mm)
{
        return -1UL >> 8;
}

/*
 * Only enforce protection keys on the current process, because there is no
 * user context to access POR_EL0 for another address space.
 */
static inline bool arch_vma_access_permitted(struct vm_area_struct *vma,
                bool write, bool execute, bool foreign)
{
        if (!system_supports_poe())
                return true;

        /* allow access if the VMA is not one from this process */
        if (foreign || vma_is_foreign(vma))
                return true;

        return por_el0_allows_pkey(vma_pkey(vma), write, execute);
}

#define deactivate_mm deactivate_mm
static inline void deactivate_mm(struct task_struct *tsk,
                        struct mm_struct *mm)
{
        gcs_free(tsk);
}


#include <asm-generic/mmu_context.h>

#endif /* !__ASSEMBLER__ */

#endif /* !__ASM_MMU_CONTEXT_H */