// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * Copyright (C) 2009 Sunplus Core Technology Co., Ltd.
 *  Chen Liqin <liqin.chen@sunplusct.com>
 *  Lennox Wu <lennox.wu@sunplusct.com>
 * Copyright (C) 2012 Regents of the University of California
 * Copyright (C) 2017 SiFive
 */

#include <linux/bitfield.h>
#include <linux/cpu.h>
#include <linux/kernel.h>
#include <linux/sched.h>
#include <linux/sched/debug.h>
#include <linux/sched/task_stack.h>
#include <linux/tick.h>
#include <linux/ptrace.h>
#include <linux/uaccess.h>
#include <linux/personality.h>
#include <linux/entry-common.h>

#include <asm/asm-prototypes.h>
#include <asm/unistd.h>
#include <asm/processor.h>
#include <asm/csr.h>
#include <asm/stacktrace.h>
#include <asm/string.h>
#include <asm/switch_to.h>
#include <asm/thread_info.h>
#include <asm/cpuidle.h>
#include <asm/vector.h>
#include <asm/cpufeature.h>
#include <asm/exec.h>
#include <asm/usercfi.h>

#if defined(CONFIG_STACKPROTECTOR) && !defined(CONFIG_STACKPROTECTOR_PER_TASK)
#include <linux/stackprotector.h>
unsigned long __stack_chk_guard __read_mostly;
EXPORT_SYMBOL(__stack_chk_guard);
#endif

extern asmlinkage void ret_from_fork_kernel_asm(void);
extern asmlinkage void ret_from_fork_user_asm(void);

void noinstr arch_cpu_idle(void)
{
        cpu_do_idle();
}

int set_unalign_ctl(struct task_struct *tsk, unsigned int val)
{
        if (!unaligned_ctl_available())
                return -EINVAL;

        tsk->thread.align_ctl = val;
        return 0;
}

int get_unalign_ctl(struct task_struct *tsk, unsigned long adr)
{
        if (!unaligned_ctl_available())
                return -EINVAL;

        return put_user(tsk->thread.align_ctl, (unsigned int __user *)adr);
}

void __show_regs(struct pt_regs *regs)
{
        show_regs_print_info(KERN_DEFAULT);

        if (!user_mode(regs)) {
                pr_cont("epc : %pS\n", (void *)regs->epc);
                pr_cont(" ra : %pS\n", (void *)regs->ra);
        }

        pr_cont("epc : " REG_FMT " ra : " REG_FMT " sp : " REG_FMT "\n",
                regs->epc, regs->ra, regs->sp);
        pr_cont(" gp : " REG_FMT " tp : " REG_FMT " t0 : " REG_FMT "\n",
                regs->gp, regs->tp, regs->t0);
        pr_cont(" t1 : " REG_FMT " t2 : " REG_FMT " s0 : " REG_FMT "\n",
                regs->t1, regs->t2, regs->s0);
        pr_cont(" s1 : " REG_FMT " a0 : " REG_FMT " a1 : " REG_FMT "\n",
                regs->s1, regs->a0, regs->a1);
        pr_cont(" a2 : " REG_FMT " a3 : " REG_FMT " a4 : " REG_FMT "\n",
                regs->a2, regs->a3, regs->a4);
        pr_cont(" a5 : " REG_FMT " a6 : " REG_FMT " a7 : " REG_FMT "\n",
                regs->a5, regs->a6, regs->a7);
        pr_cont(" s2 : " REG_FMT " s3 : " REG_FMT " s4 : " REG_FMT "\n",
                regs->s2, regs->s3, regs->s4);
        pr_cont(" s5 : " REG_FMT " s6 : " REG_FMT " s7 : " REG_FMT "\n",
                regs->s5, regs->s6, regs->s7);
        pr_cont(" s8 : " REG_FMT " s9 : " REG_FMT " s10: " REG_FMT "\n",
                regs->s8, regs->s9, regs->s10);
        pr_cont(" s11: " REG_FMT " t3 : " REG_FMT " t4 : " REG_FMT "\n",
                regs->s11, regs->t3, regs->t4);
        pr_cont(" t5 : " REG_FMT " t6 : " REG_FMT " ssp : " REG_FMT "\n",
                regs->t5, regs->t6, get_active_shstk(current));

        pr_cont("status: " REG_FMT " badaddr: " REG_FMT " cause: " REG_FMT "\n",
                regs->status, regs->badaddr, regs->cause);
}
void show_regs(struct pt_regs *regs)
{
        __show_regs(regs);
        if (!user_mode(regs))
                dump_backtrace(regs, NULL, KERN_DEFAULT);
}

unsigned long arch_align_stack(unsigned long sp)
{
        if (!(current->personality & ADDR_NO_RANDOMIZE) && randomize_va_space)
                sp -= get_random_u32_below(PAGE_SIZE);
        return sp & ~0xf;
}

#ifdef CONFIG_COMPAT
static bool compat_mode_supported __read_mostly;

bool compat_elf_check_arch(Elf32_Ehdr *hdr)
{
        return compat_mode_supported &&
               hdr->e_machine == EM_RISCV &&
               hdr->e_ident[EI_CLASS] == ELFCLASS32;
}

static int __init compat_mode_detect(void)
{
        unsigned long tmp = csr_read(CSR_STATUS);

        csr_write(CSR_STATUS, (tmp & ~SR_UXL) | SR_UXL_32);
        compat_mode_supported =
                        (csr_read(CSR_STATUS) & SR_UXL) == SR_UXL_32;

        csr_write(CSR_STATUS, tmp);

        pr_info("riscv: ELF compat mode %s",
                        compat_mode_supported ? "supported" : "unsupported");

        return 0;
}
early_initcall(compat_mode_detect);
#endif

void start_thread(struct pt_regs *regs, unsigned long pc,
        unsigned long sp)
{
        regs->status = SR_PIE;
        if (has_fpu()) {
                regs->status |= SR_FS_INITIAL;
                /*
                 * Restore the initial value to the FP register
                 * before starting the user program.
                 */
                fstate_restore(current, regs);
        }
        regs->epc = pc;
        regs->sp = sp;

        /*
         * clear shadow stack state on exec.
         * libc will set it later via prctl.
         */
        set_shstk_status(current, false);
        set_shstk_base(current, 0, 0);
        set_active_shstk(current, 0);
        /*
         * disable indirect branch tracking on exec.
         * libc will enable it later via prctl.
         */
        set_indir_lp_status(current, false);

#ifdef CONFIG_64BIT
        regs->status &= ~SR_UXL;

        if (is_compat_task())
                regs->status |= SR_UXL_32;
        else
                regs->status |= SR_UXL_64;
#endif
}

void flush_thread(void)
{
#ifdef CONFIG_FPU
        /*
         * Reset FPU state and context
         *      frm: round to nearest, ties to even (IEEE default)
         *      fflags: accrued exceptions cleared
         */
        fstate_off(current, task_pt_regs(current));
        memset(&current->thread.fstate, 0, sizeof(current->thread.fstate));
#endif
#ifdef CONFIG_RISCV_ISA_V
        /* Reset vector state */
        riscv_v_vstate_ctrl_init(current);
        riscv_v_vstate_off(task_pt_regs(current));
        kfree(current->thread.vstate.datap);
        memset(&current->thread.vstate, 0, sizeof(struct __riscv_v_ext_state));
        clear_tsk_thread_flag(current, TIF_RISCV_V_DEFER_RESTORE);
#endif
#ifdef CONFIG_RISCV_ISA_SUPM
        if (riscv_has_extension_unlikely(RISCV_ISA_EXT_SUPM))
                envcfg_update_bits(current, ENVCFG_PMM, ENVCFG_PMM_PMLEN_0);
#endif
}

void arch_release_task_struct(struct task_struct *tsk)
{
        /* Free the vector context of datap. */
        if (has_vector() || has_xtheadvector())
                riscv_v_thread_free(tsk);
}

int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src)
{
        fstate_save(src, task_pt_regs(src));
        *dst = *src;
        /* clear entire V context, including datap for a new task */
        memset(&dst->thread.vstate, 0, sizeof(struct __riscv_v_ext_state));
        memset(&dst->thread.kernel_vstate, 0, sizeof(struct __riscv_v_ext_state));
        clear_tsk_thread_flag(dst, TIF_RISCV_V_DEFER_RESTORE);

        return 0;
}

asmlinkage void ret_from_fork_kernel(void *fn_arg, int (*fn)(void *), struct pt_regs *regs)
{
        fn(fn_arg);

        syscall_exit_to_user_mode(regs);
}

asmlinkage void ret_from_fork_user(struct pt_regs *regs)
{
        syscall_exit_to_user_mode(regs);
}

int copy_thread(struct task_struct *p, const struct kernel_clone_args *args)
{
        u64 clone_flags = args->flags;
        unsigned long usp = args->stack;
        unsigned long tls = args->tls;
        unsigned long ssp = 0;
        struct pt_regs *childregs = task_pt_regs(p);

        /* Ensure all threads in this mm have the same pointer masking mode. */
        if (IS_ENABLED(CONFIG_RISCV_ISA_SUPM) && p->mm && (clone_flags & CLONE_VM))
                set_bit(MM_CONTEXT_LOCK_PMLEN, &p->mm->context.flags);

        memset(&p->thread.s, 0, sizeof(p->thread.s));

        /* p->thread holds context to be restored by __switch_to() */
        if (unlikely(args->fn)) {
                /* Kernel thread */
                memset(childregs, 0, sizeof(struct pt_regs));
                /* Supervisor/Machine, irqs on: */
                childregs->status = SR_PP | SR_PIE;

                p->thread.s[0] = (unsigned long)args->fn;
                p->thread.s[1] = (unsigned long)args->fn_arg;
                p->thread.ra = (unsigned long)ret_from_fork_kernel_asm;
        } else {
                /* allocate new shadow stack if needed. In case of CLONE_VM we have to */
                ssp = shstk_alloc_thread_stack(p, args);
                if (IS_ERR_VALUE(ssp))
                        return PTR_ERR((void *)ssp);

                *childregs = *(current_pt_regs());
                /* Turn off status.VS */
                riscv_v_vstate_off(childregs);
                if (usp) /* User fork */
                        childregs->sp = usp;
                /* if needed, set new ssp */
                if (ssp)
                        set_active_shstk(p, ssp);
                if (clone_flags & CLONE_SETTLS)
                        childregs->tp = tls;
                childregs->a0 = 0; /* Return value of fork() */
                p->thread.ra = (unsigned long)ret_from_fork_user_asm;
        }
        p->thread.riscv_v_flags = 0;
        if (has_vector() || has_xtheadvector())
                riscv_v_thread_alloc(p);
        p->thread.sp = (unsigned long)childregs; /* kernel sp */
        return 0;
}

void __init arch_task_cache_init(void)
{
        riscv_v_setup_ctx_cache();
}

#ifdef CONFIG_RISCV_ISA_SUPM
enum {
        PMLEN_0 = 0,
        PMLEN_7 = 7,
        PMLEN_16 = 16,
};

static bool have_user_pmlen_7;
static bool have_user_pmlen_16;

/*
 * Control the relaxed ABI allowing tagged user addresses into the kernel.
 */
static unsigned int tagged_addr_disabled;

long set_tagged_addr_ctrl(struct task_struct *task, unsigned long arg)
{
        unsigned long valid_mask = PR_PMLEN_MASK | PR_TAGGED_ADDR_ENABLE;
        struct thread_info *ti = task_thread_info(task);
        struct mm_struct *mm = task->mm;
        unsigned long pmm;
        u8 pmlen;

        if (!riscv_has_extension_unlikely(RISCV_ISA_EXT_SUPM))
                return -EINVAL;

        if (is_compat_thread(ti))
                return -EINVAL;

        if (arg & ~valid_mask)
                return -EINVAL;

        /*
         * Prefer the smallest PMLEN that satisfies the user's request,
         * in case choosing a larger PMLEN has a performance impact.
         */
        pmlen = FIELD_GET(PR_PMLEN_MASK, arg);
        if (pmlen == PMLEN_0) {
                pmm = ENVCFG_PMM_PMLEN_0;
        } else if (pmlen <= PMLEN_7 && have_user_pmlen_7) {
                pmlen = PMLEN_7;
                pmm = ENVCFG_PMM_PMLEN_7;
        } else if (pmlen <= PMLEN_16 && have_user_pmlen_16) {
                pmlen = PMLEN_16;
                pmm = ENVCFG_PMM_PMLEN_16;
        } else {
                return -EINVAL;
        }

        /*
         * Do not allow the enabling of the tagged address ABI if globally
         * disabled via sysctl abi.tagged_addr_disabled, if pointer masking
         * is disabled for userspace.
         */
        if (arg & PR_TAGGED_ADDR_ENABLE && (tagged_addr_disabled || !pmlen))
                return -EINVAL;

        if (!(arg & PR_TAGGED_ADDR_ENABLE)) {
                pmlen = PMLEN_0;
                pmm = ENVCFG_PMM_PMLEN_0;
        }

        if (mmap_write_lock_killable(mm))
                return -EINTR;

        if (test_bit(MM_CONTEXT_LOCK_PMLEN, &mm->context.flags) && mm->context.pmlen != pmlen) {
                mmap_write_unlock(mm);
                return -EBUSY;
        }

        envcfg_update_bits(task, ENVCFG_PMM, pmm);
        mm->context.pmlen = pmlen;

        mmap_write_unlock(mm);

        return 0;
}

long get_tagged_addr_ctrl(struct task_struct *task)
{
        struct thread_info *ti = task_thread_info(task);
        long ret = 0;

        if (!riscv_has_extension_unlikely(RISCV_ISA_EXT_SUPM))
                return -EINVAL;

        if (is_compat_thread(ti))
                return -EINVAL;

        /*
         * The mm context's pmlen is set only when the tagged address ABI is
         * enabled, so the effective PMLEN must be extracted from envcfg.PMM.
         */
        switch (task->thread.envcfg & ENVCFG_PMM) {
        case ENVCFG_PMM_PMLEN_7:
                ret = FIELD_PREP(PR_PMLEN_MASK, PMLEN_7);
                break;
        case ENVCFG_PMM_PMLEN_16:
                ret = FIELD_PREP(PR_PMLEN_MASK, PMLEN_16);
                break;
        }

        if (task->mm->context.pmlen)
                ret |= PR_TAGGED_ADDR_ENABLE;

        return ret;
}

static bool try_to_set_pmm(unsigned long value)
{
        csr_set(CSR_ENVCFG, value);
        return (csr_read_clear(CSR_ENVCFG, ENVCFG_PMM) & ENVCFG_PMM) == value;
}

/*
 * Global sysctl to disable the tagged user addresses support. This control
 * only prevents the tagged address ABI enabling via prctl() and does not
 * disable it for tasks that already opted in to the relaxed ABI.
 */

static const struct ctl_table tagged_addr_sysctl_table[] = {
        {
                .procname       = "tagged_addr_disabled",
                .mode           = 0644,
                .data           = &tagged_addr_disabled,
                .maxlen         = sizeof(int),
                .proc_handler   = proc_dointvec_minmax,
                .extra1         = SYSCTL_ZERO,
                .extra2         = SYSCTL_ONE,
        },
};

static int __init tagged_addr_init(void)
{
        if (!riscv_has_extension_unlikely(RISCV_ISA_EXT_SUPM))
                return 0;

        /*
         * envcfg.PMM is a WARL field. Detect which values are supported.
         * Assume the supported PMLEN values are the same on all harts.
         */
        csr_clear(CSR_ENVCFG, ENVCFG_PMM);
        have_user_pmlen_7 = try_to_set_pmm(ENVCFG_PMM_PMLEN_7);
        have_user_pmlen_16 = try_to_set_pmm(ENVCFG_PMM_PMLEN_16);

        if (!register_sysctl("abi", tagged_addr_sysctl_table))
                return -EINVAL;

        return 0;
}
core_initcall(tagged_addr_init);
#endif  /* CONFIG_RISCV_ISA_SUPM */