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

#include <asm/alternative.h>
#include <asm/kernel-pgtable.h>
#include <asm/sysreg.h>

/*
 * User space memory access functions
 */
#include <linux/bitops.h>
#include <linux/kasan-checks.h>
#include <linux/string.h>

#include <asm/asm-extable.h>
#include <asm/cpufeature.h>
#include <asm/mmu.h>
#include <asm/mte.h>
#include <asm/ptrace.h>
#include <asm/memory.h>
#include <asm/extable.h>

static inline int __access_ok(const void __user *ptr, unsigned long size);

/*
 * Test whether a block of memory is a valid user space address.
 * Returns 1 if the range is valid, 0 otherwise.
 *
 * This is equivalent to the following test:
 * (u65)addr + (u65)size <= (u65)TASK_SIZE_MAX
 */
static inline int access_ok(const void __user *addr, unsigned long size)
{
        /*
         * Asynchronous I/O running in a kernel thread does not have the
         * TIF_TAGGED_ADDR flag of the process owning the mm, so always untag
         * the user address before checking.
         */
        if (IS_ENABLED(CONFIG_ARM64_TAGGED_ADDR_ABI) &&
            (current->flags & PF_KTHREAD || test_thread_flag(TIF_TAGGED_ADDR)))
                addr = untagged_addr(addr);

        return likely(__access_ok(addr, size));
}
#define access_ok access_ok

#include <asm-generic/access_ok.h>

/*
 * User access enabling/disabling.
 */
#ifdef CONFIG_ARM64_SW_TTBR0_PAN
static inline void __uaccess_ttbr0_disable(void)
{
        unsigned long flags, ttbr;

        local_irq_save(flags);
        ttbr = read_sysreg(ttbr1_el1);
        ttbr &= ~TTBR_ASID_MASK;
        /* reserved_pg_dir placed before swapper_pg_dir */
        write_sysreg(ttbr - RESERVED_SWAPPER_OFFSET, ttbr0_el1);
        /* Set reserved ASID */
        write_sysreg(ttbr, ttbr1_el1);
        isb();
        local_irq_restore(flags);
}

static inline void __uaccess_ttbr0_enable(void)
{
        unsigned long flags, ttbr0, ttbr1;

        /*
         * Disable interrupts to avoid preemption between reading the 'ttbr0'
         * variable and the MSR. A context switch could trigger an ASID
         * roll-over and an update of 'ttbr0'.
         */
        local_irq_save(flags);
        ttbr0 = READ_ONCE(current_thread_info()->ttbr0);

        /* Restore active ASID */
        ttbr1 = read_sysreg(ttbr1_el1);
        ttbr1 &= ~TTBR_ASID_MASK;               /* safety measure */
        ttbr1 |= ttbr0 & TTBR_ASID_MASK;
        write_sysreg(ttbr1, ttbr1_el1);

        /* Restore user page table */
        write_sysreg(ttbr0, ttbr0_el1);
        isb();
        local_irq_restore(flags);
}

static inline bool uaccess_ttbr0_disable(void)
{
        if (!system_uses_ttbr0_pan())
                return false;
        __uaccess_ttbr0_disable();
        return true;
}

static inline bool uaccess_ttbr0_enable(void)
{
        if (!system_uses_ttbr0_pan())
                return false;
        __uaccess_ttbr0_enable();
        return true;
}
#else
static inline bool uaccess_ttbr0_disable(void)
{
        return false;
}

static inline bool uaccess_ttbr0_enable(void)
{
        return false;
}
#endif

static inline void __uaccess_disable_hw_pan(void)
{
        asm(ALTERNATIVE("nop", SET_PSTATE_PAN(0), ARM64_HAS_PAN));
}

static inline void __uaccess_enable_hw_pan(void)
{
        asm(ALTERNATIVE("nop", SET_PSTATE_PAN(1), ARM64_HAS_PAN));
}

static inline void uaccess_disable_privileged(void)
{
        mte_disable_tco();

        if (uaccess_ttbr0_disable())
                return;

        __uaccess_enable_hw_pan();
}

static inline void uaccess_enable_privileged(void)
{
        mte_enable_tco();

        if (uaccess_ttbr0_enable())
                return;

        __uaccess_disable_hw_pan();
}

/*
 * Sanitize a uaccess pointer such that it cannot reach any kernel address.
 *
 * Clearing bit 55 ensures the pointer cannot address any portion of the TTBR1
 * address range (i.e. any kernel address), and either the pointer falls within
 * the TTBR0 address range or must cause a fault.
 */
#define uaccess_mask_ptr(ptr) (__typeof__(ptr))__uaccess_mask_ptr(ptr)
static inline void __user *__uaccess_mask_ptr(const void __user *ptr)
{
        void __user *safe_ptr;

        asm volatile(
        "       bic     %0, %1, %2\n"
        : "=r" (safe_ptr)
        : "r" (ptr),
          "i" (BIT(55))
        );

        return safe_ptr;
}

/*
 * The "__xxx" versions of the user access functions do not verify the address
 * space - it must have been done previously with a separate "access_ok()"
 * call.
 *
 * The "__xxx_error" versions set the third argument to -EFAULT if an error
 * occurs, and leave it unchanged on success.
 */
#ifdef CONFIG_CC_HAS_ASM_GOTO_OUTPUT
#define __get_mem_asm(load, reg, x, addr, label, type)                  \
        asm_goto_output(                                                \
        "1:     " load "        " reg "0, [%1]\n"                       \
        _ASM_EXTABLE_##type##ACCESS(1b, %l2)                            \
        : "=r" (x)                                                      \
        : "r" (addr) : : label)
#else
#define __get_mem_asm(load, reg, x, addr, label, type) do {             \
        int __gma_err = 0;                                              \
        asm volatile(                                                   \
        "1:     " load "        " reg "1, [%2]\n"                       \
        "2:\n"                                                          \
        _ASM_EXTABLE_##type##ACCESS_ERR_ZERO(1b, 2b, %w0, %w1)          \
        : "+r" (__gma_err), "=r" (x)                                    \
        : "r" (addr));                                                  \
        if (__gma_err) goto label; } while (0)
#endif

#define __raw_get_mem(ldr, x, ptr, label, type)                                 \
do {                                                                            \
        unsigned long __gu_val;                                                 \
        switch (sizeof(*(ptr))) {                                               \
        case 1:                                                                 \
                __get_mem_asm(ldr "b", "%w", __gu_val, (ptr), label, type);     \
                break;                                                          \
        case 2:                                                                 \
                __get_mem_asm(ldr "h", "%w", __gu_val, (ptr), label, type);     \
                break;                                                          \
        case 4:                                                                 \
                __get_mem_asm(ldr, "%w", __gu_val, (ptr), label, type);         \
                break;                                                          \
        case 8:                                                                 \
                __get_mem_asm(ldr, "%x",  __gu_val, (ptr), label, type);        \
                break;                                                          \
        default:                                                                \
                BUILD_BUG();                                                    \
        }                                                                       \
        (x) = (__force __typeof__(*(ptr)))__gu_val;                             \
} while (0)

/*
 * We must not call into the scheduler between uaccess_ttbr0_enable() and
 * uaccess_ttbr0_disable(). As `x` and `ptr` could contain blocking functions,
 * we must evaluate these outside of the critical section.
 */
#define __raw_get_user(x, ptr, label)                                   \
do {                                                                    \
        __typeof__(*(ptr)) __user *__rgu_ptr = (ptr);                   \
        __typeof__(x) __rgu_val;                                        \
        __chk_user_ptr(ptr);                                            \
        do {                                                            \
                __label__ __rgu_failed;                                 \
                uaccess_ttbr0_enable();                                 \
                __raw_get_mem("ldtr", __rgu_val, __rgu_ptr, __rgu_failed, U);   \
                uaccess_ttbr0_disable();                                \
                (x) = __rgu_val;                                        \
                break;                                                  \
        __rgu_failed:                                                   \
                uaccess_ttbr0_disable();                                \
                goto label;                                             \
        } while (0);                                                    \
} while (0)

#define __get_user_error(x, ptr, err)                                   \
do {                                                                    \
        __label__ __gu_failed;                                          \
        __typeof__(*(ptr)) __user *__p = (ptr);                         \
        might_fault();                                                  \
        if (access_ok(__p, sizeof(*__p))) {                             \
                __p = uaccess_mask_ptr(__p);                            \
                __raw_get_user((x), __p, __gu_failed);                  \
        } else {                                                        \
        __gu_failed:                                                    \
                (x) = (__force __typeof__(x))0; (err) = -EFAULT;        \
        }                                                               \
} while (0)

#define __get_user(x, ptr)                                              \
({                                                                      \
        int __gu_err = 0;                                               \
        __get_user_error((x), (ptr), __gu_err);                         \
        __gu_err;                                                       \
})

#define get_user        __get_user

/*
 * We must not call into the scheduler between __mte_enable_tco_async() and
 * __mte_disable_tco_async(). As `dst` and `src` may contain blocking
 * functions, we must evaluate these outside of the critical section.
 */
#define __get_kernel_nofault(dst, src, type, err_label)                 \
do {                                                                    \
        __typeof__(dst) __gkn_dst = (dst);                              \
        __typeof__(src) __gkn_src = (src);                              \
        do {                                                            \
                __label__ __gkn_label;                                  \
                                                                        \
                __mte_enable_tco_async();                               \
                __raw_get_mem("ldr", *((type *)(__gkn_dst)),            \
                      (__force type *)(__gkn_src), __gkn_label, K);     \
                __mte_disable_tco_async();                              \
                break;                                                  \
        __gkn_label:                                                    \
                __mte_disable_tco_async();                              \
                goto err_label;                                         \
        } while (0);                                                    \
} while (0)

#define __put_mem_asm(store, reg, x, addr, label, type)                 \
        asm goto(                                                       \
        "1:     " store "       " reg "0, [%1]\n"                       \
        "2:\n"                                                          \
        _ASM_EXTABLE_##type##ACCESS(1b, %l2)                            \
        : : "rZ" (x), "r" (addr) : : label)

#define __raw_put_mem(str, x, ptr, label, type)                                 \
do {                                                                            \
        __typeof__(*(ptr)) __pu_val = (x);                                      \
        switch (sizeof(*(ptr))) {                                               \
        case 1:                                                                 \
                __put_mem_asm(str "b", "%w", __pu_val, (ptr), label, type);     \
                break;                                                          \
        case 2:                                                                 \
                __put_mem_asm(str "h", "%w", __pu_val, (ptr), label, type);     \
                break;                                                          \
        case 4:                                                                 \
                __put_mem_asm(str, "%w", __pu_val, (ptr), label, type);         \
                break;                                                          \
        case 8:                                                                 \
                __put_mem_asm(str, "%x", __pu_val, (ptr), label, type);         \
                break;                                                          \
        default:                                                                \
                BUILD_BUG();                                                    \
        }                                                                       \
} while (0)

/*
 * We must not call into the scheduler between uaccess_ttbr0_enable() and
 * uaccess_ttbr0_disable(). As `x` and `ptr` could contain blocking functions,
 * we must evaluate these outside of the critical section.
 */
#define __raw_put_user(x, ptr, label)                                   \
do {                                                                    \
        __label__ __rpu_failed;                                         \
        __typeof__(*(ptr)) __user *__rpu_ptr = (ptr);                   \
        __typeof__(*(ptr)) __rpu_val = (x);                             \
        __chk_user_ptr(__rpu_ptr);                                      \
                                                                        \
        do {                                                            \
                uaccess_ttbr0_enable();                                 \
                __raw_put_mem("sttr", __rpu_val, __rpu_ptr, __rpu_failed, U);   \
                uaccess_ttbr0_disable();                                \
                break;                                                  \
        __rpu_failed:                                                   \
                uaccess_ttbr0_disable();                                \
                goto label;                                             \
        } while (0);                                                    \
} while (0)

#define __put_user_error(x, ptr, err)                                   \
do {                                                                    \
        __label__ __pu_failed;                                          \
        __typeof__(*(ptr)) __user *__p = (ptr);                         \
        might_fault();                                                  \
        if (access_ok(__p, sizeof(*__p))) {                             \
                __p = uaccess_mask_ptr(__p);                            \
                __raw_put_user((x), __p, __pu_failed);                  \
        } else  {                                                       \
        __pu_failed:                                                    \
                (err) = -EFAULT;                                        \
        }                                                               \
} while (0)

#define __put_user(x, ptr)                                              \
({                                                                      \
        int __pu_err = 0;                                               \
        __put_user_error((x), (ptr), __pu_err);                         \
        __pu_err;                                                       \
})

#define put_user        __put_user

/*
 * We must not call into the scheduler between __mte_enable_tco_async() and
 * __mte_disable_tco_async(). As `dst` and `src` may contain blocking
 * functions, we must evaluate these outside of the critical section.
 */
#define __put_kernel_nofault(dst, src, type, err_label)                 \
do {                                                                    \
        __typeof__(dst) __pkn_dst = (dst);                              \
        __typeof__(src) __pkn_src = (src);                              \
                                                                        \
        do {                                                            \
                __label__ __pkn_err;                                    \
                __mte_enable_tco_async();                               \
                __raw_put_mem("str", *((type *)(__pkn_src)),            \
                              (__force type *)(__pkn_dst), __pkn_err, K);       \
                __mte_disable_tco_async();                              \
                break;                                                  \
        __pkn_err:                                                      \
                __mte_disable_tco_async();                              \
                goto err_label;                                         \
        } while (0);                                                    \
} while(0)

extern unsigned long __must_check __arch_copy_from_user(void *to, const void __user *from, unsigned long n);
#define raw_copy_from_user(to, from, n)                                 \
({                                                                      \
        unsigned long __acfu_ret;                                       \
        uaccess_ttbr0_enable();                                         \
        __acfu_ret = __arch_copy_from_user((to),                        \
                                      __uaccess_mask_ptr(from), (n));   \
        uaccess_ttbr0_disable();                                        \
        __acfu_ret;                                                     \
})

extern unsigned long __must_check __arch_copy_to_user(void __user *to, const void *from, unsigned long n);
#define raw_copy_to_user(to, from, n)                                   \
({                                                                      \
        unsigned long __actu_ret;                                       \
        uaccess_ttbr0_enable();                                         \
        __actu_ret = __arch_copy_to_user(__uaccess_mask_ptr(to),        \
                                    (from), (n));                       \
        uaccess_ttbr0_disable();                                        \
        __actu_ret;                                                     \
})

static __must_check __always_inline bool user_access_begin(const void __user *ptr, size_t len)
{
        if (unlikely(!access_ok(ptr,len)))
                return 0;
        uaccess_ttbr0_enable();
        return 1;
}
#define user_access_begin(a,b)  user_access_begin(a,b)
#define user_access_end()       uaccess_ttbr0_disable()
#define arch_unsafe_put_user(x, ptr, label) \
        __raw_put_mem("sttr", x, uaccess_mask_ptr(ptr), label, U)
#define arch_unsafe_get_user(x, ptr, label) \
        __raw_get_mem("ldtr", x, uaccess_mask_ptr(ptr), label, U)

/*
 * KCSAN uses these to save and restore ttbr state.
 * We do not support KCSAN with ARM64_SW_TTBR0_PAN, so
 * they are no-ops.
 */
static inline unsigned long user_access_save(void) { return 0; }
static inline void user_access_restore(unsigned long enabled) { }

/*
 * We want the unsafe accessors to always be inlined and use
 * the error labels - thus the macro games.
 */
#define unsafe_copy_loop(dst, src, len, type, label)                            \
        while (len >= sizeof(type)) {                                           \
                unsafe_put_user(*(type *)(src),(type __user *)(dst),label);     \
                dst += sizeof(type);                                            \
                src += sizeof(type);                                            \
                len -= sizeof(type);                                            \
        }

#define unsafe_copy_to_user(_dst,_src,_len,label)                       \
do {                                                                    \
        char __user *__ucu_dst = (_dst);                                \
        const char *__ucu_src = (_src);                                 \
        size_t __ucu_len = (_len);                                      \
        unsafe_copy_loop(__ucu_dst, __ucu_src, __ucu_len, u64, label);  \
        unsafe_copy_loop(__ucu_dst, __ucu_src, __ucu_len, u32, label);  \
        unsafe_copy_loop(__ucu_dst, __ucu_src, __ucu_len, u16, label);  \
        unsafe_copy_loop(__ucu_dst, __ucu_src, __ucu_len, u8, label);   \
} while (0)

#define INLINE_COPY_TO_USER
#define INLINE_COPY_FROM_USER

extern unsigned long __must_check __arch_clear_user(void __user *to, unsigned long n);
static inline unsigned long __must_check __clear_user(void __user *to, unsigned long n)
{
        if (access_ok(to, n)) {
                uaccess_ttbr0_enable();
                n = __arch_clear_user(__uaccess_mask_ptr(to), n);
                uaccess_ttbr0_disable();
        }
        return n;
}
#define clear_user      __clear_user

extern long strncpy_from_user(char *dest, const char __user *src, long count);

extern __must_check long strnlen_user(const char __user *str, long n);

#ifdef CONFIG_ARCH_HAS_UACCESS_FLUSHCACHE
extern unsigned long __must_check __copy_user_flushcache(void *to, const void __user *from, unsigned long n);

static inline int __copy_from_user_flushcache(void *dst, const void __user *src, unsigned size)
{
        kasan_check_write(dst, size);
        return __copy_user_flushcache(dst, __uaccess_mask_ptr(src), size);
}
#endif

#ifdef CONFIG_ARCH_HAS_SUBPAGE_FAULTS

/*
 * Return 0 on success, the number of bytes not probed otherwise.
 */
static inline size_t probe_subpage_writeable(const char __user *uaddr,
                                             size_t size)
{
        if (!system_supports_mte())
                return 0;
        return mte_probe_user_range(uaddr, size);
}

#endif /* CONFIG_ARCH_HAS_SUBPAGE_FAULTS */

#endif /* __ASM_UACCESS_H */