root/arch/powerpc/include/asm/uaccess.h
/* SPDX-License-Identifier: GPL-2.0 */
#ifndef _ARCH_POWERPC_UACCESS_H
#define _ARCH_POWERPC_UACCESS_H

#include <linux/sizes.h>

#include <asm/processor.h>
#include <asm/page.h>
#include <asm/extable.h>
#include <asm/kup.h>
#include <asm/asm-compat.h>

#ifdef __powerpc64__
/* We use TASK_SIZE_USER64 as TASK_SIZE is not constant */
#define TASK_SIZE_MAX           TASK_SIZE_USER64
#endif

/* Threshold above which VMX copy path is used */
#define VMX_COPY_THRESHOLD 3328

#include <asm-generic/access_ok.h>

/*
 * These are the main single-value transfer routines.  They automatically
 * use the right size if we just have the right pointer type.
 *
 * This gets kind of ugly. We want to return _two_ values in "get_user()"
 * and yet we don't want to do any pointers, because that is too much
 * of a performance impact. Thus we have a few rather ugly macros here,
 * and hide all the ugliness from the user.
 *
 * The "__xxx" versions of the user access functions are versions that
 * do not verify the address space, that must have been done previously
 * with a separate "access_ok()" call (this is used when we do multiple
 * accesses to the same area of user memory).
 *
 * As we use the same address space for kernel and user data on the
 * PowerPC, we can just do these as direct assignments.  (Of course, the
 * exception handling means that it's no longer "just"...)
 *
 */
#define __put_user(x, ptr)                                      \
({                                                              \
        long __pu_err;                                          \
        __typeof__(*(ptr)) __user *__pu_addr = (ptr);           \
        __typeof__(*(ptr)) __pu_val = (__typeof__(*(ptr)))(x);  \
        __typeof__(sizeof(*(ptr))) __pu_size = sizeof(*(ptr));  \
                                                                \
        might_fault();                                          \
        do {                                                    \
                __label__ __pu_failed;                          \
                                                                \
                allow_user_access(__pu_addr, KUAP_WRITE);       \
                __put_user_size_goto(__pu_val, __pu_addr, __pu_size, __pu_failed);      \
                prevent_user_access(KUAP_WRITE);                \
                __pu_err = 0;                                   \
                break;                                          \
                                                                \
__pu_failed:                                                    \
                prevent_user_access(KUAP_WRITE);                \
                __pu_err = -EFAULT;                             \
        } while (0);                                            \
                                                                \
        __pu_err;                                               \
})

#define put_user(x, ptr)                                                \
({                                                                      \
        __typeof__(*(ptr)) __user *_pu_addr = (ptr);                    \
                                                                        \
        access_ok(_pu_addr, sizeof(*(ptr))) ?                           \
                  __put_user(x, _pu_addr) : -EFAULT;                    \
})

/*
 * We don't tell gcc that we are accessing memory, but this is OK
 * because we do not write to any memory gcc knows about, so there
 * are no aliasing issues.
 */
/* -mprefixed can generate offsets beyond range, fall back hack */
#ifdef CONFIG_PPC_KERNEL_PREFIXED
#define __put_user_asm_goto(x, addr, label, op)                 \
        asm goto(                                       \
                "1:     " op " %0,0(%1) # put_user\n"           \
                EX_TABLE(1b, %l2)                               \
                :                                               \
                : "r" (x), "b" (addr)                           \
                :                                               \
                : label)
#else
#define __put_user_asm_goto(x, addr, label, op)                 \
        asm goto(                                       \
                "1:     " op "%U1%X1 %0,%1      # put_user\n"   \
                EX_TABLE(1b, %l2)                               \
                :                                               \
                : "r" (x), "m<>" (*addr)                        \
                :                                               \
                : label)
#endif

#ifdef __powerpc64__
#ifdef CONFIG_PPC_KERNEL_PREFIXED
#define __put_user_asm2_goto(x, ptr, label)                     \
        __put_user_asm_goto(x, ptr, label, "std")
#else
#define __put_user_asm2_goto(x, addr, label)                    \
        asm goto ("1: std%U1%X1 %0,%1   # put_user\n"           \
                EX_TABLE(1b, %l2)                               \
                :                                               \
                : "r" (x), DS_FORM_CONSTRAINT (*addr)           \
                :                                               \
                : label)
#endif // CONFIG_PPC_KERNEL_PREFIXED
#else /* __powerpc64__ */
#define __put_user_asm2_goto(x, addr, label)                    \
        asm goto(                                       \
                "1:     stw%X1 %0, %1\n"                        \
                "2:     stw%X1 %L0, %L1\n"                      \
                EX_TABLE(1b, %l2)                               \
                EX_TABLE(2b, %l2)                               \
                :                                               \
                : "r" (x), "m" (*addr)                          \
                :                                               \
                : label)
#endif /* __powerpc64__ */

#define __put_user_size_goto(x, ptr, size, label)               \
do {                                                            \
        __typeof__(*(ptr)) __user *__pus_addr = (ptr);          \
                                                                \
        switch (size) {                                         \
        case 1: __put_user_asm_goto(x, __pus_addr, label, "stb"); break;        \
        case 2: __put_user_asm_goto(x, __pus_addr, label, "sth"); break;        \
        case 4: __put_user_asm_goto(x, __pus_addr, label, "stw"); break;        \
        case 8: __put_user_asm2_goto(x, __pus_addr, label); break;              \
        default: BUILD_BUG();                                   \
        }                                                       \
} while (0)

/*
 * This does an atomic 128 byte aligned load from userspace.
 * Upto caller to do enable_kernel_vmx() before calling!
 */
#define __get_user_atomic_128_aligned(kaddr, uaddr, err)                \
        __asm__ __volatile__(                           \
                ".machine push\n"                       \
                ".machine altivec\n"                    \
                "1:     lvx  0,0,%1     # get user\n"   \
                "       stvx 0,0,%2     # put kernel\n" \
                ".machine pop\n"                        \
                "2:\n"                                  \
                ".section .fixup,\"ax\"\n"              \
                "3:     li %0,%3\n"                     \
                "       b 2b\n"                         \
                ".previous\n"                           \
                EX_TABLE(1b, 3b)                        \
                : "=r" (err)                    \
                : "b" (uaddr), "b" (kaddr), "i" (-EFAULT), "0" (err))

#ifdef CONFIG_CC_HAS_ASM_GOTO_OUTPUT

/* -mprefixed can generate offsets beyond range, fall back hack */
#ifdef CONFIG_PPC_KERNEL_PREFIXED
#define __get_user_asm_goto(x, addr, label, op)                 \
        asm_goto_output(                                        \
                "1:     "op" %0,0(%1)   # get_user\n"           \
                EX_TABLE(1b, %l2)                               \
                : "=r" (x)                                      \
                : "b" (addr)                                    \
                :                                               \
                : label)
#else
#define __get_user_asm_goto(x, addr, label, op)                 \
        asm_goto_output(                                        \
                "1:     "op"%U1%X1 %0, %1       # get_user\n"   \
                EX_TABLE(1b, %l2)                               \
                : "=r" (x)                                      \
                : "m<>" (*addr)                                 \
                :                                               \
                : label)
#endif

#ifdef __powerpc64__
#ifdef CONFIG_PPC_KERNEL_PREFIXED
#define __get_user_asm2_goto(x, addr, label)                    \
        __get_user_asm_goto(x, addr, label, "ld")
#else
#define __get_user_asm2_goto(x, addr, label)                    \
        asm_goto_output(                                        \
                "1:     ld%U1%X1 %0, %1 # get_user\n"           \
                EX_TABLE(1b, %l2)                               \
                : "=r" (x)                                      \
                : DS_FORM_CONSTRAINT (*addr)                    \
                :                                               \
                : label)
#endif // CONFIG_PPC_KERNEL_PREFIXED
#else /* __powerpc64__ */
#define __get_user_asm2_goto(x, addr, label)                    \
        asm_goto_output(                                        \
                "1:     lwz%X1 %0, %1\n"                        \
                "2:     lwz%X1 %L0, %L1\n"                      \
                EX_TABLE(1b, %l2)                               \
                EX_TABLE(2b, %l2)                               \
                : "=&r" (x)                                     \
                : "m" (*addr)                                   \
                :                                               \
                : label)
#endif /* __powerpc64__ */

#define __get_user_size_goto(x, ptr, size, label)                               \
do {                                                                            \
        BUILD_BUG_ON(size > sizeof(x));                                         \
        switch (size) {                                                         \
        case 1: __get_user_asm_goto(x, (u8 __user *)ptr, label, "lbz"); break;  \
        case 2: __get_user_asm_goto(x, (u16 __user *)ptr, label, "lhz"); break; \
        case 4: __get_user_asm_goto(x, (u32 __user *)ptr, label, "lwz"); break; \
        case 8: __get_user_asm2_goto(x, (u64 __user *)ptr, label);  break;      \
        default: x = 0; BUILD_BUG();                                            \
        }                                                                       \
} while (0)

#define __get_user_size_allowed(x, ptr, size, retval)                   \
do {                                                                    \
                __label__ __gus_failed;                                 \
                                                                        \
                __get_user_size_goto(x, ptr, size, __gus_failed);       \
                retval = 0;                                             \
                break;                                                  \
__gus_failed:                                                           \
                x = 0;                                                  \
                retval = -EFAULT;                                       \
} while (0)

#else /* CONFIG_CC_HAS_ASM_GOTO_OUTPUT */

#define __get_user_asm(x, addr, err, op)                \
        __asm__ __volatile__(                           \
                "1:     "op"%U2%X2 %1, %2       # get_user\n"   \
                "2:\n"                                  \
                ".section .fixup,\"ax\"\n"              \
                "3:     li %0,%3\n"                     \
                "       li %1,0\n"                      \
                "       b 2b\n"                         \
                ".previous\n"                           \
                EX_TABLE(1b, 3b)                        \
                : "=r" (err), "=r" (x)                  \
                : "m<>" (*addr), "i" (-EFAULT), "0" (err))

#ifdef __powerpc64__
#define __get_user_asm2(x, addr, err)                   \
        __get_user_asm(x, addr, err, "ld")
#else /* __powerpc64__ */
#define __get_user_asm2(x, addr, err)                   \
        __asm__ __volatile__(                           \
                "1:     lwz%X2 %1, %2\n"                        \
                "2:     lwz%X2 %L1, %L2\n"              \
                "3:\n"                                  \
                ".section .fixup,\"ax\"\n"              \
                "4:     li %0,%3\n"                     \
                "       li %1,0\n"                      \
                "       li %L1,0\n"                     \
                "       b 3b\n"                         \
                ".previous\n"                           \
                EX_TABLE(1b, 4b)                        \
                EX_TABLE(2b, 4b)                        \
                : "=r" (err), "=&r" (x)                 \
                : "m" (*addr), "i" (-EFAULT), "0" (err))
#endif /* __powerpc64__ */

#define __get_user_size_allowed(x, ptr, size, retval)           \
do {                                                            \
        retval = 0;                                             \
        BUILD_BUG_ON(size > sizeof(x));                         \
        switch (size) {                                         \
        case 1: __get_user_asm(x, (u8 __user *)ptr, retval, "lbz"); break;      \
        case 2: __get_user_asm(x, (u16 __user *)ptr, retval, "lhz"); break;     \
        case 4: __get_user_asm(x, (u32 __user *)ptr, retval, "lwz"); break;     \
        case 8: __get_user_asm2(x, (u64 __user *)ptr, retval);  break;  \
        default: x = 0; BUILD_BUG();                            \
        }                                                       \
} while (0)

#define __get_user_size_goto(x, ptr, size, label)               \
do {                                                            \
        long __gus_retval;                                      \
                                                                \
        __get_user_size_allowed(x, ptr, size, __gus_retval);    \
        if (__gus_retval)                                       \
                goto label;                                     \
} while (0)

#endif /* CONFIG_CC_HAS_ASM_GOTO_OUTPUT */

/*
 * This is a type: either unsigned long, if the argument fits into
 * that type, or otherwise unsigned long long.
 */
#define __long_type(x) \
        __typeof__(__builtin_choose_expr(sizeof(x) > sizeof(0UL), 0ULL, 0UL))

#define __get_user(x, ptr)                                      \
({                                                              \
        long __gu_err;                                          \
        __long_type(*(ptr)) __gu_val;                           \
        __typeof__(*(ptr)) __user *__gu_addr = (ptr);   \
        __typeof__(sizeof(*(ptr))) __gu_size = sizeof(*(ptr));  \
                                                                \
        might_fault();                                  \
        barrier_nospec();                                       \
        allow_user_access(NULL, KUAP_READ);             \
        __get_user_size_allowed(__gu_val, __gu_addr, __gu_size, __gu_err);      \
        prevent_user_access(KUAP_READ);                         \
        (x) = (__typeof__(*(ptr)))__gu_val;                     \
                                                                \
        __gu_err;                                               \
})

#define get_user(x, ptr)                                                \
({                                                                      \
        __typeof__(*(ptr)) __user *_gu_addr = (ptr);                    \
                                                                        \
        access_ok(_gu_addr, sizeof(*(ptr))) ?                           \
                  __get_user(x, _gu_addr) :                             \
                  ((x) = (__force __typeof__(*(ptr)))0, -EFAULT);       \
})

/* more complex routines */

extern unsigned long __copy_tofrom_user(void __user *to,
                const void __user *from, unsigned long size);

unsigned long __copy_tofrom_user_base(void __user *to,
                                      const void __user *from, unsigned long size);

unsigned long __copy_tofrom_user_power7_vmx(void __user *to,
                                            const void __user *from, unsigned long size);

static __always_inline bool will_use_vmx(unsigned long n)
{
        return IS_ENABLED(CONFIG_ALTIVEC) && cpu_has_feature(CPU_FTR_VMX_COPY) &&
               n > VMX_COPY_THRESHOLD;
}

static __always_inline unsigned long
raw_copy_tofrom_user(void __user *to, const void __user *from,
                     unsigned long n, unsigned long dir)
{
        unsigned long ret;

        if (will_use_vmx(n) && enter_vmx_usercopy()) {
                allow_user_access(to, dir);
                ret = __copy_tofrom_user_power7_vmx(to, from, n);
                prevent_user_access(dir);
                exit_vmx_usercopy();

                if (unlikely(ret)) {
                        allow_user_access(to, dir);
                        ret = __copy_tofrom_user_base(to, from, n);
                        prevent_user_access(dir);
                }
                return ret;
        }

        allow_user_access(to, dir);
        ret = __copy_tofrom_user(to, from, n);
        prevent_user_access(dir);
        return ret;
}

#ifdef CONFIG_PPC64
static inline unsigned long
raw_copy_in_user(void __user *to, const void __user *from, unsigned long n)
{
        barrier_nospec();
        return raw_copy_tofrom_user(to, from, n, KUAP_READ_WRITE);
}
#endif /* CONFIG_PPC64 */

static inline unsigned long raw_copy_from_user(void *to, const void __user *from, unsigned long n)
{
        return raw_copy_tofrom_user((__force void __user *)to, from, n, KUAP_READ);
}

static inline unsigned long
raw_copy_to_user(void __user *to, const void *from, unsigned long n)
{
        return raw_copy_tofrom_user(to, (__force const void __user *)from, n, KUAP_WRITE);
}

unsigned long __arch_clear_user(void __user *addr, unsigned long size);

static inline unsigned long __clear_user(void __user *addr, unsigned long size)
{
        unsigned long ret;

        might_fault();
        allow_user_access(addr, KUAP_WRITE);
        ret = __arch_clear_user(addr, size);
        prevent_user_access(KUAP_WRITE);
        return ret;
}

static inline unsigned long clear_user(void __user *addr, unsigned long size)
{
        return likely(access_ok(addr, size)) ? __clear_user(addr, size) : size;
}

extern long strncpy_from_user(char *dst, const char __user *src, long count);
extern __must_check long strnlen_user(const char __user *str, long n);

#ifdef CONFIG_ARCH_HAS_COPY_MC
unsigned long __must_check
copy_mc_generic(void *to, const void *from, unsigned long size);

static inline unsigned long __must_check
copy_mc_to_kernel(void *to, const void *from, unsigned long size)
{
        return copy_mc_generic(to, from, size);
}
#define copy_mc_to_kernel copy_mc_to_kernel

static inline unsigned long __must_check
copy_mc_to_user(void __user *to, const void *from, unsigned long n)
{
        if (check_copy_size(from, n, true)) {
                if (access_ok(to, n)) {
                        allow_user_access(to, KUAP_WRITE);
                        n = copy_mc_generic((void __force *)to, from, n);
                        prevent_user_access(KUAP_WRITE);
                }
        }

        return n;
}
#endif

extern long __copy_from_user_flushcache(void *dst, const void __user *src,
                unsigned size);

static __must_check __always_inline bool __user_access_begin(const void __user *ptr, size_t len,
                                                             unsigned long dir)
{
        if (unlikely(!access_ok(ptr, len)))
                return false;

        might_fault();

        if (dir & KUAP_READ)
                barrier_nospec();
        allow_user_access((void __user *)ptr, dir);
        return true;
}

#define user_access_begin(p, l)         __user_access_begin(p, l, KUAP_READ_WRITE)
#define user_read_access_begin(p, l)    __user_access_begin(p, l, KUAP_READ)
#define user_write_access_begin(p, l)   __user_access_begin(p, l, KUAP_WRITE)

#define user_access_end()               prevent_user_access(KUAP_READ_WRITE)
#define user_read_access_end()          prevent_user_access(KUAP_READ)
#define user_write_access_end()         prevent_user_access(KUAP_WRITE)

#define user_access_save        prevent_user_access_return
#define user_access_restore     restore_user_access

/*
 * Masking the user address is an alternative to a conditional
 * user_access_begin that can avoid the fencing. This only works
 * for dense accesses starting at the address.
 */
static inline void __user *mask_user_address_simple(const void __user *ptr)
{
        unsigned long addr = (unsigned long)ptr;
        unsigned long mask = (unsigned long)(((long)addr >> (BITS_PER_LONG - 1)) & LONG_MAX);

        return (void __user *)(addr & ~mask);
}

static inline void __user *mask_user_address_isel(const void __user *ptr)
{
        unsigned long addr;

        asm("cmplw %1, %2; iselgt %0, %2, %1" : "=r"(addr) : "r"(ptr), "r"(TASK_SIZE) : "cr0");

        return (void __user *)addr;
}

/* TASK_SIZE is a multiple of 128K for shifting by 17 to the right */
static inline void __user *mask_user_address_32(const void __user *ptr)
{
        unsigned long addr = (unsigned long)ptr;
        unsigned long mask = (unsigned long)((long)((TASK_SIZE >> 17) - 1 - (addr >> 17)) >> 31);

        addr = (addr & ~mask) | (TASK_SIZE & mask);

        return (void __user *)addr;
}

static inline void __user *mask_user_address_fallback(const void __user *ptr)
{
        unsigned long addr = (unsigned long)ptr;

        return (void __user *)(likely(addr < TASK_SIZE) ? addr : TASK_SIZE);
}

static inline void __user *mask_user_address(const void __user *ptr)
{
#ifdef MODULES_VADDR
        const unsigned long border = MODULES_VADDR;
#else
        const unsigned long border = PAGE_OFFSET;
#endif

        if (IS_ENABLED(CONFIG_PPC64))
                return mask_user_address_simple(ptr);
        if (IS_ENABLED(CONFIG_E500))
                return mask_user_address_isel(ptr);
        if (TASK_SIZE <= UL(SZ_2G) && border >= UL(SZ_2G))
                return mask_user_address_simple(ptr);
        if (IS_ENABLED(CONFIG_PPC_BARRIER_NOSPEC))
                return mask_user_address_32(ptr);
        return mask_user_address_fallback(ptr);
}

static __always_inline void __user *__masked_user_access_begin(const void __user *p,
                                                               unsigned long dir)
{
        void __user *ptr = mask_user_address(p);

        might_fault();
        allow_user_access(ptr, dir);

        return ptr;
}

#define masked_user_access_begin(p) __masked_user_access_begin(p, KUAP_READ_WRITE)
#define masked_user_read_access_begin(p) __masked_user_access_begin(p, KUAP_READ)
#define masked_user_write_access_begin(p) __masked_user_access_begin(p, KUAP_WRITE)

#define arch_unsafe_get_user(x, p, e) do {                      \
        __long_type(*(p)) __gu_val;                             \
        __typeof__(*(p)) __user *__gu_addr = (p);               \
                                                                \
        __get_user_size_goto(__gu_val, __gu_addr, sizeof(*(p)), e); \
        (x) = (__typeof__(*(p)))__gu_val;                       \
} while (0)

#define arch_unsafe_put_user(x, p, e)                           \
        __put_user_size_goto((__typeof__(*(p)))(x), (p), sizeof(*(p)), e)

#define unsafe_copy_from_user(d, s, l, e) \
do {                                                                                    \
        u8 *_dst = (u8 *)(d);                                                           \
        const u8 __user *_src = (const u8 __user *)(s);                                 \
        size_t _len = (l);                                                              \
        int _i;                                                                         \
                                                                                        \
        for (_i = 0; _i < (_len & ~(sizeof(u64) - 1)); _i += sizeof(u64))               \
                unsafe_get_user(*(u64 *)(_dst + _i), (u64 __user *)(_src + _i), e);     \
        if (_len & 4) {                                                                 \
                unsafe_get_user(*(u32 *)(_dst + _i), (u32 __user *)(_src + _i), e);     \
                _i += 4;                                                                \
        }                                                                               \
        if (_len & 2) {                                                                 \
                unsafe_get_user(*(u16 *)(_dst + _i), (u16 __user *)(_src + _i), e);     \
                _i += 2;                                                                \
        }                                                                               \
        if (_len & 1)                                                                   \
                unsafe_get_user(*(u8 *)(_dst + _i), (u8 __user *)(_src + _i), e);       \
} while (0)

#define unsafe_copy_to_user(d, s, l, e) \
do {                                                                    \
        u8 __user *_dst = (u8 __user *)(d);                             \
        const u8 *_src = (const u8 *)(s);                               \
        size_t _len = (l);                                              \
        int _i;                                                         \
                                                                        \
        for (_i = 0; _i < (_len & ~(sizeof(u64) - 1)); _i += sizeof(u64))       \
                unsafe_put_user(*(u64 *)(_src + _i), (u64 __user *)(_dst + _i), e); \
        if (_len & 4) {                                                 \
                unsafe_put_user(*(u32*)(_src + _i), (u32 __user *)(_dst + _i), e); \
                _i += 4;                                                \
        }                                                               \
        if (_len & 2) {                                                 \
                unsafe_put_user(*(u16*)(_src + _i), (u16 __user *)(_dst + _i), e); \
                _i += 2;                                                \
        }                                                               \
        if (_len & 1) \
                unsafe_put_user(*(u8*)(_src + _i), (u8 __user *)(_dst + _i), e); \
} while (0)

#define arch_get_kernel_nofault(dst, src, type, err_label)              \
        __get_user_size_goto(*((type *)(dst)),                          \
                (__force type __user *)(src), sizeof(type), err_label)

#define arch_put_kernel_nofault(dst, src, type, err_label)              \
        __put_user_size_goto(*((type *)(src)),                          \
                (__force type __user *)(dst), sizeof(type), err_label)

#endif  /* _ARCH_POWERPC_UACCESS_H */