/* SPDX-License-Identifier: GPL-2.0 */
#ifndef _ASM_SW64_UACCESS_H
#define _ASM_SW64_UACCESS_H

/*
 * The fs value determines whether argument validity checking should be
 * performed or not.  If get_fs() == USER_DS, checking is performed, with
 * get_fs() == KERNEL_DS, checking is bypassed.
 *
 * Or at least it did once upon a time.  Nowadays it is a mask that
 * defines which bits of the address space are off limits.  This is a
 * wee bit faster than the above.
 *
 * For historical reasons, these macros are grossly misnamed.
 */

#define KERNEL_DS	((mm_segment_t) { 0UL })
#define USER_DS		((mm_segment_t) { -0x10000000000000UL  })

#define get_fs()	(current_thread_info()->addr_limit)
#define get_ds()	(KERNEL_DS)
#define set_fs(x)	(current_thread_info()->addr_limit = (x))

#define uaccess_kernel()       (get_fs().seg == KERNEL_DS.seg)

/*
 * Is a address valid? This does a straightforward calculation rather
 * than tests.
 *
 * Address valid if:
 *  - "addr" doesn't have any high-bits set
 *  - AND "size" doesn't have any high-bits set
 *  - AND "addr+size-(size != 0)" doesn't have any high-bits set
 *  - OR we are in kernel mode.
 */
#define __access_ok(addr, size) ({				\
	unsigned long __ao_a = (addr), __ao_b = (size);		\
	unsigned long __ao_end = __ao_a + __ao_b - !!__ao_b;	\
	(get_fs().seg & (__ao_a | __ao_b | __ao_end)) == 0; })

#define access_ok(addr, size)				\
({							\
	__chk_user_ptr(addr);				\
	__access_ok(((unsigned long)(addr)), (size));		\
})

/*
 * These are the main single-value transfer routines.  They automatically
 * use the right size if we just have the right pointer type.
 *
 * As the sw64 uses the same address space for kernel and user
 * data, we can just do these as direct assignments.  (Of course, the
 * exception handling means that it's no longer "just"...)
 *
 * Careful to not
 * (a) re-use the arguments for side effects (sizeof/typeof is ok)
 * (b) require any knowledge of processes at this stage
 */
#define put_user(x, ptr) \
	__put_user_check((__typeof__(*(ptr)))(x), (ptr), sizeof(*(ptr)))
#define get_user(x, ptr) \
	__get_user_check((x), (ptr), sizeof(*(ptr)))

/*
 * The "__xxx" versions do not do address space checking, useful when
 * doing multiple accesses to the same area (the programmer has to do the
 * checks by hand with "access_ok()")
 */
#define __put_user(x, ptr) \
	__put_user_nocheck((__typeof__(*(ptr)))(x), (ptr), sizeof(*(ptr)))
#define __get_user(x, ptr) \
	__get_user_nocheck((x), (ptr), sizeof(*(ptr)))
/*
 * The "ldi %1, 2b-1b(%0)" bits are magic to get the assembler to
 * encode the bits we need for resolving the exception.  See the
 * more extensive comments with fixup_inline_exception below for
 * more information.
 */

extern void __get_user_unknown(void);

#define __get_user_nocheck(x, ptr, size)			\
({								\
	long __gu_err = 0;					\
	unsigned long __gu_val;					\
	__chk_user_ptr(ptr);					\
	switch (size) {						\
	case 1:							\
		__get_user_8(ptr);				\
		break;						\
	case 2:							\
		__get_user_16(ptr);				\
		break;						\
	case 4:							\
		__get_user_32(ptr);				\
		break;						\
	case 8:							\
		__get_user_64(ptr);				\
		break;						\
	default:						\
		__get_user_unknown();				\
		break;						\
	}							\
	(x) = (__force __typeof__(*(ptr))) __gu_val;		\
	__gu_err;						\
})

#define __get_user_check(x, ptr, size)				\
({								\
	long __gu_err = -EFAULT;				\
	unsigned long __gu_val = 0;				\
	const __typeof__(*(ptr)) __user *__gu_addr = (ptr);	\
	if (__access_ok((unsigned long)__gu_addr, size)) {	\
		__gu_err = 0;					\
		switch (size) {					\
		case 1:						\
			__get_user_8(__gu_addr);		\
			break;					\
		case 2:						\
			__get_user_16(__gu_addr);		\
			break;					\
		case 4:						\
			__get_user_32(__gu_addr);		\
			break;					\
		case 8:						\
			__get_user_64(__gu_addr);		\
			break;					\
		default:					\
			__get_user_unknown();			\
			break;					\
		}						\
	}							\
	(x) = (__force __typeof__(*(ptr))) __gu_val;		\
	__gu_err;						\
})

struct __large_struct { unsigned long buf[100]; };
#define __m(x) (*(struct __large_struct __user *)(x))

#define __get_user_64(addr)					\
	__asm__("1: ldl %0,%2\n"				\
	"2:\n"							\
	".section __ex_table,\"a\"\n"				\
	"	.long 1b - .\n"					\
	"	ldi %0, 2b-1b(%1)\n"				\
	".previous"						\
		: "=r"(__gu_val), "=r"(__gu_err)		\
		: "m"(__m(addr)), "1"(__gu_err))

#define __get_user_32(addr)					\
	__asm__("1: ldw %0,%2\n"				\
	"2:\n"							\
	".section __ex_table,\"a\"\n"				\
	"	.long 1b - .\n"					\
	"	ldi %0, 2b-1b(%1)\n"				\
	".previous"						\
		: "=r"(__gu_val), "=r"(__gu_err)		\
		: "m"(__m(addr)), "1"(__gu_err))

#define __get_user_16(addr)					\
	__asm__("1: ldhu %0,%2\n"				\
	"2:\n"							\
	".section __ex_table,\"a\"\n"				\
	"	.long 1b - .\n"					\
	"	ldi %0, 2b-1b(%1)\n"				\
	".previous"						\
		: "=r"(__gu_val), "=r"(__gu_err)		\
		: "m"(__m(addr)), "1"(__gu_err))

#define __get_user_8(addr)					\
	__asm__("1: ldbu %0,%2\n"				\
	"2:\n"							\
	".section __ex_table,\"a\"\n"				\
	"	.long 1b - .\n"					\
	"	ldi %0, 2b-1b(%1)\n"				\
	".previous"						\
		: "=r"(__gu_val), "=r"(__gu_err)		\
		: "m"(__m(addr)), "1"(__gu_err))

extern void __put_user_unknown(void);

#define __put_user_nocheck(x, ptr, size)			\
({								\
	long __pu_err = 0;					\
	__chk_user_ptr(ptr);					\
	switch (size) {						\
	case 1:							\
		__put_user_8(x, ptr);				\
		break;						\
	case 2:							\
		__put_user_16(x, ptr);				\
		break;						\
	case 4:							\
		__put_user_32(x, ptr);				\
		break;						\
	case 8:							\
		__put_user_64(x, ptr);				\
		break;						\
	default:						\
		__put_user_unknown();				\
		break;						\
	}							\
	__pu_err;						\
})

#define __put_user_check(x, ptr, size)				\
({								\
	long __pu_err = -EFAULT;				\
	__typeof__(*(ptr)) __user *__pu_addr = (ptr);		\
	if (__access_ok((unsigned long)__pu_addr, size)) {	\
		__pu_err = 0;					\
		switch (size) {					\
		case 1:						\
			__put_user_8(x, __pu_addr);		\
			break;					\
		case 2:						\
			__put_user_16(x, __pu_addr);		\
			break;					\
		case 4:						\
			__put_user_32(x, __pu_addr);		\
			break;					\
		case 8:						\
			__put_user_64(x, __pu_addr);		\
			break;					\
		default:					\
			__put_user_unknown();			\
			break;					\
		}						\
	}							\
	__pu_err;						\
})

/*
 * The "__put_user_xx()" macros tell gcc they read from memory
 * instead of writing: this is because they do not write to
 * any memory gcc knows about, so there are no aliasing issues
 */
#define __put_user_64(x, addr)					\
__asm__ __volatile__("1: stl %r2, %1\n"				\
	"2:\n"							\
	".section __ex_table, \"a\"\n"				\
	"	.long 1b - .\n"					\
	"	ldi $31, 2b-1b(%0)\n"				\
	".previous"						\
		: "=r"(__pu_err)				\
		: "m" (__m(addr)), "rJ" (x), "0"(__pu_err))

#define __put_user_32(x, addr)					\
__asm__ __volatile__("1: stw %r2, %1\n"				\
	"2:\n"							\
	".section __ex_table, \"a\"\n"				\
	"	.long 1b - .\n"					\
	"	ldi $31, 2b-1b(%0)\n"				\
	".previous"						\
		: "=r"(__pu_err)				\
		: "m"(__m(addr)), "rJ"(x), "0"(__pu_err))

#define __put_user_16(x, addr)					\
__asm__ __volatile__("1: sth %r2, %1\n"				\
	"2:\n"							\
	".section __ex_table, \"a\"\n"				\
	"	.long 1b - .\n"					\
	"	ldi $31, 2b-1b(%0)\n"				\
	".previous"						\
		: "=r"(__pu_err)				\
		: "m"(__m(addr)), "rJ"(x), "0"(__pu_err))

#define __put_user_8(x, addr)					\
__asm__ __volatile__("1: stb %r2, %1\n"				\
	"2:\n"							\
	".section __ex_table, \"a\"\n"				\
	"	.long 1b - .\n"					\
	"	ldi $31, 2b-1b(%0)\n"				\
	".previous"						\
		: "=r"(__pu_err)				\
		: "m"(__m(addr)), "rJ"(x), "0"(__pu_err))

/*
 * Complex access routines
 */

extern long __copy_user(void *to, const void *from, long len);

static inline unsigned long
raw_copy_from_user(void *to, const void __user *from, unsigned long len)
{
	return __copy_user(to, (__force const void *)from, len);
}

static inline unsigned long
raw_copy_to_user(void __user *to, const void *from, unsigned long len)
{
	return __copy_user((__force void *)to, from, len);
}

extern long __clear_user(void __user *to, long len);

static inline long
clear_user(void __user *to, long len)
{
	if (__access_ok((unsigned long)to, len))
		len = __clear_user(to, len);
	return len;
}

#define user_addr_max()	(uaccess_kernel() ? ~0UL : TASK_SIZE)

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

#include <asm/extable.h>
#endif /* _ASM_SW64_UACCESS_H */