linux/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 size_t copy_from_user_flushcache(void *dst, const void __user *src, size_t 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 */