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linux/arch/x86/include/asm/uaccess.h
Linus Torvalds b9bd9f605c x86: uaccess: move 32-bit and 64-bit parts into proper <asm/uaccess_N.h> header 
The x86 <asm/uaccess.h> file has grown features that are specific to
x86-64 like LAM support and the related access_ok() changes.  They
really should be in the <asm/uaccess_64.h> file and not pollute the
generic x86 header.

Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2023-05-03 10:37:22 -07:00

643 lines
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/* SPDX-License-Identifier: GPL-2.0 */
#ifndef _ASM_X86_UACCESS_H
#define _ASM_X86_UACCESS_H
/*
* User space memory access functions
*/
#include <linux/compiler.h>
#include <linux/instrumented.h>
#include <linux/kasan-checks.h>
#include <linux/mm_types.h>
#include <linux/string.h>
#include <linux/mmap_lock.h>
#include <asm/asm.h>
#include <asm/page.h>
#include <asm/smap.h>
#include <asm/extable.h>
#include <asm/tlbflush.h>
#ifdef CONFIG_X86_32
# include <asm/uaccess_32.h>
#else
# include <asm/uaccess_64.h>
#endif
#include <asm-generic/access_ok.h>
extern int __get_user_1(void);
extern int __get_user_2(void);
extern int __get_user_4(void);
extern int __get_user_8(void);
extern int __get_user_nocheck_1(void);
extern int __get_user_nocheck_2(void);
extern int __get_user_nocheck_4(void);
extern int __get_user_nocheck_8(void);
extern int __get_user_bad(void);
#define __uaccess_begin() stac()
#define __uaccess_end() clac()
#define __uaccess_begin_nospec() \
({ \
stac(); \
barrier_nospec(); \
})
/*
* This is the smallest unsigned integer type that can fit a value
* (up to 'long long')
*/
#define __inttype(x) __typeof__( \
__typefits(x,char, \
__typefits(x,short, \
__typefits(x,int, \
__typefits(x,long,0ULL)))))
#define __typefits(x,type,not) \
__builtin_choose_expr(sizeof(x)<=sizeof(type),(unsigned type)0,not)
/*
* This is used for both get_user() and __get_user() to expand to
* the proper special function call that has odd calling conventions
* due to returning both a value and an error, and that depends on
* the size of the pointer passed in.
*
* Careful: we have to cast the result to the type of the pointer
* for sign reasons.
*
* The use of _ASM_DX as the register specifier is a bit of a
* simplification, as gcc only cares about it as the starting point
* and not size: for a 64-bit value it will use %ecx:%edx on 32 bits
* (%ecx being the next register in gcc's x86 register sequence), and
* %rdx on 64 bits.
*
* Clang/LLVM cares about the size of the register, but still wants
* the base register for something that ends up being a pair.
*/
#define do_get_user_call(fn,x,ptr) \
({ \
int __ret_gu; \
register __inttype(*(ptr)) __val_gu asm("%"_ASM_DX); \
__chk_user_ptr(ptr); \
asm volatile("call __" #fn "_%P4" \
: "=a" (__ret_gu), "=r" (__val_gu), \
ASM_CALL_CONSTRAINT \
: "0" (ptr), "i" (sizeof(*(ptr)))); \
instrument_get_user(__val_gu); \
(x) = (__force __typeof__(*(ptr))) __val_gu; \
__builtin_expect(__ret_gu, 0); \
})
/**
* get_user - Get a simple variable from user space.
* @x: Variable to store result.
* @ptr: Source address, in user space.
*
* Context: User context only. This function may sleep if pagefaults are
* enabled.
*
* This macro copies a single simple variable from user space to kernel
* space. It supports simple types like char and int, but not larger
* data types like structures or arrays.
*
* @ptr must have pointer-to-simple-variable type, and the result of
* dereferencing @ptr must be assignable to @x without a cast.
*
* Return: zero on success, or -EFAULT on error.
* On error, the variable @x is set to zero.
*/
#define get_user(x,ptr) ({ might_fault(); do_get_user_call(get_user,x,ptr); })
/**
* __get_user - Get a simple variable from user space, with less checking.
* @x: Variable to store result.
* @ptr: Source address, in user space.
*
* Context: User context only. This function may sleep if pagefaults are
* enabled.
*
* This macro copies a single simple variable from user space to kernel
* space. It supports simple types like char and int, but not larger
* data types like structures or arrays.
*
* @ptr must have pointer-to-simple-variable type, and the result of
* dereferencing @ptr must be assignable to @x without a cast.
*
* Caller must check the pointer with access_ok() before calling this
* function.
*
* Return: zero on success, or -EFAULT on error.
* On error, the variable @x is set to zero.
*/
#define __get_user(x,ptr) do_get_user_call(get_user_nocheck,x,ptr)
#ifdef CONFIG_X86_32
#define __put_user_goto_u64(x, addr, label) \
asm_volatile_goto("\n" \
"1: movl %%eax,0(%1)\n" \
"2: movl %%edx,4(%1)\n" \
_ASM_EXTABLE_UA(1b, %l2) \
_ASM_EXTABLE_UA(2b, %l2) \
: : "A" (x), "r" (addr) \
: : label)
#else
#define __put_user_goto_u64(x, ptr, label) \
__put_user_goto(x, ptr, "q", "er", label)
#endif
extern void __put_user_bad(void);
/*
* Strange magic calling convention: pointer in %ecx,
* value in %eax(:%edx), return value in %ecx. clobbers %rbx
*/
extern void __put_user_1(void);
extern void __put_user_2(void);
extern void __put_user_4(void);
extern void __put_user_8(void);
extern void __put_user_nocheck_1(void);
extern void __put_user_nocheck_2(void);
extern void __put_user_nocheck_4(void);
extern void __put_user_nocheck_8(void);
/*
* ptr must be evaluated and assigned to the temporary __ptr_pu before
* the assignment of x to __val_pu, to avoid any function calls
* involved in the ptr expression (possibly implicitly generated due
* to KASAN) from clobbering %ax.
*/
#define do_put_user_call(fn,x,ptr) \
({ \
int __ret_pu; \
void __user *__ptr_pu; \
register __typeof__(*(ptr)) __val_pu asm("%"_ASM_AX); \
__typeof__(*(ptr)) __x = (x); /* eval x once */ \
__typeof__(ptr) __ptr = (ptr); /* eval ptr once */ \
__chk_user_ptr(__ptr); \
__ptr_pu = __ptr; \
__val_pu = __x; \
asm volatile("call __" #fn "_%P[size]" \
: "=c" (__ret_pu), \
ASM_CALL_CONSTRAINT \
: "0" (__ptr_pu), \
"r" (__val_pu), \
[size] "i" (sizeof(*(ptr))) \
:"ebx"); \
instrument_put_user(__x, __ptr, sizeof(*(ptr))); \
__builtin_expect(__ret_pu, 0); \
})
/**
* put_user - Write a simple value into user space.
* @x: Value to copy to user space.
* @ptr: Destination address, in user space.
*
* Context: User context only. This function may sleep if pagefaults are
* enabled.
*
* This macro copies a single simple value from kernel space to user
* space. It supports simple types like char and int, but not larger
* data types like structures or arrays.
*
* @ptr must have pointer-to-simple-variable type, and @x must be assignable
* to the result of dereferencing @ptr.
*
* Return: zero on success, or -EFAULT on error.
*/
#define put_user(x, ptr) ({ might_fault(); do_put_user_call(put_user,x,ptr); })
/**
* __put_user - Write a simple value into user space, with less checking.
* @x: Value to copy to user space.
* @ptr: Destination address, in user space.
*
* Context: User context only. This function may sleep if pagefaults are
* enabled.
*
* This macro copies a single simple value from kernel space to user
* space. It supports simple types like char and int, but not larger
* data types like structures or arrays.
*
* @ptr must have pointer-to-simple-variable type, and @x must be assignable
* to the result of dereferencing @ptr.
*
* Caller must check the pointer with access_ok() before calling this
* function.
*
* Return: zero on success, or -EFAULT on error.
*/
#define __put_user(x, ptr) do_put_user_call(put_user_nocheck,x,ptr)
#define __put_user_size(x, ptr, size, label) \
do { \
__typeof__(*(ptr)) __x = (x); /* eval x once */ \
__typeof__(ptr) __ptr = (ptr); /* eval ptr once */ \
__chk_user_ptr(__ptr); \
switch (size) { \
case 1: \
__put_user_goto(__x, __ptr, "b", "iq", label); \
break; \
case 2: \
__put_user_goto(__x, __ptr, "w", "ir", label); \
break; \
case 4: \
__put_user_goto(__x, __ptr, "l", "ir", label); \
break; \
case 8: \
__put_user_goto_u64(__x, __ptr, label); \
break; \
default: \
__put_user_bad(); \
} \
instrument_put_user(__x, __ptr, size); \
} while (0)
#ifdef CONFIG_CC_HAS_ASM_GOTO_OUTPUT
#ifdef CONFIG_X86_32
#define __get_user_asm_u64(x, ptr, label) do { \
unsigned int __gu_low, __gu_high; \
const unsigned int __user *__gu_ptr; \
__gu_ptr = (const void __user *)(ptr); \
__get_user_asm(__gu_low, __gu_ptr, "l", "=r", label); \
__get_user_asm(__gu_high, __gu_ptr+1, "l", "=r", label); \
(x) = ((unsigned long long)__gu_high << 32) | __gu_low; \
} while (0)
#else
#define __get_user_asm_u64(x, ptr, label) \
__get_user_asm(x, ptr, "q", "=r", label)
#endif
#define __get_user_size(x, ptr, size, label) \
do { \
__chk_user_ptr(ptr); \
switch (size) { \
case 1: { \
unsigned char x_u8__; \
__get_user_asm(x_u8__, ptr, "b", "=q", label); \
(x) = x_u8__; \
break; \
} \
case 2: \
__get_user_asm(x, ptr, "w", "=r", label); \
break; \
case 4: \
__get_user_asm(x, ptr, "l", "=r", label); \
break; \
case 8: \
__get_user_asm_u64(x, ptr, label); \
break; \
default: \
(x) = __get_user_bad(); \
} \
instrument_get_user(x); \
} while (0)
#define __get_user_asm(x, addr, itype, ltype, label) \
asm_volatile_goto("\n" \
"1: mov"itype" %[umem],%[output]\n" \
_ASM_EXTABLE_UA(1b, %l2) \
: [output] ltype(x) \
: [umem] "m" (__m(addr)) \
: : label)
#else // !CONFIG_CC_HAS_ASM_GOTO_OUTPUT
#ifdef CONFIG_X86_32
#define __get_user_asm_u64(x, ptr, retval) \
({ \
__typeof__(ptr) __ptr = (ptr); \
asm volatile("\n" \
"1: movl %[lowbits],%%eax\n" \
"2: movl %[highbits],%%edx\n" \
"3:\n" \
_ASM_EXTABLE_TYPE_REG(1b, 3b, EX_TYPE_EFAULT_REG | \
EX_FLAG_CLEAR_AX_DX, \
%[errout]) \
_ASM_EXTABLE_TYPE_REG(2b, 3b, EX_TYPE_EFAULT_REG | \
EX_FLAG_CLEAR_AX_DX, \
%[errout]) \
: [errout] "=r" (retval), \
[output] "=&A"(x) \
: [lowbits] "m" (__m(__ptr)), \
[highbits] "m" __m(((u32 __user *)(__ptr)) + 1), \
"0" (retval)); \
})
#else
#define __get_user_asm_u64(x, ptr, retval) \
__get_user_asm(x, ptr, retval, "q")
#endif
#define __get_user_size(x, ptr, size, retval) \
do { \
unsigned char x_u8__; \
\
retval = 0; \
__chk_user_ptr(ptr); \
switch (size) { \
case 1: \
__get_user_asm(x_u8__, ptr, retval, "b"); \
(x) = x_u8__; \
break; \
case 2: \
__get_user_asm(x, ptr, retval, "w"); \
break; \
case 4: \
__get_user_asm(x, ptr, retval, "l"); \
break; \
case 8: \
__get_user_asm_u64(x, ptr, retval); \
break; \
default: \
(x) = __get_user_bad(); \
} \
} while (0)
#define __get_user_asm(x, addr, err, itype) \
asm volatile("\n" \
"1: mov"itype" %[umem],%[output]\n" \
"2:\n" \
_ASM_EXTABLE_TYPE_REG(1b, 2b, EX_TYPE_EFAULT_REG | \
EX_FLAG_CLEAR_AX, \
%[errout]) \
: [errout] "=r" (err), \
[output] "=a" (x) \
: [umem] "m" (__m(addr)), \
"0" (err))
#endif // CONFIG_CC_HAS_ASM_GOTO_OUTPUT
#ifdef CONFIG_CC_HAS_ASM_GOTO_TIED_OUTPUT
#define __try_cmpxchg_user_asm(itype, ltype, _ptr, _pold, _new, label) ({ \
bool success; \
__typeof__(_ptr) _old = (__typeof__(_ptr))(_pold); \
__typeof__(*(_ptr)) __old = *_old; \
__typeof__(*(_ptr)) __new = (_new); \
asm_volatile_goto("\n" \
"1: " LOCK_PREFIX "cmpxchg"itype" %[new], %[ptr]\n"\
_ASM_EXTABLE_UA(1b, %l[label]) \
: CC_OUT(z) (success), \
[ptr] "+m" (*_ptr), \
[old] "+a" (__old) \
: [new] ltype (__new) \
: "memory" \
: label); \
if (unlikely(!success)) \
*_old = __old; \
likely(success); })
#ifdef CONFIG_X86_32
#define __try_cmpxchg64_user_asm(_ptr, _pold, _new, label) ({ \
bool success; \
__typeof__(_ptr) _old = (__typeof__(_ptr))(_pold); \
__typeof__(*(_ptr)) __old = *_old; \
__typeof__(*(_ptr)) __new = (_new); \
asm_volatile_goto("\n" \
"1: " LOCK_PREFIX "cmpxchg8b %[ptr]\n" \
_ASM_EXTABLE_UA(1b, %l[label]) \
: CC_OUT(z) (success), \
"+A" (__old), \
[ptr] "+m" (*_ptr) \
: "b" ((u32)__new), \
"c" ((u32)((u64)__new >> 32)) \
: "memory" \
: label); \
if (unlikely(!success)) \
*_old = __old; \
likely(success); })
#endif // CONFIG_X86_32
#else // !CONFIG_CC_HAS_ASM_GOTO_TIED_OUTPUT
#define __try_cmpxchg_user_asm(itype, ltype, _ptr, _pold, _new, label) ({ \
int __err = 0; \
bool success; \
__typeof__(_ptr) _old = (__typeof__(_ptr))(_pold); \
__typeof__(*(_ptr)) __old = *_old; \
__typeof__(*(_ptr)) __new = (_new); \
asm volatile("\n" \
"1: " LOCK_PREFIX "cmpxchg"itype" %[new], %[ptr]\n"\
CC_SET(z) \
"2:\n" \
_ASM_EXTABLE_TYPE_REG(1b, 2b, EX_TYPE_EFAULT_REG, \
%[errout]) \
: CC_OUT(z) (success), \
[errout] "+r" (__err), \
[ptr] "+m" (*_ptr), \
[old] "+a" (__old) \
: [new] ltype (__new) \
: "memory"); \
if (unlikely(__err)) \
goto label; \
if (unlikely(!success)) \
*_old = __old; \
likely(success); })
#ifdef CONFIG_X86_32
/*
* Unlike the normal CMPXCHG, use output GPR for both success/fail and error.
* There are only six GPRs available and four (EAX, EBX, ECX, and EDX) are
* hardcoded by CMPXCHG8B, leaving only ESI and EDI. If the compiler uses
* both ESI and EDI for the memory operand, compilation will fail if the error
* is an input+output as there will be no register available for input.
*/
#define __try_cmpxchg64_user_asm(_ptr, _pold, _new, label) ({ \
int __result; \
__typeof__(_ptr) _old = (__typeof__(_ptr))(_pold); \
__typeof__(*(_ptr)) __old = *_old; \
__typeof__(*(_ptr)) __new = (_new); \
asm volatile("\n" \
"1: " LOCK_PREFIX "cmpxchg8b %[ptr]\n" \
"mov $0, %[result]\n\t" \
"setz %b[result]\n" \
"2:\n" \
_ASM_EXTABLE_TYPE_REG(1b, 2b, EX_TYPE_EFAULT_REG, \
%[result]) \
: [result] "=q" (__result), \
"+A" (__old), \
[ptr] "+m" (*_ptr) \
: "b" ((u32)__new), \
"c" ((u32)((u64)__new >> 32)) \
: "memory", "cc"); \
if (unlikely(__result < 0)) \
goto label; \
if (unlikely(!__result)) \
*_old = __old; \
likely(__result); })
#endif // CONFIG_X86_32
#endif // CONFIG_CC_HAS_ASM_GOTO_TIED_OUTPUT
/* FIXME: this hack is definitely wrong -AK */
struct __large_struct { unsigned long buf[100]; };
#define __m(x) (*(struct __large_struct __user *)(x))
/*
* Tell gcc we read from memory instead of writing: this is because
* we do not write to any memory gcc knows about, so there are no
* aliasing issues.
*/
#define __put_user_goto(x, addr, itype, ltype, label) \
asm_volatile_goto("\n" \
"1: mov"itype" %0,%1\n" \
_ASM_EXTABLE_UA(1b, %l2) \
: : ltype(x), "m" (__m(addr)) \
: : label)
extern unsigned long
copy_from_user_nmi(void *to, const void __user *from, unsigned long n);
extern __must_check 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_to_kernel(void *to, const void *from, unsigned len);
#define copy_mc_to_kernel copy_mc_to_kernel
unsigned long __must_check
copy_mc_to_user(void *to, const void *from, unsigned len);
#endif
/*
* movsl can be slow when source and dest are not both 8-byte aligned
*/
#ifdef CONFIG_X86_INTEL_USERCOPY
extern struct movsl_mask {
int mask;
} ____cacheline_aligned_in_smp movsl_mask;
#endif
#define ARCH_HAS_NOCACHE_UACCESS 1
/*
* The "unsafe" user accesses aren't really "unsafe", but the naming
* is a big fat warning: you have to not only do the access_ok()
* checking before using them, but you have to surround them with the
* user_access_begin/end() pair.
*/
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_begin_nospec();
return 1;
}
#define user_access_begin(a,b) user_access_begin(a,b)
#define user_access_end() __uaccess_end()
#define user_access_save() smap_save()
#define user_access_restore(x) smap_restore(x)
#define unsafe_put_user(x, ptr, label) \
__put_user_size((__typeof__(*(ptr)))(x), (ptr), sizeof(*(ptr)), label)
#ifdef CONFIG_CC_HAS_ASM_GOTO_OUTPUT
#define unsafe_get_user(x, ptr, err_label) \
do { \
__inttype(*(ptr)) __gu_val; \
__get_user_size(__gu_val, (ptr), sizeof(*(ptr)), err_label); \
(x) = (__force __typeof__(*(ptr)))__gu_val; \
} while (0)
#else // !CONFIG_CC_HAS_ASM_GOTO_OUTPUT
#define unsafe_get_user(x, ptr, err_label) \
do { \
int __gu_err; \
__inttype(*(ptr)) __gu_val; \
__get_user_size(__gu_val, (ptr), sizeof(*(ptr)), __gu_err); \
(x) = (__force __typeof__(*(ptr)))__gu_val; \
if (unlikely(__gu_err)) goto err_label; \
} while (0)
#endif // CONFIG_CC_HAS_ASM_GOTO_OUTPUT
extern void __try_cmpxchg_user_wrong_size(void);
#ifndef CONFIG_X86_32
#define __try_cmpxchg64_user_asm(_ptr, _oldp, _nval, _label) \
__try_cmpxchg_user_asm("q", "r", (_ptr), (_oldp), (_nval), _label)
#endif
/*
* Force the pointer to u<size> to match the size expected by the asm helper.
* clang/LLVM compiles all cases and only discards the unused paths after
* processing errors, which breaks i386 if the pointer is an 8-byte value.
*/
#define unsafe_try_cmpxchg_user(_ptr, _oldp, _nval, _label) ({ \
bool __ret; \
__chk_user_ptr(_ptr); \
switch (sizeof(*(_ptr))) { \
case 1: __ret = __try_cmpxchg_user_asm("b", "q", \
(__force u8 *)(_ptr), (_oldp), \
(_nval), _label); \
break; \
case 2: __ret = __try_cmpxchg_user_asm("w", "r", \
(__force u16 *)(_ptr), (_oldp), \
(_nval), _label); \
break; \
case 4: __ret = __try_cmpxchg_user_asm("l", "r", \
(__force u32 *)(_ptr), (_oldp), \
(_nval), _label); \
break; \
case 8: __ret = __try_cmpxchg64_user_asm((__force u64 *)(_ptr), (_oldp),\
(_nval), _label); \
break; \
default: __try_cmpxchg_user_wrong_size(); \
} \
__ret; })
/* "Returns" 0 on success, 1 on failure, -EFAULT if the access faults. */
#define __try_cmpxchg_user(_ptr, _oldp, _nval, _label) ({ \
int __ret = -EFAULT; \
__uaccess_begin_nospec(); \
__ret = !unsafe_try_cmpxchg_user(_ptr, _oldp, _nval, _label); \
_label: \
__uaccess_end(); \
__ret; \
})
/*
* 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)
#ifdef CONFIG_CC_HAS_ASM_GOTO_OUTPUT
#define __get_kernel_nofault(dst, src, type, err_label) \
__get_user_size(*((type *)(dst)), (__force type __user *)(src), \
sizeof(type), err_label)
#else // !CONFIG_CC_HAS_ASM_GOTO_OUTPUT
#define __get_kernel_nofault(dst, src, type, err_label) \
do { \
int __kr_err; \
\
__get_user_size(*((type *)(dst)), (__force type __user *)(src), \
sizeof(type), __kr_err); \
if (unlikely(__kr_err)) \
goto err_label; \
} while (0)
#endif // CONFIG_CC_HAS_ASM_GOTO_OUTPUT
#define __put_kernel_nofault(dst, src, type, err_label) \
__put_user_size(*((type *)(src)), (__force type __user *)(dst), \
sizeof(type), err_label)
#endif /* _ASM_X86_UACCESS_H */
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