cregit-Linux how code gets into the kernel

Release 4.7 include/asm-generic/uaccess.h

#ifndef __ASM_GENERIC_UACCESS_H

#define __ASM_GENERIC_UACCESS_H

/*
 * User space memory access functions, these should work
 * on any machine that has kernel and user data in the same
 * address space, e.g. all NOMMU machines.
 */
#include <linux/sched.h>
#include <linux/string.h>

#include <asm/segment.h>


#define MAKE_MM_SEG(s)	((mm_segment_t) { (s) })

#ifndef KERNEL_DS

#define KERNEL_DS	MAKE_MM_SEG(~0UL)
#endif

#ifndef USER_DS

#define USER_DS		MAKE_MM_SEG(TASK_SIZE - 1)
#endif

#ifndef get_fs

#define get_ds()	(KERNEL_DS)

#define get_fs()	(current_thread_info()->addr_limit)


static inline void set_fs(mm_segment_t fs) { current_thread_info()->addr_limit = fs; }

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#endif #ifndef segment_eq #define segment_eq(a, b) ((a).seg == (b).seg) #endif #define VERIFY_READ 0 #define VERIFY_WRITE 1 #define access_ok(type, addr, size) __access_ok((unsigned long)(addr),(size)) /* * The architecture should really override this if possible, at least * doing a check on the get_fs() */ #ifndef __access_ok
static inline int __access_ok(unsigned long addr, unsigned long size) { return 1; }

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#endif /* * The exception table consists of pairs of addresses: the first is the * address of an instruction that is allowed to fault, and the second is * the address at which the program should continue. No registers are * modified, so it is entirely up to the continuation code to figure out * what to do. * * All the routines below use bits of fixup code that are out of line * with the main instruction path. This means when everything is well, * we don't even have to jump over them. Further, they do not intrude * on our cache or tlb entries. */ struct exception_table_entry { unsigned long insn, fixup; }; /* Returns 0 if exception not found and fixup otherwise. */ extern unsigned long search_exception_table(unsigned long); /* * architectures with an MMU should override these two */ #ifndef __copy_from_user
static inline __must_check long __copy_from_user(void *to, const void __user * from, unsigned long n) { if (__builtin_constant_p(n)) { switch(n) { case 1: *(u8 *)to = *(u8 __force *)from; return 0; case 2: *(u16 *)to = *(u16 __force *)from; return 0; case 4: *(u32 *)to = *(u32 __force *)from; return 0; #ifdef CONFIG_64BIT case 8: *(u64 *)to = *(u64 __force *)from; return 0; #endif default: break; } } memcpy(to, (const void __force *)from, n); return 0; }

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#endif #ifndef __copy_to_user
static inline __must_check long __copy_to_user(void __user *to, const void *from, unsigned long n) { if (__builtin_constant_p(n)) { switch(n) { case 1: *(u8 __force *)to = *(u8 *)from; return 0; case 2: *(u16 __force *)to = *(u16 *)from; return 0; case 4: *(u32 __force *)to = *(u32 *)from; return 0; #ifdef CONFIG_64BIT case 8: *(u64 __force *)to = *(u64 *)from; return 0; #endif default: break; } } memcpy((void __force *)to, from, n); return 0; }

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#endif /* * These are the main single-value transfer routines. They automatically * use the right size if we just have the right pointer type. * This version just falls back to copy_{from,to}_user, which should * provide a fast-path for small values. */ #define __put_user(x, ptr) \ ({ \ __typeof__(*(ptr)) __x = (x); \ int __pu_err = -EFAULT; \ __chk_user_ptr(ptr); \ switch (sizeof (*(ptr))) { \ case 1: \ case 2: \ case 4: \ case 8: \ __pu_err = __put_user_fn(sizeof (*(ptr)), \ ptr, &__x); \ break; \ default: \ __put_user_bad(); \ break; \ } \ __pu_err; \ }) #define put_user(x, ptr) \ ({ \ void *__p = (ptr); \ might_fault(); \ access_ok(VERIFY_WRITE, __p, sizeof(*ptr)) ? \ __put_user((x), ((__typeof__(*(ptr)) *)__p)) : \ -EFAULT; \ }) #ifndef __put_user_fn
static inline int __put_user_fn(size_t size, void __user *ptr, void *x) { size = __copy_to_user(ptr, x, size); return size ? -EFAULT : size; }

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#define __put_user_fn(sz, u, k) __put_user_fn(sz, u, k) #endif extern int __put_user_bad(void) __attribute__((noreturn)); #define __get_user(x, ptr) \ ({ \ int __gu_err = -EFAULT; \ __chk_user_ptr(ptr); \ switch (sizeof(*(ptr))) { \ case 1: { \ unsigned char __x; \ __gu_err = __get_user_fn(sizeof (*(ptr)), \ ptr, &__x); \ (x) = *(__force __typeof__(*(ptr)) *) &__x; \ break; \ }; \ case 2: { \ unsigned short __x; \ __gu_err = __get_user_fn(sizeof (*(ptr)), \ ptr, &__x); \ (x) = *(__force __typeof__(*(ptr)) *) &__x; \ break; \ }; \ case 4: { \ unsigned int __x; \ __gu_err = __get_user_fn(sizeof (*(ptr)), \ ptr, &__x); \ (x) = *(__force __typeof__(*(ptr)) *) &__x; \ break; \ }; \ case 8: { \ unsigned long long __x; \ __gu_err = __get_user_fn(sizeof (*(ptr)), \ ptr, &__x); \ (x) = *(__force __typeof__(*(ptr)) *) &__x; \ break; \ }; \ default: \ __get_user_bad(); \ break; \ } \ __gu_err; \ }) #define get_user(x, ptr) \ ({ \ const void *__p = (ptr); \ might_fault(); \ access_ok(VERIFY_READ, __p, sizeof(*ptr)) ? \ __get_user((x), (__typeof__(*(ptr)) *)__p) : \ -EFAULT; \ }) #ifndef __get_user_fn
static inline int __get_user_fn(size_t size, const void __user *ptr, void *x) { size = __copy_from_user(x, ptr, size); return size ? -EFAULT : size; }

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#define __get_user_fn(sz, u, k) __get_user_fn(sz, u, k) #endif extern int __get_user_bad(void) __attribute__((noreturn)); #ifndef __copy_from_user_inatomic #define __copy_from_user_inatomic __copy_from_user #endif #ifndef __copy_to_user_inatomic #define __copy_to_user_inatomic __copy_to_user #endif
static inline long copy_from_user(void *to, const void __user * from, unsigned long n) { might_fault(); if (access_ok(VERIFY_READ, from, n)) return __copy_from_user(to, from, n); else return n; }

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Total49100.00%3100.00%


static inline long copy_to_user(void __user *to, const void *from, unsigned long n) { might_fault(); if (access_ok(VERIFY_WRITE, to, n)) return __copy_to_user(to, from, n); else return n; }

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michael s. tsirkinmichael s. tsirkin12.04%133.33%
Total49100.00%3100.00%

/* * Copy a null terminated string from userspace. */ #ifndef __strncpy_from_user
static inline long __strncpy_from_user(char *dst, const char __user *src, long count) { char *tmp; strncpy(dst, (const char __force *)src, count); for (tmp = dst; *tmp && count > 0; tmp++, count--) ; return (tmp - dst); }

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#endif
static inline long strncpy_from_user(char *dst, const char __user *src, long count) { if (!access_ok(VERIFY_READ, src, 1)) return -EFAULT; return __strncpy_from_user(dst, src, count); }

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/* * Return the size of a string (including the ending 0) * * Return 0 on exception, a value greater than N if too long */ #ifndef __strnlen_user #define __strnlen_user(s, n) (strnlen((s), (n)) + 1) #endif /* * Unlike strnlen, strnlen_user includes the nul terminator in * its returned count. Callers should check for a returned value * greater than N as an indication the string is too long. */
static inline long strnlen_user(const char __user *src, long n) { if (!access_ok(VERIFY_READ, src, 1)) return 0; return __strnlen_user(src, n); }

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guan xuetaoguan xuetao37.69%133.33%
Total39100.00%3100.00%


static inline long strlen_user(const char __user *src) { return strnlen_user(src, 32767); }

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/* * Zero Userspace */ #ifndef __clear_user
static inline __must_check unsigned long __clear_user(void __user *to, unsigned long n) { memset((void __force *)to, 0, n); return 0; }

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#endif
static inline __must_check unsigned long clear_user(void __user *to, unsigned long n) { might_fault(); if (!access_ok(VERIFY_WRITE, to, n)) return n; return __clear_user(to, n); }

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Total44100.00%3100.00%

#endif /* __ASM_GENERIC_UACCESS_H */

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guan xuetaoguan xuetao90.88%110.00%
mark saltermark salter70.68%110.00%
michael s. tsirkinmichael s. tsirkin30.29%110.00%
yoshinori satoyoshinori sato20.20%110.00%
geert uytterhoevengeert uytterhoeven10.10%110.00%
Total1024100.00%10100.00%
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