cregit-Linux how code gets into the kernel

Release 4.14 arch/parisc/include/asm/uaccess.h

/* SPDX-License-Identifier: GPL-2.0 */
#ifndef __PARISC_UACCESS_H

#define __PARISC_UACCESS_H

/*
 * User space memory access functions
 */
#include <asm/page.h>
#include <asm/cache.h>

#include <linux/bug.h>
#include <linux/string.h>


#define KERNEL_DS	((mm_segment_t){0})

#define USER_DS 	((mm_segment_t){1})


#define segment_eq(a, b) ((a).seg == (b).seg)


#define get_ds()	(KERNEL_DS)

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

#define set_fs(x)	(current_thread_info()->addr_limit = (x))

/*
 * Note that since kernel addresses are in a separate address space on
 * parisc, we don't need to do anything for access_ok().
 * We just let the page fault handler do the right thing. This also means
 * that put_user is the same as __put_user, etc.
 */


#define access_ok(type, uaddr, size)	\
	( (uaddr) == (uaddr) )


#define put_user __put_user

#define get_user __get_user

#if !defined(CONFIG_64BIT)

#define LDD_USER(val, ptr)	__get_user_asm64(val, ptr)

#define STD_USER(x, ptr)	__put_user_asm64(x, ptr)
#else

#define LDD_USER(val, ptr)	__get_user_asm(val, "ldd", ptr)

#define STD_USER(x, ptr)	__put_user_asm("std", x, ptr)
#endif

/*
 * The exception table contains two values: the first is the relative offset to
 * the address of the instruction that is allowed to fault, and the second is
 * the relative offset to the address of the fixup routine. Since relative
 * addresses are used, 32bit values are sufficient even on 64bit kernel.
 */


#define ARCH_HAS_RELATIVE_EXTABLE

struct exception_table_entry {
	
int insn;	/* relative address of insn that is allowed to fault. */
	
int fixup;	/* relative address of fixup routine */
};


#define ASM_EXCEPTIONTABLE_ENTRY( fault_addr, except_addr )\
	".section __ex_table,\"aw\"\n"                     \
        ".word (" #fault_addr " - .), (" #except_addr " - .)\n\t" \
        ".previous\n"

/*
 * ASM_EXCEPTIONTABLE_ENTRY_EFAULT() creates a special exception table entry
 * (with lowest bit set) for which the fault handler in fixup_exception() will
 * load -EFAULT into %r8 for a read or write fault, and zeroes the target
 * register in case of a read fault in get_user().
 */

#define ASM_EXCEPTIONTABLE_ENTRY_EFAULT( fault_addr, except_addr )\
	ASM_EXCEPTIONTABLE_ENTRY( fault_addr, except_addr + 1)

/*
 * load_sr2() preloads the space register %%sr2 - based on the value of
 * get_fs() - with either a value of 0 to access kernel space (KERNEL_DS which
 * is 0), or with the current value of %%sr3 to access user space (USER_DS)
 * memory. The following __get_user_asm() and __put_user_asm() functions have
 * %%sr2 hard-coded to access the requested memory.
 */

#define load_sr2() \
	__asm__(" or,=  %0,%%r0,%%r0\n\t"       \
                " mfsp %%sr3,%0\n\t"            \
                " mtsp %0,%%sr2\n\t"            \
                : : "r"(get_fs()) : )


#define __get_user_internal(val, ptr)			\
({                                                      \
        register long __gu_err __asm__ ("r8") = 0;      \
                                                        \
        switch (sizeof(*(ptr))) {                       \
        case 1: __get_user_asm(val, "ldb", ptr); break; \
        case 2: __get_user_asm(val, "ldh", ptr); break; \
        case 4: __get_user_asm(val, "ldw", ptr); break; \
        case 8: LDD_USER(val, ptr); break;              \
        default: BUILD_BUG();                           \
        }                                               \
                                                        \
        __gu_err;                                       \
})


#define __get_user(val, ptr)				\
({                                                      \
        load_sr2();                                     \
        __get_user_internal(val, ptr);                  \
})


#define __get_user_asm(val, ldx, ptr)			\
{                                                       \
        register long __gu_val;                         \
                                                        \
        __asm__("1: " ldx " 0(%%sr2,%2),%0\n"           \
                "9:\n"                                  \
                ASM_EXCEPTIONTABLE_ENTRY_EFAULT(1b, 9b) \
                : "=r"(__gu_val), "=r"(__gu_err)        \
                : "r"(ptr), "1"(__gu_err));             \
                                                        \
        (val) = (__force __typeof__(*(ptr))) __gu_val;  \
}

#if !defined(CONFIG_64BIT)


#define __get_user_asm64(val, ptr)			\
{                                                       \
        union {                                         \
                unsigned long long      l;              \
                __typeof__(*(ptr))      t;              \
        } __gu_tmp;                                     \
                                                        \
        __asm__("   copy %%r0,%R0\n"                    \
                "1: ldw 0(%%sr2,%2),%0\n"               \
                "2: ldw 4(%%sr2,%2),%R0\n"              \
                "9:\n"                                  \
                ASM_EXCEPTIONTABLE_ENTRY_EFAULT(1b, 9b) \
                ASM_EXCEPTIONTABLE_ENTRY_EFAULT(2b, 9b) \
                : "=&r"(__gu_tmp.l), "=r"(__gu_err)     \
                : "r"(ptr), "1"(__gu_err));             \
                                                        \
        (val) = __gu_tmp.t;                             \
}

#endif /* !defined(CONFIG_64BIT) */



#define __put_user_internal(x, ptr)				\
({                                                              \
        register long __pu_err __asm__ ("r8") = 0;              \
        __typeof__(*(ptr)) __x = (__typeof__(*(ptr)))(x);       \
                                                                \
        switch (sizeof(*(ptr))) {                               \
        case 1: __put_user_asm("stb", __x, ptr); break;         \
        case 2: __put_user_asm("sth", __x, ptr); break;         \
        case 4: __put_user_asm("stw", __x, ptr); break;         \
        case 8: STD_USER(__x, ptr); break;                      \
        default: BUILD_BUG();                                   \
        }                                                       \
                                                                \
        __pu_err;                                               \
})


#define __put_user(x, ptr)					\
({                                                              \
        load_sr2();                                             \
        __put_user_internal(x, ptr);                            \
})


/*
 * The "__put_user/kernel_asm()" 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. These macros must
 * also be aware that fixups are executed in the context of the fault,
 * and any registers used there must be listed as clobbers.
 * r8 is already listed as err.
 */


#define __put_user_asm(stx, x, ptr)                         \
	__asm__ __volatile__ (                              \
                "1: " stx " %2,0(%%sr2,%1)\n"               \
                "9:\n"                                      \
                ASM_EXCEPTIONTABLE_ENTRY_EFAULT(1b, 9b)     \
                : "=r"(__pu_err)                            \
                : "r"(ptr), "r"(x), "0"(__pu_err))


#if !defined(CONFIG_64BIT)


#define __put_user_asm64(__val, ptr) do {                \
        __asm__ __volatile__ (                              \
                "1: stw %2,0(%%sr2,%1)\n"                   \
                "2: stw %R2,4(%%sr2,%1)\n"                  \
                "9:\n"                                      \
                ASM_EXCEPTIONTABLE_ENTRY_EFAULT(1b, 9b)     \
                ASM_EXCEPTIONTABLE_ENTRY_EFAULT(2b, 9b)     \
                : "=r"(__pu_err)                            \
                : "r"(ptr), "r"(__val), "0"(__pu_err));     \
} while (0)

#endif /* !defined(CONFIG_64BIT) */


/*
 * Complex access routines -- external declarations
 */

extern long strncpy_from_user(char *, const char __user *, long);
extern unsigned lclear_user(void __user *, unsigned long);
extern long lstrnlen_user(const char __user *, long);
/*
 * Complex access routines -- macros
 */

#define user_addr_max() (~0UL)


#define strnlen_user lstrnlen_user

#define clear_user lclear_user

#define __clear_user lclear_user

unsigned long __must_check raw_copy_to_user(void __user *dst, const void *src,
					    unsigned long len);
unsigned long __must_check raw_copy_from_user(void *dst, const void __user *src,
					    unsigned long len);
unsigned long __must_check raw_copy_in_user(void __user *dst, const void __user *src,
					    unsigned long len);

#define INLINE_COPY_TO_USER

#define INLINE_COPY_FROM_USER

struct pt_regs;
int fixup_exception(struct pt_regs *regs);

#endif /* __PARISC_UACCESS_H */

Overall Contributors

PersonTokensPropCommitsCommitProp
Matthew Wilcox14435.04%620.00%
Linus Torvalds (pre-git)12229.68%13.33%
Helge Deller11828.71%1550.00%
Al Viro92.19%26.67%
Kyle McMartin92.19%13.33%
James Bottomley30.73%13.33%
Michael S. Tsirkin20.49%13.33%
Ingo Molnar20.49%13.33%
Jesper Juhl10.24%13.33%
Greg Kroah-Hartman10.24%13.33%
Total411100.00%30100.00%
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