/* * include/asm-xtensa/uaccess.h * * User space memory access functions * * These routines provide basic accessing functions to the user memory * space for the kernel. This header file provides fuctions such as: * * This file is subject to the terms and conditions of the GNU General Public * License. See the file "COPYING" in the main directory of this archive * for more details. * * Copyright (C) 2001 - 2005 Tensilica Inc. */ #ifndef _XTENSA_UACCESS_H #define _XTENSA_UACCESS_H #include <linux/errno.h> #define VERIFY_READ 0 #define VERIFY_WRITE 1 #ifdef __ASSEMBLY__ #define _ASMLANGUAGE #include <asm/current.h> #include <asm/asm-offsets.h> #include <asm/processor.h> /* * These assembly macros mirror the C macros that follow below. They * should always have identical functionality. See * arch/xtensa/kernel/sys.S for usage. */ #define KERNEL_DS 0 #define USER_DS 1 #define get_ds (KERNEL_DS) /* * get_fs reads current->thread.current_ds into a register. * On Entry: * <ad> anything * <sp> stack * On Exit: * <ad> contains current->thread.current_ds */ .macro get_fs ad, sp GET_CURRENT(\ad,\sp) l32i \ad, \ad, THREAD_CURRENT_DS .endm /* * set_fs sets current->thread.current_ds to some value. * On Entry: * <at> anything (temp register) * <av> value to write * <sp> stack * On Exit: * <at> destroyed (actually, current) * <av> preserved, value to write */ .macro set_fs at, av, sp GET_CURRENT(\at,\sp) s32i \av, \at, THREAD_CURRENT_DS .endm /* * kernel_ok determines whether we should bypass addr/size checking. * See the equivalent C-macro version below for clarity. * On success, kernel_ok branches to a label indicated by parameter * <success>. This implies that the macro falls through to the next * insruction on an error. * * Note that while this macro can be used independently, we designed * in for optimal use in the access_ok macro below (i.e., we fall * through on error). * * On Entry: * <at> anything (temp register) * <success> label to branch to on success; implies * fall-through macro on error * <sp> stack pointer * On Exit: * <at> destroyed (actually, current->thread.current_ds) */ #if ((KERNEL_DS != 0) || (USER_DS == 0)) # error Assembly macro kernel_ok fails #endif .macro kernel_ok at, sp, success get_fs \at, \sp beqz \at, \success .endm /* * user_ok determines whether the access to user-space memory is allowed. * See the equivalent C-macro version below for clarity. * * On error, user_ok branches to a label indicated by parameter * <error>. This implies that the macro falls through to the next * instruction on success. * * Note that while this macro can be used independently, we designed * in for optimal use in the access_ok macro below (i.e., we fall * through on success). * * On Entry: * <aa> register containing memory address * <as> register containing memory size * <at> temp register * <error> label to branch to on error; implies fall-through * macro on success * On Exit: * <aa> preserved * <as> preserved * <at> destroyed (actually, (TASK_SIZE + 1 - size)) */ .macro user_ok aa, as, at, error movi \at, (TASK_SIZE+1) bgeu \as, \at, \error sub \at, \at, \as bgeu \aa, \at, \error .endm /* * access_ok determines whether a memory access is allowed. See the * equivalent C-macro version below for clarity. * * On error, access_ok branches to a label indicated by parameter * <error>. This implies that the macro falls through to the next * instruction on success. * * Note that we assume success is the common case, and we optimize the * branch fall-through case on success. * * On Entry: * <aa> register containing memory address * <as> register containing memory size * <at> temp register * <sp> * <error> label to branch to on error; implies fall-through * macro on success * On Exit: * <aa> preserved * <as> preserved * <at> destroyed */ .macro access_ok aa, as, at, sp, error kernel_ok \at, \sp, .Laccess_ok_\@ user_ok \aa, \as, \at, \error .Laccess_ok_\@: .endm #else /* __ASSEMBLY__ not defined */ #include <linux/sched.h> #include <asm/types.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. * * For historical reasons (Data Segment Register?), these macros are * grossly misnamed. */ #define KERNEL_DS ((mm_segment_t) { 0 }) #define USER_DS ((mm_segment_t) { 1 }) #define get_ds() (KERNEL_DS) #define get_fs() (current->thread.current_ds) #define set_fs(val) (current->thread.current_ds = (val)) #define segment_eq(a,b) ((a).seg == (b).seg) #define __kernel_ok (segment_eq(get_fs(), KERNEL_DS)) #define __user_ok(addr,size) (((size) <= TASK_SIZE)&&((addr) <= TASK_SIZE-(size))) #define __access_ok(addr,size) (__kernel_ok || __user_ok((addr),(size))) #define access_ok(type,addr,size) __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. * * 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 uglyness from the user. * * Careful to not * (a) re-use the arguments for side effects (sizeof is ok) * (b) require any knowledge of processes at this stage */ #define put_user(x,ptr) __put_user_check((x),(ptr),sizeof(*(ptr))) #define get_user(x,ptr) __get_user_check((x),(ptr),sizeof(*(ptr))) /* * 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). */ #define __put_user(x,ptr) __put_user_nocheck((x),(ptr),sizeof(*(ptr))) #define __get_user(x,ptr) __get_user_nocheck((x),(ptr),sizeof(*(ptr))) extern long __put_user_bad(void); #define __put_user_nocheck(x,ptr,size) \ ({ \ long __pu_err; \ __put_user_size((x),(ptr),(size),__pu_err); \ __pu_err; \ }) #define __put_user_check(x,ptr,size) \ ({ \ long __pu_err = -EFAULT; \ __typeof__(*(ptr)) *__pu_addr = (ptr); \ if (access_ok(VERIFY_WRITE,__pu_addr,size)) \ __put_user_size((x),__pu_addr,(size),__pu_err); \ __pu_err; \ }) #define __put_user_size(x,ptr,size,retval) \ do { \ retval = 0; \ switch (size) { \ case 1: __put_user_asm(x,ptr,retval,1,"s8i"); break; \ case 2: __put_user_asm(x,ptr,retval,2,"s16i"); break; \ case 4: __put_user_asm(x,ptr,retval,4,"s32i"); break; \ case 8: { \ __typeof__(*ptr) __v64 = x; \ retval = __copy_to_user(ptr,&__v64,8); \ break; \ } \ default: __put_user_bad(); \ } \ } while (0) /* * Consider a case of a user single load/store would cause both an * unaligned exception and an MMU-related exception (unaligned * exceptions happen first): * * User code passes a bad variable ptr to a system call. * Kernel tries to access the variable. * Unaligned exception occurs. * Unaligned exception handler tries to make aligned accesses. * Double exception occurs for MMU-related cause (e.g., page not mapped). * do_page_fault() thinks the fault address belongs to the kernel, not the * user, and panics. * * The kernel currently prohibits user unaligned accesses. We use the * __check_align_* macros to check for unaligned addresses before * accessing user space so we don't crash the kernel. Both * __put_user_asm and __get_user_asm use these alignment macros, so * macro-specific labels such as 0f, 1f, %0, %2, and %3 must stay in * sync. */ #define __check_align_1 "" #define __check_align_2 \ " _bbci.l %2, 0, 1f \n" \ " movi %0, %3 \n" \ " _j 2f \n" #define __check_align_4 \ " _bbsi.l %2, 0, 0f \n" \ " _bbci.l %2, 1, 1f \n" \ "0: movi %0, %3 \n" \ " _j 2f \n" /* * 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. * * WARNING: If you modify this macro at all, verify that the * __check_align_* macros still work. */ #define __put_user_asm(x, addr, err, align, insn) \ __asm__ __volatile__( \ __check_align_##align \ "1: "insn" %1, %2, 0 \n" \ "2: \n" \ " .section .fixup,\"ax\" \n" \ " .align 4 \n" \ "4: \n" \ " .long 2b \n" \ "5: \n" \ " l32r %2, 4b \n" \ " movi %0, %3 \n" \ " jx %2 \n" \ " .previous \n" \ " .section __ex_table,\"a\" \n" \ " .long 1b, 5b \n" \ " .previous" \ :"=r" (err) \ :"r" ((int)(x)), "r" (addr), "i" (-EFAULT), "0" (err)) #define __get_user_nocheck(x,ptr,size) \ ({ \ long __gu_err, __gu_val; \ __get_user_size(__gu_val,(ptr),(size),__gu_err); \ (x) = (__typeof__(*(ptr)))__gu_val; \ __gu_err; \ }) #define __get_user_check(x,ptr,size) \ ({ \ long __gu_err = -EFAULT, __gu_val = 0; \ const __typeof__(*(ptr)) *__gu_addr = (ptr); \ if (access_ok(VERIFY_READ,__gu_addr,size)) \ __get_user_size(__gu_val,__gu_addr,(size),__gu_err); \ (x) = (__typeof__(*(ptr)))__gu_val; \ __gu_err; \ }) extern long __get_user_bad(void); #define __get_user_size(x,ptr,size,retval) \ do { \ retval = 0; \ switch (size) { \ case 1: __get_user_asm(x,ptr,retval,1,"l8ui"); break; \ case 2: __get_user_asm(x,ptr,retval,2,"l16ui"); break; \ case 4: __get_user_asm(x,ptr,retval,4,"l32i"); break; \ case 8: retval = __copy_from_user(&x,ptr,8); break; \ default: (x) = __get_user_bad(); \ } \ } while (0) /* * WARNING: If you modify this macro at all, verify that the * __check_align_* macros still work. */ #define __get_user_asm(x, addr, err, align, insn) \ __asm__ __volatile__( \ __check_align_##align \ "1: "insn" %1, %2, 0 \n" \ "2: \n" \ " .section .fixup,\"ax\" \n" \ " .align 4 \n" \ "4: \n" \ " .long 2b \n" \ "5: \n" \ " l32r %2, 4b \n" \ " movi %1, 0 \n" \ " movi %0, %3 \n" \ " jx %2 \n" \ " .previous \n" \ " .section __ex_table,\"a\" \n" \ " .long 1b, 5b \n" \ " .previous" \ :"=r" (err), "=r" (x) \ :"r" (addr), "i" (-EFAULT), "0" (err)) /* * Copy to/from user space */ /* * We use a generic, arbitrary-sized copy subroutine. The Xtensa * architecture would cause heavy code bloat if we tried to inline * these functions and provide __constant_copy_* equivalents like the * i386 versions. __xtensa_copy_user is quite efficient. See the * .fixup section of __xtensa_copy_user for a discussion on the * X_zeroing equivalents for Xtensa. */ extern unsigned __xtensa_copy_user(void *to, const void *from, unsigned n); #define __copy_user(to,from,size) __xtensa_copy_user(to,from,size) static inline unsigned long __generic_copy_from_user_nocheck(void *to, const void *from, unsigned long n) { return __copy_user(to,from,n); } static inline unsigned long __generic_copy_to_user_nocheck(void *to, const void *from, unsigned long n) { return __copy_user(to,from,n); } static inline unsigned long __generic_copy_to_user(void *to, const void *from, unsigned long n) { prefetch(from); if (access_ok(VERIFY_WRITE, to, n)) return __copy_user(to,from,n); return n; } static inline unsigned long __generic_copy_from_user(void *to, const void *from, unsigned long n) { prefetchw(to); if (access_ok(VERIFY_READ, from, n)) return __copy_user(to,from,n); else memset(to, 0, n); return n; } #define copy_to_user(to,from,n) __generic_copy_to_user((to),(from),(n)) #define copy_from_user(to,from,n) __generic_copy_from_user((to),(from),(n)) #define __copy_to_user(to,from,n) __generic_copy_to_user_nocheck((to),(from),(n)) #define __copy_from_user(to,from,n) __generic_copy_from_user_nocheck((to),(from),(n)) #define __copy_to_user_inatomic __copy_to_user #define __copy_from_user_inatomic __copy_from_user /* * We need to return the number of bytes not cleared. Our memset() * returns zero if a problem occurs while accessing user-space memory. * In that event, return no memory cleared. Otherwise, zero for * success. */ static inline unsigned long __xtensa_clear_user(void *addr, unsigned long size) { if ( ! memset(addr, 0, size) ) return size; return 0; } static inline unsigned long clear_user(void *addr, unsigned long size) { if (access_ok(VERIFY_WRITE, addr, size)) return __xtensa_clear_user(addr, size); return size ? -EFAULT : 0; } #define __clear_user __xtensa_clear_user extern long __strncpy_user(char *, const char *, long); #define __strncpy_from_user __strncpy_user static inline long strncpy_from_user(char *dst, const char *src, long count) { if (access_ok(VERIFY_READ, src, 1)) return __strncpy_from_user(dst, src, count); return -EFAULT; } #define strlen_user(str) strnlen_user((str), TASK_SIZE - 1) /* * Return the size of a string (including the ending 0!) */ extern long __strnlen_user(const char *, long); static inline long strnlen_user(const char *str, long len) { unsigned long top = __kernel_ok ? ~0UL : TASK_SIZE - 1; if ((unsigned long)str > top) return 0; return __strnlen_user(str, len); } struct exception_table_entry { unsigned long insn, fixup; }; /* Returns 0 if exception not found and fixup.unit otherwise. */ extern unsigned long search_exception_table(unsigned long addr); extern void sort_exception_table(void); /* Returns the new pc */ #define fixup_exception(map_reg, fixup_unit, pc) \ ({ \ fixup_unit; \ }) #endif /* __ASSEMBLY__ */ #endif /* _XTENSA_UACCESS_H */