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Diffstat (limited to 'include/asm-xtensa/uaccess.h')
| -rw-r--r-- | include/asm-xtensa/uaccess.h | 532 |
1 files changed, 532 insertions, 0 deletions
diff --git a/include/asm-xtensa/uaccess.h b/include/asm-xtensa/uaccess.h new file mode 100644 index 00000000000..35576b25c7b --- /dev/null +++ b/include/asm-xtensa/uaccess.h @@ -0,0 +1,532 @@ +/* + * 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/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 + +/* + * verify_area determines whether a memory access is allowed. It's + * mostly an unnecessary wrapper for access_ok, but we provide it as a + * duplicate of the verify_area() C inline function below. See the + * equivalent C version below for clarity. + * + * On error, verify_area 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 + * <error> label to branch to on error; implies fall-through + * macro on success + * On Exit: + * <aa> preserved + * <as> preserved + * <at> destroyed + */ + .macro verify_area aa, as, at, sp, error + access_ok \at, \aa, \as, \sp, \error + .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)) + +extern inline int verify_area(int type, const void * addr, unsigned long size) +{ + return access_ok(type,addr,size) ? 0 : -EFAULT; +} + +/* + * 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. + */ + +extern inline unsigned long +__xtensa_clear_user(void *addr, unsigned long size) +{ + if ( ! memset(addr, 0, size) ) + return size; + return 0; +} + +extern 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 + +extern 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); + +extern 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 */ |