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tile: add <asm/word-at-a-time.h> and enable support functions

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This change enables the generic strncpy_from_user() and strnlen_user()
using word-at-a-time.h.  The tile implementation is trivial since
both tilepro and tilegx have SIMD operations that do byte-wise
comparisons against immediate zero for each byte, and return an
0x01 byte in each position where there is a 0x00 byte.

Signed-off-by: Chris Metcalf <cmetcalf@ezchip.com>
This commit is contained in:
Chris Metcalf
2015-04-30 15:12:42 -04:00
parent 627ae54854
commit 5bf6c07a18
6 changed files with 48 additions and 150 deletions
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66
arch/tile/include/asm/uaccess.h
View File

@@ -64,6 +64,13 @@ static inline int is_arch_mappable_range(unsigned long addr,
#define is_arch_mappable_range(addr, size) 0
#endif
/*
* Note that using this definition ignores is_arch_mappable_range(),
* so on tilepro code that uses user_addr_max() is constrained not
* to reference the tilepro user-interrupt region.
*/
#define user_addr_max() (current_thread_info()->addr_limit.seg)
/*
* Test whether a block of memory is a valid user space address.
* Returns 0 if the range is valid, nonzero otherwise.
@@ -465,62 +472,9 @@ copy_in_user(void __user *to, const void __user *from, unsigned long n)
#endif
/**
* strlen_user: - Get the size of a string in user space.
* @str: The string to measure.
*
* Context: User context only. This function may sleep.
*
* Get the size of a NUL-terminated string in user space.
*
* Returns the size of the string INCLUDING the terminating NUL.
* On exception, returns 0.
*
* If there is a limit on the length of a valid string, you may wish to
* consider using strnlen_user() instead.
*/
extern long strnlen_user_asm(const char __user *str, long n);
static inline long __must_check strnlen_user(const char __user *str, long n)
{
might_fault();
return strnlen_user_asm(str, n);
}
#define strlen_user(str) strnlen_user(str, LONG_MAX)
/**
* strncpy_from_user: - Copy a NUL terminated string from userspace, with less checking.
* @dst: Destination address, in kernel space. This buffer must be at
* least @count bytes long.
* @src: Source address, in user space.
* @count: Maximum number of bytes to copy, including the trailing NUL.
*
* Copies a NUL-terminated string from userspace to kernel space.
* Caller must check the specified block with access_ok() before calling
* this function.
*
* On success, returns the length of the string (not including the trailing
* NUL).
*
* If access to userspace fails, returns -EFAULT (some data may have been
* copied).
*
* If @count is smaller than the length of the string, copies @count bytes
* and returns @count.
*/
extern long strncpy_from_user_asm(char *dst, const char __user *src, long);
static inline long __must_check __strncpy_from_user(
char *dst, const char __user *src, long count)
{
might_fault();
return strncpy_from_user_asm(dst, src, count);
}
static inline long __must_check strncpy_from_user(
char *dst, const char __user *src, long count)
{
if (access_ok(VERIFY_READ, src, 1))
return __strncpy_from_user(dst, src, count);
return -EFAULT;
}
extern long strnlen_user(const char __user *str, long n);
extern long strlen_user(const char __user *str);
extern long strncpy_from_user(char *dst, const char __user *src, long);
/**
* clear_user: - Zero a block of memory in user space.

36
arch/tile/include/asm/word-at-a-time.h Normal file
View File

@@ -0,0 +1,36 @@
#ifndef _ASM_WORD_AT_A_TIME_H
#define _ASM_WORD_AT_A_TIME_H
#include <asm/byteorder.h>
struct word_at_a_time { /* unused */ };
#define WORD_AT_A_TIME_CONSTANTS {}
/* Generate 0x01 byte values for non-zero bytes using a SIMD instruction. */
static inline unsigned long has_zero(unsigned long val, unsigned long *data,
const struct word_at_a_time *c)
{
#ifdef __tilegx__
unsigned long mask = __insn_v1cmpeqi(val, 0);
#else /* tilepro */
unsigned long mask = __insn_seqib(val, 0);
#endif
*data = mask;
return mask;
}
/* These operations are both nops. */
#define prep_zero_mask(val, data, c) (data)
#define create_zero_mask(data) (data)
/* And this operation just depends on endianness. */
static inline long find_zero(unsigned long mask)
{
#ifdef __BIG_ENDIAN
return __builtin_clzl(mask) >> 3;
#else
return __builtin_ctzl(mask) >> 3;
#endif
}
#endif /* _ASM_WORD_AT_A_TIME_H */