Revision 36a8032d77649430f5ef11fbf0df2bb026be0b04 authored by Linus Torvalds on 26 April 2015, 20:36:02 UTC, committed by Linus Torvalds on 26 April 2015, 20:36:02 UTC
Pull chrome platform updates from Olof Johansson: "Here's a set of updates to the Chrome OS platform drivers for this merge window. Main new things this cycle is: - Driver changes to expose the lightbar to users. With this, you can make your own blinkenlights on Chromebook Pixels. - Changes in the way that the atmel_mxt trackpads are probed. The laptop driver is trying to be smart and not instantiate the devices that don't answer to probe. For the trackpad that can come up in two modes (bootloader or regular), this gets complicated since the driver already knows how to handle the two modes including the actual addresses used. So now the laptop driver needs to know more too, instantiating the regular address even if the bootloader one is the probe that passed. - mfd driver improvements by Javier Martines Canillas, and a few bugfixes from him, kbuild and myself" * tag 'chrome-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/olof/chrome-platform: platform/chrome: chromeos_laptop - instantiate Atmel at primary address platform/chrome: cros_ec_lpc - Depend on X86 || COMPILE_TEST platform/chrome: cros_ec_lpc - Include linux/io.h header file platform/chrome: fix platform_no_drv_owner.cocci warnings platform/chrome: cros_ec_lightbar - fix duplicate const warning platform/chrome: cros_ec_dev - fix Unknown escape '%' warning platform/chrome: Expose Chrome OS Lightbar to users platform/chrome: Create sysfs attributes for the ChromeOS EC mfd: cros_ec: Instantiate ChromeOS EC character device platform/chrome: Add Chrome OS EC userspace device interface platform/chrome: Add cros_ec_lpc driver for x86 devices mfd: cros_ec: Add char dev and virtual dev pointers mfd: cros_ec: Use fixed size arrays to transfer data with the EC
strnlen_user.c
#include <linux/kernel.h>
#include <linux/export.h>
#include <linux/uaccess.h>
#include <asm/word-at-a-time.h>
/* Set bits in the first 'n' bytes when loaded from memory */
#ifdef __LITTLE_ENDIAN
# define aligned_byte_mask(n) ((1ul << 8*(n))-1)
#else
# define aligned_byte_mask(n) (~0xfful << (BITS_PER_LONG - 8 - 8*(n)))
#endif
/*
* Do a strnlen, return length of string *with* final '\0'.
* 'count' is the user-supplied count, while 'max' is the
* address space maximum.
*
* Return 0 for exceptions (which includes hitting the address
* space maximum), or 'count+1' if hitting the user-supplied
* maximum count.
*
* NOTE! We can sometimes overshoot the user-supplied maximum
* if it fits in a aligned 'long'. The caller needs to check
* the return value against "> max".
*/
static inline long do_strnlen_user(const char __user *src, unsigned long count, unsigned long max)
{
const struct word_at_a_time constants = WORD_AT_A_TIME_CONSTANTS;
long align, res = 0;
unsigned long c;
/*
* Truncate 'max' to the user-specified limit, so that
* we only have one limit we need to check in the loop
*/
if (max > count)
max = count;
/*
* Do everything aligned. But that means that we
* need to also expand the maximum..
*/
align = (sizeof(long) - 1) & (unsigned long)src;
src -= align;
max += align;
if (unlikely(__get_user(c,(unsigned long __user *)src)))
return 0;
c |= aligned_byte_mask(align);
for (;;) {
unsigned long data;
if (has_zero(c, &data, &constants)) {
data = prep_zero_mask(c, data, &constants);
data = create_zero_mask(data);
return res + find_zero(data) + 1 - align;
}
res += sizeof(unsigned long);
if (unlikely(max < sizeof(unsigned long)))
break;
max -= sizeof(unsigned long);
if (unlikely(__get_user(c,(unsigned long __user *)(src+res))))
return 0;
}
res -= align;
/*
* Uhhuh. We hit 'max'. But was that the user-specified maximum
* too? If so, return the marker for "too long".
*/
if (res >= count)
return count+1;
/*
* Nope: we hit the address space limit, and we still had more
* characters the caller would have wanted. That's 0.
*/
return 0;
}
/**
* strnlen_user: - Get the size of a user string INCLUDING final NUL.
* @str: The string to measure.
* @count: Maximum count (including NUL character)
*
* 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.
* If the string is too long, returns 'count+1'.
* On exception (or invalid count), returns 0.
*/
long strnlen_user(const char __user *str, long count)
{
unsigned long max_addr, src_addr;
if (unlikely(count <= 0))
return 0;
max_addr = user_addr_max();
src_addr = (unsigned long)str;
if (likely(src_addr < max_addr)) {
unsigned long max = max_addr - src_addr;
return do_strnlen_user(str, count, max);
}
return 0;
}
EXPORT_SYMBOL(strnlen_user);
/**
* strlen_user: - Get the size of a user string INCLUDING final NUL.
* @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.
*/
long strlen_user(const char __user *str)
{
unsigned long max_addr, src_addr;
max_addr = user_addr_max();
src_addr = (unsigned long)str;
if (likely(src_addr < max_addr)) {
unsigned long max = max_addr - src_addr;
return do_strnlen_user(str, ~0ul, max);
}
return 0;
}
EXPORT_SYMBOL(strlen_user);
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