@@ -372,6 +372,7 @@ static int yas537_measure(struct yas5xx *yas5xx, u16 *t, u16 *x, u16 *y1, u16 *y
u8 data[8];
u16 xy1y2[3];
s32 h[3], s[3];
+ int half_range = BIT(13);
int i, ret;
mutex_lock(&yas5xx->lock);
@@ -406,13 +407,13 @@ static int yas537_measure(struct yas5xx *yas5xx, u16 *t, u16 *x, u16 *y1, u16 *y
/* The second version of YAS537 needs to include calibration coefficients */
if (yas5xx->version == YAS537_VERSION_1) {
for (i = 0; i < 3; i++)
- s[i] = xy1y2[i] - BIT(13);
- h[0] = (c->k * (128 * s[0] + c->a2 * s[1] + c->a3 * s[2])) / BIT(13);
- h[1] = (c->k * (c->a4 * s[0] + c->a5 * s[1] + c->a6 * s[2])) / BIT(13);
- h[2] = (c->k * (c->a7 * s[0] + c->a8 * s[1] + c->a9 * s[2])) / BIT(13);
+ s[i] = xy1y2[i] - half_range;
+ h[0] = (c->k * (128 * s[0] + c->a2 * s[1] + c->a3 * s[2])) / half_range;
+ h[1] = (c->k * (c->a4 * s[0] + c->a5 * s[1] + c->a6 * s[2])) / half_range;
+ h[2] = (c->k * (c->a7 * s[0] + c->a8 * s[1] + c->a9 * s[2])) / half_range;
for (i = 0; i < 3; i++) {
- clamp_val(h[i], -BIT(13), BIT(13) - 1);
- xy1y2[i] = h[i] + BIT(13);
+ h[i] = clamp(h[i], -half_range, half_range - 1);
+ xy1y2[i] = h[i] + half_range;
}
}
In the function yas537_measure() there is a clamp_val() with limits of -BIT(13) and BIT(13) - 1. The input clamp value h[] is of type s32. The BIT() is of type unsigned long integer due to its define in include/vdso/bits.h. The lower limit -BIT(13) is recognized as -8192 but expressed as an unsigned long integer. The size of an unsigned long integer differs between 32-bit and 64-bit architectures. Converting this to type s32 may lead to undesired behavior. Additionally, in the calculation lines h[0], h[1] and h[2] the unsigned long integer divisor BIT(13) causes an unsigned division, shifting the left-hand side of the equation back and forth, possibly ending up in large positive values instead of negative values on 32-bit architectures. To solve those two issues, declare a signed integer with a value of BIT(13). There is another omission in the clamp line: clamp_val() returns a value and it's going nowhere here. Self-assign it to h[i] to make use of the clamp macro. Finally, replace clamp_val() macro by clamp() because after changing the limits from type unsigned long integer to signed integer it's fine that way. Reported-by: kernel test robot <lkp@intel.com> Closes: https://lore.kernel.org/oe-kbuild-all/202411230458.dhZwh3TT-lkp@intel.com/ Closes: https://lore.kernel.org/oe-kbuild-all/202411282222.oF0B4110-lkp@intel.com/ Fixes: 65f79b501030 ("iio: magnetometer: yas530: Add YAS537 variant") Cc: David Laight <david.laight@aculab.com> Signed-off-by: Jakob Hauser <jahau@rocketmail.com> --- The patch is based on torvalds/linux v6.12. The calculation lines h[0], h[1] and h[2] exceed the limit of 80 characters per line. In terms of readability I would prefer to keep it that way. Changes in v2: - Self-assigned the clamp macro to h[i]. - Changed from clamp_val() macro to clamp(). - In commit message added issues on divisor BIT(13) and missing clamp assignment. - In tags added another (duplicate) report by the kernel test robot. Link to v1: https://lore.kernel.org/linux-iio/20241126234021.19749-1-jahau@rocketmail.com/T/#t --- drivers/iio/magnetometer/yamaha-yas530.c | 13 +++++++------ 1 file changed, 7 insertions(+), 6 deletions(-)