[PATCH v6 4/4] drm/xe/hwmon: Cast to output precision before multiplying operands
Karthik Poosa
karthik.poosa at intel.com
Thu Apr 4 10:08:27 UTC 2024
Address potential overflow in result of multiplication of two lower
precision (u32) operands before widening it to higher precision (u64).
Fixes: 4446fcf220ce ("drm/xe/hwmon: Expose power1_max_interval")
Signed-off-by: Karthik Poosa <karthik.poosa at intel.com>
Reviewed-by: Anshuman Gupta <anshuman.gupta at intel.com>
Cc: Badal Nilawar <badal.nilawar at intel.com>
---
drivers/gpu/drm/xe/xe_hwmon.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/drivers/gpu/drm/xe/xe_hwmon.c b/drivers/gpu/drm/xe/xe_hwmon.c
index e234321c165c..9511476478cb 100644
--- a/drivers/gpu/drm/xe/xe_hwmon.c
+++ b/drivers/gpu/drm/xe/xe_hwmon.c
@@ -297,7 +297,7 @@ xe_hwmon_power_max_interval_show(struct device *dev, struct device_attribute *at
* As y can be < 2, we compute tau4 = (4 | x) << y
* and then add 2 when doing the final right shift to account for units
*/
- tau4 = ((1 << x_w) | x) << y;
+ tau4 = (u64)((1 << x_w) | x) << y;
/* val in hwmon interface units (millisec) */
out = mul_u64_u32_shr(tau4, SF_TIME, hwmon->scl_shift_time + x_w);
@@ -338,7 +338,7 @@ xe_hwmon_power_max_interval_store(struct device *dev, struct device_attribute *a
r = FIELD_PREP(PKG_MAX_WIN, PKG_MAX_WIN_DEFAULT);
x = REG_FIELD_GET(PKG_MAX_WIN_X, r);
y = REG_FIELD_GET(PKG_MAX_WIN_Y, r);
- tau4 = ((1 << x_w) | x) << y;
+ tau4 = (u64)((1 << x_w) | x) << y;
max_win = mul_u64_u32_shr(tau4, SF_TIME, hwmon->scl_shift_time + x_w);
if (val > max_win)
--
2.25.1
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