[PATCH 6.8 101/172] drm/xe/hwmon: Cast result to output precision on left shift of operand

Greg Kroah-Hartman
2024-04-15T14:28:27Z

From: Karthik Poosa <karthik.poosa@intel.com>

[ Upstream commit a8ad8715472bb8f6a2ea8b4072a28151eb9f4f24 ]

Address potential overflow in result of left shift of a
lower precision (u32) operand before assignment to higher
precision (u64) variable.

v2:
- Update commit message. (Himal)

Fixes: 4446fcf220ce ("drm/xe/hwmon: Expose power1_max_interval")
Signed-off-by: Karthik Poosa <karthik.poosa@intel.com>
Reviewed-by: Anshuman Gupta <anshuman.gupta@intel.com>
Cc: Badal Nilawar <badal.nilawar@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240405130127.1392426-5-karthik.poosa@intel.com
Signed-off-by: Lucas De Marchi <lucas.demarchi@intel.com>
(cherry picked from commit 883232b47b81108b0252197c747f396ecd51455a)
Signed-off-by: Lucas De Marchi <lucas.demarchi@intel.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
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 174ed2185481e..a6f43446c779a 100644
--- a/drivers/gpu/drm/xe/xe_hwmon.c
+++ b/drivers/gpu/drm/xe/xe_hwmon.c
@@ -288,7 +288,7 @@ xe_hwmon_power1_max_interval_show(struct device *dev, struct device_attribute *a
* 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);
@@ -328,7 +328,7 @@ xe_hwmon_power1_max_interval_store(struct device *dev, struct device_attribute *
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)
--
2.43.0