The patch below does not apply to the 5.9-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable@xxxxxxxxxxxxxxx>.
thanks,
greg k-h
------------------ original commit in Linus's tree ------------------
>From 5ab7943187f22b572fd12d517bd699771b88ce91 Mon Sep 17 00:00:00 2001
From: Krunoslav Kovac <Krunoslav.Kovac@xxxxxxx>
Date: Thu, 6 Aug 2020 17:54:47 -0400
Subject: [PATCH] drm/amd/display: fix pow() crashing when given base 0
[Why&How]
pow(a,x) is implemented as exp(x*log(a)). log(0) will crash.
So return 0^x = 0, unless x=0, convention seems to be 0^0 = 1.
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Krunoslav Kovac <Krunoslav.Kovac@xxxxxxx>
Reviewed-by: Anthony Koo <Anthony.Koo@xxxxxxx>
Acked-by: Rodrigo Siqueira <Rodrigo.Siqueira@xxxxxxx>
Signed-off-by: Alex Deucher <alexander.deucher@xxxxxxx>
diff --git a/drivers/gpu/drm/amd/display/include/fixed31_32.h b/drivers/gpu/drm/amd/display/include/fixed31_32.h
index 89ef9f6860e5..16df2a485dd0 100644
--- a/drivers/gpu/drm/amd/display/include/fixed31_32.h
+++ b/drivers/gpu/drm/amd/display/include/fixed31_32.h
@@ -431,6 +431,9 @@ struct fixed31_32 dc_fixpt_log(struct fixed31_32 arg);
*/
static inline struct fixed31_32 dc_fixpt_pow(struct fixed31_32 arg1, struct fixed31_32 arg2)
{
+ if (arg1.value == 0)
+ return arg2.value == 0 ? dc_fixpt_one : dc_fixpt_zero;
+
return dc_fixpt_exp(
dc_fixpt_mul(
dc_fixpt_log(arg1),
