linux-kernel - [PATCH AUTOSEL 6.14 14/15] drm/amd/display: Call FP Protect Before Mode Programming/Mode Support

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Message-Id: <20250512180352.437356-14-sashal@kernel.org>
Date: Mon, 12 May 2025 14:03:49 -0400
From: Sasha Levin <sashal@...nel.org>
To: patches@...ts.linux.dev,
	stable@...r.kernel.org
Cc: Austin Zheng <Austin.Zheng@....com>,
	Alvin Lee <alvin.lee2@....com>,
	Ray Wu <ray.wu@....com>,
	Daniel Wheeler <daniel.wheeler@....com>,
	Alex Deucher <alexander.deucher@....com>,
	Sasha Levin <sashal@...nel.org>,
	austin.zheng@....com,
	jun.lei@....com,
	harry.wentland@....com,
	sunpeng.li@....com,
	christian.koenig@....com,
	airlied@...il.com,
	simona@...ll.ch,
	dillon.varone@....com,
	aurabindo.pillai@....com,
	alex.hung@....com,
	chenhuacai@...nel.org,
	jerry.zuo@....com,
	rostrows@....com,
	chris.park@....com,
	jiapeng.chong@...ux.alibaba.com,
	amd-gfx@...ts.freedesktop.org,
	dri-devel@...ts.freedesktop.org,
	linux-kernel@...r.kernel.org
Subject: [PATCH AUTOSEL 6.14 14/15] drm/amd/display: Call FP Protect Before Mode Programming/Mode Support

From: Austin Zheng <Austin.Zheng@....com>

[ Upstream commit eba692ca3abca258b3214a6e4126afefad1822f0 ]

[Why]
Memory allocation occurs within dml21_validate() for adding phantom planes.
May cause kernel to be tainted due to usage of FP Start.

[How]
Move FP start from dml21_validate to before mode programming/mode support.
Calculations requiring floating point are all done within mode programming
or mode support.

Reviewed-by: Alvin Lee <alvin.lee2@....com>
Signed-off-by: Austin Zheng <Austin.Zheng@....com>
Signed-off-by: Ray Wu <ray.wu@....com>
Tested-by: Daniel Wheeler <daniel.wheeler@....com>
Signed-off-by: Alex Deucher <alexander.deucher@....com>
(cherry picked from commit fe3250f10819b411808ab9ae1d824c5fc9b59170)
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 drivers/gpu/drm/amd/display/dc/dml2/dml21/dml21_wrapper.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/drivers/gpu/drm/amd/display/dc/dml2/dml21/dml21_wrapper.c b/drivers/gpu/drm/amd/display/dc/dml2/dml21/dml21_wrapper.c
index d6fd13f43c08f..e011dc56be828 100644
--- a/drivers/gpu/drm/amd/display/dc/dml2/dml21/dml21_wrapper.c
+++ b/drivers/gpu/drm/amd/display/dc/dml2/dml21/dml21_wrapper.c
@@ -220,7 +220,9 @@ static bool dml21_mode_check_and_programming(const struct dc *in_dc, struct dc_s
 	if (!result)
 		return false;
 
+	DC_FP_START();
 	result = dml2_build_mode_programming(mode_programming);
+	DC_FP_END();
 	if (!result)
 		return false;
 
@@ -263,7 +265,9 @@ static bool dml21_check_mode_support(const struct dc *in_dc, struct dc_state *co
 	mode_support->dml2_instance = dml_init->dml2_instance;
 	dml21_map_dc_state_into_dml_display_cfg(in_dc, context, dml_ctx);
 	dml_ctx->v21.mode_programming.dml2_instance->scratch.build_mode_programming_locals.mode_programming_params.programming = dml_ctx->v21.mode_programming.programming;
+	DC_FP_START();
 	is_supported = dml2_check_mode_supported(mode_support);
+	DC_FP_END();
 	if (!is_supported)
 		return false;
 
@@ -274,16 +278,12 @@ bool dml21_validate(const struct dc *in_dc, struct dc_state *context, struct dml
 {
 	bool out = false;
 
-	DC_FP_START();
-
 	/* Use dml_validate_only for fast_validate path */
 	if (fast_validate)
 		out = dml21_check_mode_support(in_dc, context, dml_ctx);
 	else
 		out = dml21_mode_check_and_programming(in_dc, context, dml_ctx);
 
-	DC_FP_END();
-
 	return out;
 }
 
-- 
2.39.5