[PATCH AUTOSEL 5.10 6/7] drm/amd/display: Mark dml30's UseMinimumDCFCLK() as noinline for stack usage

[PATCH AUTOSEL 5.10 6/7] drm/amd/display: Mark dml30's UseMinimumDCFCLK() as noinline for stack usage

[Sasha Levin]

From: Nathan Chancellor <nathan@kernel.org>

[ Upstream commit 41012d715d5d7b9751ae84b8fb255e404ac9c5d0 ]

This function consumes a lot of stack space and it blows up the size of
dml30_ModeSupportAndSystemConfigurationFull() with clang:

  drivers/gpu/drm/amd/amdgpu/../display/dc/dml/dcn30/display_mode_vba_30.c:3542:6: error: stack frame size (2200) exceeds limit (2048) in 'dml30_ModeSupportAndSystemConfigurationFull' [-Werror,-Wframe-larger-than]
  void dml30_ModeSupportAndSystemConfigurationFull(struct display_mode_lib *mode_lib)
       ^
  1 error generated.

Commit a0f7e7f759cf ("drm/amd/display: fix i386 frame size warning")
aimed to address this for i386 but it did not help x86_64.

To reduce the amount of stack space that
dml30_ModeSupportAndSystemConfigurationFull() uses, mark
UseMinimumDCFCLK() as noinline, using the _for_stack variant for
documentation. While this will increase the total amount of stack usage
between the two functions (1632 and 1304 bytes respectively), it will
make sure both stay below the limit of 2048 bytes for these files. The
aforementioned change does help reduce UseMinimumDCFCLK()'s stack usage
so it should not be reverted in favor of this change.

Link: https://github.com/ClangBuiltLinux/linux/issues/1681
Reported-by: "Sudip Mukherjee (Codethink)" <sudipm.mukherjee@gmail.com>
Tested-by: Maíra Canal <mairacanal@riseup.net>
Reviewed-by: Rodrigo Siqueira <Rodrigo.Siqueira@amd.com>
Signed-off-by: Nathan Chancellor <nathan@kernel.org>
Signed-off-by: Rodrigo Siqueira <Rodrigo.Siqueira@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/gpu/drm/amd/display/dc/dml/dcn30/display_mode_vba_30.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/amd/display/dc/dml/dcn30/display_mode_vba_30.c b/drivers/gpu/drm/amd/display/dc/dml/dcn30/display_mode_vba_30.c
index 2663f1b31842..e427f4ffa080 100644
--- a/drivers/gpu/drm/amd/display/dc/dml/dcn30/display_mode_vba_30.c
+++ b/drivers/gpu/drm/amd/display/dc/dml/dcn30/display_mode_vba_30.c
@@ -6653,8 +6653,7 @@ static double CalculateUrgentLatency(
 	return ret;
 }
 
-
-static void UseMinimumDCFCLK(
+static noinline_for_stack void UseMinimumDCFCLK(
 		struct display_mode_lib *mode_lib,
 		int MaxInterDCNTileRepeaters,
 		int MaxPrefetchMode,
-- 
2.35.1

[PATCH AUTOSEL 5.10 7/7] drm/rockchip: Fix return type of cdn_dp_connector_mode_valid

[Sasha Levin]

From: Nathan Huckleberry <nhuck@google.com>

[ Upstream commit b0b9408f132623dc88e78adb5282f74e4b64bb57 ]

The mode_valid field in drm_connector_helper_funcs is expected to be of
type:
enum drm_mode_status (* mode_valid) (struct drm_connector *connector,
				     struct drm_display_mode *mode);

The mismatched return type breaks forward edge kCFI since the underlying
function definition does not match the function hook definition.

The return type of cdn_dp_connector_mode_valid should be changed from
int to enum drm_mode_status.

Reported-by: Dan Carpenter <error27@gmail.com>
Link: https://github.com/ClangBuiltLinux/linux/issues/1703
Cc: llvm@lists.linux.dev
Signed-off-by: Nathan Huckleberry <nhuck@google.com>
Reviewed-by: Nathan Chancellor <nathan@kernel.org>
Signed-off-by: Heiko Stuebner <heiko@sntech.de>
Link: https://patchwork.freedesktop.org/patch/msgid/20220913205555.155149-1-nhuck@google.com
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/gpu/drm/rockchip/cdn-dp-core.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/rockchip/cdn-dp-core.c b/drivers/gpu/drm/rockchip/cdn-dp-core.c
index dec54c70e008..857c47c69ef1 100644
--- a/drivers/gpu/drm/rockchip/cdn-dp-core.c
+++ b/drivers/gpu/drm/rockchip/cdn-dp-core.c
@@ -276,8 +276,9 @@ static int cdn_dp_connector_get_modes(struct drm_connector *connector)
 	return ret;
 }
 
-static int cdn_dp_connector_mode_valid(struct drm_connector *connector,
-				       struct drm_display_mode *mode)
+static enum drm_mode_status
+cdn_dp_connector_mode_valid(struct drm_connector *connector,
+			    struct drm_display_mode *mode)
 {
 	struct cdn_dp_device *dp = connector_to_dp(connector);
 	struct drm_display_info *display_info = &dp->connector.display_info;
-- 
2.35.1