[PATCH] drm/amd/pm: avoid potential UBSAN issue on legacy asics

[Guchun Chen]

Prevent further dpm casting on legacy asics without od_enabled in
amdgpu_dpm_is_overdrive_supported. This can avoid UBSAN complain
in init sequence.

v2: add a macro to check legacy dpm instead of checking asic family/type

Suggested-by: Evan Quan <evan.quan at amd.com>
Signed-off-by: Guchun Chen <guchun.chen at amd.com>
---
 drivers/gpu/drm/amd/pm/amdgpu_dpm.c | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/amd/pm/amdgpu_dpm.c b/drivers/gpu/drm/amd/pm/amdgpu_dpm.c
index 86246f69dbe1..4b28fd62ed7a 100644
--- a/drivers/gpu/drm/amd/pm/amdgpu_dpm.c
+++ b/drivers/gpu/drm/amd/pm/amdgpu_dpm.c
@@ -36,6 +36,8 @@
 #define amdgpu_dpm_enable_bapm(adev, e) \
 		((adev)->powerplay.pp_funcs->enable_bapm((adev)->powerplay.pp_handle, (e)))
 
+#define is_legacy_dpm(adev) ((adev)->powerplay.pp_handle == (adev))
+
 int amdgpu_dpm_get_sclk(struct amdgpu_device *adev, bool low)
 {
 	const struct amd_pm_funcs *pp_funcs = adev->powerplay.pp_funcs;
@@ -1467,8 +1469,11 @@ int amdgpu_dpm_is_overdrive_supported(struct amdgpu_device *adev)
 	} else {
 		struct pp_hwmgr *hwmgr;
 
-		/* SI asic does not carry od_enabled */
-		if (adev->family == AMDGPU_FAMILY_SI)
+		/*
+		 * dpm on some legacy asics don't carry od_enabled member
+		 * as its pp_handle is casted directly from adev.
+		 */
+		if (is_legacy_dpm(adev))
 			return false;
 
 		hwmgr = (struct pp_hwmgr *)adev->powerplay.pp_handle;
-- 
2.25.1