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drm/amd/display: Fix sanitizer check for the DML frame size limit

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Building x86_64 allmodconfig with clang fails:

  .../dml2_0/dml21/src/dml2_core/dml2_core_dcn4_calcs.c:10491:13:
  error: stack frame size (3128) exceeds limit (3072) in
  'dml_core_mode_programming' [-Werror,-Wframe-larger-than]

That config enables both KASAN and UBSAN, and should get the 4096
byte limit meant for clang COMPILE_TEST sanitizer builds. The check
in the dml and dml2_0 Makefiles concatenates the three symbols with
no separator:

  ifeq ($(filter y,$(CONFIG_KASAN)$(CONFIG_KCSAN)$(CONFIG_UBSAN)),y)

KASAN and KCSAN cannot be enabled together, so before UBSAN was
added the string was at most "y". UBSAN can be enabled alongside
either of them, and with both set the string becomes "yy",
$(filter y,yy) is empty, and the build falls through to the
non-sanitizer limit of 3072. Adding UBSAN to the check therefore
lowered the limit for the most heavily instrumented builds instead
of raising it.

Separate the symbols with spaces so that $(filter) sees individual
words, and test for a non-empty result. Only the configs with two
sanitizers enabled change behaviour.

Found by KernelCI builds of the linus-next tree.

Fixes: ebf8b0fd85 ("drm/amd/display: Relax DML frame limit with UBSAN")
Assisted-by: LLM
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
(cherry picked from commit 0400d53fd0)
Cc: stable@vger.kernel.org
This commit is contained in:
Sasha Levin 2026-09-27 12:16:01 -04:00 committed by Alex Deucher
parent e3e7fdece7
commit fbc988f236
2 changed files with 2 additions and 2 deletions
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2
drivers/gpu/drm/amd/display/dc/dml/Makefile
View File

@ -29,7 +29,7 @@ dml_ccflags := $(CC_FLAGS_FPU)
dml_rcflags := $(CC_FLAGS_NO_FPU)
ifneq ($(CONFIG_FRAME_WARN),0)
ifeq ($(filter y,$(CONFIG_KASAN)$(CONFIG_KCSAN)$(CONFIG_UBSAN)),y)
ifneq ($(filter y,$(CONFIG_KASAN) $(CONFIG_KCSAN) $(CONFIG_UBSAN)),)
ifeq ($(CONFIG_CC_IS_CLANG)$(CONFIG_COMPILE_TEST),yy)
frame_warn_limit := 4096
else

2
drivers/gpu/drm/amd/display/dc/dml2_0/Makefile
View File

@ -28,7 +28,7 @@ dml2_ccflags := $(CC_FLAGS_FPU)
dml2_rcflags := $(CC_FLAGS_NO_FPU)
ifneq ($(CONFIG_FRAME_WARN),0)
ifeq ($(filter y,$(CONFIG_KASAN)$(CONFIG_KCSAN)$(CONFIG_UBSAN)),y)
ifneq ($(filter y,$(CONFIG_KASAN) $(CONFIG_KCSAN) $(CONFIG_UBSAN)),)
ifeq ($(CONFIG_CC_IS_CLANG)$(CONFIG_COMPILE_TEST),yy)
frame_warn_limit := 4096
else