From: Nathan Chancellor nathan@kernel.org
[ Upstream commit e4479aecf6581af81bc0908575447878d2a07e01 ]
Commit 24909d9ec7c3 ("drm/amd/display: Overwriting dualDPP UBF values before usage") added a new warning in dml2/display_mode_core.c when building allmodconfig with clang:
drivers/gpu/drm/amd/amdgpu/../display/dc/dml2/display_mode_core.c:6268:13: error: stack frame size (3128) exceeds limit (3072) in 'dml_prefetch_check' [-Werror,-Wframe-larger-than] 6268 | static void dml_prefetch_check(struct display_mode_lib_st *mode_lib) | ^
Commit be4e3509314a ("drm/amd/display: DML21 Reintegration For Various Fixes") introduced one in dml2_core/dml2_core_dcn4_calcs.c with the same configuration:
drivers/gpu/drm/amd/amdgpu/../display/dc/dml2/dml21/src/dml2_core/dml2_core_dcn4_calcs.c:7236:13: error: stack frame size (3256) exceeds limit (3072) in 'dml_core_mode_support' [-Werror,-Wframe-larger-than] 7236 | static bool dml_core_mode_support(struct dml2_core_calcs_mode_support_ex *in_out_params) | ^
In the case of the first warning, the stack usage was already at the limit at the parent change, so the offending change was rather innocuous. In the case of the second warning, there was a rather dramatic increase in stack usage compared to the parent:
drivers/gpu/drm/amd/amdgpu/../display/dc/dml2/dml21/src/dml2_core/dml2_core_dcn4_calcs.c:7032:13: error: stack frame size (2696) exceeds limit (2048) in 'dml_core_mode_support' [-Werror,-Wframe-larger-than] 7032 | static bool dml_core_mode_support(struct dml2_core_calcs_mode_support_ex *in_out_params) | ^
This is an unfortunate interaction between an issue with stack slot reuse in LLVM that gets exacerbated by sanitization (which gets enabled with all{mod,yes}config) and function calls using a much higher number of parameters than is typical in the kernel, necessitating passing most of these values on the stack.
While it is possible that there should be source code changes to address these warnings, this code is difficult to modify for various reasons, as has been noted in other changes that have occurred for similar reasons, such as commit 6740ec97bcdb ("drm/amd/display: Increase frame warning limit with KASAN or KCSAN in dml2").
Increase the frame larger than limit when compile testing with clang and the sanitizers enabled to avoid this breakage in all{mod,yes}config, as they are commonly used and valuable testing targets. While it is not the best to hide this issue, it is not really relevant when compile testing, as the sanitizers are commonly stressful on optimizations and they are only truly useful at runtime, which COMPILE_TEST states will not occur with the current build.
Reported-by: kernel test robot lkp@intel.com Closes: https://lore.kernel.org/oe-kbuild-all/202412121748.chuX4sap-lkp@intel.com/ Signed-off-by: Nathan Chancellor nathan@kernel.org Signed-off-by: Alex Deucher alexander.deucher@amd.com Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/gpu/drm/amd/display/dc/dml2/Makefile | 4 ++++ 1 file changed, 4 insertions(+)
diff --git a/drivers/gpu/drm/amd/display/dc/dml2/Makefile b/drivers/gpu/drm/amd/display/dc/dml2/Makefile index c4378e620cbf9..986a69c5bd4bc 100644 --- a/drivers/gpu/drm/amd/display/dc/dml2/Makefile +++ b/drivers/gpu/drm/amd/display/dc/dml2/Makefile @@ -29,7 +29,11 @@ dml2_rcflags := $(CC_FLAGS_NO_FPU)
ifneq ($(CONFIG_FRAME_WARN),0) ifeq ($(filter y,$(CONFIG_KASAN)$(CONFIG_KCSAN)),y) +ifeq ($(CONFIG_CC_IS_CLANG)$(CONFIG_COMPILE_TEST),yy) +frame_warn_flag := -Wframe-larger-than=4096 +else frame_warn_flag := -Wframe-larger-than=3072 +endif else frame_warn_flag := -Wframe-larger-than=2048 endif