Building the DCN 1.0 Raven display driver with CONFIG_KCOV_INSTRUMENT_ALL=y and CONFIG_KCOV_ENABLE_COMPARISONS=y results in warnings about many functions that do a comparison of floating-point variables:
drivers/gpu/drm/amd/display/dc/calcs/dcn_calcs.o: In function `dcn_bw_calc_rq_dlg_ttu': dcn_calcs.c:(.text+0x263): undefined reference to `__sanitizer_cov_trace_cmpf' drivers/gpu/drm/amd/display/dc/calcs/dcn_calcs.o: In function `hack_force_pipe_split': dcn_calcs.c:(.text+0x155b): undefined reference to `__sanitizer_cov_trace_cmpf' drivers/gpu/drm/amd/display/dc/calcs/dcn_calcs.o: In function `dcn_find_dcfclk_suits_all': dcn_calcs.c:(.text+0x190e): undefined reference to `__sanitizer_cov_trace_cmpf' drivers/gpu/drm/amd/display/dc/calcs/dcn_calcs.o: In function `dcn_validate_bandwidth': dcn_calcs.c:(.text+0xe121): undefined reference to `__sanitizer_cov_trace_cmpd' drivers/gpu/drm/amd/display/dc/calcs/dcn_calc_math.o: In function `dcn_bw_mod': dcn_calc_math.c:(.text+0x22): undefined reference to `__sanitizer_cov_trace_cmpf' drivers/gpu/drm/amd/display/dc/calcs/dcn_calc_math.o: In function `dcn_bw_min2': dcn_calc_math.c:(.text+0xb2): undefined reference to `__sanitizer_cov_trace_cmpf' drivers/gpu/drm/amd/display/dc/calcs/dcn_calc_math.o: In function `dcn_bw_ceil2': dcn_calc_math.c:(.text+0x2a0): undefined reference to `__sanitizer_cov_trace_cmpd' drivers/gpu/drm/amd/display/dc/calcs/dcn_calc_math.o: In function `dcn_bw_max3': dcn_calc_math.c:(.text+0x325): undefined reference to `__sanitizer_cov_trace_cmpf' drivers/gpu/drm/amd/display/dc/calcs/dcn_calc_math.o: In function `dcn_bw_max5': dcn_calc_math.c:(.text+0x3c3): undefined reference to `__sanitizer_cov_trace_cmpf' drivers/gpu/drm/amd/display/dc/calcs/dcn_calc_math.o: In function `dcn_bw_log': dcn_calc_math.c:(.text+0x54e): undefined reference to `__sanitizer_cov_trace_cmpd' dcn_calc_math.c:(.text+0x57c): undefined reference to `__sanitizer_cov_trace_cmpd' drivers/gpu/drm/amd/display/dc/calcs/dcn_calc_auto.o: In function `scaler_settings_calculation': dcn_calc_auto.c:(.text+0x5c5): undefined reference to `__sanitizer_cov_trace_cmpf' drivers/gpu/drm/amd/display/dc/calcs/dcn_calc_auto.o: In function `mode_support_and_system_configuration': dcn_calc_auto.c:(.text+0x137c): undefined reference to `__sanitizer_cov_trace_cmpd' drivers/gpu/drm/amd/display/dc/calcs/dcn_calc_auto.o: In function `mode_support_and_system_configuration': dcn_calc_auto.c:(.text+0x9233): undefined reference to `__sanitizer_cov_trace_cmpd' drivers/gpu/drm/amd/display/dc/calcs/dcn_calc_auto.o: In function `mode_support_and_system_configuration': dcn_calc_auto.c:(.text+0xb70f): undefined reference to `__sanitizer_cov_trace_cmpd' drivers/gpu/drm/amd/display/dc/calcs/dcn_calc_auto.o: In function `mode_support_and_system_configuration': dcn_calc_auto.c:(.text+0x121fd): undefined reference to `__sanitizer_cov_trace_cmpd' drivers/gpu/drm/amd/display/dc/calcs/dcn_calc_auto.o: In function `display_pipe_configuration': dcn_calc_auto.c:(.text+0x15a2f): undefined reference to `__sanitizer_cov_trace_cmpd' drivers/gpu/drm/amd/display/dc/calcs/dcn_calc_auto.o: In function `dispclkdppclkdcfclk_deep_sleep_prefetch_parameters_watermarks_and_performance_calculation': dcn_calc_auto.c:(.text+0x17c2d): undefined reference to `__sanitizer_cov_trace_cmpf' drivers/gpu/drm/amd/display/dc/calcs/dcn_calc_auto.o: In function `dispclkdppclkdcfclk_deep_sleep_prefetch_parameters_watermarks_and_performance_calculation': dcn_calc_auto.c:(.text+0x19362): undefined reference to `__sanitizer_cov_trace_cmpd' drivers/gpu/drm/amd/display/dc/calcs/dcn_calc_auto.o: In function `dispclkdppclkdcfclk_deep_sleep_prefetch_parameters_watermarks_and_performance_calculation': dcn_calc_auto.c:(.text+0x25575): undefined reference to `__sanitizer_cov_trace_cmpd' drivers/gpu/drm/amd/display/dc/calcs/dcn_calc_auto.o: In function `dispclkdppclkdcfclk_deep_sleep_prefetch_parameters_watermarks_and_performance_calculation': dcn_calc_auto.c:(.text+0x27f33): undefined reference to `__sanitizer_cov_trace_cmpd' drivers/gpu/drm/amd/display/dc/dml/display_rq_dlg_calc.o: In function `get_refcyc_per_delivery': display_rq_dlg_calc.c:(.text+0xb5): undefined reference to `__sanitizer_cov_trace_cmpd' drivers/gpu/drm/amd/display/dc/dml/display_rq_dlg_calc.o: In function `calculate_ttu_cursor.isra.1': display_rq_dlg_calc.c:(.text+0x9f6): undefined reference to `__sanitizer_cov_trace_cmpd' drivers/gpu/drm/amd/display/dc/dml/display_rq_dlg_calc.o: In function `dml_rq_dlg_get_dlg_params': display_rq_dlg_calc.c:(.text+0x82cc): undefined reference to `__sanitizer_cov_trace_cmpf' drivers/gpu/drm/amd/display/dc/dml/dml1_display_rq_dlg_calc.o: In function `get_refcyc_per_delivery.isra.0': dml1_display_rq_dlg_calc.c:(.text+0x6c4): undefined reference to `__sanitizer_cov_trace_cmpd' drivers/gpu/drm/amd/display/dc/dml/dml1_display_rq_dlg_calc.o: In function `get_vratio_pre.isra.2': dml1_display_rq_dlg_calc.c:(.text+0x957): undefined reference to `__sanitizer_cov_trace_cmpd' drivers/gpu/drm/amd/display/dc/dml/dml1_display_rq_dlg_calc.o: In function `get_swath_need.isra.3': dml1_display_rq_dlg_calc.c:(.text+0xc8e): undefined reference to `__sanitizer_cov_trace_cmpf' drivers/gpu/drm/amd/display/dc/dml/dml1_display_rq_dlg_calc.o: In function `dml1_extract_rq_regs': dml1_display_rq_dlg_calc.c:(.text+0x30a8): undefined reference to `__sanitizer_cov_trace_cmpd' drivers/gpu/drm/amd/display/dc/dml/dml1_display_rq_dlg_calc.o: In function `dml1_rq_dlg_get_dlg_params': dml1_display_rq_dlg_calc.c:(.text+0x41ee): undefined reference to `__sanitizer_cov_trace_cmpd' drivers/gpu/drm/amd/display/dc/dml/dml1_display_rq_dlg_calc.o: In function `dml1_rq_dlg_get_dlg_params': dml1_display_rq_dlg_calc.c:(.text+0x8f95): undefined reference to `__sanitizer_cov_trace_cmpf' drivers/gpu/drm/amd/display/dc/dml/dml_common_defs.o: In function `dml_round': dml_common_defs.c:(.text+0x77): undefined reference to `__sanitizer_cov_trace_cmpd' drivers/gpu/drm/amd/display/dc/dml/display_mode_vba.o: In function `adjust_ReturnBW': display_mode_vba.c:(.text+0x4490): undefined reference to `__sanitizer_cov_trace_cmpd'
We already prevent the driver from being built on non-x86 architectures because of its use of floating-point arithmetic, this extends the dependency to also cover Kcov-enabled builds, which arguably is a much more severe limitation.
I tried implementing the two functions in KCOV: __sanitizer_cov_trace_cmpd and __sanitizer_cov_trace_cmpf, but that fails to build on architectures that do not support any floating-point functions, or would require making that code x86 specific as well. I also looked at what it would take to convert the code to fixed-point arithmetic, but quickly gave up. This is probably the right approach, but it requires a non-trivial amount of work and certainly won't be appropriate as a bugfix.
Fixes: bf2e2e2e0ea9 ("drm/amd/display: Limit DCN to x86 arch") Fixes: 4841203102a3 ("drm/amdgpu/display: Replace CONFIG_DRM_AMD_DC_DCN1_0 with CONFIG_X86") Link: drm: amd: dc: don't use FP math when Kcov is enabled Signed-off-by: Arnd Bergmann arnd@arndb.de --- v3: rebase on top of 4841203102a3, which removed the option for CONFIG_DRM_AMD_DC_DCN1_0. The problem still gets hit occasionally in randconfig testing. --- drivers/gpu/drm/amd/display/Kconfig | 1 + 1 file changed, 1 insertion(+)
diff --git a/drivers/gpu/drm/amd/display/Kconfig b/drivers/gpu/drm/amd/display/Kconfig index 325083b0297e..b132d434e572 100644 --- a/drivers/gpu/drm/amd/display/Kconfig +++ b/drivers/gpu/drm/amd/display/Kconfig @@ -3,6 +3,7 @@ menu "Display Engine Configuration"
config DRM_AMD_DC bool "AMD DC - Enable new display engine" + depends on !X86 || !(KCOV_INSTRUMENT_ALL && KCOV_ENABLE_COMPARISONS) || BROKEN default y help Choose this option if you want to use the new display engine