On 2017-12-05 07:05 AM, Arnd Bergmann wrote: > On Mon, Dec 4, 2017 at 9:34 PM, Harry Wentland <harry.wentland at amd.com> wrote: >> On 2017-12-04 08:08 AM, Arnd Bergmann wrote: >>> 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' >>> >> >> Is this with clang? I don't seem to get these with gcc. > > This was with gcc-8. I just tried other versions and found that gcc-7 > and earlier > (i.e. all released versions) don't support CONFIG_KCOV_ENABLE_COMPARISONS > and won't be affected by this. > > I've also tried building it with clang-5, but that rejects the > -mpreferred-stack-boundary=4 > argument and (once I fixed that) did not have the issue either. > Presumably, clang-6 > will do the same thing as gcc-8, but I haven't built a clang-6 snapshot yet. > >>> diff --git a/drivers/gpu/drm/amd/display/Kconfig b/drivers/gpu/drm/amd/display/Kconfig >>> index ec3285f65517..5cd5906c9bee 100644 >>> --- a/drivers/gpu/drm/amd/display/Kconfig >>> +++ b/drivers/gpu/drm/amd/display/Kconfig >>> @@ -30,6 +30,8 @@ config DRM_AMD_DC_FBC >>> config DRM_AMD_DC_DCN1_0 >>> bool "DCN 1.0 Raven family" >>> depends on DRM_AMD_DC && X86 >>> + # x86 floating point math here breaks with KCOV: >>> + depends on !(KCOV_INSTRUMENT_ALL && KCOV_ENABLE_COMPARISONS) || BROKEN >> >> I don't think it makes sense to make this depend on BROKEN as it works and is quite >> useful to people with Raven systems. > > Well, it's clearly broken when using with CONFIG_KCOV_ENABLE_COMPARISONS. > Fortunately that option doesn't do anything unless used with gcc-8, which won't > be released until next spring, so that leaves some time to change the code into > fixed-point arithmetic or find a different workaround. > Thanks, Arnd. This is what I was missing. I'll take another look. It would still work without KCOV, although I agree that's not ideal by any means. Harry > Arnd >
