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([2a02:908:1257:4460:1ab8:55c1:a639:6740]) by smtp.gmail.com with ESMTPSA id m35-v6sm30918209wrf.41.2018.08.12.00.55.11 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Sun, 12 Aug 2018 00:55:12 -0700 (PDT) Reply-To: christian.koenig@amd.com Subject: Re: [PATCH] [v3] drm: amd: dc: don't use FP math when Kcov is enabled To: Arnd Bergmann , Alex Deucher , =?UTF-8?Q?Christian_K=c3=b6nig?= , "David (ChunMing) Zhou" , "Wentland, Harry" Cc: David Airlie , =?UTF-8?Q?Michel_D=c3=a4nzer?= , linux-kernel@vger.kernel.org, amd-gfx@lists.freedesktop.org, Shirish S , "Jerry (Fangzhi) Zuo" , dri-devel@lists.freedesktop.org References: <20180811155554.3382650-1-arnd@arndb.de> From: =?UTF-8?Q?Christian_K=c3=b6nig?= Message-ID: <593dd8e1-fa23-3216-3550-274401d88bcb@gmail.com> Date: Sun, 12 Aug 2018 09:55:11 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.9.1 MIME-Version: 1.0 In-Reply-To: <20180811155554.3382650-1-arnd@arndb.de> Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Content-Language: en-US Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Adding Harry as well. Am 11.08.2018 um 17:54 schrieb Arnd Bergmann: > 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 > --- > 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