Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752431AbdLEMFT (ORCPT ); Tue, 5 Dec 2017 07:05:19 -0500 Received: from mail-oi0-f68.google.com ([209.85.218.68]:41667 "EHLO mail-oi0-f68.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751383AbdLEMFQ (ORCPT ); Tue, 5 Dec 2017 07:05:16 -0500 X-Google-Smtp-Source: AGs4zMZRFWy4Vlmuu2e1TDOzBmIVBBKpvTMw9BAs7RR8HbZ80UoCwbgQjERbK0gPOaZ9w0PlG3EETeLJFeUMwBE+we4= MIME-Version: 1.0 In-Reply-To: <7a8f0af3-89cf-81d2-cedc-3d80905b9458@amd.com> References: <20171204131031.1418828-1-arnd@arndb.de> <7a8f0af3-89cf-81d2-cedc-3d80905b9458@amd.com> From: Arnd Bergmann Date: Tue, 5 Dec 2017 13:05:14 +0100 X-Google-Sender-Auth: Dtk-YXF3inadT7a5eGgPN8RDg5M Message-ID: Subject: Re: [PATCH] drm: amd: dc: don't use FP math when Kcov is enabled To: Harry Wentland Cc: Alex Deucher , =?UTF-8?Q?Christian_K=C3=B6nig?= , David Airlie , Jordan Lazare , Roman Li , Shirish S , amd-gfx@lists.freedesktop.org, dri-devel , Linux Kernel Mailing List Content-Type: text/plain; charset="UTF-8" Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 7900 Lines: 104 On Mon, Dec 4, 2017 at 9:34 PM, Harry Wentland 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. Arnd