linux-kernel - [PATCH] drm/amd/display: add -msse2 to prevent Clang from emitting libcalls to undefined SW FP routines

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Date:   Thu, 24 Jan 2019 16:52:59 -0800
From:   ndesaulniers@...gle.com
To:     airlied@...ux.ie, daniel@...ll.ch
Cc:     Nick Desaulniers <ndesaulniers@...gle.com>, stable@...r.kernel.org,
        S@...gle.com, Shirish <Shirish.S@....com>,
        Matthias Kaehlcke <mka@...gle.com>,
        James Y Knight <jyknight@...gle.com>,
        Nathan Chancellor <natechancellor@...il.com>,
        Guenter Roeck <linux@...ck-us.net>,
        Harry Wentland <harry.wentland@....com>,
        Leo Li <sunpeng.li@....com>,
        Alex Deucher <alexander.deucher@....com>,
        "Christian König" <christian.koenig@....com>,
        "David (ChunMing) Zhou" <David1.Zhou@....com>,
        Matthias Kaehlcke <mka@...omium.org>,
        "Michel Dänzer" <michel.daenzer@....com>,
        Tony Cheng <Tony.Cheng@....com>,
        Dmytro Laktyushkin <Dmytro.Laktyushkin@....com>,
        amd-gfx@...ts.freedesktop.org, dri-devel@...ts.freedesktop.org,
        linux-kernel@...r.kernel.org
Subject: [PATCH] drm/amd/display: add -msse2 to prevent Clang from emitting
 libcalls to undefined SW FP routines

arch/x86/Makefile disables SSE and SSE2 for the whole kernel.  The
AMDGPU drivers modified in this patch re-enable SSE but not SSE2.  Turn
on SSE2 to support emitting double precision floating point instructions
rather than calls to non-existent (usually available from gcc_s or
compiler_rt) floating point helper routines.

Link: https://gcc.gnu.org/onlinedocs/gccint/Soft-float-library-routines.html
Link: https://github.com/ClangBuiltLinux/linux/issues/327
Cc: stable@...r.kernel.org # 4.19
Reported-by: S, Shirish <Shirish.S@....com>
Reported-by: Matthias Kaehlcke <mka@...gle.com>
Suggested-by: James Y Knight <jyknight@...gle.com>
Suggested-by: Nathan Chancellor <natechancellor@...il.com>
Signed-off-by: Nick Desaulniers <ndesaulniers@...gle.com>
Tested-by: Guenter Roeck <linux@...ck-us.net>
---
 drivers/gpu/drm/amd/display/dc/calcs/Makefile | 2 +-
 drivers/gpu/drm/amd/display/dc/dml/Makefile   | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/amd/display/dc/calcs/Makefile b/drivers/gpu/drm/amd/display/dc/calcs/Makefile
index 95f332ee3e7e..dc85a3c088af 100644
--- a/drivers/gpu/drm/amd/display/dc/calcs/Makefile
+++ b/drivers/gpu/drm/amd/display/dc/calcs/Makefile
@@ -30,7 +30,7 @@ else ifneq ($(call cc-option, -mstack-alignment=16),)
 	cc_stack_align := -mstack-alignment=16
 endif
 
-calcs_ccflags := -mhard-float -msse $(cc_stack_align)
+calcs_ccflags := -mhard-float -msse -msse2 $(cc_stack_align)
 
 CFLAGS_dcn_calcs.o := $(calcs_ccflags)
 CFLAGS_dcn_calc_auto.o := $(calcs_ccflags)
diff --git a/drivers/gpu/drm/amd/display/dc/dml/Makefile b/drivers/gpu/drm/amd/display/dc/dml/Makefile
index d97ca6528f9d..33c7d7588712 100644
--- a/drivers/gpu/drm/amd/display/dc/dml/Makefile
+++ b/drivers/gpu/drm/amd/display/dc/dml/Makefile
@@ -30,7 +30,7 @@ else ifneq ($(call cc-option, -mstack-alignment=16),)
 	cc_stack_align := -mstack-alignment=16
 endif
 
-dml_ccflags := -mhard-float -msse $(cc_stack_align)
+dml_ccflags := -mhard-float -msse -msse2 $(cc_stack_align)
 
 CFLAGS_display_mode_lib.o := $(dml_ccflags)
 CFLAGS_display_pipe_clocks.o := $(dml_ccflags)
-- 
2.20.1.321.g9e740568ce-goog