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From 0549828354c1707532b672c9e9d08ecc418c1421 Mon Sep 17 00:00:00 2001
From: Nick Desaulniers <ndesaulniers@google.com>
Date: Wed, 16 Oct 2019 16:02:07 -0700
Subject: [PATCH 4308/4736] drm/amdgpu: fix stack alignment ABI mismatch for
Clang
The x86 kernel is compiled with an 8B stack alignment via
`-mpreferred-stack-boundary=3` for GCC since 3.6-rc1 via
commit d9b0cde91c60 ("x86-64, gcc: Use -mpreferred-stack-boundary=3 if supported")
or `-mstack-alignment=8` for Clang. Parts of the AMDGPU driver are
compiled with 16B stack alignment.
Generally, the stack alignment is part of the ABI. Linking together two
different translation units with differing stack alignment is dangerous,
particularly when the translation unit with the smaller stack alignment
makes calls into the translation unit with the larger stack alignment.
While 8B aligned stacks are sometimes also 16B aligned, they are not
always.
Multiple users have reported General Protection Faults (GPF) when using
the AMDGPU driver compiled with Clang. Clang is placing objects in stack
slots assuming the stack is 16B aligned, and selecting instructions that
require 16B aligned memory operands.
At runtime, syscall handlers with 8B aligned stack call into code that
assumes 16B stack alignment. When the stack is a multiple of 8B but not
16B, these instructions result in a GPF.
Remove the code that added compatibility between the differing compiler
flags, as it will result in runtime GPFs when built with Clang. Cleanups
for GCC will be sent in later patches in the series.
Link: https://github.com/ClangBuiltLinux/linux/issues/735
Tested-by: Shirish S <shirish.s@amd.com>
Debugged-by: Yuxuan Shui <yshuiv7@gmail.com>
Reported-by: Shirish S <shirish.s@amd.com>
Reported-by: Yuxuan Shui <yshuiv7@gmail.com>
Suggested-by: Andrew Cooper <andrew.cooper3@citrix.com>
Signed-off-by: Nick Desaulniers <ndesaulniers@google.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
---
drivers/gpu/drm/amd/display/dc/calcs/Makefile | 10 ++++------
drivers/gpu/drm/amd/display/dc/dcn20/Makefile | 10 ++++------
drivers/gpu/drm/amd/display/dc/dcn21/Makefile | 10 ++++------
drivers/gpu/drm/amd/display/dc/dml/Makefile | 10 ++++------
drivers/gpu/drm/amd/display/dc/dsc/Makefile | 10 ++++------
5 files changed, 20 insertions(+), 30 deletions(-)
diff --git a/drivers/gpu/drm/amd/display/dc/calcs/Makefile b/drivers/gpu/drm/amd/display/dc/calcs/Makefile
index 16614d73a5fc..ab522ea992d2 100644
--- a/drivers/gpu/drm/amd/display/dc/calcs/Makefile
+++ b/drivers/gpu/drm/amd/display/dc/calcs/Makefile
@@ -24,13 +24,11 @@
# It calculates Bandwidth and Watermarks values for HW programming
#
-ifneq ($(call cc-option, -mpreferred-stack-boundary=4),)
- cc_stack_align := -mpreferred-stack-boundary=4
-else ifneq ($(call cc-option, -mstack-alignment=16),)
- cc_stack_align := -mstack-alignment=16
-endif
+calcs_ccflags := -mhard-float -msse
-calcs_ccflags := -mhard-float -msse $(cc_stack_align)
+ifdef CONFIG_CC_IS_GCC
+calcs_ccflags += -mpreferred-stack-boundary=4
+endif
ifdef CONFIG_CC_IS_CLANG
calcs_ccflags += -msse2
diff --git a/drivers/gpu/drm/amd/display/dc/dcn20/Makefile b/drivers/gpu/drm/amd/display/dc/dcn20/Makefile
index f57a3b281408..a02e02980310 100644
--- a/drivers/gpu/drm/amd/display/dc/dcn20/Makefile
+++ b/drivers/gpu/drm/amd/display/dc/dcn20/Makefile
@@ -10,13 +10,11 @@ ifdef CONFIG_DRM_AMD_DC_DSC_SUPPORT
DCN20 += dcn20_dsc.o
endif
-ifneq ($(call cc-option, -mpreferred-stack-boundary=4),)
- cc_stack_align := -mpreferred-stack-boundary=4
-else ifneq ($(call cc-option, -mstack-alignment=16),)
- cc_stack_align := -mstack-alignment=16
-endif
+CFLAGS_dcn20_resource.o := -mhard-float -msse
-CFLAGS_dcn20_resource.o := -mhard-float -msse $(cc_stack_align)
+ifdef CONFIG_CC_IS_GCC
+CFLAGS_dcn20_resource.o += -mpreferred-stack-boundary=4
+endif
ifdef CONFIG_CC_IS_CLANG
CFLAGS_dcn20_resource.o += -msse2
diff --git a/drivers/gpu/drm/amd/display/dc/dcn21/Makefile b/drivers/gpu/drm/amd/display/dc/dcn21/Makefile
index 4ddd4037c1f8..0fa857b69143 100644
--- a/drivers/gpu/drm/amd/display/dc/dcn21/Makefile
+++ b/drivers/gpu/drm/amd/display/dc/dcn21/Makefile
@@ -3,13 +3,11 @@
DCN21 = dcn21_hubp.o dcn21_hubbub.o dcn21_resource.o dcn21_hwseq.o dcn21_link_encoder.o
-ifneq ($(call cc-option, -mpreferred-stack-boundary=4),)
- cc_stack_align := -mpreferred-stack-boundary=4
-else ifneq ($(call cc-option, -mstack-alignment=16),)
- cc_stack_align := -mstack-alignment=16
-endif
+CFLAGS_dcn21_resource.o := -mhard-float -msse
-CFLAGS_dcn21_resource.o := -mhard-float -msse $(cc_stack_align)
+ifdef CONFIG_CC_IS_GCC
+CFLAGS_dcn21_resource.o += -mpreferred-stack-boundary=4
+endif
ifdef CONFIG_CC_IS_CLANG
CFLAGS_dcn21_resource.o += -msse2
diff --git a/drivers/gpu/drm/amd/display/dc/dml/Makefile b/drivers/gpu/drm/amd/display/dc/dml/Makefile
index af2a864a6da0..b3db0900b473 100644
--- a/drivers/gpu/drm/amd/display/dc/dml/Makefile
+++ b/drivers/gpu/drm/amd/display/dc/dml/Makefile
@@ -24,13 +24,11 @@
# It provides the general basic services required by other DAL
# subcomponents.
-ifneq ($(call cc-option, -mpreferred-stack-boundary=4),)
- cc_stack_align := -mpreferred-stack-boundary=4
-else ifneq ($(call cc-option, -mstack-alignment=16),)
- cc_stack_align := -mstack-alignment=16
-endif
+dml_ccflags := -mhard-float -msse
-dml_ccflags := -mhard-float -msse $(cc_stack_align)
+ifdef CONFIG_CC_IS_GCC
+dml_ccflags += -mpreferred-stack-boundary=4
+endif
ifdef CONFIG_CC_IS_CLANG
dml_ccflags += -msse2
diff --git a/drivers/gpu/drm/amd/display/dc/dsc/Makefile b/drivers/gpu/drm/amd/display/dc/dsc/Makefile
index 17db603f2d1f..4d18e2b60223 100644
--- a/drivers/gpu/drm/amd/display/dc/dsc/Makefile
+++ b/drivers/gpu/drm/amd/display/dc/dsc/Makefile
@@ -1,13 +1,11 @@
#
# Makefile for the 'dsc' sub-component of DAL.
-ifneq ($(call cc-option, -mpreferred-stack-boundary=4),)
- cc_stack_align := -mpreferred-stack-boundary=4
-else ifneq ($(call cc-option, -mstack-alignment=16),)
- cc_stack_align := -mstack-alignment=16
-endif
+dsc_ccflags := -mhard-float -msse
-dsc_ccflags := -mhard-float -msse $(cc_stack_align)
+ifdef CONFIG_CC_IS_GCC
+dsc_ccflags += -mpreferred-stack-boundary=4
+endif
ifdef CONFIG_CC_IS_CLANG
dsc_ccflags += -msse2
--
2.17.1
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