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9ec051bf44
When we want to use float point operation on Linux
we need to use within special kernel protection
(`kernel_fpu_{begin,end}()`.), otherwise the kernel
can clobber userspace FPU register state. For detecting
these issues we use a tool named objtool (with -Ffa
flags) to highlight the FPU problems, all warnings can
be summed up as follows:
./tools/objtool/objtool check -Ffa
drivers/gpu/drm/amd/display/dc/dml/dml_common_defs.o
[..] dc/dsc/rc_calc.o: warning: objtool: get_qp_set()+0x2f8:
FPU instruction outside of kernel_fpu_{begin,end}()
[..] dc/dsc/rc_calc.o: warning: objtool: dsc_roundf()+0x5:
FPU instruction outside of kernel_fpu_{begin,end}()
[..] dc/dsc/rc_calc.o: warning: objtool: dsc_ceil()+0x5:
FPU instruction outside of kernel_fpu_{begin,end}()
[..] dc/dsc/rc_calc.o: warning: objtool: get_ofs_set()+0x3eb:
FPU instruction outside of kernel_fpu_{begin,end}()
[..] dc/dsc/rc_calc.o: warning: objtool: calc_rc_params()+0x3c:
FPU instruction outside of kernel_fpu_{begin,end}()
[..] dc/dsc/dc_dsc.o: warning: objtool:
get_dsc_bandwidth_range.isra.0()+0x8d:
FPU instruction outside of kernel_fpu_{begin,end}()
[..] dc/dsc/dc_dsc.o: warning: objtool: setup_dsc_config()+0x2ef:
FPU instruction outside of kernel_fpu_{begin,end}()
[..] dc/dsc/rc_calc_dpi.o: warning: objtool:copy_pps_fields()+0xbb:
FPU instruction outside of kernel_fpu_{begin,end}()
[..] dc/dsc/rc_calc_dpi.o: warning: objtool:
dscc_compute_dsc_parameters()+0x7b:
FPU instruction outside of kernel_fpu_{begin,end}()
This commit fixes the above issues by rework DSC as described:
1. Isolate all FPU operations in a single file;
2. Use FPU flags only in the file that handles FPU operations;
3. Isolate all functions that require float point operation in static
functions;
4. Add a mid-layer function that does not use any float point operation,
and that could be safely invoked in other parts of the code.
5. Keep float point operation under DC_FP_{START/END} macro.
CC: Christian König <christian.koenig@amd.com>
CC: Alexander Deucher <Alexander.Deucher@amd.com>
CC: Peter Zijlstra <peterz@infradead.org>
CC: Tony Cheng <tony.cheng@amd.com>
CC: Harry Wentland <hwentlan@amd.com>
Signed-off-by: Rodrigo Siqueira <Rodrigo.Siqueira@amd.com>
Reviewed-by: Mikita Lipski <Mikita.Lipski@amd.com>
Acked-by: Qingqing Zhuo <qingqing.zhuo@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
37 lines
761 B
Makefile
37 lines
761 B
Makefile
# SPDX-License-Identifier: MIT
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#
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# Makefile for the 'dsc' sub-component of DAL.
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ifdef CONFIG_X86
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dsc_ccflags := -mhard-float -msse
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endif
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ifdef CONFIG_PPC64
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dsc_ccflags := -mhard-float -maltivec
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endif
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ifdef CONFIG_CC_IS_GCC
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ifeq ($(call cc-ifversion, -lt, 0701, y), y)
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IS_OLD_GCC = 1
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endif
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endif
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ifdef CONFIG_X86
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ifdef IS_OLD_GCC
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# Stack alignment mismatch, proceed with caution.
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# GCC < 7.1 cannot compile code using `double` and -mpreferred-stack-boundary=3
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# (8B stack alignment).
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dsc_ccflags += -mpreferred-stack-boundary=4
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else
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dsc_ccflags += -msse2
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endif
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endif
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CFLAGS_$(AMDDALPATH)/dc/dsc/rc_calc.o := $(dsc_ccflags)
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DSC = dc_dsc.o rc_calc.o rc_calc_dpi.o
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AMD_DAL_DSC = $(addprefix $(AMDDALPATH)/dc/dsc/,$(DSC))
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AMD_DISPLAY_FILES += $(AMD_DAL_DSC)
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