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4827d0cf74
When DSP extensions are present, some of the regular integer instructions such as DIV, MACD etc are executed in the DSP unit with semantics alterable by flags in DSP_CTRL aux register. This register is writable by userspace and thus can potentially affect corresponding instructions in kernel code, intentionally or otherwise. So safegaurd kernel by effectively disabling DSP_CTRL upon bootup and every entry to kernel. Do note that for this config we simply zero out the DSP_CTRL reg assuming userspace doesn't really care about DSP. The next patch caters to the DSP aware userspace where this reg is saved/restored upon kernel entry/exit. Reviewed-by: Vineet Gupta <vgupta@synopsys.com> Signed-off-by: Eugeniy Paltsev <Eugeniy.Paltsev@synopsys.com> Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
54 lines
1.1 KiB
C
54 lines
1.1 KiB
C
/* SPDX-License-Identifier: GPL-2.0-only */
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/*
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* Copyright (C) 2020 Synopsys, Inc. (www.synopsys.com)
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*
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* Author: Eugeniy Paltsev <Eugeniy.Paltsev@synopsys.com>
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*/
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#ifndef __ASM_ARC_DSP_IMPL_H
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#define __ASM_ARC_DSP_IMPL_H
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#define DSP_CTRL_DISABLED_ALL 0
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#ifdef __ASSEMBLY__
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/* clobbers r5 register */
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.macro DSP_EARLY_INIT
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lr r5, [ARC_AUX_DSP_BUILD]
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bmsk r5, r5, 7
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breq r5, 0, 1f
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mov r5, DSP_CTRL_DISABLED_ALL
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sr r5, [ARC_AUX_DSP_CTRL]
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1:
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.endm
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/* clobbers r10, r11 registers pair */
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.macro DSP_SAVE_REGFILE_IRQ
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#if defined(CONFIG_ARC_DSP_KERNEL)
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/*
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* Drop any changes to DSP_CTRL made by userspace so userspace won't be
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* able to break kernel - reset it to DSP_CTRL_DISABLED_ALL value
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*/
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mov r10, DSP_CTRL_DISABLED_ALL
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sr r10, [ARC_AUX_DSP_CTRL]
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#endif /* ARC_DSP_KERNEL */
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.endm
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#else /* __ASEMBLY__ */
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#include <asm/asserts.h>
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static inline bool dsp_exist(void)
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{
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struct bcr_generic bcr;
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READ_BCR(ARC_AUX_DSP_BUILD, bcr);
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return !!bcr.ver;
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}
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static inline void dsp_config_check(void)
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{
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CHK_OPT_STRICT(CONFIG_ARC_DSP_HANDLED, dsp_exist());
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}
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#endif /* __ASEMBLY__ */
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#endif /* __ASM_ARC_DSP_IMPL_H */
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