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authorEugeniy Paltsev <Eugeniy.Paltsev@synopsys.com>2020-03-05 23:02:50 +0300
committerVineet Gupta <vgupta@synopsys.com>2020-03-16 10:23:44 -0700
commit4827d0cf744e7e9cc73f10e1f4eaca904a3868c1 (patch)
tree2b7f88fe8cb98dcba5aaffebf23bd07570ce6e27 /arch/arc/include
parent240c84b1c22c9912ed1c8a96251b44e85d2ca2ed (diff)
downloadlinux-4827d0cf744e7e9cc73f10e1f4eaca904a3868c1.tar.gz
ARC: handle DSP presence in HW
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>
Diffstat (limited to 'arch/arc/include')
-rw-r--r--arch/arc/include/asm/arcregs.h12
-rw-r--r--arch/arc/include/asm/dsp-impl.h54
-rw-r--r--arch/arc/include/asm/entry-arcv2.h3
3 files changed, 69 insertions, 0 deletions
diff --git a/arch/arc/include/asm/arcregs.h b/arch/arc/include/asm/arcregs.h
index f7e432448e4b..135f6ec08a69 100644
--- a/arch/arc/include/asm/arcregs.h
+++ b/arch/arc/include/asm/arcregs.h
@@ -118,6 +118,18 @@
#define ARC_AUX_DPFP_2H 0x304
#define ARC_AUX_DPFP_STAT 0x305
+/*
+ * DSP-related registers
+ */
+#define ARC_AUX_DSP_BUILD 0x7A
+#define ARC_AUX_ACC0_LO 0x580
+#define ARC_AUX_ACC0_GLO 0x581
+#define ARC_AUX_ACC0_HI 0x582
+#define ARC_AUX_ACC0_GHI 0x583
+#define ARC_AUX_DSP_BFLY0 0x598
+#define ARC_AUX_DSP_CTRL 0x59F
+#define ARC_AUX_DSP_FFT_CTRL 0x59E
+
#ifndef __ASSEMBLY__
#include <soc/arc/aux.h>
diff --git a/arch/arc/include/asm/dsp-impl.h b/arch/arc/include/asm/dsp-impl.h
new file mode 100644
index 000000000000..606620383eca
--- /dev/null
+++ b/arch/arc/include/asm/dsp-impl.h
@@ -0,0 +1,54 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Copyright (C) 2020 Synopsys, Inc. (www.synopsys.com)
+ *
+ * Author: Eugeniy Paltsev <Eugeniy.Paltsev@synopsys.com>
+ */
+#ifndef __ASM_ARC_DSP_IMPL_H
+#define __ASM_ARC_DSP_IMPL_H
+
+#define DSP_CTRL_DISABLED_ALL 0
+
+#ifdef __ASSEMBLY__
+
+/* clobbers r5 register */
+.macro DSP_EARLY_INIT
+ lr r5, [ARC_AUX_DSP_BUILD]
+ bmsk r5, r5, 7
+ breq r5, 0, 1f
+ mov r5, DSP_CTRL_DISABLED_ALL
+ sr r5, [ARC_AUX_DSP_CTRL]
+1:
+.endm
+
+/* clobbers r10, r11 registers pair */
+.macro DSP_SAVE_REGFILE_IRQ
+#if defined(CONFIG_ARC_DSP_KERNEL)
+ /*
+ * Drop any changes to DSP_CTRL made by userspace so userspace won't be
+ * able to break kernel - reset it to DSP_CTRL_DISABLED_ALL value
+ */
+ mov r10, DSP_CTRL_DISABLED_ALL
+ sr r10, [ARC_AUX_DSP_CTRL]
+#endif /* ARC_DSP_KERNEL */
+.endm
+
+#else /* __ASEMBLY__ */
+
+#include <asm/asserts.h>
+
+static inline bool dsp_exist(void)
+{
+ struct bcr_generic bcr;
+
+ READ_BCR(ARC_AUX_DSP_BUILD, bcr);
+ return !!bcr.ver;
+}
+
+static inline void dsp_config_check(void)
+{
+ CHK_OPT_STRICT(CONFIG_ARC_DSP_HANDLED, dsp_exist());
+}
+
+#endif /* __ASEMBLY__ */
+#endif /* __ASM_ARC_DSP_IMPL_H */
diff --git a/arch/arc/include/asm/entry-arcv2.h b/arch/arc/include/asm/entry-arcv2.h
index 0b8b63d0bec1..dd6aa18b51ca 100644
--- a/arch/arc/include/asm/entry-arcv2.h
+++ b/arch/arc/include/asm/entry-arcv2.h
@@ -4,6 +4,7 @@
#define __ASM_ARC_ENTRY_ARCV2_H
#include <asm/asm-offsets.h>
+#include <asm/dsp-impl.h>
#include <asm/irqflags-arcv2.h>
#include <asm/thread_info.h> /* For THREAD_SIZE */
@@ -165,6 +166,8 @@
ST2 r58, r59, PT_r58
#endif
+ /* clobbers r10, r11 registers pair */
+ DSP_SAVE_REGFILE_IRQ
.endm
/*------------------------------------------------------------------------*/