ARC: add support for DSP-enabled userspace applications

To be able to run DSP-enabled userspace applications we need to
save and restore following DSP-related registers:
At IRQ/exception entry/exit:
 * DSP_CTRL (save it and reset to value suitable for kernel)
 * ACC0_LO, ACC0_HI (we already save them as r58, r59 pair)
At context switch:
 * ACC0_GLO, ACC0_GHI
 * DSP_BFLY0, DSP_FFT_CTRL

Reviewed-by: Vineet Gupta <vgupta@synopsys.com>
Signed-off-by: Eugeniy Paltsev <Eugeniy.Paltsev@synopsys.com>
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>

diff --git a/arch/arc/Kconfig b/arch/arc/Kconfig
index 55432a8..eb3bcb2 100644 (file)
--- a/arch/arc/Kconfig
+++ b/arch/arc/Kconfig
@@ -411,6 +411,9 @@ config ARC_HAS_ACCL_REGS
 config ARC_DSP_HANDLED
        def_bool n
 
+config ARC_DSP_SAVE_RESTORE_REGS
+       def_bool n
+
 choice
        prompt "DSP support"
        default ARC_DSP_NONE
@@ -433,6 +436,15 @@ config ARC_DSP_KERNEL
          DSP extension presence in HW, no support for DSP-enabled userspace
          applications. We don't save / restore DSP registers and only do
          some minimal preparations so userspace won't be able to break kernel
+
+config ARC_DSP_USERSPACE
+       bool "Support DSP for userspace apps"
+       select ARC_HAS_ACCL_REGS
+       select ARC_DSP_HANDLED
+       select ARC_DSP_SAVE_RESTORE_REGS
+       help
+         DSP extension presence in HW, support save / restore DSP registers to
+         run DSP-enabled userspace applications
 endchoice
 
 config ARC_IRQ_NO_AUTOSAVE

diff --git a/arch/arc/include/asm/arcregs.h b/arch/arc/include/asm/arcregs.h
index 135f6ec..aee1ee2 100644 (file)
--- a/arch/arc/include/asm/arcregs.h
+++ b/arch/arc/include/asm/arcregs.h
@@ -120,6 +120,8 @@
 
 /*
  * DSP-related registers
+ * Registers names must correspond to dsp_callee_regs structure fields names
+ * for automatic offset calculation in DSP_AUX_SAVE_RESTORE macros.
  */
 #define ARC_AUX_DSP_BUILD      0x7A
 #define ARC_AUX_ACC0_LO                0x580

diff --git a/arch/arc/include/asm/dsp-impl.h b/arch/arc/include/asm/dsp-impl.h
index 6066203..8380f7b 100644 (file)
--- a/arch/arc/include/asm/dsp-impl.h
+++ b/arch/arc/include/asm/dsp-impl.h
@@ -7,6 +7,8 @@
 #ifndef __ASM_ARC_DSP_IMPL_H
 #define __ASM_ARC_DSP_IMPL_H
 
+#include <asm/dsp.h>
+
 #define DSP_CTRL_DISABLED_ALL          0
 
 #ifdef __ASSEMBLY__
@@ -30,12 +32,82 @@
         */
        mov     r10, DSP_CTRL_DISABLED_ALL
        sr      r10, [ARC_AUX_DSP_CTRL]
-#endif /* ARC_DSP_KERNEL */
+
+#elif defined(CONFIG_ARC_DSP_SAVE_RESTORE_REGS)
+       /*
+        * Save DSP_CTRL register and reset it to value suitable for kernel
+        * (DSP_CTRL_DISABLED_ALL)
+        */
+       mov     r10, DSP_CTRL_DISABLED_ALL
+       aex     r10, [ARC_AUX_DSP_CTRL]
+       st      r10, [sp, PT_DSP_CTRL]
+
+#endif
+.endm
+
+/* clobbers r10, r11 registers pair */
+.macro DSP_RESTORE_REGFILE_IRQ
+#if defined(CONFIG_ARC_DSP_SAVE_RESTORE_REGS)
+       ld      r10, [sp, PT_DSP_CTRL]
+       sr      r10, [ARC_AUX_DSP_CTRL]
+
+#endif
 .endm
 
 #else /* __ASEMBLY__ */
 
+#include <linux/sched.h>
 #include <asm/asserts.h>
+#include <asm/switch_to.h>
+
+#ifdef CONFIG_ARC_DSP_SAVE_RESTORE_REGS
+
+/*
+ * As we save new and restore old AUX register value in the same place we
+ * can optimize a bit and use AEX instruction (swap contents of an auxiliary
+ * register with a core register) instead of LR + SR pair.
+ */
+#define AUX_SAVE_RESTORE(_saveto, _readfrom, _offt, _aux)              \
+do {                                                                   \
+       long unsigned int _scratch;                                     \
+                                                                       \
+       __asm__ __volatile__(                                           \
+               "ld     %0, [%2, %4]                    \n"             \
+               "aex    %0, [%3]                        \n"             \
+               "st     %0, [%1, %4]                    \n"             \
+               :                                                       \
+                 "=&r" (_scratch)      /* must be early clobber */     \
+               :                                                       \
+                  "r" (_saveto),                                       \
+                  "r" (_readfrom),                                     \
+                  "Ir" (_aux),                                         \
+                  "Ir" (_offt)                                         \
+               :                                                       \
+                 "memory"                                              \
+       );                                                              \
+} while (0)
+
+#define DSP_AUX_SAVE_RESTORE(_saveto, _readfrom, _aux)                 \
+       AUX_SAVE_RESTORE(_saveto, _readfrom,                            \
+               offsetof(struct dsp_callee_regs, _aux),                 \
+               ARC_AUX_##_aux)
+
+static inline void dsp_save_restore(struct task_struct *prev,
+                                       struct task_struct *next)
+{
+       long unsigned int *saveto = &prev->thread.dsp.ACC0_GLO;
+       long unsigned int *readfrom = &next->thread.dsp.ACC0_GLO;
+
+       DSP_AUX_SAVE_RESTORE(saveto, readfrom, ACC0_GLO);
+       DSP_AUX_SAVE_RESTORE(saveto, readfrom, ACC0_GHI);
+
+       DSP_AUX_SAVE_RESTORE(saveto, readfrom, DSP_BFLY0);
+       DSP_AUX_SAVE_RESTORE(saveto, readfrom, DSP_FFT_CTRL);
+}
+
+#else /* !CONFIG_ARC_DSP_SAVE_RESTORE_REGS */
+#define dsp_save_restore(p, n)
+#endif /* CONFIG_ARC_DSP_SAVE_RESTORE_REGS */
 
 static inline bool dsp_exist(void)
 {

diff --git a/arch/arc/include/asm/dsp.h b/arch/arc/include/asm/dsp.h
new file mode 100644 (file)
index 0000000..b016f4d
--- /dev/null
+++ b/arch/arc/include/asm/dsp.h
@@ -0,0 +1,24 @@
+/* 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_H
+#define __ASM_ARC_DSP_H
+
+#ifndef __ASSEMBLY__
+
+/*
+ * DSP-related saved registers - need to be saved only when you are
+ * scheduled out.
+ * structure fields name must correspond to aux register defenitions for
+ * automatic offset calculation in DSP_AUX_SAVE_RESTORE macros
+ */
+struct dsp_callee_regs {
+       unsigned long ACC0_GLO, ACC0_GHI, DSP_BFLY0, DSP_FFT_CTRL;
+};
+
+#endif /* !__ASSEMBLY__ */
+
+#endif /* __ASM_ARC_DSP_H */

diff --git a/arch/arc/include/asm/entry-arcv2.h b/arch/arc/include/asm/entry-arcv2.h
index dd6aa18..ae0aa53 100644 (file)
--- a/arch/arc/include/asm/entry-arcv2.h
+++ b/arch/arc/include/asm/entry-arcv2.h
@@ -192,6 +192,9 @@
        ld      r25, [sp, PT_user_r25]
 #endif
 
+       /* clobbers r10, r11 registers pair */
+       DSP_RESTORE_REGFILE_IRQ
+
 #ifdef CONFIG_ARC_HAS_ACCL_REGS
        LD2     r58, r59, PT_r58
 #endif

diff --git a/arch/arc/include/asm/processor.h b/arch/arc/include/asm/processor.h
index ec532d1..0fcea5b 100644 (file)
--- a/arch/arc/include/asm/processor.h
+++ b/arch/arc/include/asm/processor.h
@@ -14,6 +14,7 @@
 #ifndef __ASSEMBLY__
 
 #include <asm/ptrace.h>
+#include <asm/dsp.h>
 #include <asm/fpu.h>
 
 #ifdef CONFIG_ARC_PLAT_EZNPS
@@ -31,6 +32,9 @@ struct thread_struct {
        unsigned long ksp;      /* kernel mode stack pointer */
        unsigned long callee_reg;       /* pointer to callee regs */
        unsigned long fault_address;    /* dbls as brkpt holder as well */
+#ifdef CONFIG_ARC_DSP_SAVE_RESTORE_REGS
+       struct dsp_callee_regs dsp;
+#endif
 #ifdef CONFIG_ARC_FPU_SAVE_RESTORE
        struct arc_fpu fpu;
 #endif

diff --git a/arch/arc/include/asm/ptrace.h b/arch/arc/include/asm/ptrace.h
index ba9854e..2fdb87a 100644 (file)
--- a/arch/arc/include/asm/ptrace.h
+++ b/arch/arc/include/asm/ptrace.h
@@ -91,6 +91,9 @@ struct pt_regs {
 #ifdef CONFIG_ARC_HAS_ACCL_REGS
        unsigned long r58, r59; /* ACCL/ACCH used by FPU / DSP MPY */
 #endif
+#ifdef CONFIG_ARC_DSP_SAVE_RESTORE_REGS
+       unsigned long DSP_CTRL;
+#endif
 
        /*------- Below list auto saved by h/w -----------*/
        unsigned long r0, r1, r2, r3, r4, r5, r6, r7, r8, r9, r10, r11;

diff --git a/arch/arc/include/asm/switch_to.h b/arch/arc/include/asm/switch_to.h
index aadf65b..4a3d679 100644 (file)
--- a/arch/arc/include/asm/switch_to.h
+++ b/arch/arc/include/asm/switch_to.h
@@ -9,6 +9,7 @@
 #ifndef __ASSEMBLY__
 
 #include <linux/sched.h>
+#include <asm/dsp-impl.h>
 #include <asm/fpu.h>
 
 #ifdef CONFIG_ARC_PLAT_EZNPS
@@ -24,6 +25,7 @@ struct task_struct *__switch_to(struct task_struct *p, struct task_struct *n);
 #define switch_to(prev, next, last)    \
 do {                                   \
        ARC_EZNPS_DP_PREV(prev, next);  \
+       dsp_save_restore(prev, next);   \
        fpu_save_restore(prev, next);   \
        last = __switch_to(prev, next);\
        mb();                           \

diff --git a/arch/arc/kernel/asm-offsets.c b/arch/arc/kernel/asm-offsets.c
index c783bcd..0e88403 100644 (file)
--- a/arch/arc/kernel/asm-offsets.c
+++ b/arch/arc/kernel/asm-offsets.c
@@ -12,6 +12,7 @@
 #include <asm/hardirq.h>
 #include <asm/page.h>
 
+
 int main(void)
 {
        DEFINE(TASK_THREAD, offsetof(struct task_struct, thread));
@@ -75,6 +76,9 @@ int main(void)
        OFFSET(PT_r58, pt_regs, r58);
        OFFSET(PT_r59, pt_regs, r59);
 #endif
+#ifdef CONFIG_ARC_DSP_SAVE_RESTORE_REGS
+       OFFSET(PT_DSP_CTRL, pt_regs, DSP_CTRL);
+#endif
 
        return 0;
 }