xiaoxiang781216 commented on a change in pull request #5782:
URL: https://github.com/apache/incubator-nuttx/pull/5782#discussion_r837771274
##########
File path: arch/risc-v/src/common/riscv_internal.h
##########
@@ -283,6 +285,60 @@ int riscv_pause_handler(int irq, void *c, void *arg);
uintptr_t riscv_mhartid(void);
+#ifdef CONFIG_ARCH_USE_S_MODE
+/* If kernel runs in Supervisor mode, declare proper function prototypes,
+ * this is because it is not possible to ecall from S mode to S mode
+ */
+
+int riscv_saveusercontext(uintptr_t *saveregs);
+void riscv_fullcontextrestore(uintptr_t *restoreregs) noreturn_function;
+void riscv_switchcontext(uintptr_t **saveregs, uintptr_t *restoreregs);
+void riscv_syscall_return(void);
+void riscv_syscall_dispatch(void) noreturn_function;
+
+#else
+
+/* Context switching via system calls ***************************************/
+
+/* SYS call 0:
+ *
+ * int riscv_saveusercontext(uintptr_t *saveregs);
+ *
+ * Return:
+ * 0: Normal Return
+ * 1: Context Switch Return
+ */
+
+#define riscv_saveusercontext(saveregs) \
+ sys_call1(SYS_save_context, (uintptr_t)saveregs)
+
+/* SYS call 1:
+ *
+ * void riscv_fullcontextrestore(uintptr_t *restoreregs) noreturn_function;
+ */
+
+#define riscv_fullcontextrestore(restoreregs) \
+ sys_call1(SYS_restore_context, (uintptr_t)restoreregs)
Review comment:
since ksys_callx is merged into sys_callx, all context switch related
macros could forward to syscallx directly regardless which mode these are
running in.
##########
File path: arch/risc-v/src/common/supervisor/riscv_vectors.S
##########
@@ -0,0 +1,52 @@
+/****************************************************************************
+ * arch/risc-v/src/common/supervisor/riscv_vectors.S
+ *
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership. The
+ * ASF licenses this file to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance with the
+ * License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+ * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+ * License for the specific language governing permissions and limitations
+ * under the License.
+ *
+ ****************************************************************************/
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+ .section .text
+ .balign 8
+ .global __trap_vec
+ .global __irq_vec
+
+/****************************************************************************
+ * Name: __trap_vec
+ *
+ * Description:
+ * All M-mode exceptions and interrupts will be handled from here.
+ *
+ ****************************************************************************/
+
+__trap_vec:
Review comment:
could be shared with the machine version?
##########
File path: arch/risc-v/src/Makefile
##########
@@ -24,10 +24,19 @@ ifeq ($(CONFIG_OPENSBI),y)
include opensbi/Make.defs
endif
+# Kernel runs in supervisor mode or machine mode ?
+
+ifeq ($(CONFIG_ARCH_USE_S_MODE),y)
+ARCH_CMN_MODE_DIR = supervisor
Review comment:
change to ARCH_MODDIR like ARCH_SRCDIR
##########
File path: arch/risc-v/src/common/riscv_swint.c
##########
@@ -179,6 +187,31 @@ int riscv_swint(int irq, void *context, void *arg)
riscv_registerdump(regs);
#endif
+ /* Handle the syscall */
+
+ regs = riscv_handle_syscall(regs);
+
+ /* Report what happened. That might difficult in the case of a context
+ * switch
+ */
+
+#ifdef CONFIG_DEBUG_SYSCALL_INFO
Review comment:
should we move the log at the begin and end to riscv_handle_syscall?
##########
File path: arch/risc-v/src/common/riscv_swint.c
##########
@@ -144,7 +148,11 @@ static void dispatch_syscall(void)
" addi sp, sp, 4\n" /* Destroy the stack frame */
" mv a2, a0\n" /* a2=Save return value in a0 */
" li a0, 3\n" /* a0=SYS_syscall_return (3) */
+#ifdef CONFIG_ARCH_USE_S_MODE
Review comment:
look like we can merge 32bit and 64bit implementation into one by always
subtracting 16B.
##########
File path: arch/risc-v/src/common/riscv_swint.c
##########
@@ -179,6 +187,31 @@ int riscv_swint(int irq, void *context, void *arg)
riscv_registerdump(regs);
#endif
+ /* Handle the syscall */
+
+ regs = riscv_handle_syscall(regs);
+
+ /* Report what happened. That might difficult in the case of a context
+ * switch
+ */
+
+#ifdef CONFIG_DEBUG_SYSCALL_INFO
+ if (regs != CURRENT_REGS)
+ {
+ svcinfo("SWInt Return: Context switch!\n");
+ riscv_registerdump((const uintptr_t *)CURRENT_REGS);
+ }
+ else
+ {
+ svcinfo("SWInt Return: %d\n", regs[REG_A0]);
+ }
+#endif
+
+ return OK;
+}
+
+void *riscv_handle_syscall(uintptr_t *regs)
Review comment:
how about change riscv_handle_syscall to riscv_do_swint?
##########
File path: arch/risc-v/src/common/supervisor/riscv_exception_common.S
##########
@@ -0,0 +1,137 @@
+/****************************************************************************
+ * arch/risc-v/src/common/supervisor/riscv_exception_common.S
+ *
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership. The
+ * ASF licenses this file to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance with the
+ * License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+ * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+ * License for the specific language governing permissions and limitations
+ * under the License.
+ *
+ ****************************************************************************/
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#include <nuttx/config.h>
+#include <arch/irq.h>
+
+#include "riscv_exception_macros.S"
+
+/****************************************************************************
+ * Public Symbols
+ ****************************************************************************/
+
+/****************************************************************************
+ * Name: exception_common
+ *
+ * Description:
+ * Handles delegated interrupts in S-mode interrupt handler.
+ *
+ ****************************************************************************/
+
+ .section .text
+ .global exception_common
+ .align 8
+
+exception_common:
Review comment:
what's the real difference make the machine and supervisor mode can't
share the same code base? I suppose that the macros in mode.h can unify the
difference.
##########
File path: arch/risc-v/src/common/supervisor/riscv_context.S
##########
@@ -0,0 +1,234 @@
+/****************************************************************************
+ * arch/risc-v/src/common/supervisor/riscv_context.S
+ *
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership. The
+ * ASF licenses this file to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance with the
+ * License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+ * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+ * License for the specific language governing permissions and limitations
+ * under the License.
+ *
+ ****************************************************************************/
+
+.file "riscv_context.S"
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#include <nuttx/config.h>
+#include <arch/mode.h>
+
+#include "riscv_exception_macros.S"
+
+/****************************************************************************
+ * Pre-processor Definitions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Public Symbols
+ ****************************************************************************/
+
+ .globl riscv_saveusercontext
+ .globl riscv_fullcontextrestore
+ .globl riscv_switchcontext
+ .globl riscv_syscall_return
+
+/****************************************************************************
+ * Name: riscv_saveusercontext
+ *
+ * Description:
+ * Save user context, partially destroys the caller's context
+ *
+ * C Function Prototype:
+ * int riscv_saveusercontext(uintptr_t *saveregs);
+ *
+ * Input Parameters:
+ * saveregs - Context to save
+ *
+ * Returned Value:
+ * 0 on context switch
+ * 1 on no context switch
+ *
+ * Assumptions:
+ * Global interrupts disabled by the caller.
+ *
+ ****************************************************************************/
+
+.type riscv_saveusercontext, function
+
+riscv_saveusercontext:
Review comment:
can we reuse the syscall implementation like this:
riscv_saveusercontext->sys_call1->riscv_syscall_dispatch->riscv_handle_syscall.
So the machine and supervisor mode share all most code base.
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