sim: Initial support on MacOS M1 and Linux AARCH64 based hosts.

arch/sim/src/Makefile

@@ -49,6 +49,8 @@ else ifeq ($(CONFIG_HOST_X86),y)
   ASRCS += up_vfork_x86.S
 else ifeq ($(CONFIG_HOST_ARM),y)
   ASRCS += up_vfork_arm.S
+else ifeq ($(CONFIG_HOST_ARM64),y)
+  ASRCS += up_vfork_arm64.S
 endif
 
 AOBJS = $(ASRCS:.S=$(OBJEXT))

arch/sim/src/sim/up_hostmemory.c

@@ -63,8 +63,16 @@ void *host_alloc_heap(size_t sz)
 {
   void *p;
 
+#if defined(CONFIG_HOST_MACOS) && defined(CONFIG_HOST_ARM64)
+  /* see: https://developer.apple.com/forums/thread/672804 */
+
+  p = mmap(NULL, sz, PROT_READ | PROT_WRITE,
+           MAP_ANON | MAP_SHARED, -1, 0);
+#else
   p = mmap(NULL, sz, PROT_READ | PROT_WRITE | PROT_EXEC,
            MAP_ANON | MAP_PRIVATE, -1, 0);
+#endif
+
   if (p == MAP_FAILED)
     {
       return NULL;

arch/sim/src/sim/up_initialstate.c

@@ -82,12 +82,19 @@ void up_initial_state(struct tcb_s *tcb)
    * Thus, we need to emulate the effect of a CALL here, by subtracting
    * sizeof(xcpt_reg_t), which is the amount a CALL would move RSP to store
    * the return address.
+   *
+   * Note: On ARM64 architectures the return address is passed via LR
+   *       register. No extra adjustment for the stack needed.
    */
 
-  tcb->xcp.regs[JB_SP] = (xcpt_reg_t)tcb->stack_base_ptr +
-                                     tcb->adj_stack_size -
-                                     sizeof(xcpt_reg_t);
+  tcb->xcp.regs[JB_SP] = (xcpt_reg_t)tcb->stack_base_ptr
+#if !defined(CONFIG_HOST_ARM64)
+                                   - sizeof(xcpt_reg_t)
+#endif
+                                   + tcb->adj_stack_size;
+
   tcb->xcp.regs[JB_PC] = (xcpt_reg_t)tcb->start;
+
 #ifdef CONFIG_SIM_ASAN
   __asan_unpoison_memory_region(tcb->stack_alloc_ptr, tcb->adj_stack_size);
 #endif

arch/sim/src/sim/up_vfork_arm64.S

@@ -0,0 +1,116 @@
+/****************************************************************************
+ * arch/sim/src/sim/up_vfork_arm64.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>
+
+/****************************************************************************
+ * Pre-processor Definitions
+ ***************************************************************************/
+
+#if defined(CONFIG_HOST_MACOS)
+	#define SYMBOL(x) _##x
+#else
+	#define SYMBOL(x) x
+#endif
+
+/****************************************************************************
+ * Public Symbols
+ ***************************************************************************/
+
+    .file  "up_vfork_arm64.S"
+    .globl SYMBOL(up_vfork)
+    .globl SYMBOL(setjmp)
+
+/****************************************************************************
+ * Public Functions
+ ***************************************************************************/
+
+/****************************************************************************
+ * Name: vfork
+ *
+ * Description:
+ *   The vfork() function has the same effect as fork(), except that the
+ *   behavior is undefined if the process created by vfork() either modifies
+ *   any data other than a variable of type pid_t used to store the return
+ *   value from vfork(), or returns from the function in which vfork() was
+ *   called, or calls any other function before successfully calling _exit()
+ *   or one of the exec family of functions.
+ *
+ *   This thin layer implements vfork by simply calling up_vfork() with the
+ *   vfork() context as an argument.  The overall sequence is:
+ *
+ *   1) User code calls vfork().  vfork() collects context information and
+ *      transfers control up up_vfork().
+ *   2) up_vfork() and calls nxtask_setup_vfork().
+ *   3) nxtask_setup_vfork() allocates and configures the child task's TCB.
+ *      This consists of:
+ *      - Allocation of the child task's TCB.
+ *      - Initialization of file descriptors and streams
+ *      - Configuration of environment variables
+ *      - Allocate and initialize the stack
+ *      - Setup the input parameters for the task.
+ *      - Initialization of the TCB (including call to up_initial_state())
+ *   4) up_vfork() provides any additional operating context. up_vfork must:
+ *      - Initialize special values in any CPU registers that were not
+ *        already configured by up_initial_state()
+ *   5) up_vfork() then calls nxtask_start_vfork()
+ *   6) nxtask_start_vfork() then executes the child thread.
+ *
+ * Input Parameters:
+ *   None
+ *
+ * Returned Value:
+ *   Upon successful completion, vfork() returns 0 to the child process and
+ *   returns the process ID of the child process to the parent process.
+ *   Otherwise, -1 is returned to the parent, no child process is created,
+ *   and errno is set to indicate the error.
+ *
+ ***************************************************************************/
+
+	.text
+	.globl	SYMBOL(vfork)
+	.align	4
+
+SYMBOL(vfork):
+
+	stp		x29, x30, [sp]				/* save FP/LR register */
+	sub		sp, sp, #XCPTCONTEXT_SIZE	/* area from stack for setjmp() */
+
+	mov		x0, sp						/* pass stack area to setjmp() */
+	bl		SYMBOL(setjmp)				/* save register for longjmp() */
+
+	subs	x0, x0, #1					/* 0: parent / 1: child */
+	cbz		x0, 1f						/* child --> return */
+
+	mov		x0, sp						/* pass stack area to up_vfork() */
+	bl		SYMBOL(up_vfork)			/* further process task creation */
+
+1:
+	add		sp, sp, #XCPTCONTEXT_SIZE	/* release area from stack */
+	ldp		x29, x30, [sp]				/* restore FP/LR register */
+
+	ret
+
+	.end