RISC-V: Prepare for CONFIG_BUILD_KERNEL

- Thread context prior to system call needs to be preserved
- Allocate a kernel heap

arch/risc-v/include/irq.h

@@ -471,7 +471,7 @@
 struct xcpt_syscall_s
 {
   uintptr_t sysreturn;   /* The return PC */
-#ifdef CONFIG_BUILD_PROTECTED
+#ifndef CONFIG_BUILD_FLAT
   uintptr_t int_ctx;     /* Interrupt context (i.e. mstatus) */
 #endif
 };
@@ -501,7 +501,7 @@ struct xcptcontext
   uintptr_t saved_epc;     /* Trampoline PC */
   uintptr_t saved_int_ctx; /* Interrupt context with interrupts disabled. */
 
-#ifdef CONFIG_BUILD_PROTECTED
+#ifndef CONFIG_BUILD_FLAT
   /* This is the saved address to use when returning from a user-space
    * signal handler.
    */

arch/risc-v/src/common/riscv_schedulesigaction.c

@@ -138,7 +138,7 @@ void up_schedule_sigaction(struct tcb_s *tcb, sig_deliver_t sigdeliver)
 
               int_ctx                     = CURRENT_REGS[REG_INT_CTX];
               int_ctx                    &= ~MSTATUS_MPIE;
-#ifdef CONFIG_BUILD_PROTECTED
+#ifndef CONFIG_BUILD_FLAT
               int_ctx                    |= MSTATUS_MPPM;
 #endif
 
@@ -303,7 +303,7 @@ void up_schedule_sigaction(struct tcb_s *tcb, sig_deliver_t sigdeliver)
 
                   int_ctx                   = CURRENT_REGS[REG_INT_CTX];
                   int_ctx                   &= ~MSTATUS_MPIE;
-#ifdef CONFIG_BUILD_PROTECTED
+#ifndef CONFIG_BUILD_FLAT
                   int_ctx                   |= MSTATUS_MPPM;
 #endif
 

arch/risc-v/src/common/riscv_swint.c

@@ -276,7 +276,7 @@ int riscv_swint(int irq, void *context, void *arg)
            */
 
           regs[REG_EPC]         = rtcb->xcp.syscall[index].sysreturn;
-#ifdef CONFIG_BUILD_PROTECTED
+#ifndef CONFIG_BUILD_FLAT
           regs[REG_INT_CTX]     = rtcb->xcp.syscall[index].int_ctx;
 #endif
 
@@ -313,19 +313,27 @@ int riscv_swint(int irq, void *context, void *arg)
        *   A3 = argv
        */
 
-#ifdef CONFIG_BUILD_PROTECTED
+#ifndef CONFIG_BUILD_FLAT
       case SYS_task_start:
         {
           /* Set up to return to the user-space task start-up function in
            * unprivileged mode.
            */
 
-          regs[REG_EPC]      = (uintptr_t)USERSPACE->task_startup & ~1;
+#if defined (CONFIG_BUILD_PROTECTED)
+          /* Use the nxtask_startup trampoline function */
 
+          regs[REG_EPC]      = (uintptr_t)USERSPACE->task_startup & ~1;
           regs[REG_A0]       = regs[REG_A1]; /* Task entry */
           regs[REG_A1]       = regs[REG_A2]; /* argc */
           regs[REG_A2]       = regs[REG_A3]; /* argv */
+#else
+          /* Start the user task directly */
 
+          regs[REG_EPC]      = (uintptr_t)regs[REG_A1] & ~1;
+          regs[REG_A0]       = regs[REG_A2]; /* argc */
+          regs[REG_A1]       = regs[REG_A3]; /* argv */
+#endif
           regs[REG_INT_CTX] &= ~MSTATUS_MPPM; /* User mode */
         }
         break;
@@ -377,7 +385,7 @@ int riscv_swint(int irq, void *context, void *arg)
        *   R4 = ucontext
        */
 
-#ifdef CONFIG_BUILD_PROTECTED
+#ifndef CONFIG_BUILD_FLAT
       case SYS_signal_handler:
         {
           struct tcb_s *rtcb   = nxsched_self();
@@ -391,7 +399,12 @@ int riscv_swint(int irq, void *context, void *arg)
            * unprivileged mode.
            */
 
+#if defined (CONFIG_BUILD_PROTECTED)
           regs[REG_EPC]        = (uintptr_t)USERSPACE->signal_handler & ~1;
+#else
+          regs[REG_EPC]        =
+              (uintptr_t)ARCH_DATA_RESERVE->ar_sigtramp & ~1;
+#endif
           regs[REG_INT_CTX]   &= ~MSTATUS_MPPM; /* User mode */
 
           /* Change the parameter ordering to match the expectation of struct
@@ -415,7 +428,7 @@ int riscv_swint(int irq, void *context, void *arg)
        *   R0 = SYS_signal_handler_return
        */
 
-#ifdef CONFIG_BUILD_PROTECTED
+#ifndef CONFIG_BUILD_FLAT
       case SYS_signal_handler_return:
         {
           struct tcb_s *rtcb   = nxsched_self();
@@ -455,7 +468,7 @@ int riscv_swint(int irq, void *context, void *arg)
           /* Setup to return to dispatch_syscall in privileged mode. */
 
           rtcb->xcp.syscall[index].sysreturn  = regs[REG_EPC];
-#ifdef CONFIG_BUILD_PROTECTED
+#ifndef CONFIG_BUILD_FLAT
           rtcb->xcp.syscall[index].int_ctx     = regs[REG_INT_CTX];
 #endif
 
@@ -463,7 +476,7 @@ int riscv_swint(int irq, void *context, void *arg)
 
           regs[REG_EPC]        = (uintptr_t)dispatch_syscall & ~1;
 
-#ifdef CONFIG_BUILD_PROTECTED
+#ifndef CONFIG_BUILD_FLAT
           regs[REG_INT_CTX]   |= MSTATUS_MPPM; /* Machine mode */
 #endif
 

arch/risc-v/src/mpfs/Make.defs

@@ -63,13 +63,14 @@ CHIP_CSRCS += mpfs_dma.c
 endif
 
 ifeq ($(CONFIG_BUILD_PROTECTED),y)
+CHIP_CSRCS += mpfs_userspace.c
+CMN_UASRCS += riscv_signal_handler.S
+endif
+
+ifneq ($(CONFIG_BUILD_FLAT),y)
 CMN_CSRCS += riscv_task_start.c
 CMN_CSRCS += riscv_pthread_start.c
 CMN_CSRCS += riscv_signal_dispatch.c
-
-CMN_UASRCS += riscv_signal_handler.S
-
-CHIP_CSRCS += mpfs_userspace.c
 endif
 
 ifeq ($(CONFIG_ARCH_USE_MPU),y)

arch/risc-v/src/mpfs/mpfs_allocateheap.c

@@ -75,7 +75,7 @@
  *   Kernel heap               Size determined by CONFIG_MM_KERNEL_HEAPSIZE
  *
  ****************************************************************************/
-
+#ifndef CONFIG_BUILD_KERNEL
 void up_allocate_heap(void **heap_start, size_t *heap_size)
 {
 #if defined(CONFIG_BUILD_PROTECTED) && defined(CONFIG_MM_KERNEL_HEAP)
@@ -100,8 +100,9 @@ void up_allocate_heap(void **heap_start, size_t *heap_size)
 
   *heap_start = (void *)g_idle_topstack;
   *heap_size = KRAM_END - g_idle_topstack;
-#endif
+#endif /* CONFIG_BUILD_PROTECTED && CONFIG_MM_KERNEL_HEAP */
 }
+#endif /* CONFIG_BUILD_KERNEL */
 
 /****************************************************************************
  * Name: up_allocate_kheap
@@ -113,7 +114,7 @@ void up_allocate_heap(void **heap_start, size_t *heap_size)
  *
  ****************************************************************************/
 
-#if defined(CONFIG_BUILD_PROTECTED) && defined(CONFIG_MM_KERNEL_HEAP)
+#if !defined(CONFIG_BUILD_FLAT) && defined(CONFIG_MM_KERNEL_HEAP)
 void up_allocate_kheap(void **heap_start, size_t *heap_size)
 {
   /* Return the kernel heap settings. */
@@ -121,7 +122,7 @@ void up_allocate_kheap(void **heap_start, size_t *heap_size)
   *heap_start = (void *)g_idle_topstack;
   *heap_size = KRAM_END - g_idle_topstack;
 }
-#endif
+#endif /* !CONFIG_BUILD_FLAT && CONFIG_MM_KERNEL_HEAP */
 
 /****************************************************************************
  * Name: up_addregion

arch/risc-v/src/mpfs/mpfs_irq.c

@@ -107,7 +107,7 @@ void up_irqinitialize(void)
 
   irq_attach(RISCV_IRQ_ECALLM, riscv_swint, NULL);
 
-#ifdef CONFIG_BUILD_PROTECTED
+#ifndef CONFIG_BUILD_FLAT
   irq_attach(RISCV_IRQ_ECALLU, riscv_swint, NULL);
 #endif
 

binfmt/binfmt_execmodule.c

@@ -189,7 +189,7 @@ int exec_module(FAR const struct binary_s *binp,
       goto errout_with_addrenv;
     }
 
-#if defined(CONFIG_ARCH_ADDRENV) && defined(CONFIG_BUILD_KERNEL)
+#if defined(CONFIG_ARCH_ADDRENV) && defined(CONFIG_ARCH_KERNEL_STACK)
   /* Allocate the kernel stack */
 
   ret = up_addrenv_kstackalloc(&tcb->cmn);

sched/init/nx_start.c

@@ -38,6 +38,7 @@
 #include <nuttx/mm/iob.h>
 #include <nuttx/mm/mm.h>
 #include <nuttx/kmalloc.h>
+#include <nuttx/pgalloc.h>
 #include <nuttx/sched_note.h>
 #include <nuttx/binfmt/binfmt.h>
 #include <nuttx/drivers/drivers.h>