Switch to user-mode before starting a new task

git-svn-id: svn://svn.code.sf.net/p/nuttx/code/trunk@5742 42af7a65-404d-4744-a932-0658087f49c3

1 files changed, 45 insertions, 14 deletions

diff --git a/nuttx/arch/arm/src/armv7-m/up_svcall.c b/nuttx/arch/arm/src/armv7-m/up_svcall.c
index 8321cd3bb..8f7efc1da 100644
--- a/nuttx/arch/arm/src/armv7-m/up_svcall.c
+++ b/nuttx/arch/arm/src/armv7-m/up_svcall.c
@@ -237,9 +237,9 @@ int up_svcall(int irq, FAR void *context)
         }
         break;
 
-      /* R0=SYS_syscall_return: This a switch context command:
+      /* R0=SYS_syscall_return: This a syscall return command:
        *
-       *   void up_sycall_return(void);
+       *   void up_syscall_return(void);
        *
        * At this point, the following values are saved in context:
        *
@@ -256,23 +256,54 @@ int up_svcall(int irq, FAR void *context)
 
           /* Make sure that there is a saved syscall return address. */
 
-          svcdbg("sysreturn: %08x excreturn: %08x\n",
-                 rtcb->xcp.sysreturn, rtcb->xcp.excreturn);
           DEBUGASSERT(rtcb->xcp.sysreturn != 0);
 
           /* Setup to return to the saved syscall return address in
            * the original mode.
            */
 
-          current_regs[REG_PC]         = rtcb->xcp.sysreturn;
-          current_regs[REG_EXC_RETURN] = rtcb->xcp.excreturn;
-          rtcb->xcp.sysreturn          = 0;
+          regs[REG_PC]         = rtcb->xcp.sysreturn;
+          regs[REG_EXC_RETURN] = rtcb->xcp.excreturn;
+          rtcb->xcp.sysreturn  = 0;
 
           /* The return value must be in R0-R1.  dispatch_syscall() temporarily
            * moved the value for R0 into R2.
            */
 
-          current_regs[REG_R0]         = current_regs[REG_R2];
+          regs[REG_R0]         = regs[REG_R2];
+        }
+        break;
+#endif
+
+      /* R0=SYS_task_start: This a user task start
+       *
+       *   void up_task_start(main_t taskentry, int argc, FAR char *argv[]) noreturn_function;
+       *
+       * At this point, the following values are saved in context:
+       *
+       *   R0 = SYS_task_start
+       *   R1 = taskentry
+       *   R2 = argc
+       *   R3 = argv
+       */
+
+#ifdef CONFIG_NUTTX_KERNEL
+      case SYS_task_start:
+        {
+          /* Set up to return to the user-space task start-up function in
+           * unprivileged mode.
+           */
+
+          regs[REG_PC]         = (uint32_t)USERSPACE->task_startup;
+          regs[REG_EXC_RETURN] = EXC_RETURN_UNPRIVTHR;
+
+          /* Change the paramter ordering to match the expection of struct
+           * userpace_s task_startup:
+           */
+
+          regs[REG_R0]         = regs[REG_R1]; /* Task entry */
+          regs[REG_R1]         = regs[REG_R2]; /* argc */
+          regs[REG_R2]         = regs[REG_R3]; /* argv */
         }
         break;
 #endif
@@ -289,7 +320,7 @@ int up_svcall(int irq, FAR void *context)
 
           /* Verify that the SYS call number is within range */
 
-          DEBUGASSERT(current_regs[REG_R0] < SYS_maxsyscall);
+          DEBUGASSERT(regs[REG_R0] < SYS_maxsyscall);
 
           /* Make sure that we got here that there is a no saved syscall
            * return address.  We cannot yet handle nested system calls.
@@ -299,15 +330,15 @@ int up_svcall(int irq, FAR void *context)
 
           /* Setup to return to dispatch_syscall in privileged mode. */
 
-          rtcb->xcp.sysreturn          = regs[REG_PC];
-          rtcb->xcp.excreturn          = current_regs[REG_EXC_RETURN];
+          rtcb->xcp.sysreturn  = regs[REG_PC];
+          rtcb->xcp.excreturn  = regs[REG_EXC_RETURN];
 
-          current_regs[REG_PC]         = (uint32_t)dispatch_syscall;
-          current_regs[REG_EXC_RETURN] = EXC_RETURN_PRIVTHR;
+          regs[REG_PC]         = (uint32_t)dispatch_syscall;
+          regs[REG_EXC_RETURN] = EXC_RETURN_PRIVTHR;
 
           /* Offset R0 to account for the reserved values */
 
-          current_regs[REG_R0]        -= CONFIG_SYS_RESERVED;
+          regs[REG_R0]        -= CONFIG_SYS_RESERVED;
 #else
           slldbg("ERROR: Bad SYS call: %d\n", regs[REG_R0]);
 #endif