Add task init and signal scheduling logic

git-svn-id: svn://svn.code.sf.net/p/nuttx/code/trunk@3338 42af7a65-404d-4744-a932-0658087f49c3

1 files changed, 198 insertions, 0 deletions

diff --git a/nuttx/arch/x86/src/i486/up_schedulesigaction.c b/nuttx/arch/x86/src/i486/up_schedulesigaction.c
new file mode 100644
index 000000000..6bcc3c656
--- /dev/null
+++ b/nuttx/arch/x86/src/i486/up_schedulesigaction.c
@@ -0,0 +1,198 @@
+/****************************************************************************
+ * arch/x86/src/i486/up_schedulesigaction.c
+ *
+ *   Copyright (C) 2011 Gregory Nutt. All rights reserved.
+ *   Author: Gregory Nutt <spudmonkey@racsa.co.cr>
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ * 3. Neither the name NuttX nor the names of its contributors may be
+ *    used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
+ * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ *
+ ****************************************************************************/
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#include <nuttx/config.h>
+
+#include <stdint.h>
+#include <sched.h>
+#include <debug.h>
+
+#include <nuttx/arch.h>
+
+#include "os_internal.h"
+#include "up_internal.h"
+#include "up_arch.h"
+
+#ifndef CONFIG_DISABLE_SIGNALS
+
+/****************************************************************************
+ * Pre-processor Definitions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Private Data
+ ****************************************************************************/
+
+/****************************************************************************
+ * Private Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Public Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Name: up_schedule_sigaction
+ *
+ * Description:
+ *   This function is called by the OS when one or more signal handling
+ *   actions have been queued for execution.  The architecture specific code
+ *   must configure things so that the 'sigdeliver' callback is executed on
+ *   the thread specified by 'tcb' as soon as possible.
+ *
+ *   This function may be called from interrupt handling logic.
+ *
+ *   This operation should not cause the task to be unblocked nor should it
+ *   cause any immediate execution of sigdeliver. Typically, a few cases need
+ *   to be considered:
+ *
+ *   (1) This function may be called from an interrupt handler. During
+ *       interrupt processing, all xcptcontext structures should be valid for
+ *       all tasks.  That structure should be modified to invoke sigdeliver()
+ *       either on return from (this) interrupt or on some subsequent context
+ *       switch to the recipient task.
+ *   (2) If not in an interrupt handler and the tcb is NOT the currently
+ *       executing task, then again just modify the saved xcptcontext
+ *       structure for the recipient task so it will invoke sigdeliver when
+ *       that task is later resumed.
+ *   (3) If not in an interrupt handler and the tcb IS the currently
+ *       executing task -- just call the signal handler now.
+ *
+ ****************************************************************************/
+
+void up_schedule_sigaction(_TCB *tcb, sig_deliver_t sigdeliver)
+{
+  /* Refuse to handle nested signal actions */
+
+  sdbg("tcb=0x%p sigdeliver=0x%p\n", tcb, sigdeliver);
+
+  if (!tcb->xcp.sigdeliver)
+    {
+      irqstate_t flags;
+
+      /* Make sure that interrupts are disabled */
+
+      flags = irqsave();
+
+      /* First, handle some special cases when the signal is being delivered
+	   * to the currently executing task.
+       */
+
+      sdbg("rtcb=0x%p current_regs=0x%p\n", g_readytorun.head, current_regs);
+
+      if (tcb == (_TCB*)g_readytorun.head)
+        {
+          /* CASE 1:  We are not in an interrupt handler and a task is
+		   * signalling itself for some reason.
+           */
+
+          if (!current_regs)
+            {
+              /* In this case just deliver the signal now. */
+
+              sigdeliver(tcb);
+            }
+
+          /* CASE 2:  We are in an interrupt handler AND the interrupted task
+		   * is the same as the one that must receive the signal, then we will
+		   * have to modify the return state as well as the state in the TCB.
+           *
+           * Hmmm... there looks like a latent bug here: The following logic
+		   * would fail in the strange case where we are in an interrupt
+		   * handler, the thread is signalling itself, but a context switch to
+		   * another task has occurred so that current_regs does not refer to
+		   * the thread at g_readytorun.head!
+           */
+
+          else
+            {
+              /* Save the return lr and cpsr and one scratch register. These
+			   * will be restored by the signal trampoline after the signals
+			   * have been delivered.
+               */
+
+              tcb->xcp.sigdeliver       = sigdeliver;
+              tcb->xcp.saved_pc         = current_regs[REG_PC];
+              tcb->xcp.saved_flags      = current_regs[REG_FLAGS];
+
+              /* Then set up to vector to the trampoline with interrupts
+               * disabled
+               */
+
+              current_regs[REG_PC]      = (uint32_t)up_sigdeliver;
+              current_regs[REG_FLAGS]   = 0;
+
+              /* And make sure that the saved context in the TCB
+               * is the same as the interrupt return context.
+               */
+
+              up_savestate(tcb->xcp.regs);
+            }
+        }
+
+      /* Otherwise, we are (1) signaling a task is not running
+       * from an interrupt handler or (2) we are not in an
+       * interrupt handler and the running task is signalling
+       * some non-running task.
+       */
+
+      else
+        {
+          /* Save the return lr and cpsr and one scratch register
+           * These will be restored by the signal trampoline after
+           * the signals have been delivered.
+           */
+
+          tcb->xcp.sigdeliver       = sigdeliver;
+          tcb->xcp.saved_pc         = tcb->xcp.regs[REG_PC];
+          tcb->xcp.saved_flags      = tcb->xcp.regs[REG_FLAGS];
+
+          /* Then set up to vector to the trampoline with interrupts
+           * disabled
+           */
+
+          tcb->xcp.regs[REG_PC]      = (uint32_t)up_sigdeliver;
+          tcb->xcp.regs[REG_FLAGS]   = 0;
+        }
+
+      irqrestore(flags);
+    }
+}
+
+#endif /* !CONFIG_DISABLE_SIGNALS */