Add support for delivery of use-mode signals in the kernel build.

arch/arm/include/armv7-a/irq.h

@@ -240,6 +240,15 @@ struct xcptcontext
 
   uint32_t saved_pc;
   uint32_t saved_cpsr;
+
+# ifdef CONFIG_BUILD_KERNEL
+  /* This is the saved address to use when returning from a user-space
+   * signal handler.
+   */
+
+  uint32_t sigreturn;
+
+# endif
 #endif
 
   /* Register save area */

arch/arm/src/a1x/Make.defs

@@ -83,7 +83,7 @@ CMN_CSRCS += arm_va2pte.c
 endif
 
 ifeq ($(CONFIG_BUILD_KERNEL),y)
-CMN_CSRCS += up_task_start.c up_pthread_start.c
+CMN_CSRCS += up_task_start.c up_pthread_start.c up_signal_dispatch.c
 endif
 
 ifeq ($(CONFIG_ARCH_ADDRENV),y)

arch/arm/src/armv7-a/arm_addrenv.c

@@ -332,7 +332,7 @@ static void up_addrenv_destroy_region(FAR uintptr_t **list,
  *     needed by the task.  This region may be read/write only.  NOTE: The
  *     actual size of the data region that is allocated will include a
  *     OS private reserved region at the beginning.  The size of the
- *     private, reserved region is give by ARCH_DATA_RESERVE.
+ *     private, reserved region is give by ARCH_DATA_RESERVE_SIZE.
  *   addrenv - The location to return the representation of the task address
  *     environment.
  *
@@ -378,7 +378,7 @@ int up_addrenv_create(size_t textsize, size_t datasize,
 
   ret = up_addrenv_create_region(addrenv->data, ARCH_DATA_NSECTS,
                                  CONFIG_ARCH_DATA_VBASE,
-                                 datasize + ARCH_DATA_RESERVE,
+                                 datasize + ARCH_DATA_RESERVE_SIZE,
                                  MMU_L2_UDATAFLAGS);
   if (ret < 0)
     {
@@ -495,7 +495,7 @@ int up_addrenv_vdata(FAR group_addrenv_t *addrenv, uintptr_t textsize,
   /* Not much to do in this case */
 
   DEBUGASSERT(addrenv && vdata);
-  *vdata = (FAR void *)(CONFIG_ARCH_DATA_VBASE + ARCH_DATA_RESERVE);
+  *vdata = (FAR void *)(CONFIG_ARCH_DATA_VBASE + ARCH_DATA_RESERVE_SIZE);
   return OK;
 }
 

arch/arm/src/armv7-a/arm_syscall.c

@@ -47,6 +47,7 @@
 
 #include <arch/irq.h>
 #include <nuttx/sched.h>
+#include <nuttx/addrenv.h>
 
 #include "arm.h"
 #include "svcall.h"
@@ -128,7 +129,7 @@ static void dispatch_syscall(void)
     " add sp, sp, #16\n"           /* Destroy the stack frame */
     " mov r2, r0\n"                /* R2=Save return value in R2 */
     " mov r0, #0\n"                /* R0=SYS_syscall_return */
-    " svc #0x900001"               /* Return from the SYSCALL */
+    " svc #0x900001\n"             /* Return from the SYSCALL */
   );
 }
 #endif
@@ -202,7 +203,7 @@ uint32_t *arm_syscall(uint32_t *regs)
 
       case SYS_syscall_return:
         {
-          struct tcb_s *rtcb = sched_self();
+          FAR struct tcb_s *rtcb = sched_self();
           int index = (int)rtcb->xcp.nsyscalls - 1;
 
           /* Make sure that there is a saved SYSCALL return address. */
@@ -293,6 +294,7 @@ uint32_t *arm_syscall(uint32_t *regs)
         break;
 #endif
 
+#if defined(CONFIG_BUILD_KERNEL) && !defined(CONFIG_DISABLE_SIGNALS)
       /* R0=SYS_signal_handler:  This a user signal handler callback
        *
        * void signal_handler(_sa_sigaction_t sighand, int signo,
@@ -307,12 +309,9 @@ uint32_t *arm_syscall(uint32_t *regs)
        *        ucontext (on the stack)
        */
 
-#if defined(CONFIG_BUILD_KERNEL) && !defined(CONFIG_DISABLE_SIGNALS)
       case SYS_signal_handler:
         {
-#warning Missing logic
+          FAR struct tcb_s *rtcb = sched_self();
-#if 0
-          struct tcb_s *rtcb = sched_self();
 
           /* Remember the caller's return address */
 
@@ -323,7 +322,7 @@ uint32_t *arm_syscall(uint32_t *regs)
            * unprivileged mode.
            */
 
-          regs[REG_PC]   = (uint32_t)USERSPACE->signal_handler;
+          regs[REG_PC]   = (uint32_t)ARCH_DATA_RESERVE->ar_sigtramp;
           cpsr           = regs[REG_CPSR] & ~PSR_MODE_MASK;
           regs[REG_CPSR] = cpsr | PSR_MODE_USR;
 
@@ -340,11 +339,11 @@ uint32_t *arm_syscall(uint32_t *regs)
            */
 
           regs[REG_R3]   = *(uint32_t*)(regs[REG_SP+4]);
-#endif
         }
         break;
 #endif
 
+#if defined(CONFIG_BUILD_KERNEL) && !defined(CONFIG_DISABLE_SIGNALS)
       /* R0=SYS_signal_handler_return:  This a user signal handler callback
        *
        *   void signal_handler_return(void);
@@ -354,12 +353,9 @@ uint32_t *arm_syscall(uint32_t *regs)
        *   R0 = SYS_signal_handler_return
        */
 
-#if defined(CONFIG_BUILD_KERNEL) && !defined(CONFIG_DISABLE_SIGNALS)
       case SYS_signal_handler_return:
         {
-#warning Missing logic
+          FAR struct tcb_s *rtcb = sched_self();
-#if 0
-          struct tcb_s *rtcb = sched_self();
 
           /* Set up to return to the kernel-mode signal dispatching logic. */
 
@@ -369,7 +365,6 @@ uint32_t *arm_syscall(uint32_t *regs)
           cpsr                 = regs[REG_CPSR] & ~PSR_MODE_MASK;
           regs[REG_CPSR]       = cpsr | PSR_MODE_SVC;
           rtcb->xcp.sigreturn  = 0;
-#endif
         }
         break;
 #endif

arch/arm/src/armv7-a/crt0.c

@@ -41,6 +41,8 @@
 
 #include <sys/types.h>
 
+#include <nuttx/addrenv.h>
+
 #ifdef CONFIG_BUILD_KERNEL
 
 /****************************************************************************
@@ -61,6 +63,48 @@ extern main_t main;
  * Private Functions
  ****************************************************************************/
 
+/****************************************************************************
+ * Name: up_signal_handler
+ *
+ * Description:
+ *   This function is the user-space, signal handler trampoline function.  It
+ *   is called from up_signal_dispatch() in user-mode.
+ *
+ *     R0-R3, R11 - volatile registers need not be preserved.
+ *     R4-R10 - static registers must be preserved
+ *     R12-R14 - LR and SP must be preserved
+ *
+ * Inputs:
+ *   R0 = sighand
+ *     The address user-space signal handling function
+ *   R1-R3 = signo, info, and ucontext
+ *     Standard arguments to be passed to the signal handling function.
+ *
+ * Return:
+ *   None.  This function does not return in the normal sense.  It returns
+ *   via the SYS_signal_handler_return (see svcall.h)
+ *
+ ****************************************************************************/
+
+#ifndef CONFIG_DISABLE_SIGNALS
+static void sig_trampoline(void) naked_function;
+static void sig_trampoline(void)
+{
+  __asm__ __volatile__
+  (
+    " push {lr}\n"       /* Save LR on the stack */
+    " mov  ip, r0\n"     /* IP=sighand */
+    " mov  r0, r1\n"     /* R0=signo */
+    " mov  r1, r2\n"     /* R1=info */
+    " mov  r2, r3\n"     /* R2=ucontext */
+    " blx  ip\n"         /* Call the signal handler */
+    " pop  {r2}\n"       /* Recover LR in R2 */
+    " mov  lr, r2\n"     /* Restore LR */
+    " mov  r0, #4\n"     /* SYS_signal_handler_return
+    " svc #0x900001\n"   /* Return from the signal handler */
+}
+#endif
+
 /****************************************************************************
  * Public Functions
  ****************************************************************************/
@@ -89,6 +133,14 @@ void _start(int argc, FAR char *argv[])
 {
   int ret;
 
+#ifndef CONFIG_DISABLE_SIGNALS
+  /* Initialize the reserved area at the beginning of the .bss/.data region
+   * that is visible to the RTOS.
+   */
+
+  ADDRENV_DATA_RESERVE->ar_sigtramp = (addrenv_sigtramp_t)sig_trampoline;
+#endif
+
   /* Call C++ constructors */
   /* Setup so that C++ destructors called on task exit */
   /* REVISIT: Missing logic */

arch/arm/src/armv7-m/up_signal_handler.S

@@ -1,5 +1,5 @@
 /****************************************************************************
- * arch/arm/srcm/armv7-m/up_signal_handler.S
+ * arch/arm/src/armv7-m/up_signal_handler.S
  *
  *   Copyright (C) 2013 Gregory Nutt. All rights reserved.
  *   Author: Gregory Nutt <gnutt@nuttx.org>

arch/arm/src/sama5/Make.defs

@@ -85,7 +85,7 @@ CMN_CSRCS += arm_va2pte.c
 endif
 
 ifeq ($(CONFIG_BUILD_KERNEL),y)
-CMN_CSRCS += up_task_start.c up_pthread_start.c
+CMN_CSRCS += up_task_start.c up_pthread_start.c up_signal_dispatch.c
 endif
 
 ifeq ($(CONFIG_ARCH_ADDRENV),y)