Add support for nested system calls

git-svn-id: svn://svn.code.sf.net/p/nuttx/code/trunk@5752 42af7a65-404d-4744-a932-0658087f49c3

arch/arm/include/armv6-m/irq.h

@@ -57,8 +57,14 @@
 /****************************************************************************
  * Pre-processor Definitions
  ****************************************************************************/
+/* Configuration ************************************************************/
+/* If this is a kernel build, how many nested system calls should we support? */
 
-/* IRQ Stack Frame Format:
+#ifndef CONFIG_SYS_NNEST
+#  define CONFIG_SYS_NNEST 2
+#endif
+
+/* IRQ Stack Frame Format ***************************************************
  *
  * The following additional registers are stored by the interrupt handling
  * logic.
@@ -140,11 +146,22 @@
  * Public Types
  ****************************************************************************/
 
+#ifndef __ASSEMBLY__
+
+/* This structure represents the return state from a system call */
+
+#ifdef CONFIG_NUTTX_KERNEL
+struct xcpt_syscall_s
+{
+  uint32_t excreturn;   /* The EXC_RETURN value */
+  uint32_t sysreturn;   /* The return PC */
+};
+#endif
+
 /* The following structure is included in the TCB and defines the complete
  * state of the thread.
  */
 
-#ifndef __ASSEMBLY__
 struct xcptcontext
 {
 #ifndef CONFIG_DISABLE_SIGNALS
@@ -168,16 +185,17 @@ struct xcptcontext
    */
 
   uint32_t sigreturn;
+
 # endif
 #endif
 
 #ifdef CONFIG_NUTTX_KERNEL
-  /* The following holds the return address and the exc_return value needed
+  /* The following array holds the return address and the exc_return value
-   * to return from a system call.
+   * needed to return from each nested system call.
    */
 
-  uint32_t excreturn;
+  uint8_t nsyscalls;
-  uint32_t sysreturn;
+  struct xcpt_syscall_s syscall[CONFIG_SYS_NNEST];
 #endif
 
   /* Register save area */

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

@@ -67,8 +67,14 @@
 /****************************************************************************
  * Pre-processor Definitions
  ****************************************************************************/
+/* Configuration ************************************************************/
+/* If this is a kernel build, how many nested system calls should we support? */
 
-/* Alternate register names */
+#ifndef CONFIG_SYS_NNEST
+#  define CONFIG_SYS_NNEST 2
+#endif
+
+/* Alternate register names *************************************************/
 
 #define REG_A1              REG_R0
 #define REG_A2              REG_R1
@@ -98,12 +104,22 @@
 /****************************************************************************
  * Public Types
  ****************************************************************************/
+#ifndef __ASSEMBLY__
+
+/* This structure represents the return state from a system call */
+
+#ifdef CONFIG_NUTTX_KERNEL
+struct xcpt_syscall_s
+{
+  uint32_t excreturn;   /* The EXC_RETURN value */
+  uint32_t sysreturn;   /* The return PC */
+};
+#endif
 
 /* The following structure is included in the TCB and defines the complete
  * state of the thread.
  */
 
-#ifndef __ASSEMBLY__
 struct xcptcontext
 {
 #ifndef CONFIG_DISABLE_SIGNALS
@@ -131,16 +147,18 @@ struct xcptcontext
    */
 
   uint32_t sigreturn;
+
 # endif
 #endif
 
 #ifdef CONFIG_NUTTX_KERNEL
-  /* The following holds the return address and the exc_return value needed
+  /* The following array holds the return address and the exc_return value
-   * to return from a system call.
+   * needed to return from each nested system call.
    */
 
-  uint32_t excreturn;
+  uint8_t nsyscalls;
-  uint32_t sysreturn;
+  struct xcpt_syscall_s syscall[CONFIG_SYS_NNEST];
+
 #endif
 
   /* Register save area */

arch/arm/src/armv6-m/up_svcall.c

@@ -258,18 +258,19 @@ int up_svcall(int irq, FAR void *context)
       case SYS_syscall_return:
         {
           struct tcb_s *rtcb = sched_self();
+          int index = (int)rtcb->xcp.nsyscalls - 1;
 
           /* Make sure that there is a saved syscall return address. */
 
-          DEBUGASSERT(rtcb->xcp.sysreturn != 0);
+          DEBUGASSERT(index >= 0);
 
           /* Setup to return to the saved syscall return address in
            * the original mode.
            */
 
-          regs[REG_PC]         = rtcb->xcp.sysreturn;
+          regs[REG_PC]         = rtcb->xcp.syscall[index].sysreturn;
-          regs[REG_EXC_RETURN] = rtcb->xcp.excreturn;
+          regs[REG_EXC_RETURN] = rtcb->xcp.syscall[index].excreturn;
-          rtcb->xcp.sysreturn  = 0;
+          rtcb->xcp.nsyscalls  = index;
 
           /* The return value must be in R0-R1.  dispatch_syscall() temporarily
            * moved the value for R0 into R2.
@@ -425,6 +426,7 @@ int up_svcall(int irq, FAR void *context)
         {
 #ifdef CONFIG_NUTTX_KERNEL
           FAR struct tcb_s *rtcb = sched_self();
+          int index = rtcb->xcp.nsyscalls;
 
           /* Verify that the SYS call number is within range */
 
@@ -434,12 +436,13 @@ int up_svcall(int irq, FAR void *context)
            * cannot yet handle nested system calls.
            */
 
-          DEBUGASSERT(rtcb->xcp.sysreturn == 0);
+          DEBUGASSERT(index < CONFIG_SYS_NNEST);
 
           /* Setup to return to dispatch_syscall in privileged mode. */
 
-          rtcb->xcp.sysreturn  = regs[REG_PC];
+          rtcb->xcp.syscall[index].sysreturn  = regs[REG_PC];
-          rtcb->xcp.excreturn  = regs[REG_EXC_RETURN];
+          rtcb->xcp.syscall[index].excreturn  = regs[REG_EXC_RETURN];
+          rtcb->xcp.nsyscalls  = index + 1;
 
           regs[REG_PC]         = (uint32_t)dispatch_syscall;
           regs[REG_EXC_RETURN] = EXC_RETURN_PRIVTHR;

arch/arm/src/armv7-m/up_svcall.c

@@ -262,18 +262,19 @@ int up_svcall(int irq, FAR void *context)
       case SYS_syscall_return:
         {
           struct tcb_s *rtcb = sched_self();
+          int index = (int)rtcb->xcp.nsyscalls - 1;
 
           /* Make sure that there is a saved syscall return address. */
 
-          DEBUGASSERT(rtcb->xcp.sysreturn != 0);
+          DEBUGASSERT(index >= 0);
 
           /* Setup to return to the saved syscall return address in
            * the original mode.
            */
 
-          regs[REG_PC]         = rtcb->xcp.sysreturn;
+          regs[REG_PC]         = rtcb->xcp.syscall[index].sysreturn;
-          regs[REG_EXC_RETURN] = rtcb->xcp.excreturn;
+          regs[REG_EXC_RETURN] = rtcb->xcp.syscall[index].excreturn;
-          rtcb->xcp.sysreturn  = 0;
+          rtcb->xcp.nsyscalls  = index;
 
           /* The return value must be in R0-R1.  dispatch_syscall() temporarily
            * moved the value for R0 into R2.
@@ -429,6 +430,7 @@ int up_svcall(int irq, FAR void *context)
         {
 #ifdef CONFIG_NUTTX_KERNEL
           FAR struct tcb_s *rtcb = sched_self();
+          int index = rtcb->xcp.nsyscalls;
 
           /* Verify that the SYS call number is within range */
 
@@ -438,12 +440,13 @@ int up_svcall(int irq, FAR void *context)
            * cannot yet handle nested system calls.
            */
 
-          DEBUGASSERT(rtcb->xcp.sysreturn == 0);
+          DEBUGASSERT(index < CONFIG_SYS_NNEST);
 
           /* Setup to return to dispatch_syscall in privileged mode. */
 
-          rtcb->xcp.sysreturn  = regs[REG_PC];
+          rtcb->xcp.syscall[index].sysreturn  = regs[REG_PC];
-          rtcb->xcp.excreturn  = regs[REG_EXC_RETURN];
+          rtcb->xcp.syscall[index].excreturn  = regs[REG_EXC_RETURN];
+          rtcb->xcp.nsyscalls  = index + 1;
 
           regs[REG_PC]         = (uint32_t)dispatch_syscall;
           regs[REG_EXC_RETURN] = EXC_RETURN_PRIVTHR;

arch/mips/include/mips32/irq.h

@@ -61,6 +61,12 @@
 #  define MIPS32_SAVE_GP 1
 #endif
 
+/* If this is a kernel build, how many nested system calls should we support? */
+
+#ifndef CONFIG_SYS_NNEST
+#  define CONFIG_SYS_NNEST 2
+#endif
+
 /* Register save state structure ********************************************/
 /* Co processor registers */
 
@@ -308,6 +314,19 @@
 
 #ifndef __ASSEMBLY__
 
+/* This structure represents the return state from a system call */
+
+#ifdef CONFIG_NUTTX_KERNEL
+struct xcpt_syscall_s
+{
+  uint32_t sysreturn;   /* The return PC */
+};
+#endif
+
+/* The following structure is included in the TCB and defines the complete
+ * state of the thread.
+ */
+
 struct xcptcontext
 {
 #ifndef CONFIG_DISABLE_SIGNALS
@@ -323,12 +342,25 @@ struct xcptcontext
 
   uint32_t saved_epc;    /* Trampoline PC */
   uint32_t saved_status; /* Status with interrupts disabled. */
+
+# ifdef CONFIG_NUTTX_KERNEL
+  /* This is the saved address to use when returning from a user-space
+   * signal handler.
+   */
+
+  uint32_t sigreturn;
+
+# endif
 #endif
 
 #ifdef CONFIG_NUTTX_KERNEL
-  /* The following holds the return address from a system call */
+  /* The following array holds information needed to return from each nested
+   * system call.
+   */
+
+  uint8_t nsyscalls;
+  struct xcpt_syscall_s syscall[CONFIG_SYS_NNEST];
 
-  uint32_t sysreturn;
 #endif
 
   /* Register save area */

arch/mips/src/mips32/up_swint0.c

@@ -238,18 +238,19 @@ int up_swint0(int irq, FAR void *context)
       case SYS_syscall_return:
         {
           struct tcb_s *rtcb = sched_self();
+          int index = (int)rtcb->xcp.nsyscalls - 1;
 
           /* Make sure that there is a saved syscall return address. */
 
-          DEBUGASSERT(rtcb->xcp.sysreturn != 0);
+          DEBUGASSERT(index >= 0);
 
           /* Setup to return to the saved syscall return address in
            * the original mode.
            */
 
-          current_regs[REG_EPC] = rtcb->xcp.sysreturn;
+          current_regs[REG_EPC] = rtcb->xcp.syscall[index].sysreturn;
 #error "Missing logic -- need to restore the original mode"
-          rtcb->sysreturn       = 0;
+          rtcb->xcp.nsyscalls   = index;
         }
         break;
 #endif
@@ -263,6 +264,7 @@ int up_swint0(int irq, FAR void *context)
         {
 #ifdef CONFIG_NUTTX_KERNEL
           FAR struct tcb_s *rtcb = sched_self();
+          int index = rtcb->xcp.nsyscalls;
 
           /* Verify that the SYS call number is within range */
 
@@ -272,11 +274,14 @@ int up_swint0(int irq, FAR void *context)
            * return address.  We cannot yet handle nested system calls.
            */
 
-          DEBUGASSERT(rtcb->xcp.sysreturn == 0);
+          DEBUGASSERT(index < CONFIG_SYS_NNEST);
 
           /* Setup to return to dispatch_syscall in privileged mode. */
 
-          rtcb->sysreturn              = regs[REG_EPC];
+          rtcb->xcpsyscall[index].sysreturn = regs[REG_EPC];
+#error "Missing logic -- Need to save mode"
+          rtcb->xcp.nsyscalls  = index + 1;
+
           regs[REG_EPC] = (uint32_t)dispatch_syscall;
 #error "Missing logic -- Need to set privileged mode"