arm: remove g_running_tasks[this_cpu()] = NULL

reason: We hope to keep g_running_tasks valid forever. Signed-off-by: hujun5 <[email protected]>
apache · Dec 2, 2024 · 6f44449 · 6f44449
1 parent 99bc691
commit 6f44449
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Showing 15 changed files with 127 additions and 79 deletions.
diff --git a/arch/arm/src/arm/arm_sigdeliver.c b/arch/arm/src/arm/arm_sigdeliver.c
@@ -97,7 +97,6 @@ void arm_sigdeliver(void)
 
   board_autoled_off(LED_SIGNAL);
 
-  g_running_tasks[this_cpu()] = NULL;
   rtcb->xcp.regs = rtcb->xcp.saved_regs;
   arm_fullcontextrestore();
 }
diff --git a/arch/arm/src/arm/arm_syscall.c b/arch/arm/src/arm/arm_syscall.c
@@ -56,31 +56,51 @@ uint32_t *arm_syscall(uint32_t *regs)
 {
   struct tcb_s **running_task = &g_running_tasks[this_cpu()];
   FAR struct tcb_s *tcb = this_task();
+  bool switch_context = false;
   uint32_t cmd;
 
   /* Nested interrupts are not supported */
 
   DEBUGASSERT(!up_interrupt_context());
 
-  if (*running_task != NULL)
-    {
-      (*running_task)->xcp.regs = regs;
-    }
-
-  /* Set irq flag */
+  /* Current regs non-zero indicates that we are processing an interrupt;
+   * current_regs is also used to manage interrupt level context switches.
+   */
 
   up_set_interrupt_context(true);
 
   /* The SYSCALL command is in R0 on entry.  Parameters follow in R1..R7 */
 
   cmd = regs[REG_R0];
 
+  /* if cmd == SYS_restore_context (*running_task)->xcp.regs is valid
+   * should not be overwriten
+   */
+
+  if (cmd != SYS_restore_context)
+    {
+      (*running_task)->xcp.regs = regs;
+    }
+
   /* Handle the SVCall according to the command in R0 */
 
   switch (cmd)
     {
       case SYS_restore_context:
+        switch_context = true;
+
+        /* Update scheduler parameters */
+
+        nxsched_resume_scheduler(tcb);
+        break;
       case SYS_switch_context:
+        switch_context = true;
+
+        /* Update scheduler parameters */
+
+        nxsched_suspend_scheduler(*running_task);
+        nxsched_resume_scheduler(tcb);
+        *running_task = tcb;
         break;
 
       default:
@@ -92,7 +112,7 @@ uint32_t *arm_syscall(uint32_t *regs)
         break;
     }
 
-  if (*running_task != tcb)
+  if (switch_context)
     {
 #ifdef CONFIG_ARCH_ADDRENV
       /* Make sure that the address environment for the previously
@@ -103,13 +123,6 @@ uint32_t *arm_syscall(uint32_t *regs)
 
       addrenv_switch(NULL);
 #endif
-      /* Update scheduler parameters */
-
-      nxsched_suspend_scheduler(*running_task);
-      nxsched_resume_scheduler(tcb);
-
-      *running_task = tcb;
-
       /* Restore the cpu lock */
 
       restore_critical_section(tcb, this_cpu());

diff --git a/arch/arm/src/armv6-m/arm_doirq.c b/arch/arm/src/armv6-m/arm_doirq.c
@@ -59,7 +59,11 @@ uint32_t *arm_doirq(int irq, uint32_t *regs)
   struct tcb_s **running_task = &g_running_tasks[this_cpu()];
   FAR struct tcb_s *tcb;
 
-  if (*running_task != NULL)
+  /* This judgment proves that (*running_task)->xcp.regs
+   * is invalid, and we can safely overwrite it.
+   */
+
+  if (!(NVIC_IRQ_SVCALL == irq && regs[REG_R0] == SYS_restore_context))
     {
       (*running_task)->xcp.regs = regs;
     }

diff --git a/arch/arm/src/armv6-m/arm_sigdeliver.c b/arch/arm/src/armv6-m/arm_sigdeliver.c
@@ -162,7 +162,7 @@ void arm_sigdeliver(void)
   leave_critical_section((uint16_t)regs[REG_PRIMASK]);
   rtcb->irqcount--;
 #endif
-  g_running_tasks[this_cpu()] = NULL;
+
   rtcb->xcp.regs = rtcb->xcp.saved_regs;
   arm_fullcontextrestore();
   UNUSED(regs);

diff --git a/arch/arm/src/armv7-a/arm_sigdeliver.c b/arch/arm/src/armv7-a/arm_sigdeliver.c
@@ -161,7 +161,6 @@ void arm_sigdeliver(void)
   rtcb->irqcount--;
 #endif
 
-  g_running_tasks[this_cpu()] = NULL;
   rtcb->xcp.regs = rtcb->xcp.saved_regs;
   arm_fullcontextrestore();
   UNUSED(regs);

diff --git a/arch/arm/src/armv7-a/arm_syscall.c b/arch/arm/src/armv7-a/arm_syscall.c
@@ -161,6 +161,7 @@ uint32_t *arm_syscall(uint32_t *regs)
 {
   struct tcb_s **running_task = &g_running_tasks[this_cpu()];
   struct tcb_s *tcb = this_task();
+  bool switch_context = false;
   uint32_t cmd;
 #ifdef CONFIG_BUILD_KERNEL
   uint32_t cpsr;
@@ -170,19 +171,25 @@ uint32_t *arm_syscall(uint32_t *regs)
 
   DEBUGASSERT(!up_interrupt_context());
 
-  if (*running_task != NULL)
-    {
-      (*running_task)->xcp.regs = regs;
-    }
-
-  /* Set irq flag */
+  /* Current regs non-zero indicates that we are processing an interrupt;
+   * current_regs is also used to manage interrupt level context switches.
+   */
 
   up_set_interrupt_context(true);
 
   /* The SYSCALL command is in R0 on entry.  Parameters follow in R1..R7 */
 
   cmd = regs[REG_R0];
 
+  /* if cmd == SYS_restore_context (*running_task)->xcp.regs is valid
+   * should not be overwriten
+   */
+
+  if (cmd != SYS_restore_context)
+    {
+      (*running_task)->xcp.regs = regs;
+    }
+
   /* The SVCall software interrupt is called with R0 = system call command
    * and R1..R7 =  variable number of arguments depending on the system call.
    */
@@ -255,8 +262,22 @@ uint32_t *arm_syscall(uint32_t *regs)
         }
         break;
 #endif
+
       case SYS_restore_context:
+        switch_context = true;
+
+        /* Update scheduler parameters */
+
+        nxsched_resume_scheduler(tcb);
+        break;
       case SYS_switch_context:
+        switch_context = true;
+
+        /* Update scheduler parameters */
+
+        nxsched_suspend_scheduler(*running_task);
+        nxsched_resume_scheduler(tcb);
+        *running_task = tcb;
         break;
 
       /* R0=SYS_task_start:  This a user task start
@@ -522,7 +543,7 @@ uint32_t *arm_syscall(uint32_t *regs)
         break;
     }
 
-  if (*running_task != tcb)
+  if (switch_context)
     {
 #ifdef CONFIG_ARCH_ADDRENV
       /* Make sure that the address environment for the previously
@@ -534,17 +555,6 @@ uint32_t *arm_syscall(uint32_t *regs)
       addrenv_switch(NULL);
 #endif
 
-      /* Update scheduler parameters */
-
-      nxsched_suspend_scheduler(*running_task);
-      nxsched_resume_scheduler(tcb);
-
-      /* Record the new "running" task.  g_running_tasks[] is only used by
-       * assertion logic for reporting crashes.
-       */
-
-      *running_task = tcb;
-
       /* Restore the cpu lock */
 
       restore_critical_section(tcb, this_cpu());

diff --git a/arch/arm/src/armv7-m/arm_doirq.c b/arch/arm/src/armv7-m/arm_doirq.c
@@ -59,7 +59,11 @@ uint32_t *arm_doirq(int irq, uint32_t *regs)
   struct tcb_s **running_task = &g_running_tasks[this_cpu()];
   FAR struct tcb_s *tcb;
 
-  if (*running_task != NULL)
+  /* This judgment proves that (*running_task)->xcp.regs
+   * is invalid, and we can safely overwrite it.
+   */
+
+  if (!(NVIC_IRQ_SVCALL == irq && regs[REG_R0] == SYS_restore_context))
     {
       (*running_task)->xcp.regs = regs;
     }

diff --git a/arch/arm/src/armv7-m/arm_sigdeliver.c b/arch/arm/src/armv7-m/arm_sigdeliver.c
@@ -175,7 +175,6 @@ void arm_sigdeliver(void)
   rtcb->irqcount--;
 #endif
 
-  g_running_tasks[this_cpu()] = NULL;
   rtcb->xcp.regs = rtcb->xcp.saved_regs;
   arm_fullcontextrestore();
   UNUSED(regs);

diff --git a/arch/arm/src/armv7-r/arm_sigdeliver.c b/arch/arm/src/armv7-r/arm_sigdeliver.c
@@ -158,7 +158,6 @@ void arm_sigdeliver(void)
   rtcb->irqcount--;
 #endif
 
-  g_running_tasks[this_cpu()] = NULL;
   rtcb->xcp.regs = rtcb->xcp.saved_regs;
   arm_fullcontextrestore();
   UNUSED(regs);

diff --git a/arch/arm/src/armv7-r/arm_syscall.c b/arch/arm/src/armv7-r/arm_syscall.c
@@ -158,6 +158,7 @@ uint32_t *arm_syscall(uint32_t *regs)
 {
   struct tcb_s **running_task = &g_running_tasks[this_cpu()];
   FAR struct tcb_s *tcb = this_task();
+  bool switch_context = false;
   uint32_t cmd;
 #ifdef CONFIG_BUILD_PROTECTED
   uint32_t cpsr;
@@ -167,19 +168,25 @@ uint32_t *arm_syscall(uint32_t *regs)
 
   DEBUGASSERT(!up_interrupt_context());
 
-  if (*running_task != NULL)
-    {
-      (*running_task)->xcp.regs = regs;
-    }
-
-  /* Set irq flag */
+  /* Current regs non-zero indicates that we are processing an interrupt;
+   * current_regs is also used to manage interrupt level context switches.
+   */
 
   up_set_interrupt_context(true);
 
   /* The SYSCALL command is in R0 on entry.  Parameters follow in R1..R7 */
 
   cmd = regs[REG_R0];
 
+  /* if cmd == SYS_restore_context (*running_task)->xcp.regs is valid
+   * should not be overwriten
+   */
+
+  if (cmd != SYS_restore_context)
+    {
+      (*running_task)->xcp.regs = regs;
+    }
+
   /* The SVCall software interrupt is called with R0 = system call command
    * and R1..R7 =  variable number of arguments depending on the system call.
    */
@@ -254,7 +261,20 @@ uint32_t *arm_syscall(uint32_t *regs)
 #endif
 
       case SYS_restore_context:
+        switch_context = true;
+
+        /* Update scheduler parameters */
+
+        nxsched_resume_scheduler(tcb);
+        break;
       case SYS_switch_context:
+        switch_context = true;
+
+        /* Update scheduler parameters */
+
+        nxsched_suspend_scheduler(*running_task);
+        nxsched_resume_scheduler(tcb);
+        *running_task = tcb;
         break;
 
       /* R0=SYS_task_start:  This a user task start
@@ -520,19 +540,8 @@ uint32_t *arm_syscall(uint32_t *regs)
         break;
     }
 
-  if (*running_task != tcb)
+  if (switch_context)
     {
-      /* Update scheduler parameters */
-
-      nxsched_suspend_scheduler(*running_task);
-      nxsched_resume_scheduler(tcb);
-
-      /* Record the new "running" task.  g_running_tasks[] is only used by
-       * assertion logic for reporting crashes.
-       */
-
-      *running_task = tcb;
-
       /* Restore the cpu lock */
 
       restore_critical_section(tcb, this_cpu());

diff --git a/arch/arm/src/armv8-m/arm_doirq.c b/arch/arm/src/armv8-m/arm_doirq.c
@@ -70,7 +70,11 @@ uint32_t *arm_doirq(int irq, uint32_t *regs)
   struct tcb_s **running_task = &g_running_tasks[this_cpu()];
   FAR struct tcb_s *tcb;
 
-  if (*running_task != NULL)
+  /* This judgment proves that (*running_task)->xcp.regs
+   * is invalid, and we can safely overwrite it.
+   */
+
+  if (!(NVIC_IRQ_SVCALL == irq && regs[REG_R0] == SYS_restore_context))
     {
       (*running_task)->xcp.regs = regs;
     }

diff --git a/arch/arm/src/armv8-m/arm_sigdeliver.c b/arch/arm/src/armv8-m/arm_sigdeliver.c
@@ -174,7 +174,7 @@ void arm_sigdeliver(void)
 #endif
   rtcb->irqcount--;
 #endif
-  g_running_tasks[this_cpu()] = NULL;
+
   rtcb->xcp.regs = rtcb->xcp.saved_regs;
   arm_fullcontextrestore();
   UNUSED(regs);

diff --git a/arch/arm/src/armv8-r/arm_sigdeliver.c b/arch/arm/src/armv8-r/arm_sigdeliver.c
@@ -156,7 +156,6 @@ void arm_sigdeliver(void)
   rtcb->irqcount--;
 #endif
 
-  g_running_tasks[this_cpu()] = NULL;
   rtcb->xcp.regs = rtcb->xcp.saved_regs;
   arm_fullcontextrestore();
   UNUSED(regs);