Merge pull request 'PDEC possible fixes' (#393) from pdec_possible_fixes_and_fdir into develop

Reviewed-on: #393
Reviewed-by: Jakob Meier <meierj@irs.uni-stuttgart.de>

CHANGELOG.md

@@ -17,6 +17,17 @@ change warranting a new major release:
 
 # [unreleased]
 
+## Added
+
+- PDEC: Added basic FDIR to limit the number of allowed TC interrupts and to allow complete task
+  lockups in the case an IRQ is immediately re-raised by the PDEC module. This is done by only
+  allowing a certain number of handled IRQs (whether they yield a valid TC or not) during
+  time windows of one second. Right now, 800 IRQs/TCs are allowed per time window.
+  This time window is reset if a TC reception timeout after 500ms occurs. TBD whether the maximum
+  allowed number will be a configurable parameter. If the number of occured IRQs is exceeded,
+  an event is triggered and the task is delayed for 400 ms.
+  PR: https://egit.irs.uni-stuttgart.de/eive/eive-obsw/pulls/393
+
 # [v1.29.1]
 
 ## Fixed
@@ -56,6 +67,8 @@ eive-tmtc: v2.13.0
 
 - Patch version which compiles for EM
 - CFDP Funnel bugfix: CCSDS wrapping was buggy and works properly now.
+- PDEC: Some adaptions to prevent task lockups on invalid FAR states.
+  PR: https://egit.irs.uni-stuttgart.de/eive/eive-obsw/pulls/393
 - CMakeLists.txt fix which broke CI/CD builds when server could not retrieve full git SHA.
 - Possible regression in the MAX31865 polling task: Using a `ManualCsLockGuard` for reconfiguring
   and then polling the sensor is problematic, invalid sensor values will be read.

linux/ipcore/PdecHandler.cpp

@@ -1,6 +1,7 @@
 #include "PdecHandler.h"
 
 #include <fcntl.h>
+#include <fsfw/tasks/TaskFactory.h>
 #include <poll.h>
 #include <sys/mman.h>
 #include <unistd.h>
@@ -113,7 +114,7 @@ ReturnValue_t PdecHandler::polledOperation() {
         // Requires reconfiguration and reinitialization of PDEC
         triggerEvent(INVALID_FAR);
         state = State::WAIT_FOR_RECOVERY;
-        return result;
+        break;
       }
       state = State::RUNNING;
       break;
@@ -145,8 +146,9 @@ ReturnValue_t PdecHandler::irqOperation() {
 
   // Used to unmask IRQ
   uint32_t info = 1;
-  ssize_t nb = 0;
+
-  int ret = 0;
+  interruptWindowCd.resetTimer();
+
   // Clear interrupts with dummy read before unmasking the interrupt. Use a volatile to prevent
   // read being optimized away.
   volatile uint32_t dummy = *(registerBaseAddress + PDEC_PIR_OFFSET);
@@ -157,7 +159,7 @@ ReturnValue_t PdecHandler::irqOperation() {
     readCommandQueue();
     switch (state) {
       case State::INIT:
-        resetFarStatFlag();
+        result = resetFarStatFlag();
         if (result != returnvalue::OK) {
           // Requires reconfiguration and reinitialization of PDEC
           triggerEvent(INVALID_FAR);
@@ -167,7 +169,26 @@ ReturnValue_t PdecHandler::irqOperation() {
         state = State::RUNNING;
         break;
       case State::RUNNING: {
-        nb = write(fd, &info, sizeof(info));
+        checkAndHandleIrqs(fd, info);
+        break;
+      }
+      case State::WAIT_FOR_RECOVERY:
+        TaskFactory::delayTask(400);
+        break;
+      default:
+        // Should never happen.
+        sif::error << "PdecHandler::performOperation: Invalid state" << std::endl;
+        TaskFactory::delayTask(400);
+        break;
+    }
+  }
+  // To avoid compiler warning
+  static_cast<void>(dummy);
+  return returnvalue::OK;
+}
+
+ReturnValue_t PdecHandler::checkAndHandleIrqs(int fd, uint32_t& info) {
+  ssize_t nb = write(fd, &info, sizeof(info));
   if (nb != static_cast<ssize_t>(sizeof(info))) {
     sif::error << "PdecHandler::irqOperation: Unmasking IRQ failed" << std::endl;
     triggerEvent(WRITE_SYSCALL_ERROR_PDEC, errno);
@@ -176,13 +197,16 @@ ReturnValue_t PdecHandler::irqOperation() {
     return returnvalue::FAILED;
   }
   struct pollfd fds = {.fd = fd, .events = POLLIN, .revents = 0};
-        ret = poll(&fds, 1, IRQ_TIMEOUT_MS);
+  int ret = poll(&fds, 1, IRQ_TIMEOUT_MS);
   if (ret == 0) {
     // No TCs for timeout period
     checkLocks();
-          lockCheckCd.resetTimer();
+    genericCheckCd.resetTimer();
+    resetIrqLimiters();
   } else if (ret >= 1) {
+    // Interrupt handling.
     nb = read(fd, &info, sizeof(info));
+    interruptCounter++;
     if (nb == static_cast<ssize_t>(sizeof(info))) {
       uint32_t pisr = *(registerBaseAddress + PDEC_PISR_OFFSET);
       if ((pisr & TC_NEW_MASK) == TC_NEW_MASK) {
@@ -197,12 +221,25 @@ ReturnValue_t PdecHandler::irqOperation() {
         CURRENT_FAR = readFar();
         checkFrameAna(CURRENT_FAR);
       }
-            if (lockCheckCd.hasTimedOut()) {
+      // Clear interrupts with dummy read. Volatile is important here to prevent
+      // compiler opitmizations in release builds!
+      volatile uint32_t dummy = *(registerBaseAddress + PDEC_PIR_OFFSET);
+      static_cast<void>(dummy);
+
+      if (genericCheckCd.hasTimedOut()) {
         checkLocks();
-              lockCheckCd.resetTimer();
+        genericCheckCd.resetTimer();
+        if (interruptWindowCd.hasTimedOut()) {
+          if (interruptCounter >= MAX_ALLOWED_IRQS_PER_WINDOW) {
+            sif::error << "PdecHandler::irqOperation: Possible IRQ storm" << std::endl;
+            triggerEvent(TOO_MANY_IRQS, MAX_ALLOWED_IRQS_PER_WINDOW);
+            resetIrqLimiters();
+            TaskFactory::delayTask(400);
+            return returnvalue::FAILED;
+          }
+          resetIrqLimiters();
+        }
       }
-            // Clear interrupts with dummy read
-            dummy = *(registerBaseAddress + PDEC_PIR_OFFSET);
     }
   } else {
     sif::error << "PdecHandler::irqOperation: Poll error with errno " << errno << ": "
@@ -212,17 +249,6 @@ ReturnValue_t PdecHandler::irqOperation() {
     state = State::INIT;
     return returnvalue::FAILED;
   }
-        break;
-      }
-      case State::WAIT_FOR_RECOVERY:
-        break;
-      default:
-        sif::error << "PdecHandler::performOperation: Invalid state" << std::endl;
-        break;
-    }
-  }
-  // To avoid compiler warning
-  static_cast<void>(dummy);
   return returnvalue::OK;
 }
 
@@ -618,6 +644,11 @@ void PdecHandler::printPdecMon() {
 
 uint32_t PdecHandler::readFar() { return *(registerBaseAddress + PDEC_FAR_OFFSET); }
 
+void PdecHandler::resetIrqLimiters() {
+  interruptWindowCd.resetTimer();
+  interruptCounter = 0;
+}
+
 std::string PdecHandler::getMonStatusString(uint32_t status) {
   switch (status) {
     case TC_CHANNEL_INACTIVE:

linux/ipcore/PdecHandler.h

@@ -87,6 +87,8 @@ class PdecHandler : public SystemObject, public ExecutableObjectIF, public HasAc
   static const Event LOST_CARRIER_LOCK_PDEC = MAKE_EVENT(5, severity::INFO);
   //! [EXPORT] : [COMMENT] Lost bit lock
   static const Event LOST_BIT_LOCK_PDEC = MAKE_EVENT(6, severity::INFO);
+  //! [EXPORT] : [COMMENT] Too many IRQs over the time window of one second. P1: Allowed TCs
+  static constexpr Event TOO_MANY_IRQS = MAKE_EVENT(7, severity::MEDIUM);
   static constexpr Event POLL_SYSCALL_ERROR_PDEC =
       event::makeEvent(SUBSYSTEM_ID, 7, severity::MEDIUM);
   static constexpr Event WRITE_SYSCALL_ERROR_PDEC =
@@ -180,6 +182,8 @@ class PdecHandler : public SystemObject, public ExecutableObjectIF, public HasAc
   // discarded
   static const uint8_t MAP_CLK_FREQ = 2;
 
+  static constexpr uint32_t MAX_ALLOWED_IRQS_PER_WINDOW = 800;
+
   enum class FrameAna_t : uint8_t {
     ABANDONED_CLTU,
     FRAME_DIRTY,
@@ -206,13 +210,16 @@ class PdecHandler : public SystemObject, public ExecutableObjectIF, public HasAc
 
   static uint32_t CURRENT_FAR;
 
-  Countdown lockCheckCd = Countdown(IRQ_TIMEOUT_MS);
+  Countdown genericCheckCd = Countdown(IRQ_TIMEOUT_MS);
   object_id_t tcDestinationId;
 
   AcceptsTelecommandsIF* tcDestination = nullptr;
 
   LinuxLibgpioIF* gpioComIF = nullptr;
 
+  uint32_t interruptCounter = 0;
+  Countdown interruptWindowCd = Countdown(1000);
+
   /**
    * Reset signal is required to hold PDEC in reset state until the configuration has been
    * written to the appropriate memory space.
@@ -259,6 +266,7 @@ class PdecHandler : public SystemObject, public ExecutableObjectIF, public HasAc
 
   ReturnValue_t polledOperation();
   ReturnValue_t irqOperation();
+  ReturnValue_t checkAndHandleIrqs(int fd, uint32_t& info);
 
   uint32_t readFar();
 
@@ -294,6 +302,8 @@ class PdecHandler : public SystemObject, public ExecutableObjectIF, public HasAc
    */
   void checkLocks();
 
+  void resetIrqLimiters();
+
   /**
    * @brief   Analyzes the FramAna field (frame analysis data) of a FAR report.
    *