riscv: add generic way to detect if inside interrupt context

Author: bbawj

portable/GCC/RISC-V/port.c

@@ -97,6 +97,12 @@ volatile uint64_t * pullMachineTimerCompareRegister = NULL;
 size_t xCriticalNesting = ( size_t ) 0xaaaaaaaa;
 size_t * pxCriticalNesting = &xCriticalNesting;
 
+/*
+ * Counts the interrupt nesting depth.
+ */
+size_t xInterruptNesting = 0;
+size_t * pxInterruptNesting = &xInterruptNesting;
+
 /* Used to catch tasks that attempt to return from their implementing function. */
 size_t xTaskReturnAddress = ( size_t ) portTASK_RETURN_ADDRESS;
 
@@ -205,3 +211,9 @@ void vPortEndScheduler( void )
     }
 }
 /*-----------------------------------------------------------*/
+
+BaseType_t xPortIsInsideInterrupt( void )
+{
+  return ( xInterruptNesting == 0 ) ? pdFALSE : pdTRUE;
+}
+/*-----------------------------------------------------------*/

portable/GCC/RISC-V/portASM.S

@@ -162,6 +162,7 @@ definitions. */
  * where the global and thread pointers are currently assumed to be constant so
  * are not saved:
  *
+ * xInterruptNesting
  * xCriticalNesting
  * x31
  * x30
@@ -198,6 +199,8 @@ definitions. */
  * pxCode
  */
 pxPortInitialiseStack:
+    addi a0, a0, -portWORD_SIZE         /* Space for interrupt nesting count. */
+
     addi a0, a0, -portWORD_SIZE         /* Space for critical nesting count. */
     store_x x0, 0(a0)                   /* Critical nesting count starts at 0 for every task. */
 

portable/GCC/RISC-V/portContext.h

@@ -57,11 +57,13 @@
  * specific version of freertos_risc_v_chip_specific_extensions.h.  See the
  * notes at the top of portASM.S file. */
 #ifdef __riscv_32e
-    #define portCONTEXT_SIZE               ( 15 * portWORD_SIZE )
+    #define portCONTEXT_SIZE               ( 16 * portWORD_SIZE )
     #define portCRITICAL_NESTING_OFFSET    14
+    #define portINTERRUPT_NESTING_OFFSET   15
 #else
-    #define portCONTEXT_SIZE               ( 31 * portWORD_SIZE )
+    #define portCONTEXT_SIZE               ( 32 * portWORD_SIZE )
     #define portCRITICAL_NESTING_OFFSET    30
+    #define portINTERRUPT_NESTING_OFFSET   31
 #endif
 
 #if ( configENABLE_FPU == 1 )
@@ -122,6 +124,8 @@
 .extern xISRStackTop
 .extern xCriticalNesting
 .extern pxCriticalNesting
+.extern xInterruptNesting
+.extern pxInterruptNesting
 /*-----------------------------------------------------------*/
 
     .macro portcontexSAVE_FPU_CONTEXT
@@ -306,6 +310,12 @@ store_x x15, 13 * portWORD_SIZE( sp )
 load_x t0, xCriticalNesting                                   /* Load the value of xCriticalNesting into t0. */
 store_x t0, portCRITICAL_NESTING_OFFSET * portWORD_SIZE( sp ) /* Store the critical nesting value to the stack. */
 
+load_x t0, xInterruptNesting                                   /* Load the value of xInterruptNesting into t0. */
+store_x t0, portINTERRUPT_NESTING_OFFSET * portWORD_SIZE( sp ) /* Store the interrupt nesting value to the stack. */
+addi t0, t0, 1
+load_x t1, pxInterruptNesting           /* Load the address of xInterruptNesting into t1. */
+store_x t0, 0( t1 )                     /* Increment xInterruptNesting by 1 */
+
 #if( configENABLE_FPU == 1 )
     csrr t0, mstatus
     srl t1, t0, MSTATUS_FS_OFFSET
@@ -425,6 +435,10 @@ csrw mstatus, t3
 6:
 #endif /* ifdef portasmSTORE_FPU_CONTEXT */
 
+load_x t0, portINTERRUPT_NESTING_OFFSET * portWORD_SIZE( sp ) /* Obtain saved xInterruptNesting value from task's stack. */
+load_x t1, pxInterruptNesting                                 /* Load the address of xInterruptNesting into t1. */
+store_x t0, 0 ( t1 )                                          /* Restore the interrupt nesting value. */
+
 load_x t0, portCRITICAL_NESTING_OFFSET * portWORD_SIZE( sp ) /* Obtain xCriticalNesting value for this task from task's stack. */
 load_x t1, pxCriticalNesting                                 /* Load the address of xCriticalNesting into t1. */
 store_x t0, 0 ( t1 )                                         /* Restore the critical nesting value for this task. */

portable/GCC/RISC-V/portmacro.h

@@ -106,6 +106,8 @@ extern void vTaskSwitchContext( void );
         }                                        \
     } while( 0 )
 #define portYIELD_FROM_ISR( x )    portEND_SWITCHING_ISR( x )
+
+BaseType_t xPortIsInsideInterrupt( void );
 /*-----------------------------------------------------------*/
 
 /* Critical section management. */