Reduce SVCall priority on ARMv7-M with MPU (#1470)
Restore the original SVCall priority for the ARMv7-M MPU ports from
before #832. This change reduces the SVCall preemption priority from
zero (the highest) to a priority just higher than
configMAX_SYSCALL_INTERRUPT_PRIORITY (numerically lower).
---------
Co-authored-by: Gaurav-Aggarwal-AWS <33462878+aggarg@users.noreply.github.com>
diff --git a/portable/GCC/ARM_CM3_MPU/port.c b/portable/GCC/ARM_CM3_MPU/port.c
index 96d781d..6b7ed02 100644
--- a/portable/GCC/ARM_CM3_MPU/port.c
+++ b/portable/GCC/ARM_CM3_MPU/port.c
@@ -96,12 +96,14 @@
#define portPERIPHERALS_START_ADDRESS 0x40000000UL
#define portPERIPHERALS_END_ADDRESS 0x5FFFFFFFUL
-/* Constants required to access and manipulate the SysTick. */
+/* Constants required to access and manipulate the SysTick and other FreeRTOS
+ * interrupts. */
#define portNVIC_SYSTICK_INT ( 0x00000002UL )
#define portNVIC_SYSTICK_ENABLE ( 0x00000001UL )
#define portMIN_INTERRUPT_PRIORITY ( 255UL )
#define portNVIC_PENDSV_PRI ( ( ( uint32_t ) portMIN_INTERRUPT_PRIORITY ) << 16UL )
#define portNVIC_SYSTICK_PRI ( ( ( uint32_t ) portMIN_INTERRUPT_PRIORITY ) << 24UL )
+#define portNVIC_SVC_PRI ( ( ( uint32_t ) configMAX_SYSCALL_INTERRUPT_PRIORITY - 1UL ) << 24UL )
/* Constants required to set up the initial stack. */
#define portINITIAL_XPSR ( 0x01000000 )
@@ -877,12 +879,11 @@
}
#endif /* configASSERT_DEFINED */
- /* Make PendSV and SysTick the lowest priority interrupts, and make SVCall
- * the highest priority. */
+ /* Make PendSV and SysTick the lowest priority interrupts, and configure
+ * SVCall for sufficient preemption priority. */
portNVIC_SHPR3_REG |= portNVIC_PENDSV_PRI;
portNVIC_SHPR3_REG |= portNVIC_SYSTICK_PRI;
- portNVIC_SHPR2_REG = 0;
-
+ portNVIC_SHPR2_REG = portNVIC_SVC_PRI;
/* Configure the regions in the MPU that are common to all tasks. */
prvSetupMPU();
diff --git a/portable/GCC/ARM_CM4_MPU/port.c b/portable/GCC/ARM_CM4_MPU/port.c
index 146798c..e1a70c5 100644
--- a/portable/GCC/ARM_CM4_MPU/port.c
+++ b/portable/GCC/ARM_CM4_MPU/port.c
@@ -106,12 +106,14 @@
#define portPERIPHERALS_START_ADDRESS 0x40000000UL
#define portPERIPHERALS_END_ADDRESS 0x5FFFFFFFUL
-/* Constants required to access and manipulate the SysTick. */
+/* Constants required to access and manipulate the SysTick and other FreeRTOS
+ * interrupts. */
#define portNVIC_SYSTICK_INT ( 0x00000002UL )
#define portNVIC_SYSTICK_ENABLE ( 0x00000001UL )
#define portMIN_INTERRUPT_PRIORITY ( 255UL )
#define portNVIC_PENDSV_PRI ( ( ( uint32_t ) portMIN_INTERRUPT_PRIORITY ) << 16UL )
#define portNVIC_SYSTICK_PRI ( ( ( uint32_t ) portMIN_INTERRUPT_PRIORITY ) << 24UL )
+#define portNVIC_SVC_PRI ( ( ( uint32_t ) configMAX_SYSCALL_INTERRUPT_PRIORITY - 1UL ) << 24UL )
/* Constants required to manipulate the VFP. */
#define portFPCCR ( ( volatile uint32_t * ) 0xe000ef34UL ) /* Floating point context control register. */
@@ -965,11 +967,11 @@
}
#endif /* configASSERT_DEFINED */
- /* Make PendSV and SysTick the lowest priority interrupts, and make SVCall
- * the highest priority. */
+ /* Make PendSV and SysTick the lowest priority interrupts, and configure
+ * SVCall for sufficient preemption priority. */
portNVIC_SHPR3_REG |= portNVIC_PENDSV_PRI;
portNVIC_SHPR3_REG |= portNVIC_SYSTICK_PRI;
- portNVIC_SHPR2_REG = 0;
+ portNVIC_SHPR2_REG = portNVIC_SVC_PRI;
/* Configure the regions in the MPU that are common to all tasks. */
prvSetupMPU();
diff --git a/portable/IAR/ARM_CM4F_MPU/port.c b/portable/IAR/ARM_CM4F_MPU/port.c
index 423d0a7..a3b6517 100644
--- a/portable/IAR/ARM_CM4F_MPU/port.c
+++ b/portable/IAR/ARM_CM4F_MPU/port.c
@@ -120,9 +120,11 @@
#define portCORTEX_M7_r0p1_ID ( 0x410FC271UL )
#define portCORTEX_M7_r0p0_ID ( 0x410FC270UL )
+/* Constants to manipulate FreeRTOS interrupt priorities. */
#define portMIN_INTERRUPT_PRIORITY ( 255UL )
#define portNVIC_PENDSV_PRI ( ( ( uint32_t ) portMIN_INTERRUPT_PRIORITY ) << 16UL )
#define portNVIC_SYSTICK_PRI ( ( ( uint32_t ) portMIN_INTERRUPT_PRIORITY ) << 24UL )
+#define portNVIC_SVC_PRI ( ( ( uint32_t ) configMAX_SYSCALL_INTERRUPT_PRIORITY - 1UL ) << 24UL )
/* Constants used to check the installation of the FreeRTOS interrupt handlers. */
#define portSCB_VTOR_REG ( *( ( portISR_t ** ) 0xE000ED08 ) )
@@ -862,11 +864,11 @@
}
#endif /* configASSERT_DEFINED */
- /* Make PendSV and SysTick the lowest priority interrupts, and make SVCall
- * the highest priority. */
+ /* Make PendSV and SysTick the lowest priority interrupts, and configure
+ * SVCall for sufficient preemption priority. */
portNVIC_SHPR3_REG |= portNVIC_PENDSV_PRI;
portNVIC_SHPR3_REG |= portNVIC_SYSTICK_PRI;
- portNVIC_SHPR2_REG = 0;
+ portNVIC_SHPR2_REG = portNVIC_SVC_PRI;
/* Configure the regions in the MPU that are common to all tasks. */
prvSetupMPU();
diff --git a/portable/RVDS/ARM_CM4_MPU/port.c b/portable/RVDS/ARM_CM4_MPU/port.c
index 77c497a..7cdf3ea 100644
--- a/portable/RVDS/ARM_CM4_MPU/port.c
+++ b/portable/RVDS/ARM_CM4_MPU/port.c
@@ -95,13 +95,15 @@
#define portPERIPHERALS_START_ADDRESS 0x40000000UL
#define portPERIPHERALS_END_ADDRESS 0x5FFFFFFFUL
-/* Constants required to access and manipulate the SysTick. */
+/* Constants required to access and manipulate the SysTick and other FreeRTOS
+ * interrupts. */
#define portNVIC_SYSTICK_CLK ( 0x00000004UL )
#define portNVIC_SYSTICK_INT ( 0x00000002UL )
#define portNVIC_SYSTICK_ENABLE ( 0x00000001UL )
#define portMIN_INTERRUPT_PRIORITY ( 255UL )
#define portNVIC_PENDSV_PRI ( ( ( uint32_t ) portMIN_INTERRUPT_PRIORITY ) << 16UL )
#define portNVIC_SYSTICK_PRI ( ( ( uint32_t ) portMIN_INTERRUPT_PRIORITY ) << 24UL )
+#define portNVIC_SVC_PRI ( ( ( uint32_t ) configMAX_SYSCALL_INTERRUPT_PRIORITY - 1UL ) << 24UL )
/* Constants required to manipulate the VFP. */
#define portFPCCR ( ( volatile uint32_t * ) 0xe000ef34UL ) /* Floating point context control register. */
@@ -966,12 +968,11 @@
}
#endif /* configASSERT_DEFINED */
- /* Make PendSV and SysTick the same priority as the kernel, and the SVC
- * handler highest priority so it can be used to exit a critical section
- * (where lower priorities are masked). */
+ /* Make PendSV and SysTick the lowest priority interrupts, and configure
+ * SVCall for sufficient preemption priority. */
portNVIC_SHPR3_REG |= portNVIC_PENDSV_PRI;
portNVIC_SHPR3_REG |= portNVIC_SYSTICK_PRI;
- portNVIC_SHPR2_REG = 0;
+ portNVIC_SHPR2_REG = portNVIC_SVC_PRI;
/* Configure the regions in the MPU that are common to all tasks. */
prvSetupMPU();
