diff --git a/portable/GCC/ARM_CR5/port.c b/portable/GCC/ARM_CR5/port.c index 970b304a5..8b9933fb3 100644 --- a/portable/GCC/ARM_CR5/port.c +++ b/portable/GCC/ARM_CR5/port.c @@ -146,20 +146,6 @@ #define portTASK_RETURN_ADDRESS prvTaskExitError #endif - -/* Adding the necessary stuff in order to be able to determine from C code wheter or not the IRQs are enabled at the processor level (not interrupt controller level) */ -#define GET_CPSR() \ - ( { u32 rval = 0U; \ - __asm__ __volatile__ ( \ - "mrs %0, cpsr\n"\ - : "=r" ( rval ) \ - ); \ - rval; \ - } ) - -#define CPSR_IRQ_ENABLE_MASK 0x80U - -#define IS_IRQ_DISABLED() ( { unsigned int val = 0; val = ( GET_CPSR() & CPSR_IRQ_ENABLE_MASK ) ? 1 : 0; val; } ) /*-----------------------------------------------------------*/ /* @@ -481,12 +467,6 @@ void vPortClearInterruptMask( uint32_t ulNewMaskValue ) uint32_t ulPortSetInterruptMask( void ) { uint32_t ulReturn; - uint32_t wasIRQDisabled; - - /* We keep track of if the IRQ are enabled in the CPU (as opposed to interrupts masked in the interrupt controller, like the intend of this function). - * This is very important because when the CPU is interrupted, among other things, the hardware clears the IRQ Enable bit in the CPSR of the IRQ CPU Mode in which - * we enter. */ - wasIRQDisabled = IS_IRQ_DISABLED(); /* Interrupt in the CPU must be turned off while the ICCPMR is being * updated. */ @@ -505,20 +485,7 @@ uint32_t ulPortSetInterruptMask( void ) "isb \n"::: "memory" ); } - /* Just like this function returns a value of wether or not the interrupts where masked in the interrupt controller in order to avoid race condition when - * calling its matching vPortClearInterruptMask function, we needed a 'wasIRQDisabled' variable holding the state of the IRQ Enable bit in the CPSR in order - * to leave that bit in it's original state. Like mentioned above, hardware automatically clear the IRQEnable bit upon trapping into IRQ Mode, so the programmer - * cannot make assumption about it's state. Very rare, but very important race condition is avoided with this when this function is called in an ISR. The race - * condition in question was discovered when integrating tracealyzer code. Inside the function 'void vTaskSwitchContext( void )' in tasks.c, there is a macro 'traceTASK_SWITCHED_IN();' - * which gets replaced by something when using the tracing capabilities. That macro protects some critical section with matching calls to 'ulPortSetInterruptMask' - * and 'vPortClearInterruptMask'. At the time of calling those functions, the interrupt mask is not set in the interrupt controller, thus the only protecting barrier - * against the CPU traping into recursive interrupt was the IRQ Enable bit in the CPSR. By not taking it into acount, the very code that protects the CPU against - * critical section violation just enabled it to happen : A SysTick was waiting to happen, and calling 'portCPU_IRQ_ENABLE' would enable it to occur... Thus triggering a - * switch of context while already performing a switch context. */ - if( !wasIRQDisabled ) - { - portCPU_IRQ_ENABLE(); - } + portCPU_IRQ_ENABLE(); return ulReturn; }