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Diffstat (limited to 'FreeRTOS/Demo/Safer_Interrupts_M33F_NXP_LPC55S69_MCUXpresso/NXP_Code/source/semihost_hardfault.c')
-rw-r--r-- | FreeRTOS/Demo/Safer_Interrupts_M33F_NXP_LPC55S69_MCUXpresso/NXP_Code/source/semihost_hardfault.c | 98 |
1 files changed, 98 insertions, 0 deletions
diff --git a/FreeRTOS/Demo/Safer_Interrupts_M33F_NXP_LPC55S69_MCUXpresso/NXP_Code/source/semihost_hardfault.c b/FreeRTOS/Demo/Safer_Interrupts_M33F_NXP_LPC55S69_MCUXpresso/NXP_Code/source/semihost_hardfault.c new file mode 100644 index 000000000..0ac5d0cbb --- /dev/null +++ b/FreeRTOS/Demo/Safer_Interrupts_M33F_NXP_LPC55S69_MCUXpresso/NXP_Code/source/semihost_hardfault.c @@ -0,0 +1,98 @@ +// **************************************************************************** +// semihost_hardfault.c +// - Provides hard fault handler to allow semihosting code not +// to hang application when debugger not connected. +// +// **************************************************************************** +// Copyright 2017-2021 NXP +// All rights reserved. +// +// NXP Confidential. This software is owned or controlled by NXP and may only be +// used strictly in accordance with the applicable license terms. +// +// By expressly accepting such terms or by downloading, installing, activating +// and/or otherwise using the software, you are agreeing that you have read, and +// that you agree to comply with and are bound by, such license terms. +// +// If you do not agree to be bound by the applicable license terms, then you may not +// retain, install, activate or otherwise use the software. +// **************************************************************************** +// +// ===== DESCRIPTION ===== +// +// One of the issues with applications that make use of semihosting operations +// (such as printf calls) is that the code will not execute correctly when the +// debugger is not connected. Generally this will show up with the application +// appearing to just hang. This may include the application running from reset +// or powering up the board (with the application already in FLASH), and also +// as the application failing to continue to execute after a debug session is +// terminated. +// +// The problem here is that the "bottom layer" of the semihosted variants of +// the C library, semihosting is implemented by a "BKPT 0xAB" instruction. +// When the debug tools are not connected, this instruction triggers a hard +// fault - and the default hard fault handler within an application will +// typically just contains an infinite loop - causing the application to +// appear to have hang when no debugger is connected. +// +// The below code provides an example hard fault handler which instead looks +// to see what the instruction that caused the hard fault was - and if it +// was a "BKPT 0xAB", then it instead returns back to the user application. +// +// In most cases this will allow applications containing semihosting +// operations to execute (to some degree) when the debugger is not connected. +// +// == NOTE == +// +// Correct execution of the application containing semihosted operations +// which are vectored onto this hard fault handler cannot be guaranteed. This +// is because the handler may not return data or return codes that the higher +// level C library code or application code expects. This hard fault handler +// is meant as a development aid, and it is not recommended to leave +// semihosted code in a production build of your application! +// +// **************************************************************************** + +// Allow handler to be removed by setting a define (via command line) +#if !defined (__SEMIHOST_HARDFAULT_DISABLE) + +__attribute__((naked)) +void HardFault_Handler(void){ + __asm( ".syntax unified\n" + // Check which stack is in use + "MOVS R0, #4 \n" + "MOV R1, LR \n" + "TST R0, R1 \n" + "BEQ _MSP \n" + "MRS R0, PSP \n" + "B _process \n" + "_MSP: \n" + "MRS R0, MSP \n" + // Load the instruction that triggered hard fault + "_process: \n" + "LDR R1,[R0,#24] \n" + "LDRH R2,[r1] \n" + // Semihosting instruction is "BKPT 0xAB" (0xBEAB) + "LDR R3,=0xBEAB \n" + "CMP R2,R3 \n" + "BEQ _semihost_return \n" + // Wasn't semihosting instruction so enter infinite loop + "B . \n" + // Was semihosting instruction, so adjust location to + // return to by 1 instruction (2 bytes), then exit function + "_semihost_return: \n" + "ADDS R1,#2 \n" + "STR R1,[R0,#24] \n" + // Set a return value from semihosting operation. + // 32 is slightly arbitrary, but appears to allow most + // C Library IO functions sitting on top of semihosting to + // continue to operate to some degree + "MOVS R1,#32 \n" + "STR R1,[ R0,#0 ] \n" // R0 is at location 0 on stack + // Return from hard fault handler to application + "BX LR \n" + ".syntax divided\n") ; +} + +#endif + |