From ed46e1a38ae2de97b55c1843bad8b813bd4936e3 Mon Sep 17 00:00:00 2001 From: mindchasers Date: Sun, 7 Jul 2019 17:58:07 -0400 Subject: initial commit of private island ARM test suite --- source/semihost_hardfault.c | 109 ++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 109 insertions(+) create mode 100644 source/semihost_hardfault.c (limited to 'source/semihost_hardfault.c') diff --git a/source/semihost_hardfault.c b/source/semihost_hardfault.c new file mode 100644 index 0000000..dc8d3ae --- /dev/null +++ b/source/semihost_hardfault.c @@ -0,0 +1,109 @@ +// **************************************************************************** +// semihost_hardfault.c +// - Provides hard fault handler to allow semihosting code not +// to hang application when debugger not connected. +// +// **************************************************************************** +// Copyright(C) NXP Semiconductors, 2017-2018 +// All rights reserved. +// +// Software that is described herein is for illustrative purposes only +// which provides customers with programming information regarding the +// NXP Cortex-M based MCUs. This software is supplied "AS IS" without any +// warranties of any kind, and NXP Semiconductors and its licensor disclaim any +// and all warranties, express or implied, including all implied warranties of +// merchantability, fitness for a particular purpose and non-infringement of +// intellectual property rights. NXP Semiconductors assumes no responsibility +// or liability for the use of the software, conveys no license or rights under +// any patent, copyright, mask work right, or any other intellectual property +// rights in or to any products. NXP Semiconductors reserves the right to make +// changes in the software without notification. NXP Semiconductors also makes +// no representation or warranty that such application will be suitable for the +// specified use without further testing or modification. +// +// Permission to use, copy, modify, and distribute this software and its +// documentation is hereby granted, under NXP Semiconductors' and its +// licensor's relevant copyrights in the software, without fee, provided that it +// is used in conjunction with NXP Semiconductors microcontrollers. This +// copyright, permission, and disclaimer notice must appear in all copies of +// this code. +// **************************************************************************** +// +// ===== 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 + -- cgit v1.2.3-8-gadcc