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arch/armv7-m: Adds dwt helper functions for controlling watchpoints in code.

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In scenarios where there is suspicion that someone might be touching your data when you don't expect, you can setup a watchpoint, and then guard accesses that you know are valid. If the debugger halts due to the watchpoint, you'll see where the unexpected access is coming from.
This commit is contained in:
Anthony Merlino 2021-03-06 22:36:42 -05:00 committed by Xiang Xiao
parent 70442d1f9d
commit afd6ad4ff5
1 changed files with 139 additions and 0 deletions
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139
arch/arm/src/armv7-m/dwt.h
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@ -63,6 +63,12 @@
#ifndef __ARCH_ARM_SRC_ARMV7_M_DWT_H
#define __ARCH_ARM_SRC_ARMV7_M_DWT_H
/****************************************************************************
* Included Files
****************************************************************************/
#include "arm_arch.h"
/***********************************************************************************************
* Pre-processor Definitions
***********************************************************************************************/
@ -95,6 +101,12 @@
#define DWT_COMP3 (DWT_BASE + 0x0050) /* Comparator Register 3 */
#define DWT_MASK3 (DWT_BASE + 0x0054) /* Mask Register 3 */
#define DWT_FUNCTION3 (DWT_BASE + 0x0058) /* Function Register 3 */
#define DWT_LAR (DWT_BASE + 0x0FB0) /* Lock Access Register */
#define DWT_LAR_ACCESS (0xC5ACCE55) /* Lock Access Magic Value */
#define DWT_GRANT_ACCESS() (putreg32(DWT_LAR_ACCESS, DWT_LAR))
#define DWT_REVOKE_ACCESS() (putreg32(~DWT_LAR_ACCESS, DWT_LAR))
/* DWT Register Bit Field Definitions **********************************************************/
@ -188,4 +200,131 @@
#define DWT_FUNCTION_FUNCTION_SHIFT 0
#define DWT_FUNCTION_FUNCTION_MASK (0xful << DWT_FUNCTION_FUNCTION_SHIFT)
#define DWT_FUNCTION_WATCHPOINT_RO (0x05ul << DWT_FUNCTION_FUNCTION_SHIFT)
#define DWT_FUNCTION_WATCHPOINT_WO (0x06ul << DWT_FUNCTION_FUNCTION_SHIFT)
#define DWT_FUNCTION_WATCHPOINT_RW (0x07ul << DWT_FUNCTION_FUNCTION_SHIFT)
#define DWT_DATAVSIZE_BYTE (0x00ul << DWT_FUNCTION_DATAVSIZE_SHIFT)
#define DWT_DATAVSIZE_HALFWORD (0x01ul << DWT_FUNCTION_DATAVSIZE_SHIFT)
#define DWT_DATAVSIZE_WORD (0x02ul << DWT_FUNCTION_DATAVSIZE_SHIFT)
/****************************************************************************
* Inline Functions
****************************************************************************/
static inline void dwt_comparator_setup(int compnum, uint32_t comp,
uint32_t mask, uint32_t func)
{
DWT_GRANT_ACCESS();
switch (compnum)
{
case 0:
putreg32(comp, DWT_COMP0);
putreg32(mask, DWT_MASK0);
putreg32(func, DWT_FUNCTION0);
break;
case 1:
putreg32(comp, DWT_COMP1);
putreg32(mask, DWT_MASK1);
putreg32(func, DWT_FUNCTION1);
break;
case 2:
putreg32(comp, DWT_COMP2);
putreg32(mask, DWT_MASK2);
putreg32(func, DWT_FUNCTION2);
break;
case 3:
putreg32(comp, DWT_COMP3);
putreg32(mask, DWT_MASK3);
putreg32(func, DWT_FUNCTION3);
break;
default:
break;
}
DWT_REVOKE_ACCESS();
}
static inline void dwt_comparator_reset(int compnum)
{
DWT_GRANT_ACCESS();
switch (compnum)
{
case 0:
putreg32(0, DWT_COMP0);
putreg32(0, DWT_MASK0);
putreg32(0, DWT_FUNCTION0);
break;
case 1:
putreg32(0, DWT_COMP1);
putreg32(0, DWT_MASK1);
putreg32(0, DWT_FUNCTION1);
break;
case 2:
putreg32(0, DWT_COMP2);
putreg32(0, DWT_MASK2);
putreg32(0, DWT_FUNCTION2);
break;
case 3:
putreg32(0, DWT_COMP3);
putreg32(0, DWT_MASK3);
putreg32(0, DWT_FUNCTION3);
break;
default:
break;
}
DWT_REVOKE_ACCESS();
}
static inline uint32_t dwt_comparator_block(int compnum)
{
uint32_t funcval = 0;
DWT_GRANT_ACCESS();
switch (compnum)
{
case 0:
funcval = getreg32(DWT_FUNCTION0);
putreg32(0, DWT_FUNCTION0);
break;
case 1:
funcval = getreg32(DWT_FUNCTION1);
putreg32(0, DWT_FUNCTION1);
break;
case 2:
funcval = getreg32(DWT_FUNCTION2);
putreg32(0, DWT_FUNCTION2);
break;
case 3:
funcval = getreg32(DWT_FUNCTION3);
putreg32(0, DWT_FUNCTION3);
break;
default:
break;
}
DWT_REVOKE_ACCESS();
return funcval;
}
static inline void dwt_comparator_restore(int compnum, uint32_t func)
{
DWT_GRANT_ACCESS();
switch (compnum)
{
case 0:
putreg32(func, DWT_FUNCTION0);
break;
case 1:
putreg32(func, DWT_FUNCTION1);
break;
case 2:
putreg32(func, DWT_FUNCTION2);
break;
case 3:
putreg32(func, DWT_FUNCTION3);
break;
default:
break;
}
DWT_REVOKE_ACCESS();
}
#endif /* __ARCH_ARM_SRC_ARMV7_M_DWT_H */