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cortex-M ports: Clarify hardware-saved exception frame size variable (#1314)

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* cortex-M ports: Clarify hardware-saved exception frame size variable

- Rename ulStackFrameSize to ulHardwareSavedExceptionFrameSize to
reflect the hardware-saved exception frame (8 or 26 words based
on FPU/lazy stacking).
- Add comments explaining standard vs extended frames.
- Apply across Cortex-M ports.
- No functional change, improves readability.

Signed-off-by: Ahmed Ismail <Ahmed.Ismail@arm.com>
Signed-off-by: Gaurav Aggarwal <aggarg@amazon.com>

* kernel-checker-script: Modify Arm copyright header regex

Arm's copyright header regex is modified with the following:

* Accept both single year copyright headers (e.g., "2024")
and year range copyright headers (e.g., "2024-2025").

* Accept both single-line copyright header and also
multi-line header.

* Add the escape backslash to accept only literal dot
not any character.

Signed-off-by: Gaurav Aggarwal <aggarg@amazon.com>
Signed-off-by: Ahmed Ismail <Ahmed.Ismail@arm.com>

---------

Signed-off-by: Ahmed Ismail <Ahmed.Ismail@arm.com>
Signed-off-by: Gaurav Aggarwal <aggarg@amazon.com>
This commit is contained in:
Ahmed Ismail 2025-09-09 07:25:42 +01:00 • committed by GitHub
parent ccabdec2f8
commit 44ae6cf61a
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GPG key ID: B5690EEEBB952194
27 changed files with 561 additions and 343 deletions
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36
portable/GCC/ARM_CM33/non_secure/port.c
View file

@ -1,7 +1,7 @@
/*
* FreeRTOS Kernel <DEVELOPMENT BRANCH>
* Copyright (C) 2021 Amazon.com, Inc. or its affiliates. All Rights Reserved.
* Copyright 2024 Arm Limited and/or its affiliates
* Copyright 2024-2025 Arm Limited and/or its affiliates
* <open-source-office@arm.com>
*
* SPDX-License-Identifier: MIT
@ -1200,7 +1200,7 @@ void vPortSVCHandler_C( uint32_t * pulCallerStackAddress ) /* PRIVILEGED_FUNCTIO
extern UBaseType_t uxSystemCallImplementations[ NUM_SYSTEM_CALLS ];
xMPU_SETTINGS * pxMpuSettings;
uint32_t * pulSystemCallStack;
uint32_t ulStackFrameSize, ulSystemCallLocation, i;
uint32_t ulHardwareSavedExceptionFrameSize, ulSystemCallLocation, i;
#if defined( __ARMCC_VERSION )
@ -1236,12 +1236,16 @@ void vPortSVCHandler_C( uint32_t * pulCallerStackAddress ) /* PRIVILEGED_FUNCTIO
{
pulSystemCallStack = pxMpuSettings->xSystemCallStackInfo.pulSystemCallStack;
/* Hardware Saved Stack Frame Size upon Exception entry:
* - No FPU: basic frame (R0-R3, R12, LR, PC, and xPSR) = 8 words.
* - With FPU (lazy stacking): basic frame + S0–S15 + FPSCR + reserved word = 26 words.
*/
#if ( ( configENABLE_FPU == 1 ) || ( configENABLE_MVE == 1 ) )
{
if( ( ulLR & portEXC_RETURN_STACK_FRAME_TYPE_MASK ) == 0UL )
{
/* Extended frame i.e. FPU in use. */
ulStackFrameSize = 26;
ulHardwareSavedExceptionFrameSize = 26;
__asm volatile (
" vpush {s0} \n" /* Trigger lazy stacking. */
" vpop {s0} \n" /* Nullify the affect of the above instruction. */
@ -1251,20 +1255,20 @@ void vPortSVCHandler_C( uint32_t * pulCallerStackAddress ) /* PRIVILEGED_FUNCTIO
else
{
/* Standard frame i.e. FPU not in use. */
ulStackFrameSize = 8;
ulHardwareSavedExceptionFrameSize = 8;
}
}
#else /* if ( ( configENABLE_FPU == 1 ) || ( configENABLE_MVE == 1 ) ) */
{
ulStackFrameSize = 8;
ulHardwareSavedExceptionFrameSize = 8;
}
#endif /* configENABLE_FPU || configENABLE_MVE */
/* Make space on the system call stack for the stack frame. */
pulSystemCallStack = pulSystemCallStack - ulStackFrameSize;
pulSystemCallStack = pulSystemCallStack - ulHardwareSavedExceptionFrameSize;
/* Copy the stack frame. */
for( i = 0; i < ulStackFrameSize; i++ )
for( i = 0; i < ulHardwareSavedExceptionFrameSize; i++ )
{
pulSystemCallStack[ i ] = pulTaskStack[ i ];
}
@ -1300,7 +1304,7 @@ void vPortSVCHandler_C( uint32_t * pulCallerStackAddress ) /* PRIVILEGED_FUNCTIO
/* Remember the location where we should copy the stack frame when we exit from
* the system call. */
pxMpuSettings->xSystemCallStackInfo.pulTaskStack = pulTaskStack + ulStackFrameSize;
pxMpuSettings->xSystemCallStackInfo.pulTaskStack = pulTaskStack + ulHardwareSavedExceptionFrameSize;
/* Record if the hardware used padding to force the stack pointer
* to be double word aligned. */
@ -1350,7 +1354,7 @@ void vPortSVCHandler_C( uint32_t * pulCallerStackAddress ) /* PRIVILEGED_FUNCTIO
extern TaskHandle_t pxCurrentTCB;
xMPU_SETTINGS * pxMpuSettings;
uint32_t * pulTaskStack;
uint32_t ulStackFrameSize, ulSystemCallLocation, i;
uint32_t ulHardwareSavedExceptionFrameSize, ulSystemCallLocation, i;
#if defined( __ARMCC_VERSION )
@ -1382,12 +1386,16 @@ void vPortSVCHandler_C( uint32_t * pulCallerStackAddress ) /* PRIVILEGED_FUNCTIO
{
pulTaskStack = pxMpuSettings->xSystemCallStackInfo.pulTaskStack;
/* Hardware Saved Stack Frame Size upon Exception entry:
* - No FPU: basic frame (R0-R3, R12, LR, PC, and xPSR) = 8 words.
* - With FPU (lazy stacking): basic frame + S0–S15 + FPSCR + reserved word = 26 words.
*/
#if ( ( configENABLE_FPU == 1 ) || ( configENABLE_MVE == 1 ) )
{
if( ( ulLR & portEXC_RETURN_STACK_FRAME_TYPE_MASK ) == 0UL )
{
/* Extended frame i.e. FPU in use. */
ulStackFrameSize = 26;
ulHardwareSavedExceptionFrameSize = 26;
__asm volatile (
" vpush {s0} \n" /* Trigger lazy stacking. */
" vpop {s0} \n" /* Nullify the affect of the above instruction. */
@ -1397,20 +1405,20 @@ void vPortSVCHandler_C( uint32_t * pulCallerStackAddress ) /* PRIVILEGED_FUNCTIO
else
{
/* Standard frame i.e. FPU not in use. */
ulStackFrameSize = 8;
ulHardwareSavedExceptionFrameSize = 8;
}
}
#else /* if ( ( configENABLE_FPU == 1 ) || ( configENABLE_MVE == 1 ) ) */
{
ulStackFrameSize = 8;
ulHardwareSavedExceptionFrameSize = 8;
}
#endif /* configENABLE_FPU || configENABLE_MVE */
/* Make space on the task stack for the stack frame. */
pulTaskStack = pulTaskStack - ulStackFrameSize;
pulTaskStack = pulTaskStack - ulHardwareSavedExceptionFrameSize;
/* Copy the stack frame. */
for( i = 0; i < ulStackFrameSize; i++ )
for( i = 0; i < ulHardwareSavedExceptionFrameSize; i++ )
{
pulTaskStack[ i ] = pulSystemCallStack[ i ];
}