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Fix vPortFreeSecureContext to read xSecureContext at correct offset (#1441)

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When MPU is enabled, the first item in the TCB is not the top of the
stack but the stored context location. As a result, xSecureContext
is located at a negative offset from that position rather than at
offset 0. The current implementation unconditionally reads
xSecureContext at offset 0, which returns an incorrect value when MPU
is enabled.

This commit updates vPortFreeSecureContext to read xSecureContext at
the correcct offset based on the port configuration:
- CM33/CM35P/CM52/CM55/CM85/STAR_MC3: -20 (or -36 with PAC enabled)
- CM23: -20 (no PAC support)
- Without MPU: 0 (xSecureContext remains at the top of stack)

Signed-off-by: Gaurav Aggarwal <aggarg@amazon.com>
This commit is contained in:
Gaurav-Aggarwal-AWS
2026-07-01 23:28:41 +05:30
committed by GitHub
parent 49cec3e9b2
commit ae46383c90
18 changed files with 222 additions and 54 deletions
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18
portable/GCC/ARM_STAR_MC3/non_secure/portasm.c
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@@ -45,6 +45,16 @@
* header files. */
#undef MPU_WRAPPERS_INCLUDED_FROM_API_FILE
#if ( configENABLE_MPU == 1 )
#if ( configENABLE_PAC == 1 )
#define SECURE_CONTEXT_OFFSET -36
#else
#define SECURE_CONTEXT_OFFSET -20
#endif
#else
#define SECURE_CONTEXT_OFFSET 0
#endif
#if ( configENABLE_MPU == 1 )
void vRestoreContextOfFirstTask( void ) /* __attribute__ (( naked )) PRIVILEGED_FUNCTION */
@@ -609,13 +619,13 @@ void vPortFreeSecureContext( uint32_t * pulTCB ) /* __attribute__ (( naked )) PR
(
" .syntax unified \n"
" \n"
" ldr r2, [r0] \n" /* The first item in the TCB is the top of the stack. */
" ldr r1, [r2] \n" /* The first item on the stack is the task's xSecureContext. */
" ldr r2, [r0] \n" /* The first item in the TCB is the stored context location. */
" ldr r1, [r2, %0] \n" /* Read xSecureContext from the task's context. */
" cmp r1, #0 \n" /* Raise svc if task's xSecureContext is not NULL. */
" it ne \n"
" svcne %0 \n" /* Secure context is freed in the supervisor call. */
" svcne %1 \n" /* Secure context is freed in the supervisor call. */
" bx lr \n" /* Return. */
::"i" ( portSVC_FREE_SECURE_CONTEXT ) : "memory"
::"i" ( SECURE_CONTEXT_OFFSET ), "i" ( portSVC_FREE_SECURE_CONTEXT ) : "memory"
);
}
/*-----------------------------------------------------------*/