ARMv8.1-M: Add task dedicated PAC key support #1195
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urutva
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Thank you for your contribution @AhmedIsmail02! I have reviewed the code and I have the following suggestions -
All of my suggestions are in the following patch - 0001-Code-review-suggestions.patch. Please take a look and let me know what you think. |
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@aggarg Thank you for the valuable review. |
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urutva
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Thanks you, @AhmedIsmail02! I have the following 2 suggestions:
Note that I have not tested the second patch yet. |
ARMv8-M TrustZone variant registers stacking procedure is modified to be consistent with the NTZ port variant where one `stmdb` instruction is used instead of using 'subs' instruction along with `stmia` instruction, also, this result in more efficient context switching handling (lower latency). Signed-off-by: Ahmed Ismail <[email protected]>
To harden the security, each task is assigned a dedicated PAC key, so that attackers needs to guess the all the tasks' PAC keys right to exploit the system using Return Oriented Programming. The kernel is now updated to support the following: * A PAC key set with a random number generated and is pushed onto the task's stack when a task is created. * As part of scheduling, the task's PAC key is stacked/unstacked to/from the task's stack when a task is unscheduled/scheduled from/to run. Signed-off-by: Ahmed Ismail <[email protected]>
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When MPU wrapper v2 is used, the task's context is stored in TCB and `pxTopOfStack`` member of TCB points to the context location in TCB. We, therefore, need to read PSP to find the task's current top of stack. Signed-off-by: Ahmed Ismail <[email protected]> Signed-off-by: Gaurav Aggarwal <[email protected]>
Signed-off-by: Ahmed Ismail <[email protected]> Signed-off-by: Gaurav Aggarwal <[email protected]>
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urutva
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aggarg
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Description
To harden the security, each task is assigned with a dedicated PAC key, so that attackers needs to get the all the PAC keys right to exploit the system using Return Oriented Programming. The kernel is updated to support the following:
This commit is an improvement for MR!1216 to support MPU port variants stack overflow check.
Test Steps
Checklist:
Related Issue
Blocks FreeRTOS/FreeRTOS-Partner-Supported-Demos#19
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