Add VeriFast thread safety proof for context switches in SMP port #608
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- const pointers
- inline assembler
- statements blocks consisting of multiple elements used in expression contexts, e.g., `({e1 e2;})`
- multiple pointer declarations to user-defined types in single line, i.e., `A *p1, *p2;`
- VeriFast does not support nested union definitions. Removed those temporarily. - VeriFast does not support duplicate function prototypes. Prevented include of unguarded system header file.
…ort-specific implementation.
… to justify `memset`-ing the stack.
…overflows and underflows.
…und for over/underflows.
Fields: `pxNewTCB->ucNotifyState` and `pxNewTCB->ulNotifiedValue`
…erification of contract from portable.h
…tack` impl from RP2040 port.
…nternship-AWS-2022/FreeRTOS-Kernel into verifast_switch_context
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Add VeriFast thread safety proof for context switches in SMP port
Description
The SMP implementation of the scheduler suffers from a buffer underflow, cf. the fix proposed in PR 607. We used VeriFast, a deductive program verifier for C, to prove that once the fix from PR 607 has been applied, context switches are memory safe (i.e. no memory error) and mutually thread safe (i.e. no race condition).
The proof is an unbounded proof. That is, it considers any possible number of tasks and any possible sizes for the involved data structures. Further, it considers any possible task interleavings and any possible interrupt schedule that may occur during runtime. Taking all this into account, it ensure that no memory error and no race condition can occur during runtime, when we run multiple concurrent context switches on different cores.
See the proof README for a more detailed explanation.
Test Steps
Run one of the scripts
run-verifast.shorrun-vfide.shas descripted in the proof README.Related Issue
#607
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