Added lemmas to reason about updates to pointers in the ready list of the form pxTaskItem = pxTaskItem->pxNext

This commit is contained in:
Tobias Reinhard 2022-11-22 12:59:52 -05:00
parent 538f29caeb
commit 397cb12abb
3 changed files with 188 additions and 77 deletions

81
tasks.c
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@ -84,6 +84,8 @@
#include "verifast_port_contracts.h" #include "verifast_port_contracts.h"
#include "verifast_lock_predicates.h" #include "verifast_lock_predicates.h"
#include "verifast_lists_extended.h" #include "verifast_lists_extended.h"
#include "single_core_proofs/scp_list_predicates.h"
#include "single_core_proofs_extended/scp_list_predicates_extended.h"
#include "snippets/rp2040_port_c_snippets.c" #include "snippets/rp2040_port_c_snippets.c"
@ -1100,84 +1102,9 @@ static void prvYieldForTask( TCB_t * pxTCB,
*/ */
/*@ /*@
if( gTaskItem_0 == gListEnd ) { if( gTaskItem_0 == gListEnd ) {
open DLS(gListEnd, gEndPrev2, gListEnd, gEndPrev2, DLS_end_next_open(gReadyList, gTaskItem_0);
gCells, gVals, gReadyList);
// open DLS and xLIST_ITEM predicates to justify
// accessing `gTaskItem_0->pxNext`
assert( xLIST_ITEM(gListEnd, ?gV, ?gNext, gEndPrev2, gReadyList) );
open xLIST_ITEM(gListEnd, gV, gNext, gEndPrev2, gReadyList);
assert( DLS(gNext, gListEnd, gListEnd, gEndPrev2, drop(1, gCells), drop(1, gVals), gReadyList ) );
open DLS(gNext, gListEnd, gListEnd, gEndPrev2, drop(1, gCells), drop(1, gVals), gReadyList );
// open DLS and xLIST_ITEM predicates to prove
// `mem( gTaskItem_0->pxNext, gCells) == true )`
// which requires accessing `gTaskItem_0->pxNext`
assert( xLIST_ITEM(gNext, ?gV_next, ?gNextNext, gListEnd, gReadyList) );
open xLIST_ITEM(gNext, gV_next, gNextNext, gListEnd, gReadyList);
assert( mem(gTaskItem_0->pxNext, gCells) == true );
close xLIST_ITEM(gNext, gV_next, gNextNext, gListEnd, gReadyList);
} else { } else {
// open DLS and xLIST_ITEM predicates to justify DLS_nonEndItem_next_open(gReadyList, gTaskItem_0);
// accessing `gTaskItem_0->pxNext`
split(gListEnd, gEndPrev2, gListEnd, gEndPrev2,
gCells, gVals, gTaskItem_0, gTaskItemIndex_0);
// DLS prefix
assert( DLS(gListEnd, gEndPrev2, gTaskItem_0, ?gTaskItem_0_prev,
take(gTaskItemIndex_0, gCells), take(gTaskItemIndex_0, gVals),
gReadyList) );
// DLS suffix
assert( DLS(gTaskItem_0, gTaskItem_0_prev, gListEnd, gEndPrev2,
drop(gTaskItemIndex_0, gCells), drop(gTaskItemIndex_0, gVals),
gReadyList) );
open DLS(gTaskItem_0, gTaskItem_0_prev, gListEnd, gEndPrev2,
drop(gTaskItemIndex_0, gCells), drop(gTaskItemIndex_0, gVals),
gReadyList);
assert( xLIST_ITEM(gTaskItem_0, ?gV, ?gTaskItem_0_next, gTaskItem_0_prev, gReadyList) );
// open DLS and xLIST_ITEM predicates to prove
// `mem( gTaskItem_0->pxNext, gCells) == true )`
// which requires accessing `gTaskItem_0->pxNext`
if(gTaskItem_0 == gEndPrev2) {
// `gTaskItem_0` is last element in DLS suffix
// -> `gTaskItem_0_next` is head fo DLS prefix
// open DLS prefix
pxTaskItem->pxNext;
assert( mem(gTaskItem_0->pxNext, gCells) == true );
;
} else {
// `gTaskItem_0` is not end of DLS suffix
// -> `gTaskItem_0_next` is also in DLS suffix
// open DLS suffix one step further
assert( DLS(gTaskItem_0_next, gTaskItem_0, gListEnd, gEndPrev2,
drop(1, drop(gTaskItemIndex_0, gCells)), drop(1, drop(gTaskItemIndex_0, gVals)), //drop(gTaskItemIndex_0 + 1, gCells), drop(gTaskItemIndex_0 + 1, gVals),
gReadyList) );
open DLS(gTaskItem_0_next, gTaskItem_0, gListEnd, gEndPrev2,
drop(1, drop(gTaskItemIndex_0, gCells)), drop(1, drop(gTaskItemIndex_0, gVals)),
gReadyList);
assert( xLIST_ITEM(gTaskItem_0_next, ?gNextVal, ?gTaskItem_0_next_next, gTaskItem_0, gReadyList) );
//open xLIST_ITEM(gTaskItem_0_next, gNextVal, gTaskItem_0_next_next, gTaskItem_0, gReadyList);
pxTaskItem->pxNext;
assert( gTaskItem_0_next == pxTaskItem->pxNext );
assert( mem(gTaskItem_0_next, drop(1, drop(gTaskItemIndex_0, gCells))) == true );
//assert( gCells == cons(_, drop(1, drop(gTaskItemIndex_0, gCells)) );
assert( mem(gTaskItem_0_next, drop(gTaskItemIndex_0, gCells)) == true );
mem_suffix_implies_mem(gTaskItem_0_next, gCells, gTaskItemIndex_0);
assert( mem(gTaskItem_0_next, gCells) == true );
assert( mem(gTaskItem_0->pxNext, gCells) == true );
close xLIST_ITEM(gTaskItem_0_next, gNextVal, gTaskItem_0_next_next, gTaskItem_0, gReadyList);
close DLS(gTaskItem_0_next, gTaskItem_0, gListEnd, gEndPrev2,
drop(1, drop(gTaskItemIndex_0, gCells)), drop(1, drop(gTaskItemIndex_0, gVals)),
gReadyList);
}
} }
@*/ @*/
pxTaskItem = pxTaskItem->pxNext; pxTaskItem = pxTaskItem->pxNext;

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@ -0,0 +1,4 @@
This directory contains proofs that concern the predicates and proofs written
by Aalok Thakkar and Nathan Chong, see directory `single_core_proofs`.
For now, we want to have a clear separation between the reused proofs in
`single_core_proofs` and any new proofs.

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@ -0,0 +1,180 @@
#ifndef SCP_LIST_PREDICATES_EXTENDED_H
#define SCP_LIST_PREDICATES_EXTENDED_H
#include "single_core_proofs/scp_list_predicates.h"
/*@
lemma void DLS_end_next_open(struct xLIST* gReadyList, struct xLIST_ITEM* gTaskItem_0)
requires
DLS(?gListEnd, ?gEndPrev2, gListEnd, gEndPrev2, ?gCells, ?gVals, gReadyList) &*&
mem(gTaskItem_0, gCells) == true &*&
gListEnd == head(gCells) &*&
length(gCells) == length(gVals) &*&
length(gCells) > 1
&*&
gTaskItem_0 == gListEnd;
ensures xLIST_ITEM(gListEnd, ?gV, ?gNext, gEndPrev2, gReadyList) &*&
DLS(gNext, gListEnd, gListEnd, gEndPrev2, drop(1, gCells), drop(1, gVals), gReadyList ) &*&
mem(gNext, gCells) == true;
{
open DLS(gListEnd, gEndPrev2, gListEnd, gEndPrev2,
gCells, gVals, gReadyList);
// open DLS and xLIST_ITEM predicates to justify
// accessing `gTaskItem_0->pxNext`
assert( xLIST_ITEM(gListEnd, ?gV, ?gNext, gEndPrev2, gReadyList) );
open xLIST_ITEM(gListEnd, gV, gNext, gEndPrev2, gReadyList);
assert( DLS(gNext, gListEnd, gListEnd, gEndPrev2, drop(1, gCells), drop(1, gVals), gReadyList ) );
open DLS(gNext, gListEnd, gListEnd, gEndPrev2, drop(1, gCells), drop(1, gVals), gReadyList );
// open DLS and xLIST_ITEM predicates to prove
// `mem( gTaskItem_0->pxNext, gCells) == true )`
// which requires accessing `gTaskItem_0->pxNext`
assert( xLIST_ITEM(gNext, ?gV_next, ?gNextNext, gListEnd, gReadyList) );
open xLIST_ITEM(gNext, gV_next, gNextNext, gListEnd, gReadyList);
assert( mem(gTaskItem_0->pxNext, gCells) == true );
close xLIST_ITEM(gNext, gV_next, gNextNext, gListEnd, gReadyList);
// closing what we opened above
close DLS(gNext, gListEnd, gListEnd, gEndPrev2, drop(1, gCells), drop(1, gVals), gReadyList );
close xLIST_ITEM(gListEnd, gV, gNext, gEndPrev2, gReadyList);
}
lemma void DLS_nonEndItem_next_open(struct xLIST* gReadyList, struct xLIST_ITEM* gTaskItem_0)
requires
DLS(?gListEnd, ?gEndPrev2, gListEnd, gEndPrev2, ?gCells, ?gVals, gReadyList) &*&
mem(gTaskItem_0, gCells) == true &*&
gListEnd == head(gCells) &*&
length(gCells) == length(gVals) &*&
length(gCells) > 1
&*&
gTaskItem_0 != gListEnd;
ensures // DLS prefix
DLS(gListEnd, gEndPrev2, gTaskItem_0, ?gTaskItem_0_prev,
take(index_of(gTaskItem_0, gCells), gCells),
take(index_of(gTaskItem_0, gCells), gVals),
gReadyList)
&*&
// item of interest
xLIST_ITEM(gTaskItem_0, ?gV, ?gTaskItem_0_next, gTaskItem_0_prev, gReadyList)
&*&
// DLS suffix
(gTaskItem_0 != gEndPrev2
? DLS(gTaskItem_0_next, gTaskItem_0, gListEnd, gEndPrev2,
drop(1, drop(index_of(gTaskItem_0, gCells), gCells)),
drop(1, drop(index_of(gTaskItem_0, gCells), gVals)),
gReadyList)
: true
)
&*&
mem(gTaskItem_0_next, gCells) == true;
{
int gTaskItemIndex_0 = index_of(gTaskItem_0, gCells);
// open DLS and xLIST_ITEM predicates to justify
// accessing `gTaskItem_0->pxNext`
split(gListEnd, gEndPrev2, gListEnd, gEndPrev2,
gCells, gVals, gTaskItem_0, gTaskItemIndex_0);
// DLS prefix
assert( DLS(gListEnd, gEndPrev2, gTaskItem_0, ?gTaskItem_0_prev,
take(gTaskItemIndex_0, gCells), take(gTaskItemIndex_0, gVals),
gReadyList) );
// DLS suffix
assert( DLS(gTaskItem_0, gTaskItem_0_prev, gListEnd, gEndPrev2,
drop(gTaskItemIndex_0, gCells), drop(gTaskItemIndex_0, gVals),
gReadyList) );
open DLS(gTaskItem_0, gTaskItem_0_prev, gListEnd, gEndPrev2,
drop(gTaskItemIndex_0, gCells), drop(gTaskItemIndex_0, gVals),
gReadyList);
assert( xLIST_ITEM(gTaskItem_0, ?gV, ?gTaskItem_0_next, gTaskItem_0_prev, gReadyList) );
// open DLS and xLIST_ITEM predicates to prove
// `mem( gTaskItem_0->pxNext, gCells) == true )`
// which requires accessing `gTaskItem_0->pxNext`
if(gTaskItem_0 == gEndPrev2) {
// `gTaskItem_0` is last element in DLS suffix
// -> `gTaskItem_0_next` is head fo DLS prefix
// open DLS prefix
open xLIST_ITEM(gTaskItem_0, gV, gTaskItem_0_next, gTaskItem_0_prev, gReadyList);
assert( gCells == cons(_, _) );
assert( mem(gTaskItem_0->pxNext, gCells) == true );
// close item of interest
close xLIST_ITEM(gTaskItem_0, gV, gTaskItem_0_next, gTaskItem_0_prev, gReadyList);
} else {
// `gTaskItem_0` is not end of DLS suffix
// -> `gTaskItem_0_next` is also in DLS suffix
// open DLS suffix one step further
// rest of DLS suffix
assert( DLS(gTaskItem_0_next, gTaskItem_0, gListEnd, gEndPrev2,
drop(1, drop(gTaskItemIndex_0, gCells)), drop(1, drop(gTaskItemIndex_0, gVals)), //drop(gTaskItemIndex_0 + 1, gCells), drop(gTaskItemIndex_0 + 1, gVals),
gReadyList) );
open DLS(gTaskItem_0_next, gTaskItem_0, gListEnd, gEndPrev2,
drop(1, drop(gTaskItemIndex_0, gCells)), drop(1, drop(gTaskItemIndex_0, gVals)),
gReadyList);
assert( xLIST_ITEM(gTaskItem_0_next, ?gNextVal, ?gTaskItem_0_next_next, gTaskItem_0, gReadyList) );
open xLIST_ITEM(gTaskItem_0, gV, gTaskItem_0_next, gTaskItem_0_prev, gReadyList);
assert( gTaskItem_0_next == gTaskItem_0->pxNext );
assert( mem(gTaskItem_0_next, drop(1, drop(gTaskItemIndex_0, gCells))) == true );
//assert( gCells == cons(_, drop(1, drop(gTaskItemIndex_0, gCells)) );
assert( mem(gTaskItem_0_next, drop(gTaskItemIndex_0, gCells)) == true );
mem_suffix_implies_mem(gTaskItem_0_next, gCells, gTaskItemIndex_0);
assert( mem(gTaskItem_0_next, gCells) == true );
assert( mem(gTaskItem_0->pxNext, gCells) == true );
// close rest of DLS suffix
close xLIST_ITEM(gTaskItem_0_next, gNextVal, gTaskItem_0_next_next, gTaskItem_0, gReadyList);
close DLS(gTaskItem_0_next, gTaskItem_0, gListEnd, gEndPrev2,
drop(1, drop(gTaskItemIndex_0, gCells)), drop(1, drop(gTaskItemIndex_0, gVals)),
gReadyList);
// close item of interest
close xLIST_ITEM(gTaskItem_0, gV, gTaskItem_0_next, gTaskItem_0_prev, gReadyList);
}
}
@*/
/* By verifying the following function, we can validate that the above lemmas
* apply to the use cases they are meant for.
*/
void lemma_validation__DLS_item_next(struct xLIST_ITEM* pxTaskItem)
/*@ requires
DLS(?gListEnd, ?gEndPrev2, gListEnd, gEndPrev2, ?gCells, ?gVals, ?gReadyList) &*&
mem(pxTaskItem, gCells) == true &*&
gListEnd == head(gCells) &*&
length(gCells) == length(gVals) &*&
length(gCells) > 1;
@*/
/*@ ensures
DLS(gListEnd, gEndPrev2, gListEnd, gEndPrev2, gCells, gVals, gReadyList) &*&
mem(pxTaskItem, gCells) == true;
@*/
{
//@ int gTaskItemIndex_0 = index_of(pxTaskItem, gCells);
//@ struct xLIST_ITEM* gTaskItem_0 = pxTaskItem;
/*@
if( gTaskItem_0 == gListEnd ) {
DLS_end_next_open(gReadyList, gTaskItem_0);
} else {
DLS_nonEndItem_next_open(gReadyList, gTaskItem_0);
}
@*/
pxTaskItem = pxTaskItem->pxNext;
//@ struct xLIST_ITEM* gTaskItem_1 = pxTaskItem;
//@ assert( mem(gTaskItem_1, gCells) == true );
// ignore post condition until closing lemmas are finished
//@ assume(false);
}
#endif /* SCP_LIST_PREDICATES_EXTENDED_H */