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Enable guard pages in CHECK_CLIENT

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Change the behaviour to use PROT_NONE for reservations in CHECK_CLIENT
mode.  This means that we only provide access once data is actually
being used.
This commit is contained in:
Matthew Parkinson
2021-07-16 16:35:54 +01:00
committed by Matthew Parkinson
parent 02d2ab8f7e
commit 9df0101dfd
12 changed files with 45 additions and 51 deletions
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20
src/mem/freelist.h
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@@ -90,7 +90,7 @@ namespace snmalloc
// TODO: Should really use C++20 atomic_ref rather than a union.
AtomicCapPtr<FreeObject, CBAlloc> atomic_next_object;
};
#ifdef CHECK_CLIENT
#ifdef SNMALLOC_CHECK_CLIENT
// Encoded representation of a back pointer.
// Hard to fake, and provides consistency on
// the next pointers.
@@ -104,7 +104,7 @@ namespace snmalloc
}
/**
* Assign next_object and update its prev_encoded if CHECK_CLIENT.
* Assign next_object and update its prev_encoded if SNMALLOC_CHECK_CLIENT.
* Static so that it can be used on reference to a FreeObject.
*
* Returns a pointer to the next_object field of the next parameter as an
@@ -116,7 +116,7 @@ namespace snmalloc
CapPtr<FreeObject, CBAlloc> next,
FreeListKey& key)
{
#ifdef CHECK_CLIENT
#ifdef SNMALLOC_CHECK_CLIENT
next->prev_encoded =
signed_prev(address_cast(curr), address_cast(next), key);
#else
@@ -127,13 +127,13 @@ namespace snmalloc
}
/**
* Assign next_object and update its prev_encoded if CHECK_CLIENT
* Assign next_object and update its prev_encoded if SNMALLOC_CHECK_CLIENT
*
* Uses the atomic view of next, so can be used in the message queues.
*/
void atomic_store_next(CapPtr<FreeObject, CBAlloc> next, FreeListKey& key)
{
#ifdef CHECK_CLIENT
#ifdef SNMALLOC_CHECK_CLIENT
next->prev_encoded =
signed_prev(address_cast(this), address_cast(next), key);
#else
@@ -152,7 +152,7 @@ namespace snmalloc
CapPtr<FreeObject, CBAlloc> atomic_read_next(FreeListKey& key)
{
auto n = atomic_next_object.load(std::memory_order_acquire);
#ifdef CHECK_CLIENT
#ifdef SNMALLOC_CHECK_CLIENT
if (n != nullptr)
{
n->check_prev(signed_prev(address_cast(this), address_cast(n), key));
@@ -194,7 +194,7 @@ namespace snmalloc
class FreeListIter
{
CapPtr<FreeObject, CBAlloc> curr{nullptr};
#ifdef CHECK_CLIENT
#ifdef SNMALLOC_CHECK_CLIENT
address_t prev{0};
#endif
@@ -203,7 +203,7 @@ namespace snmalloc
CapPtr<FreeObject, CBAlloc> head, address_t prev_value)
: curr(head)
{
#ifdef CHECK_CLIENT
#ifdef SNMALLOC_CHECK_CLIENT
prev = prev_value;
#endif
UNUSED(prev_value);
@@ -237,7 +237,7 @@ namespace snmalloc
Aal::prefetch(next.unsafe_ptr());
curr = next;
#ifdef CHECK_CLIENT
#ifdef SNMALLOC_CHECK_CLIENT
c->check_prev(prev);
prev = signed_prev(address_cast(c), address_cast(next), key);
#else
@@ -251,7 +251,7 @@ namespace snmalloc
/**
* Used to build a free list in object space.
*
* Adds signing of pointers in the CHECK_CLIENT mode
* Adds signing of pointers in the SNMALLOC_CHECK_CLIENT mode
*
* We use the template parameter, so that an enclosing
* class can make use of the remaining bytes, which may not