Cheri-research/snmalloc
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

Expose Entropy

Browse Source 
Define various parts of random that can be used to make the layout of
memory more random.  Thread this through the allocator.

Expose the concept as part of the Pal. Subsequent commits will expose
that on different platforms.
This commit is contained in:
Matthew Parkinson
2021-03-26 16:22:32 +00:00
committed by Matthew Parkinson
parent c5b65d07b8
commit f15dc6ee2e
8 changed files with 186 additions and 89 deletions
Download Patch File Download Diff File Expand all files Collapse all files

22
src/mem/metaslab.h
View File

@@ -160,14 +160,19 @@ namespace snmalloc
* eventually annotate that pointer with additional information.
*/
template<ZeroMem zero_mem, SNMALLOC_CONCEPT(ConceptPAL) PAL>
static SNMALLOC_FAST_PATH void*
alloc(Metaslab* self, FreeListIter& fast_free_list, size_t rsize)
static SNMALLOC_FAST_PATH void* alloc(
Metaslab* self,
FreeListIter& fast_free_list,
size_t rsize,
LocalEntropy& entropy)
{
SNMALLOC_ASSERT(rsize == sizeclass_to_size(self->sizeclass()));
SNMALLOC_ASSERT(!self->is_full());
self->free_queue.close(fast_free_list);
void* n = fast_free_list.take();
self->free_queue.close(fast_free_list, entropy);
void* n = fast_free_list.take(entropy);
entropy.refresh_bits();
// Treat stealing the free list as allocating it all.
self->remove();
@@ -176,7 +181,7 @@ namespace snmalloc
void* p = remove_cache_friendly_offset(n, self->sizeclass());
SNMALLOC_ASSERT(is_start_of_object(self, p));
self->debug_slab_invariant(Metaslab::get_slab(p));
self->debug_slab_invariant(Metaslab::get_slab(p), entropy);
if constexpr (zero_mem == YesZero)
{
@@ -193,14 +198,14 @@ namespace snmalloc
return p;
}
void debug_slab_invariant(Slab* slab)
void debug_slab_invariant(Slab* slab, LocalEntropy& entropy)
{
#if !defined(NDEBUG) && !defined(SNMALLOC_CHEAP_CHECKS)
bool is_short = Metaslab::is_short(slab);
if (is_full())
{
size_t count = free_queue.debug_length();
size_t count = free_queue.debug_length(entropy);
SNMALLOC_ASSERT(count < threshold_for_waking_slab(is_short));
return;
}
@@ -216,7 +221,7 @@ namespace snmalloc
SNMALLOC_ASSERT(SLAB_SIZE > accounted_for);
// Account for list size
size_t count = free_queue.debug_length();
size_t count = free_queue.debug_length(entropy);
accounted_for += count * size;
SNMALLOC_ASSERT(count <= get_slab_capacity(sizeclass(), is_short));
@@ -234,6 +239,7 @@ namespace snmalloc
SNMALLOC_ASSERT(SLAB_SIZE == accounted_for);
#else
UNUSED(slab);
UNUSED(entropy);
#endif
}
};