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Expose Entropy

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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
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24
src/mem/alloc.h
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@@ -98,6 +98,7 @@ namespace snmalloc
{
LargeAlloc<MemoryProvider> large_allocator;
ChunkMap chunk_map;
LocalEntropy entropy;
/**
* Per size class bumpptr for building new free lists
@@ -683,6 +684,11 @@ namespace snmalloc
if (isFake)
return;
// Entropy must be first, so that all data-structures can use the key
// it generates.
// This must occur before any freelists are constructed.
entropy.init<typename MemoryProvider::Pal>();
init_message_queue();
message_queue().invariant();
@@ -745,10 +751,10 @@ namespace snmalloc
Slab* slab = Metaslab::get_slab(bp);
while (pointer_align_up(bp, SLAB_SIZE) != bp)
{
Slab::alloc_new_list(bp, ffl, rsize);
Slab::alloc_new_list(bp, ffl, rsize, entropy);
while (!ffl.empty())
{
small_dealloc_offseted_inner(super, slab, ffl.take(), i);
small_dealloc_offseted_inner(super, slab, ffl.take(entropy), i);
}
}
}
@@ -762,7 +768,7 @@ namespace snmalloc
auto slab = Metaslab::get_slab(head);
do
{
auto curr = small_fast_free_lists[i].take();
auto curr = small_fast_free_lists[i].take(entropy);
small_dealloc_offseted_inner(super, slab, curr, i);
} while (!small_fast_free_lists[i].empty());
@@ -1016,7 +1022,7 @@ namespace snmalloc
{
stats().alloc_request(size);
stats().sizeclass_alloc(sizeclass);
void* p = remove_cache_friendly_offset(fl.take(), sizeclass);
void* p = remove_cache_friendly_offset(fl.take(entropy), sizeclass);
if constexpr (zero_mem == YesZero)
{
MemoryProvider::Pal::zero(p, sizeclass_to_size(sizeclass));
@@ -1061,7 +1067,7 @@ namespace snmalloc
auto meta = reinterpret_cast<Metaslab*>(sl.get_next());
auto& ffl = small_fast_free_lists[sizeclass];
return Metaslab::alloc<zero_mem, typename MemoryProvider::Pal>(
meta, ffl, rsize);
meta, ffl, rsize, entropy);
}
return small_alloc_rare<zero_mem>(sizeclass, size);
}
@@ -1125,9 +1131,9 @@ namespace snmalloc
auto rsize = sizeclass_to_size(sizeclass);
auto& ffl = small_fast_free_lists[sizeclass];
SNMALLOC_ASSERT(ffl.empty());
Slab::alloc_new_list(bp, ffl, rsize);
Slab::alloc_new_list(bp, ffl, rsize, entropy);
auto p = remove_cache_friendly_offset(ffl.take(), sizeclass);
auto p = remove_cache_friendly_offset(ffl.take(entropy), sizeclass);
if constexpr (zero_mem == YesZero)
{
@@ -1213,7 +1219,7 @@ namespace snmalloc
SNMALLOC_FAST_PATH void small_dealloc_offseted_inner(
Superslab* super, Slab* slab, void* p, sizeclass_t sizeclass)
{
if (likely(Slab::dealloc_fast(slab, super, p)))
if (likely(Slab::dealloc_fast(slab, super, p, entropy)))
return;
small_dealloc_offseted_slow(super, slab, p, sizeclass);
@@ -1224,7 +1230,7 @@ namespace snmalloc
{
bool was_full = super->is_full();
SlabList* sl = &small_classes[sizeclass];
Superslab::Action a = Slab::dealloc_slow(slab, sl, super, p);
Superslab::Action a = Slab::dealloc_slow(slab, sl, super, p, entropy);
if (likely(a == Superslab::NoSlabReturn))
return;
stats().sizeclass_dealloc_slab(sizeclass);