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SP: LargeAlloc return CBChunk & chase consequences

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Even if we opt not to bound these pointers internally (if they aren't headed out
to the user program or we later derive bounded pointers), they should still be
annotated as something other than CBArena, ensuring that we do not attempt to
use them for general amplification.
This commit is contained in:
Nathaniel Filardo
2021-04-01 13:20:17 +01:00
committed by Nathaniel Wesley Filardo
parent 54fec3821f
commit f7821e11eb
10 changed files with 175 additions and 126 deletions
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36
src/mem/metaslab.h
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@@ -4,14 +4,15 @@
#include "../ds/dllist.h"
#include "../ds/helpers.h"
#include "freelist.h"
#include "ptrhelpers.h"
#include "sizeclass.h"
namespace snmalloc
{
class Slab;
using SlabList = CDLLNode<CapPtrCBArena>;
using SlabLink = CDLLNode<CapPtrCBArena>;
using SlabList = CDLLNode<CapPtrCBChunk>;
using SlabLink = CDLLNode<CapPtrCBChunk>;
static_assert(
sizeof(SlabLink) <= MIN_ALLOC_SIZE,
@@ -71,7 +72,7 @@ namespace snmalloc
return free_queue.s.next;
}
void initialise(sizeclass_t sizeclass, CapPtr<Slab, CBArena> slab)
void initialise(sizeclass_t sizeclass, CapPtr<Slab, CBChunk> slab)
{
free_queue.s.sizeclass = static_cast<uint8_t>(sizeclass);
free_queue.init();
@@ -120,8 +121,10 @@ namespace snmalloc
return bits::min(threshold, max);
}
SNMALLOC_FAST_PATH void set_full(CapPtr<Slab, CBArena> slab)
template<capptr_bounds B>
SNMALLOC_FAST_PATH void set_full(CapPtr<Slab, B> slab)
{
static_assert(B == CBChunkD || B == CBChunk);
SNMALLOC_ASSERT(free_queue.empty());
// Prepare for the next free queue to be built.
@@ -134,9 +137,13 @@ namespace snmalloc
}
template<typename T, capptr_bounds B>
static CapPtr<Slab, B> get_slab(CapPtr<T, B> p)
static SNMALLOC_FAST_PATH CapPtr<Slab, capptr_bound_chunkd_bounds<B>()>
get_slab(CapPtr<T, B> p)
{
return pointer_align_down<SLAB_SIZE, Slab>(p.as_void());
static_assert(B == CBArena || B == CBChunkD || B == CBChunk);
return capptr_bound_chunkd(
pointer_align_down<SLAB_SIZE, Slab>(p.as_void()), SLAB_SIZE);
}
template<capptr_bounds B>
@@ -145,8 +152,9 @@ namespace snmalloc
return pointer_align_down<SUPERSLAB_SIZE, Slab>(p.as_void()) == p;
}
SNMALLOC_FAST_PATH
static bool is_start_of_object(CapPtr<Metaslab, CBArena> self, address_t p)
template<capptr_bounds B>
SNMALLOC_FAST_PATH static bool
is_start_of_object(CapPtr<Metaslab, B> self, address_t p)
{
return is_multiple_of_sizeclass(
self->sizeclass(), SLAB_SIZE - (p - address_align_down<SLAB_SIZE>(p)));
@@ -159,7 +167,7 @@ namespace snmalloc
*/
template<ZeroMem zero_mem, SNMALLOC_CONCEPT(ConceptPAL) PAL>
static SNMALLOC_FAST_PATH CapPtr<void, CBAllocE> alloc(
CapPtr<Metaslab, CBArena> self,
CapPtr<Metaslab, CBChunk> self,
FreeListIter& fast_free_list,
size_t rsize,
LocalEntropy& entropy)
@@ -169,17 +177,18 @@ namespace snmalloc
self->free_queue.close(fast_free_list, entropy);
auto n = fast_free_list.take(entropy);
auto n_slab = Aal::capptr_rebound(self.as_void(), n);
entropy.refresh_bits();
// Treat stealing the free list as allocating it all.
self->remove();
self->set_full(Metaslab::get_slab(n));
self->set_full(Metaslab::get_slab(n_slab));
auto p = remove_cache_friendly_offset(n, self->sizeclass());
SNMALLOC_ASSERT(is_start_of_object(self, address_cast(p)));
self->debug_slab_invariant(Metaslab::get_slab(n), entropy);
self->debug_slab_invariant(Metaslab::get_slab(n_slab), entropy);
if constexpr (zero_mem == YesZero)
{
@@ -196,8 +205,11 @@ namespace snmalloc
return capptr_export(Aal::capptr_bound<void, CBAlloc>(p, rsize));
}
void debug_slab_invariant(CapPtr<Slab, CBArena> slab, LocalEntropy& entropy)
template<capptr_bounds B>
void debug_slab_invariant(CapPtr<Slab, B> slab, LocalEntropy& entropy)
{
static_assert(B == CBChunkD || B == CBChunk);
#if !defined(NDEBUG) && !defined(SNMALLOC_CHEAP_CHECKS)
bool is_short = Metaslab::is_short(slab);