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Pagemap requires registration of used space

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This PR exposes a pagemap interface to specify ranges that are being
used. The overall invariant is that any memory in the address space
manager has the pagemap committed. This means that individual operations
do not need to commit entries.

This is important for Windows that does not support lazy commit.  It is
also important if we want to PROT_NONE most of the pagemap to reduce the
risk of memory safety issues getting access to the pagemap.

There are minor changes to test to pull memory directly from the Pal.
There are also bug fixes in the pagemap tests.
This commit is contained in:
Matthew Parkinson
2021-07-16 14:27:16 +01:00
committed by Matthew Parkinson
parent da01d5b4ca
commit 02d2ab8f7e
7 changed files with 115 additions and 172 deletions
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11
src/backend/backend.h
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@@ -65,14 +65,13 @@ namespace snmalloc
}
template<bool fixed_range_ = fixed_range>
std::enable_if_t<fixed_range_>
init(CapPtr<void, CBChunk> base, size_t length)
std::enable_if_t<fixed_range_> init(void* base, size_t length)
{
static_assert(
fixed_range_ == fixed_range, "Don't set SFINAE parameter!");
auto [heap_base, heap_length] = pagemap.init(base, length);
address_space.add_range(heap_base, heap_length);
address_space.add_range(CapPtr<void, CBChunk>(heap_base), heap_length);
if constexpr (!fixed_range)
{
@@ -106,7 +105,7 @@ namespace snmalloc
auto& a = h.address_space;
// TODO Improve heuristics and params
auto refill_size = bits::max(size, bits::one_at_bit(21));
auto refill = a.template reserve<false>(refill_size);
auto refill = a.template reserve<false>(refill_size, h.pagemap);
if (refill == nullptr)
return nullptr;
local_state->local_address_space.template add_range<PAL>(
@@ -122,7 +121,7 @@ namespace snmalloc
else
{
auto& a = h.address_space;
p = a.template reserve_with_left_over<true>(size);
p = a.template reserve_with_left_over<true>(size, h.pagemap);
}
return p;
@@ -183,7 +182,7 @@ namespace snmalloc
a < address_cast(pointer_offset(p, size));
a += MIN_CHUNK_SIZE)
{
h.pagemap.add(a, t);
h.pagemap.set(a, t);
}
return {p, meta};
}