Files
snmalloc/src/pal/pal_bsd_aligned.h
David Chisnall fd88b8464b [NFC] Separate out support for aligned allocation from the FreeBSD PAL.
NetBSD also supports `MAP_ALIGNED()` in `mmap` (according to the man
page, at least).
2019-08-01 11:39:26 +01:00

56 lines
1.3 KiB
C++

#pragma once
#if defined(__FreeBSD__) && !defined(_KERNEL)
# include "pal_bsd.h"
namespace snmalloc
{
/**
* FreeBSD-specific platform abstraction layer.
*
* This adds aligned allocation using `MAP_ALIGNED` to the generic BSD
* implementation. This flag is supported by NetBSD and FreeBSD.
*/
template<class OS>
class PALBSD_Aligned : public PALBSD<OS>
{
public:
/**
* Bitmap of PalFeatures flags indicating the optional features that this
* PAL supports.
*
* This class adds support for aligned allocation.
*/
static constexpr uint64_t pal_features =
AlignedAllocation | PALBSD<OS>::pal_features;
/**
* Reserve memory at a specific alignment.
*/
template<bool committed>
void* reserve(const size_t* size, size_t align) noexcept
{
// Alignment must be a power of 2.
assert(align == bits::next_pow2(align));
align = bits::max<size_t>(4096, align);
size_t log2align = bits::next_pow2_bits(align);
void* p = mmap(
nullptr,
*size,
PROT_READ | PROT_WRITE,
MAP_PRIVATE | MAP_ANONYMOUS | MAP_ALIGNED(log2align),
-1,
0);
if (p == MAP_FAILED)
error("Out of memory");
return p;
}
};
} // namespace snmalloc
#endif