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pal_linux.h
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pal_linux.h
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#pragma once
#if defined(__linux__)
# include "../ds/bits.h"
# include "../mem/allocconfig.h"
# include <string.h>
# include <sys/mman.h>
extern "C" int puts(const char* str);
namespace snmalloc
{
class PALLinux
{
public:
/**
* Bitmap of PalFeatures flags indicating the optional features that this
* PAL supports.
*/
static constexpr uint64_t pal_features = LazyCommit;
static void error(const char* const str)
{
puts(str);
abort();
}
/// Notify platform that we will not be using these pages
void notify_not_using(void* p, size_t size) noexcept
{
assert(bits::is_aligned_block<OS_PAGE_SIZE>(p, size));
// Do nothing. Don't call madvise here, as the system call slows the
// allocator down too much.
UNUSED(p);
UNUSED(size);
}
/// Notify platform that we will be using these pages
template<ZeroMem zero_mem>
void notify_using(void* p, size_t size) noexcept
{
assert(
bits::is_aligned_block<OS_PAGE_SIZE>(p, size) || (zero_mem == NoZero));
if constexpr (zero_mem == YesZero)
zero<true>(p, size);
else
{
UNUSED(p);
UNUSED(size);
}
}
/// OS specific function for zeroing memory
template<bool page_aligned = false>
void zero(void* p, size_t size) noexcept
{
if (page_aligned || bits::is_aligned_block<OS_PAGE_SIZE>(p, size))
{
assert(bits::is_aligned_block<OS_PAGE_SIZE>(p, size));
madvise(p, size, MADV_DONTNEED);
}
else
{
::memset(p, 0, size);
}
}
template<bool committed>
void* reserve(const size_t* size) noexcept
{
void* p = mmap(
nullptr,
*size,
PROT_READ | PROT_WRITE,
MAP_PRIVATE | MAP_ANONYMOUS,
-1,
0);
if (p == MAP_FAILED)
error("Out of memory");
return p;
}
};
} // namespace snmalloc
#endif