53 lines
1.4 KiB
C++
53 lines
1.4 KiB
C++
#pragma once
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#if defined(__linux__)
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# include "../ds/bits.h"
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# include "../mem/allocconfig.h"
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# include "pal_posix.h"
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# include <string.h>
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# include <sys/mman.h>
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extern "C" int puts(const char* str);
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namespace snmalloc
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{
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class PALLinux : public PALPOSIX<PALLinux>
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{
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public:
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/**
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* Bitmap of PalFeatures flags indicating the optional features that this
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* PAL supports.
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*
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* Linux does not support any features other than those in a generic POSIX
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* platform. This field is declared explicitly to remind anyone who
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* extends this PAL that they may need to extend the set of advertised
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* features.
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*/
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static constexpr uint64_t pal_features = PALPOSIX::pal_features;
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/**
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* OS specific function for zeroing memory.
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*
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* Linux implements an unusual interpretation of `MADV_DONTNEED`, which
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* immediately resets the pages to the zero state (rather than marking them
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* as sensible ones to swap out in high memory pressure). We use this to
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* clear the underlying memory range.
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*/
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template<bool page_aligned = false>
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void zero(void* p, size_t size) noexcept
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{
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if (page_aligned || is_aligned_block<OS_PAGE_SIZE>(p, size))
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{
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assert(is_aligned_block<OS_PAGE_SIZE>(p, size));
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madvise(p, size, MADV_DONTNEED);
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}
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else
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{
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::memset(p, 0, size);
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}
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}
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};
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} // namespace snmalloc
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#endif
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