4fea7b8bb1
The PAL API previously allowed for returning more memory than asked for. This was when the PAL performed the alignment work, now this is done in large alloc, so removing from the PAL.
89 lines
2.1 KiB
C++
89 lines
2.1 KiB
C++
#pragma once
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#ifdef __APPLE__
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# include "pal_bsd.h"
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# include <mach/vm_statistics.h>
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namespace snmalloc
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{
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/**
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* PAL implementation for Apple systems (macOS, iOS, watchOS, tvOS...).
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*/
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template<int PALAnonID = PALAnonDefaultID>
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class PALApple : public PALBSD<PALApple<>>
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{
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public:
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/**
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* The features exported by this PAL.
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*
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* Currently, these are identical to the generic BSD PAL. This field is
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* declared explicitly to remind anyone who modifies this class that they
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* should add any required features.
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*/
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static constexpr uint64_t pal_features = PALBSD::pal_features;
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/**
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* OS specific function for zeroing memory with the Apple application
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* tag id.
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*
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* See comment below.
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*/
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template<bool page_aligned = false>
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void zero(void* p, size_t size)
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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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void* r = mmap(
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p,
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size,
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PROT_READ | PROT_WRITE,
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MAP_PRIVATE | MAP_ANONYMOUS | MAP_FIXED,
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pal_anon_id,
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0);
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if (r != MAP_FAILED)
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return;
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}
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bzero(p, size);
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}
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/**
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* Reserve memory with the Apple application tag id.
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*
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* See comment below.
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*/
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template<bool committed>
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void* reserve(size_t size)
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{
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void* p = mmap(
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nullptr,
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size,
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PROT_READ | PROT_WRITE,
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MAP_PRIVATE | MAP_ANONYMOUS,
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pal_anon_id,
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0);
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if (p == MAP_FAILED)
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error("Out of memory");
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return p;
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}
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private:
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/**
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* Anonymous page tag ID
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*
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* Darwin platform allows to gives an ID to anonymous pages via
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* the VM_MAKE_TAG's macro, from 240 up to 255 are guaranteed
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* to be free of usage, however eventually a lower could be taken
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* (e.g. LLVM sanitizers has 99) so we can monitor their states
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* via vmmap for instance.
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*/
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static constexpr int pal_anon_id = VM_MAKE_TAG(PALAnonID);
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};
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} // namespace snmalloc
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#endif
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