127 lines
3.0 KiB
C++
127 lines
3.0 KiB
C++
/**
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* =========================================================================
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* File : mem_util.cpp
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* Project : 0 A.D.
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* Description : memory allocator helper routines.
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* =========================================================================
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*/
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// license: GPL; see lib/license.txt
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#include "precompiled.h"
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#include "mem_util.h"
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#include "lib/bits.h" // round_up
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#include "lib/posix/posix_mman.h"
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#include "lib/sysdep/cpu.h" // cpu_PageSize
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size_t mem_PageSize()
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{
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static const size_t page_size = cpu_PageSize();
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return page_size;
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}
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bool mem_IsPageMultiple(uintptr_t x)
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{
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return (x & (mem_PageSize()-1)) == 0;
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}
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size_t mem_RoundUpToPage(size_t size)
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{
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return round_up(size, mem_PageSize());
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}
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size_t mem_RoundUpToAlignment(size_t size)
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{
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// all allocators should align to at least this many bytes:
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const size_t alignment = 8;
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return round_up(size, alignment);
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}
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//-----------------------------------------------------------------------------
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static inline LibError LibError_from_mmap(void* ret, bool warn_if_failed = true)
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{
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if(ret != MAP_FAILED)
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return INFO::OK;
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return LibError_from_errno(warn_if_failed);
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}
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// "anonymous" effectively means mapping /dev/zero, but is more efficient.
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// MAP_ANONYMOUS is not in SUSv3, but is a very common extension.
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// unfortunately, MacOS X only defines MAP_ANON, which Solaris says is
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// deprecated. workaround there: define MAP_ANONYMOUS in terms of MAP_ANON.
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#ifndef MAP_ANONYMOUS
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# define MAP_ANONYMOUS MAP_ANON
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#endif
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static const int mmap_flags = MAP_PRIVATE|MAP_ANONYMOUS;
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LibError mem_Reserve(size_t size, u8** pp)
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{
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errno = 0;
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void* ret = mmap(0, size, PROT_NONE, mmap_flags|MAP_NORESERVE, -1, 0);
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*pp = (u8*)ret;
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return LibError_from_mmap(ret);
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}
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LibError mem_Release(u8* p, size_t size)
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{
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errno = 0;
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int ret = munmap(p, size);
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return LibError_from_posix(ret);
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}
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LibError mem_Commit(u8* p, size_t size, int prot)
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{
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// avoid misinterpretation by mmap.
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if(prot == PROT_NONE)
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WARN_RETURN(ERR::INVALID_PARAM);
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errno = 0;
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void* ret = mmap(p, size, prot, mmap_flags|MAP_FIXED, -1, 0);
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return LibError_from_mmap(ret);
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}
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LibError mem_Decommit(u8* p, size_t size)
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{
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errno = 0;
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void* ret = mmap(p, size, PROT_NONE, mmap_flags|MAP_NORESERVE|MAP_FIXED, -1, 0);
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return LibError_from_mmap(ret);
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}
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LibError mem_Protect(u8* p, size_t size, int prot)
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{
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errno = 0;
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int ret = mprotect(p, size, prot);
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return LibError_from_posix(ret);
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}
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//-----------------------------------------------------------------------------
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// "freelist" is a pointer to the first unused element (0 if there are none);
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// its memory holds a pointer to the next free one in list.
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void mem_freelist_AddToFront(void*& freelist, void* el)
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{
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debug_assert(el != 0);
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void* prev_el = freelist;
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freelist = el;
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*(void**)el = prev_el;
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}
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void* mem_freelist_Detach(void*& freelist)
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{
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void* el = freelist;
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// nothing in list
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if(!el)
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return 0;
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freelist = *(void**)el;
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return el;
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}
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