diff options
Diffstat (limited to 'runtime/mem_map.h')
| -rw-r--r-- | runtime/mem_map.h | 33 |
1 files changed, 33 insertions, 0 deletions
diff --git a/runtime/mem_map.h b/runtime/mem_map.h index 5603963eac..0ecb414614 100644 --- a/runtime/mem_map.h +++ b/runtime/mem_map.h @@ -39,8 +39,12 @@ namespace art { #ifdef __linux__ static constexpr bool kMadviseZeroes = true; +#define HAVE_MREMAP_SYSCALL true #else static constexpr bool kMadviseZeroes = false; +// We cannot ever perform MemMap::ReplaceWith on non-linux hosts since the syscall is not +// present. +#define HAVE_MREMAP_SYSCALL false #endif // Used to keep track of mmap segments. @@ -52,6 +56,32 @@ static constexpr bool kMadviseZeroes = false; // Otherwise, calls might see uninitialized values. class MemMap { public: + static constexpr bool kCanReplaceMapping = HAVE_MREMAP_SYSCALL; + + // Replace the data in this memmmap with the data in the memmap pointed to by source. The caller + // relinquishes ownership of the source mmap. + // + // For the call to be successful: + // * The range [dest->Begin, dest->Begin() + source->Size()] must not overlap with + // [source->Begin(), source->End()]. + // * Neither source nor dest may be 'reused' mappings (they must own all the pages associated + // with them. + // * kCanReplaceMapping must be true. + // * Neither source nor dest may use manual redzones. + // * Both source and dest must have the same offset from the nearest page boundary. + // * mremap must succeed when called on the mappings. + // + // If this call succeeds it will return true and: + // * Deallocate *source + // * Sets *source to nullptr + // * The protection of this will remain the same. + // * The size of this will be the size of the source + // * The data in this will be the data from source. + // + // If this call fails it will return false and make no changes to *source or this. The ownership + // of the source mmap is returned to the caller. + bool ReplaceWith(/*in-out*/MemMap** source, /*out*/std::string* error); + // Request an anonymous region of length 'byte_count' and a requested base address. // Use null as the requested base address if you don't care. // "reuse" allows re-mapping an address range from an existing mapping. @@ -246,6 +276,9 @@ class MemMap { // unmapping. const bool reuse_; + // When already_unmapped_ is true the destructor will not call munmap. + bool already_unmapped_; + const size_t redzone_size_; #if USE_ART_LOW_4G_ALLOCATOR |