From 3cc9297245db2a7651f0710e5b3be46767047cde Mon Sep 17 00:00:00 2001 From: Jacob Lifshay Date: Sat, 2 Dec 2023 19:23:22 -0800 Subject: [PATCH] MemMMap: finish implementing brk_syscall --- src/openpower/decoder/isa/mem.py | 200 ++++++++++++++++++++++++------- 1 file changed, 156 insertions(+), 44 deletions(-) diff --git a/src/openpower/decoder/isa/mem.py b/src/openpower/decoder/isa/mem.py index bea3c7f1..14a5f4df 100644 --- a/src/openpower/decoder/isa/mem.py +++ b/src/openpower/decoder/isa/mem.py @@ -310,7 +310,8 @@ class MMapPageFlags(enum.IntFlag): """this memory block will grow when the address one page before the beginning is accessed""" - RWX = R | W | X + RW = R | W + RWX = RW | X NONE = 0 @@ -388,12 +389,15 @@ class MMapEmuBlock: self.page_indexes # check that addresses can be mapped to pages def intersects(self, other): - # type: (MMapEmuBlock) -> bool - return (other.addrs.start < self.addrs.stop - and self.addrs.start < other.addrs.stop) + # type: (MMapEmuBlock | range) -> bool + if isinstance(other, MMapEmuBlock): + other = other.addrs + if len_(other) == 0: + return False + return other.start < self.addrs.stop and self.addrs.start < other.stop @property - def is_private_mem(self): + def is_private_anon(self): return self.file is None and not self.flags & MMapPageFlags.S @property @@ -470,8 +474,7 @@ def len_(r): class MemMMap(MemCommon): def __init__(self, row_bytes=8, initial_mem=None, misaligned_ok=False, - block_addrs=DEFAULT_BLOCK_ADDRS, emulating_mmap=False, - mmap_emu_data_block=None): + block_addrs=DEFAULT_BLOCK_ADDRS, emulating_mmap=False): # we can't allocate the entire 2 ** 47 byte address space, so split # it into smaller blocks self.mem_blocks = { @@ -480,7 +483,7 @@ class MemMMap(MemCommon): "misaligned block address not supported" self.__page_flags = {} self.modified_pages = set() - self.mmap_emu_data_block = mmap_emu_data_block + self.__heap_range = None self.__mmap_emu_alloc_blocks = set() # type: set[MMapEmuBlock] | None for addr, block in self.mem_blocks.items(): @@ -495,22 +498,8 @@ class MemMMap(MemCommon): range(a, a + len(b)) for a, b in self.mem_blocks.items()] self.__mmap_emu_unbacked_blocks = tuple(self.__gaps_in(addr_ranges)) - if emulating_mmap: - if mmap_emu_data_block is not None: - if not isinstance(mmap_emu_data_block, MMapEmuBlock): - raise TypeError( - "mmap_emu_data_block must be a MMapEmuBlock") - if mmap_emu_data_block.file is not None: - raise ValueError( - "mmap_emu_data_block must be an anonymous mapping") - if not self.__mmap_emu_map_fixed(block=mmap_emu_data_block, - replace=False, dry_run=False): - raise ValueError("invalid mmap_emu_data_block") - else: + if not emulating_mmap: self.__mmap_emu_alloc_blocks = None - if mmap_emu_data_block is not None: - raise ValueError("can't set mmap_emu_data_block " - "without emulating_mmap=True") # mark blocks as readable/writable for addr, block in self.mem_blocks.items(): start_page = self.addr_to_mmap_page_idx(addr) @@ -520,6 +509,30 @@ class MemMMap(MemCommon): super().__init__(row_bytes, initial_mem, misaligned_ok) + @property + def heap_range(self): + # type: () -> range | None + return self.__heap_range + + @heap_range.setter + def heap_range(self, value): + # type: (range | None) -> None + if value is None: + self.__heap_range = value + return + if not self.emulating_mmap: + raise ValueError( + "can't set heap_range without emulating_mmap=True") + if not isinstance(value, range): + raise TypeError("heap_range must be a range or None") + if value.step != 1 or value.start > value.stop: + raise ValueError("heap_range is not a suitable range") + if value.start % MMAP_PAGE_SIZE != 0: + raise ValueError("heap_range.start must be aligned") + if value.stop % MMAP_PAGE_SIZE != 0: + raise ValueError("heap_range.stop must be aligned") + self.__heap_range = value + @staticmethod def __gaps_in(sorted_ranges, start=0, stop=2 ** 64): # type: (list[range] | tuple[range], int, int) -> list[range] @@ -559,10 +572,6 @@ class MemMMap(MemCommon): for b in intersecting_blocks: if not replace: return False - if self.mmap_emu_data_block == b: - # FIXME: what does linux do here? - raise NotImplementedError( - "mmap overlapping the data block isn't implemented") if not dry_run: self.__mmap_emu_alloc_blocks.remove(b) for replacement in b.difference(block): @@ -573,6 +582,52 @@ class MemMMap(MemCommon): self.__page_flags[page_idx] = block.flags return True + def __mmap_emu_unmap(self, block): + # type: (MMapEmuBlock) -> int + """unmap `block`, return 0 if no error, otherwise return -errno""" + assert block in self.__mmap_emu_alloc_blocks, \ + "can't unmap already unmapped block" + + # replace mapping with zeros + retval = self.__mmap_emu_zero_block(block) + if retval < 0: + return retval + # remove block + self.__mmap_emu_alloc_blocks.remove(block) + # mark pages as empty + for page_idx in block.page_indexes: + self.__page_flags.pop(page_idx) + self.modified_pages.remove(page_idx) + return retval + + def __mmap_emu_zero_block(self, block): + # type: (MMapEmuBlock) -> int + """ mmap zeros over block, return 0 if no error, + otherwise return -errno + """ + mblock = self.mem_blocks[block.underlying_block_key] + offsets = block.underlying_block_offsets + buf = (ctypes.c_ubyte * len(offsets)).from_buffer(mblock, offsets[0]) + buf_addr = ctypes.addressof(buf) + libc = ctypes.CDLL(None) + syscall = libc.syscall + syscall.restype = ctypes.c_long + syscall.argtypes = (ctypes.c_long,) * 6 + call_no = ctypes.c_long(ppc_flags.host_defines['SYS_mmap']) + host_prot = ppc_flags.host_defines['PROT_READ'] + host_prot |= ppc_flags.host_defines['PROT_WRITE'] + host_flags = ppc_flags.host_defines['MAP_ANONYMOUS'] + host_flags |= ppc_flags.host_defines['MAP_FIXED'] + host_flags |= ppc_flags.host_defines['MAP_PRIVATE'] + # map a block of zeros over it + if -1 == int(syscall( + call_no, ctypes.c_long(buf_addr), + ctypes.c_long(len(offsets)), + ctypes.c_long(host_prot), ctypes.c_long(host_flags), + ctypes.c_long(-1), ctypes.c_long(0))): + return -ctypes.get_errno() + return 0 + def __mmap_emu_resize_map_fixed(self, block, new_size): # type: (MMapEmuBlock, int) -> MMapEmuBlock | None assert block in self.__mmap_emu_alloc_blocks, \ @@ -588,28 +643,23 @@ class MemMMap(MemCommon): return None finally: self.__mmap_emu_alloc_blocks.add(block) - if not block.is_private_mem: + if not block.is_private_anon: # FIXME: implement resizing underlying mapping raise NotImplementedError else: # clear newly mapped bytes clear_addrs = range(block.addrs.stop, new_block.addrs.stop) - if len(clear_addrs): + if len_(clear_addrs): clear_block = MMapEmuBlock(clear_addrs) - mem_block = self.mem_blocks[clear_block.underlying_block_key] - assert mem_block is not None - clear_size = len(clear_addrs) - arr = (ctypes.c_ubyte * clear_size).from_buffer( - mem_block, clear_block.underlying_block_offsets.start) - ctypes.memset(arr, 0, clear_size) - if self.mmap_emu_data_block == block: - self.mmap_emu_data_block = new_block - self.__mmap_emu_alloc_blocks.remove(block) - self.__mmap_emu_alloc_blocks.add(new_block) + if self.__mmap_emu_zero_block(clear_block) < 0: + return None if new_size < len(block.addrs): # shrinking -- unmap pages at end r = range(new_block.page_indexes.stop, block.page_indexes.stop) + clear_block = MMapEmuBlock(r) + if self.__mmap_emu_zero_block(clear_block) < 0: + return None for page_idx in r: self.__page_flags.pop(page_idx) self.modified_pages.remove(page_idx) @@ -619,6 +669,8 @@ class MemMMap(MemCommon): for page_idx in r: self.__page_flags[page_idx] = block.flags self.modified_pages.remove(page_idx) # cleared page + self.__mmap_emu_alloc_blocks.remove(block) + self.__mmap_emu_alloc_blocks.add(new_block) return new_block def __mmap_emu_find_free_addr(self, block): @@ -654,14 +706,71 @@ class MemMMap(MemCommon): def brk_syscall(self, addr): assert self.emulating_mmap, "brk syscall requires emulating_mmap=True" - assert self.mmap_emu_data_block is not None, \ - "brk syscall requires a data block/segment" + assert self.heap_range is not None, "brk syscall requires a heap" + + if addr < self.heap_range.start: + # can't shrink heap to negative size + return self.heap_range.stop # don't change heap # round addr up to the nearest page addr_div_page_size = -(-addr // MMAP_PAGE_SIZE) # ceil(addr / size) addr = addr_div_page_size * MMAP_PAGE_SIZE - raise NotImplementedError # FIXME: finish + # something else could be mmap-ped in the middle of the heap, + # be careful... + + block = None + if len_(self.heap_range) != 0: + for b in self.__mmap_emu_alloc_blocks: + # we check for the end matching so we get the last heap block + # if the heap was split. + # the heap must not be a file mapping. + # the heap must not be shared, and must be RW + if b.addrs.stop == self.heap_range.stop and b.file is None \ + and b.flags == MMapPageFlags.RW: + block = b + break + + if block is not None and addr < block.addrs.start: + # heap was split by something, we can't shrink beyond + # the start of the last heap block + return self.heap_range.stop # don't change heap + + if block is not None and addr == block.addrs.start: + # unmap heap block + if self.__mmap_emu_unmap(block) < 0: + block = None # can't unmap heap block + elif addr > self.heap_range.stop and block is None: + # map new heap block + try: + addrs = range(self.heap_range.stop, addr) + block = MMapEmuBlock(addrs, flags=MMapPageFlags.RW) + if not self.__mmap_emu_map_fixed(block, + replace=False, dry_run=True): + block = None + elif 0 != self.__mmap_emu_zero_block(block): + block = None + else: + self.__mmap_emu_map_fixed(block, + replace=False, dry_run=False) + except (MemException, ValueError): + # caller could pass in invalid size, catch that + block = None + elif block is not None: # resize block + try: + block = self.__mmap_emu_resize_map_fixed( + block, addr - block.addrs.start) + except (MemException, ValueError): + # caller could pass in invalid size, catch that + block = None + + if block is None and addr != self.heap_range.start: + # can't resize heap block + return self.heap_range.stop # don't change heap + + # success! assign new heap_range + self.heap_range = range(self.heap_range.start, addr) + return self.heap_range.stop # return new brk address def mmap_syscall(self, addr, length, prot, flags, fd, offset, is_mmap2): assert self.emulating_mmap, "mmap syscall requires emulating_mmap=True" @@ -753,8 +862,6 @@ class MemMMap(MemCommon): buf_addr = ctypes.addressof(buf) libc = ctypes.CDLL(None) syscall = libc.syscall - restype = syscall.restype - argtypes = syscall.argtypes syscall.restype = ctypes.c_long syscall.argtypes = (ctypes.c_long,) * 6 call_no = ctypes.c_long(ppc_flags.host_defines['SYS_mmap']) @@ -768,6 +875,11 @@ class MemMMap(MemCommon): extra_zeros_start = 0 if file is None: host_flags |= ppc_flags.host_defines['MAP_ANONYMOUS'] + # don't remove check, since we'll eventually have shared memory + if host_flags & ppc_flags.host_defines['MAP_PRIVATE']: + # always map private memory read/write, + # so we can clear it if needed + host_prot |= ppc_flags.host_defines['PROT_WRITE'] else: file_sz = os.fstat(fd).st_size # host-page-align file_sz, rounding up -- 2.30.2