From 0aac36feb016237c6523b6416a8419711cb919dc Mon Sep 17 00:00:00 2001 From: Jacob Lifshay Date: Thu, 30 Nov 2023 23:46:50 -0800 Subject: [PATCH] mem.py: add load_elf --- src/openpower/decoder/isa/mem.py | 147 ++++++++++++++++++++++++++++++- 1 file changed, 143 insertions(+), 4 deletions(-) diff --git a/src/openpower/decoder/isa/mem.py b/src/openpower/decoder/isa/mem.py index 79fb8861..bea3c7f1 100644 --- a/src/openpower/decoder/isa/mem.py +++ b/src/openpower/decoder/isa/mem.py @@ -25,6 +25,8 @@ from nmutil import plain_data from pathlib import Path from openpower.syscalls import ppc_flags import os +from elftools.elf.elffile import ELFFile +from elftools.elf.constants import P_FLAGS def swap_order(x, nbytes): @@ -93,6 +95,8 @@ class MemCommon: self.initialize(row_bytes, initial_mem) def initialize(self, row_bytes, initial_mem): + if isinstance(initial_mem, ELFFile): + return load_elf(self, initial_mem) for addr, (val, width) in process_mem(initial_mem, row_bytes).items(): # val = swap_order(val, width) self.st(addr, val, width, swap=False) @@ -317,6 +321,7 @@ _ALLOWED_MMAP_STACK_FLAGS = MMapPageFlags.RWX | MMapPageFlags.GROWS_DOWN MMAP_PAGE_SIZE = 1 << 16 # size of chunk that we track _PAGE_COUNT = (1 << 48) // MMAP_PAGE_SIZE # 48-bit address space _NEG_PG_IDX_START = _PAGE_COUNT // 2 # start of negative half of address space +_USER_SPACE_SIZE = _NEG_PG_IDX_START * MMAP_PAGE_SIZE # code assumes BLOCK_SIZE is a power of two # BLOCK_SIZE = 1 << 32 @@ -327,10 +332,19 @@ assert MMAP_PAGE_SIZE % mmap.PAGESIZE == 0, "host's page size is too big" assert 2 ** (mmap.PAGESIZE.bit_length() - 1) == mmap.PAGESIZE, \ "host's page size isn't a power of 2" -DEFAULT_BLOCK_ADDRS = ( - 0, # low end of user space - 2 ** 47 - BLOCK_SIZE, # high end of user space -) +def _make_default_block_addrs(): + needed_page_addrs = ( + 0, # low end of user space + 0x10000000, # default ELF load address + _USER_SPACE_SIZE - MMAP_PAGE_SIZE, # high end of user space + ) + block_addrs = set() + for page_addr in needed_page_addrs: + offset = page_addr % BLOCK_SIZE + block_addrs.add(page_addr - offset) + return tuple(sorted(block_addrs)) + +DEFAULT_BLOCK_ADDRS = _make_default_block_addrs() @plain_data.plain_data(frozen=True, unsafe_hash=True) @@ -873,3 +887,128 @@ class MemMMap(MemCommon): block_addr = next_block_addr if bytes_ != zeros: yield word_idx + + +@plain_data.plain_data() +class LoadedELF: + __slots__ = "elf_file", "pc", "gprs", "fpscr" + + def __init__(self, elf_file, pc, gprs, fpscr): + self.elf_file = elf_file + self.pc = pc + self.gprs = gprs + self.fpscr = fpscr + + +def raise_if_syscall_err(result): + if -4096 < result < 0: + raise OSError(-result, os.strerror(-result)) + return result + + +# TODO: change to much smaller size once GROWSDOWN is implemented +DEFAULT_INIT_STACK_SZ = 4 << 20 + + +def load_elf(mem, elf_file, args=(), env=(), stack_size=DEFAULT_INIT_STACK_SZ): + if not isinstance(mem, MemMMap): + raise TypeError("MemMMap required to load ELFs") + if not isinstance(elf_file, ELFFile): + raise TypeError() + if elf_file.header['e_type'] != 'ET_EXEC': + raise NotImplementedError("dynamic binaries aren't implemented") + fd = elf_file.stream.fileno() + for segment in elf_file.iter_segments(): + if segment.header['p_type'] in ('PT_DYNAMIC', 'PT_INTERP'): + raise NotImplementedError("dynamic binaries aren't implemented") + elif segment.header['p_type'] == 'PT_LOAD': + flags = segment.header['p_flags'] + offset = segment.header['p_offset'] + vaddr = segment.header['p_vaddr'] + filesz = segment.header['p_filesz'] + memsz = segment.header['p_memsz'] + align = segment.header['p_align'] + if align != 0x10000: + raise NotImplementedError("non-default ELF segment alignment") + if align < MMAP_PAGE_SIZE: + raise NotImplementedError("align less than MMAP_PAGE_SIZE") + prot = ppc_flags.PROT_NONE + if flags & P_FLAGS.PF_R: + prot |= ppc_flags.PROT_READ + if flags & P_FLAGS.PF_W: + prot |= ppc_flags.PROT_WRITE + if flags & P_FLAGS.PF_X: + prot |= ppc_flags.PROT_EXEC + # align start to page + adj = offset % MMAP_PAGE_SIZE + offset -= adj + assert offset >= 0 + vaddr -= adj + filesz += adj + memsz += adj + # page-align, rounding up + filesz_aligned = ( + filesz + MMAP_PAGE_SIZE - 1) & ~(MMAP_PAGE_SIZE - 1) + page_end_init_needed = filesz < memsz and filesz < filesz_aligned + zero_pages_needed = memsz > filesz_aligned + adj_prot = prot # adjust prot for initialization + if page_end_init_needed: + # we need to initialize trailing bytes to zeros, + # so we need write access + adj_prot |= ppc_flags.PROT_WRITE + flags = ppc_flags.MAP_FIXED_NOREPLACE | ppc_flags.MAP_PRIVATE + result = mem.mmap_syscall( + vaddr, filesz, adj_prot, flags, fd, offset, is_mmap2=False) + raise_if_syscall_err(result) + if page_end_init_needed: + page_end = mem.get_ctypes( + vaddr + filesz, filesz_aligned - filesz, True) + ctypes.memset(page_end, 0, len(page_end)) + if zero_pages_needed: + result = mem.mmap_syscall( + vaddr + filesz_aligned, memsz - filesz_aligned, + prot, flags, fd=-1, offset=0, is_mmap2=False) + raise_if_syscall_err(result) + else: + log("ignoring ELF segment of type " + segment.header['p_type']) + # page-align stack_size, rounding up + stack_size = (stack_size + MMAP_PAGE_SIZE - 1) & ~(MMAP_PAGE_SIZE - 1) + stack_top = _USER_SPACE_SIZE + stack_low = stack_top - stack_size + prot = ppc_flags.PROT_READ | ppc_flags.PROT_WRITE + flags = ppc_flags.MAP_FIXED_NOREPLACE | ppc_flags.MAP_PRIVATE + result = mem.mmap_syscall( + stack_low, stack_size, prot, flags, fd=-1, offset=0, is_mmap2=False) + raise_if_syscall_err(result) + gprs = {} + if len(args): + raise NotImplementedError("allocate argv on the stack") + else: + argv = 0 + if len(env): + raise NotImplementedError("allocate envp on the stack") + else: + envp = 0 + + # FIXME: incorrect, should point to the aux vector allocated on the stack + auxv = 0 + + # make space for red zone, 512 bytes specified in + # 64-bit ELF V2 ABI Specification v1.5 section 2.2.3.4 + # https://files.openpower.foundation/s/cfA2oFPXbbZwEBK + stack_top -= 512 + + # align stack_top + stack_top -= stack_top % 16 + + # TODO: dynamically-linked binaries need to use the entry-point of ld.so + pc = elf_file.header['e_entry'] + gprs[1] = stack_top + gprs[3] = len(args) # argc + gprs[4] = argv + gprs[5] = envp + gprs[5] = auxv + gprs[7] = 0 # termination function pointer + gprs[12] = pc + fpscr = 0 + return LoadedELF(elf_file, pc, gprs, fpscr) -- 2.30.2