| #!/usr/bin/env python3 |
| # |
| # Copyright (c) 2020 Intel Corporation |
| # |
| # SPDX-License-Identifier: Apache-2.0 |
| |
| """Create the kernel's page tables for x86 CPUs. |
| |
| For additional detail on paging and x86 memory management, please |
| consult the IA Architecture SW Developer Manual, volume 3a, chapter 4. |
| |
| This script produces the initial page tables installed into the CPU |
| at early boot. These pages will have an identity mapping of the kernel |
| image. The script takes the 'zephyr_prebuilt.elf' as input to obtain region |
| sizes, certain memory addresses, and configuration values. |
| |
| If CONFIG_SRAM_REGION_PERMISSIONS is not enabled, the kernel image will be |
| mapped with the Present and Write bits set. The linker scripts shouldn't |
| add page alignment padding between sections. |
| |
| If CONFIG_SRAM_REGION_PERMISSIONS is enabled, the access permissions |
| vary: |
| - By default, the Present, Write, and Execute Disable bits are |
| set. |
| - The __text_region region will have Present and User bits set |
| - The __rodata_region region will have Present, User, and Execute |
| Disable bits set |
| - On x86_64, the _locore region will have Present set and |
| the _lorodata region will have Present and Execute Disable set. |
| |
| This script will establish a dual mapping at the address defined by |
| CONFIG_KERNEL_VM_BASE if it is not the same as CONFIG_SRAM_BASE_ADDRESS. |
| |
| - The double-mapping is used to transition the |
| instruction pointer from a physical address at early boot to the |
| virtual address where the kernel is actually linked. |
| |
| - The mapping is always double-mapped at the top-level paging structure |
| and the physical/virtual base addresses must have the same alignment |
| with respect to the scope of top-level paging structure entries. |
| This allows the same second-level paging structure(s) to be used for |
| both memory bases. |
| |
| - The double-mapping is needed so that we can still fetch instructions |
| from identity-mapped physical addresses after we program this table |
| into the MMU, then jump to the equivalent virtual address. |
| The kernel then unlinks the identity mapping before continuing, |
| the address space is purely virtual after that. |
| |
| Because the set of page tables are linked together by physical address, |
| we must know a priori the physical address of each table. The linker |
| script must define a z_x86_pagetables_start symbol where the page |
| tables will be placed, and this memory address must not shift between |
| prebuilt and final ELF builds. This script will not work on systems |
| where the physical load address of the kernel is unknown at build time. |
| |
| 64-bit systems will always build IA-32e page tables. 32-bit systems |
| build PAE page tables if CONFIG_X86_PAE is set, otherwise standard |
| 32-bit page tables are built. |
| |
| The kernel will expect to find the top-level structure of the produced |
| page tables at the physical address corresponding to the symbol |
| z_x86_kernel_ptables. The linker script will need to set that symbol |
| to the end of the binary produced by this script, minus the size of the |
| top-level paging structure as it is written out last. |
| """ |
| |
| import sys |
| import array |
| import argparse |
| import ctypes |
| import os |
| import struct |
| import re |
| import textwrap |
| |
| from distutils.version import LooseVersion |
| |
| import elftools |
| from elftools.elf.elffile import ELFFile |
| from elftools.elf.sections import SymbolTableSection |
| |
| if LooseVersion(elftools.__version__) < LooseVersion('0.24'): |
| sys.exit("pyelftools is out of date, need version 0.24 or later") |
| |
| |
| def bit(pos): |
| """Get value by shifting 1 by pos""" |
| return 1 << pos |
| |
| |
| # Page table entry flags |
| FLAG_P = bit(0) |
| FLAG_RW = bit(1) |
| FLAG_US = bit(2) |
| FLAG_CD = bit(4) |
| FLAG_SZ = bit(7) |
| FLAG_G = bit(8) |
| FLAG_XD = bit(63) |
| |
| FLAG_IGNORED0 = bit(9) |
| FLAG_IGNORED1 = bit(10) |
| FLAG_IGNORED2 = bit(11) |
| |
| ENTRY_RW = FLAG_RW | FLAG_IGNORED0 |
| ENTRY_US = FLAG_US | FLAG_IGNORED1 |
| ENTRY_XD = FLAG_XD | FLAG_IGNORED2 |
| |
| # PD_LEVEL and PT_LEVEL are used as list index to PtableSet.levels[] |
| # to get table from back of list. |
| PD_LEVEL = -2 |
| PT_LEVEL = -1 |
| |
| |
| def debug(text): |
| """Display verbose debug message""" |
| if not args.verbose: |
| return |
| sys.stdout.write(os.path.basename(sys.argv[0]) + ": " + text + "\n") |
| |
| |
| def verbose(text): |
| """Display --verbose --verbose message""" |
| if args.verbose and args.verbose > 1: |
| sys.stdout.write(os.path.basename(sys.argv[0]) + ": " + text + "\n") |
| |
| |
| def error(text): |
| """Display error message and exit program""" |
| sys.exit(os.path.basename(sys.argv[0]) + ": " + text) |
| |
| |
| def align_check(base, size, scope=4096): |
| """Make sure base and size are page-aligned""" |
| if (base % scope) != 0: |
| error("unaligned base address %x" % base) |
| if (size % scope) != 0: |
| error("Unaligned region size 0x%x for base %x" % (size, base)) |
| |
| |
| def dump_flags(flags): |
| """Translate page table flags into string""" |
| ret = "" |
| |
| if flags & FLAG_P: |
| ret += "P " |
| |
| if flags & FLAG_RW: |
| ret += "RW " |
| |
| if flags & FLAG_US: |
| ret += "US " |
| |
| if flags & FLAG_G: |
| ret += "G " |
| |
| if flags & FLAG_XD: |
| ret += "XD " |
| |
| if flags & FLAG_SZ: |
| ret += "SZ " |
| |
| if flags & FLAG_CD: |
| ret += "CD " |
| |
| return ret.strip() |
| |
| |
| def round_up(val, align): |
| """Round up val to the next multiple of align""" |
| return (val + (align - 1)) & (~(align - 1)) |
| |
| |
| def round_down(val, align): |
| """Round down val to the previous multiple of align""" |
| return val & (~(align - 1)) |
| |
| |
| # Hard-coded flags for intermediate paging levels. Permissive, we only control |
| # access or set caching properties at leaf levels. |
| INT_FLAGS = FLAG_P | FLAG_RW | FLAG_US |
| |
| class MMUTable(): |
| """Represents a particular table in a set of page tables, at any level""" |
| |
| def __init__(self): |
| self.entries = array.array(self.type_code, |
| [0 for i in range(self.num_entries)]) |
| |
| def get_binary(self): |
| """Return a bytearray representation of this table""" |
| # Always little-endian |
| ctype = "<" + self.type_code |
| entry_size = struct.calcsize(ctype) |
| ret = bytearray(entry_size * self.num_entries) |
| |
| for i in range(self.num_entries): |
| struct.pack_into(ctype, ret, entry_size * i, self.entries[i]) |
| return ret |
| |
| @property |
| def supported_flags(self): |
| """Class property indicating what flag bits are supported""" |
| raise NotImplementedError() |
| |
| @property |
| def addr_shift(self): |
| """Class property for how much to shift virtual addresses to obtain |
| the appropriate index in the table for it""" |
| raise NotImplementedError() |
| |
| @property |
| def addr_mask(self): |
| """Mask to apply to an individual entry to get the physical address |
| mapping""" |
| raise NotImplementedError() |
| |
| @property |
| def type_code(self): |
| """Struct packing letter code for table entries. Either I for |
| 32-bit entries, or Q for PAE/IA-32e""" |
| raise NotImplementedError() |
| |
| @property |
| def num_entries(self): |
| """Number of entries in the table. Varies by table type and paging |
| mode""" |
| raise NotImplementedError() |
| |
| def entry_index(self, virt_addr): |
| """Get the index of the entry in this table that corresponds to the |
| provided virtual address""" |
| return (virt_addr >> self.addr_shift) & (self.num_entries - 1) |
| |
| def has_entry(self, virt_addr): |
| """Indicate whether an entry is present in this table for the provided |
| virtual address""" |
| index = self.entry_index(virt_addr) |
| |
| return (self.entries[index] & FLAG_P) != 0 |
| |
| def lookup(self, virt_addr): |
| """Look up the physical mapping for a virtual address. |
| |
| If this is a leaf table, this is the physical address mapping. If not, |
| this is the physical address of the next level table""" |
| index = self.entry_index(virt_addr) |
| |
| return self.entries[index] & self.addr_mask |
| |
| def map(self, virt_addr, phys_addr, entry_flags): |
| """For the table entry corresponding to the provided virtual address, |
| set the corresponding physical entry in the table. Unsupported flags |
| will be filtered out. |
| |
| If this is a leaf table, this is the physical address mapping. If not, |
| this is the physical address of the next level table""" |
| index = self.entry_index(virt_addr) |
| |
| verbose("%s: mapping 0x%x to 0x%x : %s" % |
| (self.__class__.__name__, |
| phys_addr, virt_addr, dump_flags(entry_flags))) |
| |
| self.entries[index] = ((phys_addr & self.addr_mask) | |
| (entry_flags & self.supported_flags)) |
| |
| def set_perms(self, virt_addr, entry_flags): |
| """"For the table entry corresponding to the provided virtual address, |
| update just the flags, leaving the physical mapping alone. |
| Unsupported flags will be filtered out.""" |
| index = self.entry_index(virt_addr) |
| |
| verbose("%s: changing perm at 0x%x : %s" % |
| (self.__class__.__name__, |
| virt_addr, dump_flags(entry_flags))) |
| |
| self.entries[index] = ((self.entries[index] & self.addr_mask) | |
| (entry_flags & self.supported_flags)) |
| |
| |
| # Specific supported table types |
| class Pml4(MMUTable): |
| """Page mapping level 4 for IA-32e""" |
| addr_shift = 39 |
| addr_mask = 0x7FFFFFFFFFFFF000 |
| type_code = 'Q' |
| num_entries = 512 |
| supported_flags = INT_FLAGS |
| |
| class Pdpt(MMUTable): |
| """Page directory pointer table for IA-32e""" |
| addr_shift = 30 |
| addr_mask = 0x7FFFFFFFFFFFF000 |
| type_code = 'Q' |
| num_entries = 512 |
| supported_flags = INT_FLAGS | FLAG_SZ | FLAG_CD |
| |
| class PdptPAE(Pdpt): |
| """Page directory pointer table for PAE""" |
| num_entries = 4 |
| |
| class Pd(MMUTable): |
| """Page directory for 32-bit""" |
| addr_shift = 22 |
| addr_mask = 0xFFFFF000 |
| type_code = 'I' |
| num_entries = 1024 |
| supported_flags = INT_FLAGS | FLAG_SZ | FLAG_CD |
| |
| class PdXd(Pd): |
| """Page directory for either PAE or IA-32e""" |
| addr_shift = 21 |
| addr_mask = 0x7FFFFFFFFFFFF000 |
| num_entries = 512 |
| type_code = 'Q' |
| |
| class Pt(MMUTable): |
| """Page table for 32-bit""" |
| addr_shift = 12 |
| addr_mask = 0xFFFFF000 |
| type_code = 'I' |
| num_entries = 1024 |
| supported_flags = (FLAG_P | FLAG_RW | FLAG_US | FLAG_G | FLAG_CD | |
| FLAG_IGNORED0 | FLAG_IGNORED1) |
| |
| class PtXd(Pt): |
| """Page table for either PAE or IA-32e""" |
| addr_mask = 0x07FFFFFFFFFFF000 |
| type_code = 'Q' |
| num_entries = 512 |
| supported_flags = (FLAG_P | FLAG_RW | FLAG_US | FLAG_G | FLAG_XD | FLAG_CD | |
| FLAG_IGNORED0 | FLAG_IGNORED1 | FLAG_IGNORED2) |
| |
| |
| class PtableSet(): |
| """Represents a complete set of page tables for any paging mode""" |
| |
| def __init__(self, pages_start): |
| """Instantiate a set of page tables which will be located in the |
| image starting at the provided physical memory location""" |
| self.toplevel = self.levels[0]() |
| self.page_pos = pages_start |
| |
| debug("%s starting at physical address 0x%x" % |
| (self.__class__.__name__, self.page_pos)) |
| |
| # Database of page table pages. Maps physical memory address to |
| # MMUTable objects, excluding the top-level table which is tracked |
| # separately. Starts out empty as we haven't mapped anything and |
| # the top-level table is tracked separately. |
| self.tables = {} |
| |
| def get_new_mmutable_addr(self): |
| """If we need to instantiate a new MMUTable, return a physical |
| address location for it""" |
| ret = self.page_pos |
| self.page_pos += 4096 |
| return ret |
| |
| @property |
| def levels(self): |
| """Class hierarchy of paging levels, with the first entry being |
| the toplevel table class, and the last entry always being |
| some kind of leaf page table class (Pt or PtXd)""" |
| raise NotImplementedError() |
| |
| def is_mapped(self, virt_addr, level): |
| """ |
| Return True if virt_addr has already been mapped. |
| |
| level_from_last == 0 only searches leaf level page tables. |
| level_from_last == 1 searches both page directories and page tables. |
| |
| """ |
| table = self.toplevel |
| num_levels = len(self.levels) + level + 1 |
| has_mapping = False |
| |
| # Create and link up intermediate tables if necessary |
| for depth in range(0, num_levels): |
| # Create child table if needed |
| if table.has_entry(virt_addr): |
| if depth == num_levels: |
| has_mapping = True |
| else: |
| table = self.tables[table.lookup(virt_addr)] |
| |
| if has_mapping: |
| # pylint doesn't like break in the above if-block |
| break |
| |
| return has_mapping |
| |
| def is_region_mapped(self, virt_base, size, level=PT_LEVEL): |
| """Find out if a region has been mapped""" |
| align_check(virt_base, size) |
| for vaddr in range(virt_base, virt_base + size, 4096): |
| if self.is_mapped(vaddr, level): |
| return True |
| |
| return False |
| |
| def new_child_table(self, table, virt_addr, depth): |
| """Create a new child table""" |
| new_table_addr = self.get_new_mmutable_addr() |
| new_table = self.levels[depth]() |
| debug("new %s at physical addr 0x%x" |
| % (self.levels[depth].__name__, new_table_addr)) |
| self.tables[new_table_addr] = new_table |
| table.map(virt_addr, new_table_addr, INT_FLAGS) |
| |
| return new_table |
| |
| def map_page(self, virt_addr, phys_addr, flags, reserve, level=PT_LEVEL): |
| """Map a virtual address to a physical address in the page tables, |
| with provided access flags""" |
| table = self.toplevel |
| |
| num_levels = len(self.levels) + level + 1 |
| |
| # Create and link up intermediate tables if necessary |
| for depth in range(1, num_levels): |
| # Create child table if needed |
| if not table.has_entry(virt_addr): |
| table = self.new_child_table(table, virt_addr, depth) |
| else: |
| table = self.tables[table.lookup(virt_addr)] |
| |
| # Set up entry in leaf page table |
| if not reserve: |
| table.map(virt_addr, phys_addr, flags) |
| |
| def reserve(self, virt_base, size, to_level=PT_LEVEL): |
| """Reserve page table space with already aligned virt_base and size""" |
| debug("Reserving paging structures for 0x%x (0x%x)" % |
| (virt_base, size)) |
| |
| align_check(virt_base, size) |
| |
| # How much memory is covered by leaf page table |
| scope = 1 << self.levels[PD_LEVEL].addr_shift |
| |
| if virt_base % scope != 0: |
| error("misaligned virtual address space, 0x%x not a multiple of 0x%x" % |
| (virt_base, scope)) |
| |
| for addr in range(virt_base, virt_base + size, scope): |
| self.map_page(addr, 0, 0, True, to_level) |
| |
| def reserve_unaligned(self, virt_base, size, to_level=PT_LEVEL): |
| """Reserve page table space with virt_base and size alignment""" |
| # How much memory is covered by leaf page table |
| scope = 1 << self.levels[PD_LEVEL].addr_shift |
| |
| mem_start = round_down(virt_base, scope) |
| mem_end = round_up(virt_base + size, scope) |
| mem_size = mem_end - mem_start |
| |
| self.reserve(mem_start, mem_size, to_level) |
| |
| def map(self, phys_base, virt_base, size, flags, level=PT_LEVEL): |
| """Map an address range in the page tables provided access flags. |
| If virt_base is None, identity mapping using phys_base is done. |
| """ |
| is_identity_map = virt_base is None or virt_base == phys_base |
| |
| if virt_base is None: |
| virt_base = phys_base |
| |
| scope = 1 << self.levels[level].addr_shift |
| |
| debug("Mapping 0x%x (0x%x) to 0x%x: %s" % |
| (phys_base, size, virt_base, dump_flags(flags))) |
| |
| align_check(phys_base, size, scope) |
| align_check(virt_base, size, scope) |
| for paddr in range(phys_base, phys_base + size, scope): |
| if is_identity_map and paddr == 0 and level == PT_LEVEL: |
| # Never map the NULL page at page table level. |
| continue |
| |
| vaddr = virt_base + (paddr - phys_base) |
| |
| self.map_page(vaddr, paddr, flags, False, level) |
| |
| def identity_map_unaligned(self, phys_base, size, flags, level=PT_LEVEL): |
| """Identity map a region of memory""" |
| scope = 1 << self.levels[level].addr_shift |
| |
| phys_aligned_base = round_down(phys_base, scope) |
| phys_aligned_end = round_up(phys_base + size, scope) |
| phys_aligned_size = phys_aligned_end - phys_aligned_base |
| |
| self.map(phys_aligned_base, None, phys_aligned_size, flags, level) |
| |
| def map_region(self, name, flags, virt_to_phys_offset, level=PT_LEVEL): |
| """Map a named region""" |
| if not isdef(name + "_start"): |
| # Region may not exists |
| return |
| |
| region_start = syms[name + "_start"] |
| region_end = syms[name + "_end"] |
| region_size = region_end - region_start |
| |
| region_start_phys = region_start |
| |
| if virt_to_phys_offset is not None: |
| region_start_phys += virt_to_phys_offset |
| |
| self.map(region_start_phys, region_start, region_size, flags, level) |
| |
| def set_region_perms(self, name, flags, level=PT_LEVEL): |
| """Set access permissions for a named region that is already mapped |
| |
| The bounds of the region will be looked up in the symbol table |
| with _start and _size suffixes. The physical address mapping |
| is unchanged and this will not disturb any double-mapping.""" |
| if not isdef(name + "_start"): |
| # Region may not exists |
| return |
| |
| # Doesn't matter if this is a virtual address, we have a |
| # either dual mapping or it's the same as physical |
| base = syms[name + "_start"] |
| |
| if isdef(name + "_size"): |
| size = syms[name + "_size"] |
| else: |
| region_end = syms[name + "_end"] |
| size = region_end - base |
| |
| if size == 0: |
| return |
| |
| debug("change flags for %s at 0x%x (0x%x): %s" % |
| (name, base, size, dump_flags(flags))) |
| |
| num_levels = len(self.levels) + level + 1 |
| scope = 1 << self.levels[level].addr_shift |
| |
| align_check(base, size, scope) |
| |
| try: |
| for addr in range(base, base + size, scope): |
| # Never map the NULL page |
| if addr == 0: |
| continue |
| |
| table = self.toplevel |
| for _ in range(1, num_levels): |
| table = self.tables[table.lookup(addr)] |
| table.set_perms(addr, flags) |
| except KeyError: |
| error("no mapping for %s region 0x%x (size 0x%x)" % |
| (name, base, size)) |
| |
| def write_output(self, filename): |
| """Write the page tables to the output file in binary format""" |
| written_size = 0 |
| |
| with open(filename, "wb") as output_fp: |
| for addr in sorted(self.tables): |
| mmu_table = self.tables[addr] |
| mmu_table_bin = mmu_table.get_binary() |
| output_fp.write(mmu_table_bin) |
| written_size += len(mmu_table_bin) |
| |
| # We always have the top-level table be last. This is because |
| # in PAE, the top-level PDPT has only 4 entries and is not a |
| # full page in size. We do not put it in the tables dictionary |
| # and treat it as a special case. |
| debug("top-level %s at physical addr 0x%x" % |
| (self.toplevel.__class__.__name__, |
| self.get_new_mmutable_addr())) |
| top_level_bin = self.toplevel.get_binary() |
| output_fp.write(top_level_bin) |
| written_size += len(top_level_bin) |
| |
| return written_size |
| |
| # Paging mode classes, we'll use one depending on configuration |
| class Ptables32bit(PtableSet): |
| """32-bit Page Tables""" |
| levels = [Pd, Pt] |
| |
| class PtablesPAE(PtableSet): |
| """PAE Page Tables""" |
| levels = [PdptPAE, PdXd, PtXd] |
| |
| class PtablesIA32e(PtableSet): |
| """Page Tables under IA32e mode""" |
| levels = [Pml4, Pdpt, PdXd, PtXd] |
| |
| |
| def parse_args(): |
| """Parse command line arguments""" |
| global args |
| |
| parser = argparse.ArgumentParser( |
| description=__doc__, |
| formatter_class=argparse.RawDescriptionHelpFormatter) |
| |
| parser.add_argument("-k", "--kernel", required=True, |
| help="path to prebuilt kernel ELF binary") |
| parser.add_argument("-o", "--output", required=True, |
| help="output file") |
| parser.add_argument("--map", action='append', |
| help=textwrap.dedent('''\ |
| Map extra memory: |
| <physical address>,<size>[,<flags:LUWXD>[,<virtual adderss>]] |
| where flags can be empty or combination of: |
| L - Large page (2MB or 4MB), |
| U - Userspace accessible, |
| W - Writable, |
| X - Executable, |
| D - Cache disabled. |
| Default is |
| small (4KB) page, |
| supervisor only, |
| read only, |
| and execution disabled. |
| ''')) |
| parser.add_argument("-v", "--verbose", action="count", |
| help="Print extra debugging information") |
| args = parser.parse_args() |
| if "VERBOSE" in os.environ: |
| args.verbose = 1 |
| |
| |
| def get_symbols(elf_obj): |
| """Get all symbols from the ELF file""" |
| for section in elf_obj.iter_sections(): |
| if isinstance(section, SymbolTableSection): |
| return {sym.name: sym.entry.st_value |
| for sym in section.iter_symbols()} |
| |
| raise LookupError("Could not find symbol table") |
| |
| def isdef(sym_name): |
| """True if symbol is defined in ELF file""" |
| return sym_name in syms |
| |
| |
| def find_symbol(obj, name): |
| """Find symbol object from ELF file""" |
| for section in obj.iter_sections(): |
| if isinstance(section, SymbolTableSection): |
| for sym in section.iter_symbols(): |
| if sym.name == name: |
| return sym |
| |
| return None |
| |
| |
| def map_extra_regions(pt): |
| """Map extra regions specified in command line""" |
| # Extract command line arguments |
| mappings = [] |
| |
| for entry in args.map: |
| elements = entry.split(',') |
| |
| if len(elements) < 2: |
| error("Not enough arguments for --map %s" % entry) |
| |
| one_map = {} |
| |
| one_map['cmdline'] = entry |
| one_map['phys'] = int(elements[0], 0) |
| one_map['size']= int(elements[1], 0) |
| one_map['large_page'] = False |
| |
| flags = FLAG_P | ENTRY_XD |
| if len(elements) > 2: |
| map_flags = elements[2] |
| |
| # Check for allowed flags |
| if not bool(re.match('^[LUWXD]*$', map_flags)): |
| error("Unrecognized flags: %s" % map_flags) |
| |
| flags = FLAG_P | ENTRY_XD |
| if 'W' in map_flags: |
| flags |= ENTRY_RW |
| if 'X' in map_flags: |
| flags &= ~ENTRY_XD |
| if 'U' in map_flags: |
| flags |= ENTRY_US |
| if 'L' in map_flags: |
| flags |= FLAG_SZ |
| one_map['large_page'] = True |
| if 'D' in map_flags: |
| flags |= FLAG_CD |
| |
| one_map['flags'] = flags |
| |
| if len(elements) > 3: |
| one_map['virt'] = int(elements[3], 16) |
| else: |
| one_map['virt'] = one_map['phys'] |
| |
| mappings.append(one_map) |
| |
| # Map the regions |
| for one_map in mappings: |
| phys = one_map['phys'] |
| size = one_map['size'] |
| flags = one_map['flags'] |
| virt = one_map['virt'] |
| level = PD_LEVEL if one_map['large_page'] else PT_LEVEL |
| |
| # Check if addresses have already been mapped. |
| # Error out if so as they could override kernel mappings. |
| if pt.is_region_mapped(virt, size, level): |
| error(("Region 0x%x (%d) already been mapped " |
| "for --map %s" % (virt, size, one_map['cmdline']))) |
| |
| # Reserve space in page table, and map the region |
| pt.reserve_unaligned(virt, size, level) |
| pt.map(phys, virt, size, flags, level) |
| |
| |
| def main(): |
| """Main program""" |
| global syms |
| parse_args() |
| |
| with open(args.kernel, "rb") as elf_fp: |
| kernel = ELFFile(elf_fp) |
| syms = get_symbols(kernel) |
| |
| sym_dummy_pagetables = find_symbol(kernel, "dummy_pagetables") |
| if sym_dummy_pagetables: |
| reserved_pt_size = sym_dummy_pagetables['st_size'] |
| else: |
| reserved_pt_size = None |
| |
| if isdef("CONFIG_X86_64"): |
| pclass = PtablesIA32e |
| elif isdef("CONFIG_X86_PAE"): |
| pclass = PtablesPAE |
| else: |
| pclass = Ptables32bit |
| |
| debug("building %s" % pclass.__name__) |
| |
| vm_base = syms["CONFIG_KERNEL_VM_BASE"] |
| vm_size = syms["CONFIG_KERNEL_VM_SIZE"] |
| vm_offset = syms["CONFIG_KERNEL_VM_OFFSET"] |
| |
| sram_base = syms["CONFIG_SRAM_BASE_ADDRESS"] |
| sram_size = syms["CONFIG_SRAM_SIZE"] * 1024 |
| |
| mapped_kernel_base = syms["z_mapped_start"] |
| mapped_kernel_size = syms["z_mapped_size"] |
| |
| if isdef("CONFIG_SRAM_OFFSET"): |
| sram_offset = syms["CONFIG_SRAM_OFFSET"] |
| else: |
| sram_offset = 0 |
| |
| # Figure out if there is any need to do virtual-to-physical |
| # address translation |
| virt_to_phys_offset = (sram_base + sram_offset) - (vm_base + vm_offset) |
| |
| if isdef("CONFIG_ARCH_MAPS_ALL_RAM"): |
| image_base = sram_base |
| image_size = sram_size |
| else: |
| image_base = mapped_kernel_base |
| image_size = mapped_kernel_size |
| |
| image_base_phys = image_base + virt_to_phys_offset |
| |
| ptables_phys = syms["z_x86_pagetables_start"] + virt_to_phys_offset |
| |
| debug("Address space: 0x%x - 0x%x size 0x%x" % |
| (vm_base, vm_base + vm_size - 1, vm_size)) |
| |
| debug("Zephyr image: 0x%x - 0x%x size 0x%x" % |
| (image_base, image_base + image_size - 1, image_size)) |
| |
| if virt_to_phys_offset != 0: |
| debug("Physical address space: 0x%x - 0x%x size 0x%x" % |
| (sram_base, sram_base + sram_size - 1, sram_size)) |
| |
| is_perm_regions = isdef("CONFIG_SRAM_REGION_PERMISSIONS") |
| |
| # Are pages in non-boot, non-pinned sections present at boot. |
| is_generic_section_present = isdef("CONFIG_LINKER_GENERIC_SECTIONS_PRESENT_AT_BOOT") |
| |
| if image_size >= vm_size: |
| error("VM size is too small (have 0x%x need more than 0x%x)" % (vm_size, image_size)) |
| |
| map_flags = 0 |
| |
| if is_perm_regions: |
| # Don't allow execution by default for any pages. We'll adjust this |
| # in later calls to pt.set_region_perms() |
| map_flags = ENTRY_XD |
| |
| pt = pclass(ptables_phys) |
| # Instantiate all the paging structures for the address space |
| pt.reserve(vm_base, vm_size) |
| # Map the zephyr image |
| if is_generic_section_present: |
| map_flags = map_flags | FLAG_P |
| pt.map(image_base_phys, image_base, image_size, map_flags | ENTRY_RW) |
| else: |
| # When generic linker sections are not present in physical memory, |
| # the corresponding virtual pages should not be mapped to non-existent |
| # physical pages. So simply identity map them to create the page table |
| # entries but without the present bit set. |
| # Boot and pinned sections (if configured) will be mapped to |
| # physical memory below. |
| pt.map(image_base, image_base, image_size, map_flags | ENTRY_RW) |
| |
| if virt_to_phys_offset != 0: |
| # Need to identity map the physical address space |
| # as it is needed during early boot process. |
| # This will be unmapped once z_x86_mmu_init() |
| # is called. |
| # Note that this only does the identity mapping |
| # at the page directory level to minimize wasted space. |
| pt.reserve_unaligned(image_base_phys, image_size, to_level=PD_LEVEL) |
| pt.identity_map_unaligned(image_base_phys, image_size, |
| FLAG_P | FLAG_RW | FLAG_SZ, level=PD_LEVEL) |
| |
| if isdef("CONFIG_X86_64"): |
| # 64-bit has a special region in the first 64K to bootstrap other CPUs |
| # from real mode |
| locore_base = syms["_locore_start"] |
| locore_size = syms["_lodata_end"] - locore_base |
| debug("Base addresses: physical 0x%x size 0x%x" % (locore_base, |
| locore_size)) |
| pt.map(locore_base, None, locore_size, map_flags | FLAG_P | ENTRY_RW) |
| |
| if isdef("CONFIG_XIP"): |
| # Additionally identity-map all ROM as read-only |
| pt.map(syms["CONFIG_FLASH_BASE_ADDRESS"], None, |
| syms["CONFIG_FLASH_SIZE"] * 1024, map_flags | FLAG_P) |
| |
| if isdef("CONFIG_LINKER_USE_BOOT_SECTION"): |
| pt.map_region("lnkr_boot", map_flags | FLAG_P | ENTRY_RW, virt_to_phys_offset) |
| |
| if isdef("CONFIG_LINKER_USE_PINNED_SECTION"): |
| pt.map_region("lnkr_pinned", map_flags | FLAG_P | ENTRY_RW, virt_to_phys_offset) |
| |
| # Process extra mapping requests |
| if args.map: |
| map_extra_regions(pt) |
| |
| # Adjust mapped region permissions if configured |
| if is_perm_regions: |
| # Need to accomplish the following things: |
| # - Text regions need the XD flag cleared and RW flag removed |
| # if not built with gdbstub support |
| # - Rodata regions need the RW flag cleared |
| # - User mode needs access as we currently do not separate application |
| # text/rodata from kernel text/rodata |
| if isdef("CONFIG_GDBSTUB"): |
| flags = ENTRY_US | ENTRY_RW |
| else: |
| flags = ENTRY_US |
| |
| if is_generic_section_present: |
| flags = flags | FLAG_P |
| |
| pt.set_region_perms("__text_region", flags) |
| |
| if isdef("CONFIG_LINKER_USE_BOOT_SECTION"): |
| pt.set_region_perms("lnkr_boot_text", flags | FLAG_P) |
| |
| if isdef("CONFIG_LINKER_USE_PINNED_SECTION"): |
| pt.set_region_perms("lnkr_pinned_text", flags | FLAG_P) |
| |
| flags = ENTRY_US | ENTRY_XD |
| if is_generic_section_present: |
| flags = flags | FLAG_P |
| |
| pt.set_region_perms("__rodata_region", flags) |
| |
| if isdef("CONFIG_LINKER_USE_BOOT_SECTION"): |
| pt.set_region_perms("lnkr_boot_rodata", flags | FLAG_P) |
| |
| if isdef("CONFIG_LINKER_USE_PINNED_SECTION"): |
| pt.set_region_perms("lnkr_pinned_rodata", flags | FLAG_P) |
| |
| if isdef("CONFIG_COVERAGE_GCOV") and isdef("CONFIG_USERSPACE"): |
| # If GCOV is enabled, user mode must be able to write to its |
| # common data area |
| pt.set_region_perms("__gcov_bss", |
| FLAG_P | ENTRY_RW | ENTRY_US | ENTRY_XD) |
| |
| if isdef("CONFIG_X86_64"): |
| # Set appropriate permissions for locore areas much like we did |
| # with the main text/rodata regions |
| |
| if isdef("CONFIG_X86_KPTI"): |
| # Set the User bit for the read-only locore/lorodata areas. |
| # This ensures they get mapped into the User page tables if |
| # KPTI is turned on. There is no sensitive data in them, and |
| # they contain text/data needed to take an exception or |
| # interrupt. |
| flag_user = ENTRY_US |
| else: |
| flag_user = 0 |
| |
| pt.set_region_perms("_locore", FLAG_P | flag_user) |
| pt.set_region_perms("_lorodata", FLAG_P | ENTRY_XD | flag_user) |
| |
| written_size = pt.write_output(args.output) |
| debug("Written %d bytes to %s" % (written_size, args.output)) |
| |
| # Warn if reserved page table is not of correct size |
| if reserved_pt_size and written_size != reserved_pt_size: |
| # Figure out how many extra pages needed |
| size_diff = written_size - reserved_pt_size |
| page_size = syms["CONFIG_MMU_PAGE_SIZE"] |
| extra_pages_needed = int(round_up(size_diff, page_size) / page_size) |
| |
| if isdef("CONFIG_X86_EXTRA_PAGE_TABLE_PAGES"): |
| extra_pages_kconfig = syms["CONFIG_X86_EXTRA_PAGE_TABLE_PAGES"] |
| if isdef("CONFIG_X86_64"): |
| extra_pages_needed += ctypes.c_int64(extra_pages_kconfig).value |
| else: |
| extra_pages_needed += ctypes.c_int32(extra_pages_kconfig).value |
| |
| reason = "big" if reserved_pt_size > written_size else "small" |
| |
| error(("Reserved space for page table is too %s." |
| " Set CONFIG_X86_EXTRA_PAGE_TABLE_PAGES=%d") % |
| (reason, extra_pages_needed)) |
| |
| |
| if __name__ == "__main__": |
| main() |
