Nixyri/zig
1
0
Fork 0
mirror of https://github.com/ziglang/zig.git synced 2024-11-15 08:33:06 +00:00
Code Issues Packages Projects Releases Wiki Activity
63bbf66553
zig/lib/std/dwarf.zig
David Rubin 63bbf66553 riscv: remove an allocation from dwarf.zig
2024-05-11 02:17:11 -07:00

2800 lines
110 KiB
Zig
Raw Blame History

//! DWARF debugging data format.
const builtin = @import("builtin");
const std = @import("std.zig");
const debug = std.debug;
const mem = std.mem;
const math = std.math;
const assert = debug.assert;
const native_endian = builtin.cpu.arch.endian();
pub const TAG = @import("dwarf/TAG.zig");
pub const AT = @import("dwarf/AT.zig");
pub const OP = @import("dwarf/OP.zig");
pub const LANG = @import("dwarf/LANG.zig");
pub const FORM = @import("dwarf/FORM.zig");
pub const ATE = @import("dwarf/ATE.zig");
pub const EH = @import("dwarf/EH.zig");
pub const abi = @import("dwarf/abi.zig");
pub const call_frame = @import("dwarf/call_frame.zig");
pub const expressions = @import("dwarf/expressions.zig");
pub const LLE = struct {
pub const end_of_list = 0x00;
pub const base_addressx = 0x01;
pub const startx_endx = 0x02;
pub const startx_length = 0x03;
pub const offset_pair = 0x04;
pub const default_location = 0x05;
pub const base_address = 0x06;
pub const start_end = 0x07;
pub const start_length = 0x08;
};
pub const CFA = struct {
pub const advance_loc = 0x40;
pub const offset = 0x80;
pub const restore = 0xc0;
pub const nop = 0x00;
pub const set_loc = 0x01;
pub const advance_loc1 = 0x02;
pub const advance_loc2 = 0x03;
pub const advance_loc4 = 0x04;
pub const offset_extended = 0x05;
pub const restore_extended = 0x06;
pub const @"undefined" = 0x07;
pub const same_value = 0x08;
pub const register = 0x09;
pub const remember_state = 0x0a;
pub const restore_state = 0x0b;
pub const def_cfa = 0x0c;
pub const def_cfa_register = 0x0d;
pub const def_cfa_offset = 0x0e;
// DWARF 3.
pub const def_cfa_expression = 0x0f;
pub const expression = 0x10;
pub const offset_extended_sf = 0x11;
pub const def_cfa_sf = 0x12;
pub const def_cfa_offset_sf = 0x13;
pub const val_offset = 0x14;
pub const val_offset_sf = 0x15;
pub const val_expression = 0x16;
pub const lo_user = 0x1c;
pub const hi_user = 0x3f;
// SGI/MIPS specific.
pub const MIPS_advance_loc8 = 0x1d;
// GNU extensions.
pub const GNU_window_save = 0x2d;
pub const GNU_args_size = 0x2e;
pub const GNU_negative_offset_extended = 0x2f;
};
pub const CHILDREN = struct {
pub const no = 0x00;
pub const yes = 0x01;
};
pub const LNS = struct {
pub const extended_op = 0x00;
pub const copy = 0x01;
pub const advance_pc = 0x02;
pub const advance_line = 0x03;
pub const set_file = 0x04;
pub const set_column = 0x05;
pub const negate_stmt = 0x06;
pub const set_basic_block = 0x07;
pub const const_add_pc = 0x08;
pub const fixed_advance_pc = 0x09;
pub const set_prologue_end = 0x0a;
pub const set_epilogue_begin = 0x0b;
pub const set_isa = 0x0c;
};
pub const LNE = struct {
pub const end_sequence = 0x01;
pub const set_address = 0x02;
pub const define_file = 0x03;
pub const set_discriminator = 0x04;
pub const lo_user = 0x80;
pub const hi_user = 0xff;
};
pub const UT = struct {
pub const compile = 0x01;
pub const @"type" = 0x02;
pub const partial = 0x03;
pub const skeleton = 0x04;
pub const split_compile = 0x05;
pub const split_type = 0x06;
pub const lo_user = 0x80;
pub const hi_user = 0xff;
};
pub const LNCT = struct {
pub const path = 0x1;
pub const directory_index = 0x2;
pub const timestamp = 0x3;
pub const size = 0x4;
pub const MD5 = 0x5;
pub const lo_user = 0x2000;
pub const hi_user = 0x3fff;
};
pub const RLE = struct {
pub const end_of_list = 0x00;
pub const base_addressx = 0x01;
pub const startx_endx = 0x02;
pub const startx_length = 0x03;
pub const offset_pair = 0x04;
pub const base_address = 0x05;
pub const start_end = 0x06;
pub const start_length = 0x07;
};
pub const CC = enum(u8) {
normal = 0x1,
program = 0x2,
nocall = 0x3,
pass_by_reference = 0x4,
pass_by_value = 0x5,
GNU_renesas_sh = 0x40,
GNU_borland_fastcall_i386 = 0x41,
pub const lo_user = 0x40;
pub const hi_user = 0xff;
};
pub const Format = enum { @"32", @"64" };
const PcRange = struct {
start: u64,
end: u64,
};
const Func = struct {
pc_range: ?PcRange,
name: ?[]const u8,
};
pub const CompileUnit = struct {
version: u16,
format: Format,
die: Die,
pc_range: ?PcRange,
str_offsets_base: usize,
addr_base: usize,
rnglists_base: usize,
loclists_base: usize,
frame_base: ?*const FormValue,
};
const Abbrev = struct {
code: u64,
tag_id: u64,
has_children: bool,
attrs: []Attr,
fn deinit(abbrev: *Abbrev, allocator: mem.Allocator) void {
allocator.free(abbrev.attrs);
abbrev.* = undefined;
}
const Attr = struct {
id: u64,
form_id: u64,
/// Only valid if form_id is .implicit_const
payload: i64,
};
const Table = struct {
// offset from .debug_abbrev
offset: u64,
abbrevs: []Abbrev,
fn deinit(table: *Table, allocator: mem.Allocator) void {
for (table.abbrevs) |*abbrev| {
abbrev.deinit(allocator);
}
allocator.free(table.abbrevs);
table.* = undefined;
}
fn get(table: *const Table, abbrev_code: u64) ?*const Abbrev {
return for (table.abbrevs) |*abbrev| {
if (abbrev.code == abbrev_code) break abbrev;
} else null;
}
};
};
pub const FormValue = union(enum) {
addr: u64,
addrx: usize,
block: []const u8,
udata: u64,
data16: *const [16]u8,
sdata: i64,
exprloc: []const u8,
flag: bool,
sec_offset: u64,
ref: u64,
ref_addr: u64,
string: [:0]const u8,
strp: u64,
strx: usize,
line_strp: u64,
loclistx: u64,
rnglistx: u64,
fn getString(fv: FormValue, di: DwarfInfo) ![:0]const u8 {
switch (fv) {
.string => |s| return s,
.strp => |off| return di.getString(off),
.line_strp => |off| return di.getLineString(off),
else => return badDwarf(),
}
}
fn getUInt(fv: FormValue, comptime U: type) !U {
return switch (fv) {
inline .udata,
.sdata,
.sec_offset,
=> |c| math.cast(U, c) orelse badDwarf(),
else => badDwarf(),
};
}
};
const Die = struct {
tag_id: u64,
has_children: bool,
attrs: []Attr,
const Attr = struct {
id: u64,
value: FormValue,
};
fn deinit(self: *Die, allocator: mem.Allocator) void {
allocator.free(self.attrs);
self.* = undefined;
}
fn getAttr(self: *const Die, id: u64) ?*const FormValue {
for (self.attrs) |*attr| {
if (attr.id == id) return &attr.value;
}
return null;
}
fn getAttrAddr(
self: *const Die,
di: *const DwarfInfo,
id: u64,
compile_unit: CompileUnit,
) error{ InvalidDebugInfo, MissingDebugInfo }!u64 {
const form_value = self.getAttr(id) orelse return error.MissingDebugInfo;
return switch (form_value.*) {
.addr => |value| value,
.addrx => |index| di.readDebugAddr(compile_unit, index),
else => error.InvalidDebugInfo,
};
}
fn getAttrSecOffset(self: *const Die, id: u64) !u64 {
const form_value = self.getAttr(id) orelse return error.MissingDebugInfo;
return form_value.getUInt(u64);
}
fn getAttrUnsignedLe(self: *const Die, id: u64) !u64 {
const form_value = self.getAttr(id) orelse return error.MissingDebugInfo;
return switch (form_value.*) {
.Const => |value| value.asUnsignedLe(),
else => error.InvalidDebugInfo,
};
}
fn getAttrRef(self: *const Die, id: u64) !u64 {
const form_value = self.getAttr(id) orelse return error.MissingDebugInfo;
return switch (form_value.*) {
.ref => |value| value,
else => error.InvalidDebugInfo,
};
}
pub fn getAttrString(
self: *const Die,
di: *DwarfInfo,
id: u64,
opt_str: ?[]const u8,
compile_unit: CompileUnit,
) error{ InvalidDebugInfo, MissingDebugInfo }![]const u8 {
const form_value = self.getAttr(id) orelse return error.MissingDebugInfo;
switch (form_value.*) {
.string => |value| return value,
.strp => |offset| return di.getString(offset),
.strx => |index| {
const debug_str_offsets = di.section(.debug_str_offsets) orelse return badDwarf();
if (compile_unit.str_offsets_base == 0) return badDwarf();
switch (compile_unit.format) {
.@"32" => {
const byte_offset = compile_unit.str_offsets_base + 4 * index;
if (byte_offset + 4 > debug_str_offsets.len) return badDwarf();
const offset = mem.readInt(u32, debug_str_offsets[byte_offset..][0..4], di.endian);
return getStringGeneric(opt_str, offset);
},
.@"64" => {
const byte_offset = compile_unit.str_offsets_base + 8 * index;
if (byte_offset + 8 > debug_str_offsets.len) return badDwarf();
const offset = mem.readInt(u64, debug_str_offsets[byte_offset..][0..8], di.endian);
return getStringGeneric(opt_str, offset);
},
}
},
.line_strp => |offset| return di.getLineString(offset),
else => return badDwarf(),
}
}
};
const FileEntry = struct {
path: []const u8,
dir_index: u32 = 0,
mtime: u64 = 0,
size: u64 = 0,
md5: [16]u8 = [1]u8{0} ** 16,
};
const LineNumberProgram = struct {
address: u64,
file: usize,
line: i64,
column: u64,
version: u16,
is_stmt: bool,
basic_block: bool,
end_sequence: bool,
default_is_stmt: bool,
target_address: u64,
include_dirs: []const FileEntry,
prev_valid: bool,
prev_address: u64,
prev_file: usize,
prev_line: i64,
prev_column: u64,
prev_is_stmt: bool,
prev_basic_block: bool,
prev_end_sequence: bool,
// Reset the state machine following the DWARF specification
pub fn reset(self: *LineNumberProgram) void {
self.address = 0;
self.file = 1;
self.line = 1;
self.column = 0;
self.is_stmt = self.default_is_stmt;
self.basic_block = false;
self.end_sequence = false;
// Invalidate all the remaining fields
self.prev_valid = false;
self.prev_address = 0;
self.prev_file = undefined;
self.prev_line = undefined;
self.prev_column = undefined;
self.prev_is_stmt = undefined;
self.prev_basic_block = undefined;
self.prev_end_sequence = undefined;
}
pub fn init(
is_stmt: bool,
include_dirs: []const FileEntry,
target_address: u64,
version: u16,
) LineNumberProgram {
return LineNumberProgram{
.address = 0,
.file = 1,
.line = 1,
.column = 0,
.version = version,
.is_stmt = is_stmt,
.basic_block = false,
.end_sequence = false,
.include_dirs = include_dirs,
.default_is_stmt = is_stmt,
.target_address = target_address,
.prev_valid = false,
.prev_address = 0,
.prev_file = undefined,
.prev_line = undefined,
.prev_column = undefined,
.prev_is_stmt = undefined,
.prev_basic_block = undefined,
.prev_end_sequence = undefined,
};
}
pub fn checkLineMatch(
self: *LineNumberProgram,
allocator: mem.Allocator,
file_entries: []const FileEntry,
) !?debug.LineInfo {
if (self.prev_valid and
self.target_address >= self.prev_address and
self.target_address < self.address)
{
const file_index = if (self.version >= 5) self.prev_file else i: {
if (self.prev_file == 0) return missingDwarf();
break :i self.prev_file - 1;
};
if (file_index >= file_entries.len) return badDwarf();
const file_entry = &file_entries[file_index];
if (file_entry.dir_index >= self.include_dirs.len) return badDwarf();
const dir_name = self.include_dirs[file_entry.dir_index].path;
const file_name = try std.fs.path.join(allocator, &[_][]const u8{
dir_name, file_entry.path,
});
return debug.LineInfo{
.line = if (self.prev_line >= 0) @as(u64, @intCast(self.prev_line)) else 0,
.column = self.prev_column,
.file_name = file_name,
};
}
self.prev_valid = true;
self.prev_address = self.address;
self.prev_file = self.file;
self.prev_line = self.line;
self.prev_column = self.column;
self.prev_is_stmt = self.is_stmt;
self.prev_basic_block = self.basic_block;
self.prev_end_sequence = self.end_sequence;
return null;
}
};
const UnitHeader = struct {
format: Format,
header_length: u4,
unit_length: u64,
};
fn readUnitHeader(fbr: *FixedBufferReader) !UnitHeader {
return switch (try fbr.readInt(u32)) {
0...0xfffffff0 - 1 => |unit_length| .{
.format = .@"32",
.header_length = 4,
.unit_length = unit_length,
},
0xfffffff0...0xffffffff - 1 => badDwarf(),
0xffffffff => .{
.format = .@"64",
.header_length = 12,
.unit_length = try fbr.readInt(u64),
},
};
}
fn parseFormValue(
fbr: *FixedBufferReader,
form_id: u64,
format: Format,
implicit_const: ?i64,
) anyerror!FormValue {
return switch (form_id) {
FORM.addr => .{ .addr = try fbr.readAddress(switch (@bitSizeOf(usize)) {
32 => .@"32",
64 => .@"64",
else => @compileError("unsupported @sizeOf(usize)"),
}) },
FORM.addrx1 => .{ .addrx = try fbr.readInt(u8) },
FORM.addrx2 => .{ .addrx = try fbr.readInt(u16) },
FORM.addrx3 => .{ .addrx = try fbr.readInt(u24) },
FORM.addrx4 => .{ .addrx = try fbr.readInt(u32) },
FORM.addrx => .{ .addrx = try fbr.readUleb128(usize) },
FORM.block1,
FORM.block2,
FORM.block4,
FORM.block,
=> .{ .block = try fbr.readBytes(switch (form_id) {
FORM.block1 => try fbr.readInt(u8),
FORM.block2 => try fbr.readInt(u16),
FORM.block4 => try fbr.readInt(u32),
FORM.block => try fbr.readUleb128(usize),
else => unreachable,
}) },
FORM.data1 => .{ .udata = try fbr.readInt(u8) },
FORM.data2 => .{ .udata = try fbr.readInt(u16) },
FORM.data4 => .{ .udata = try fbr.readInt(u32) },
FORM.data8 => .{ .udata = try fbr.readInt(u64) },
FORM.data16 => .{ .data16 = (try fbr.readBytes(16))[0..16] },
FORM.udata => .{ .udata = try fbr.readUleb128(u64) },
FORM.sdata => .{ .sdata = try fbr.readIleb128(i64) },
FORM.exprloc => .{ .exprloc = try fbr.readBytes(try fbr.readUleb128(usize)) },
FORM.flag => .{ .flag = (try fbr.readByte()) != 0 },
FORM.flag_present => .{ .flag = true },
FORM.sec_offset => .{ .sec_offset = try fbr.readAddress(format) },
FORM.ref1 => .{ .ref = try fbr.readInt(u8) },
FORM.ref2 => .{ .ref = try fbr.readInt(u16) },
FORM.ref4 => .{ .ref = try fbr.readInt(u32) },
FORM.ref8 => .{ .ref = try fbr.readInt(u64) },
FORM.ref_udata => .{ .ref = try fbr.readUleb128(u64) },
FORM.ref_addr => .{ .ref_addr = try fbr.readAddress(format) },
FORM.ref_sig8 => .{ .ref = try fbr.readInt(u64) },
FORM.string => .{ .string = try fbr.readBytesTo(0) },
FORM.strp => .{ .strp = try fbr.readAddress(format) },
FORM.strx1 => .{ .strx = try fbr.readInt(u8) },
FORM.strx2 => .{ .strx = try fbr.readInt(u16) },
FORM.strx3 => .{ .strx = try fbr.readInt(u24) },
FORM.strx4 => .{ .strx = try fbr.readInt(u32) },
FORM.strx => .{ .strx = try fbr.readUleb128(usize) },
FORM.line_strp => .{ .line_strp = try fbr.readAddress(format) },
FORM.indirect => parseFormValue(fbr, try fbr.readUleb128(u64), format, implicit_const),
FORM.implicit_const => .{ .sdata = implicit_const orelse return badDwarf() },
FORM.loclistx => .{ .loclistx = try fbr.readUleb128(u64) },
FORM.rnglistx => .{ .rnglistx = try fbr.readUleb128(u64) },
else => {
//debug.print("unrecognized form id: {x}\n", .{form_id});
return badDwarf();
},
};
}
pub const DwarfSection = enum {
debug_info,
debug_abbrev,
debug_str,
debug_str_offsets,
debug_line,
debug_line_str,
debug_ranges,
debug_loclists,
debug_rnglists,
debug_addr,
debug_names,
debug_frame,
eh_frame,
eh_frame_hdr,
};
pub const DwarfInfo = struct {
pub const Section = struct {
data: []const u8,
// Module-relative virtual address.
// Only set if the section data was loaded from disk.
virtual_address: ?usize = null,
// If `data` is owned by this DwarfInfo.
owned: bool,
// For sections that are not memory mapped by the loader, this is an offset
// from `data.ptr` to where the section would have been mapped. Otherwise,
// `data` is directly backed by the section and the offset is zero.
pub fn virtualOffset(self: Section, base_address: usize) i64 {
return if (self.virtual_address) |va|
@as(i64, @intCast(base_address + va)) -
@as(i64, @intCast(@intFromPtr(self.data.ptr)))
else
0;
}
};
const num_sections = std.enums.directEnumArrayLen(DwarfSection, 0);
pub const SectionArray = [num_sections]?Section;
pub const null_section_array = [_]?Section{null} ** num_sections;
endian: std.builtin.Endian,
sections: SectionArray = null_section_array,
is_macho: bool,
// Filled later by the initializer
abbrev_table_list: std.ArrayListUnmanaged(Abbrev.Table) = .{},
compile_unit_list: std.ArrayListUnmanaged(CompileUnit) = .{},
func_list: std.ArrayListUnmanaged(Func) = .{},
eh_frame_hdr: ?ExceptionFrameHeader = null,
// These lookup tables are only used if `eh_frame_hdr` is null
cie_map: std.AutoArrayHashMapUnmanaged(u64, CommonInformationEntry) = .{},
// Sorted by start_pc
fde_list: std.ArrayListUnmanaged(FrameDescriptionEntry) = .{},
pub fn section(di: DwarfInfo, dwarf_section: DwarfSection) ?[]const u8 {
return if (di.sections[@intFromEnum(dwarf_section)]) |s| s.data else null;
}
pub fn sectionVirtualOffset(di: DwarfInfo, dwarf_section: DwarfSection, base_address: usize) ?i64 {
return if (di.sections[@intFromEnum(dwarf_section)]) |s| s.virtualOffset(base_address) else null;
}
pub fn deinit(di: *DwarfInfo, allocator: mem.Allocator) void {
for (di.sections) |opt_section| {
if (opt_section) |s| if (s.owned) allocator.free(s.data);
}
for (di.abbrev_table_list.items) |*abbrev| {
abbrev.deinit(allocator);
}
di.abbrev_table_list.deinit(allocator);
for (di.compile_unit_list.items) |*cu| {
cu.die.deinit(allocator);
}
di.compile_unit_list.deinit(allocator);
di.func_list.deinit(allocator);
di.cie_map.deinit(allocator);
di.fde_list.deinit(allocator);
di.* = undefined;
}
pub fn getSymbolName(di: *DwarfInfo, address: u64) ?[]const u8 {
for (di.func_list.items) |*func| {
if (func.pc_range) |range| {
if (address >= range.start and address < range.end) {
return func.name;
}
}
}
return null;
}
fn scanAllFunctions(di: *DwarfInfo, allocator: mem.Allocator) !void {
var fbr: FixedBufferReader = .{ .buf = di.section(.debug_info).?, .endian = di.endian };
var this_unit_offset: u64 = 0;
while (this_unit_offset < fbr.buf.len) {
try fbr.seekTo(this_unit_offset);
const unit_header = try readUnitHeader(&fbr);
if (unit_header.unit_length == 0) return;
const next_offset = unit_header.header_length + unit_header.unit_length;
const version = try fbr.readInt(u16);
if (version < 2 or version > 5) return badDwarf();
var address_size: u8 = undefined;
var debug_abbrev_offset: u64 = undefined;
if (version >= 5) {
const unit_type = try fbr.readInt(u8);
if (unit_type != UT.compile) return badDwarf();
address_size = try fbr.readByte();
debug_abbrev_offset = try fbr.readAddress(unit_header.format);
} else {
debug_abbrev_offset = try fbr.readAddress(unit_header.format);
address_size = try fbr.readByte();
}
if (address_size != @sizeOf(usize)) return badDwarf();
const abbrev_table = try di.getAbbrevTable(allocator, debug_abbrev_offset);
var max_attrs: usize = 0;
var zig_padding_abbrev_code: u7 = 0;
for (abbrev_table.abbrevs) |abbrev| {
max_attrs = @max(max_attrs, abbrev.attrs.len);
if (math.cast(u7, abbrev.code)) |code| {
if (abbrev.tag_id == TAG.ZIG_padding and
!abbrev.has_children and
abbrev.attrs.len == 0)
{
zig_padding_abbrev_code = code;
}
}
}
const attrs_buf = try allocator.alloc(Die.Attr, max_attrs * 3);
defer allocator.free(attrs_buf);
var attrs_bufs: [3][]Die.Attr = undefined;
for (&attrs_bufs, 0..) |*buf, index| buf.* = attrs_buf[index * max_attrs ..][0..max_attrs];
const next_unit_pos = this_unit_offset + next_offset;
var compile_unit: CompileUnit = .{
.version = version,
.format = unit_header.format,
.die = undefined,
.pc_range = null,
.str_offsets_base = 0,
.addr_base = 0,
.rnglists_base = 0,
.loclists_base = 0,
.frame_base = null,
};
while (true) {
fbr.pos = mem.indexOfNonePos(u8, fbr.buf, fbr.pos, &.{
zig_padding_abbrev_code, 0,
}) orelse fbr.buf.len;
if (fbr.pos >= next_unit_pos) break;
var die_obj = (try parseDie(
&fbr,
attrs_bufs[0],
abbrev_table,
unit_header.format,
)) orelse continue;
switch (die_obj.tag_id) {
TAG.compile_unit => {
compile_unit.die = die_obj;
compile_unit.die.attrs = attrs_bufs[1][0..die_obj.attrs.len];
@memcpy(compile_unit.die.attrs, die_obj.attrs);
compile_unit.str_offsets_base = if (die_obj.getAttr(AT.str_offsets_base)) |fv| try fv.getUInt(usize) else 0;
compile_unit.addr_base = if (die_obj.getAttr(AT.addr_base)) |fv| try fv.getUInt(usize) else 0;
compile_unit.rnglists_base = if (die_obj.getAttr(AT.rnglists_base)) |fv| try fv.getUInt(usize) else 0;
compile_unit.loclists_base = if (die_obj.getAttr(AT.loclists_base)) |fv| try fv.getUInt(usize) else 0;
compile_unit.frame_base = die_obj.getAttr(AT.frame_base);
},
TAG.subprogram, TAG.inlined_subroutine, TAG.subroutine, TAG.entry_point => {
const fn_name = x: {
var this_die_obj = die_obj;
// Prevent endless loops
for (0..3) |_| {
if (this_die_obj.getAttr(AT.name)) |_| {
break :x try this_die_obj.getAttrString(di, AT.name, di.section(.debug_str), compile_unit);
} else if (this_die_obj.getAttr(AT.abstract_origin)) |_| {
const after_die_offset = fbr.pos;
defer fbr.pos = after_die_offset;
// Follow the DIE it points to and repeat
const ref_offset = try this_die_obj.getAttrRef(AT.abstract_origin);
if (ref_offset > next_offset) return badDwarf();
try fbr.seekTo(this_unit_offset + ref_offset);
this_die_obj = (try parseDie(
&fbr,
attrs_bufs[2],
abbrev_table,
unit_header.format,
)) orelse return badDwarf();
} else if (this_die_obj.getAttr(AT.specification)) |_| {
const after_die_offset = fbr.pos;
defer fbr.pos = after_die_offset;
// Follow the DIE it points to and repeat
const ref_offset = try this_die_obj.getAttrRef(AT.specification);
if (ref_offset > next_offset) return badDwarf();
try fbr.seekTo(this_unit_offset + ref_offset);
this_die_obj = (try parseDie(
&fbr,
attrs_bufs[2],
abbrev_table,
unit_header.format,
)) orelse return badDwarf();
} else {
break :x null;
}
}
break :x null;
};
var range_added = if (die_obj.getAttrAddr(di, AT.low_pc, compile_unit)) |low_pc| blk: {
if (die_obj.getAttr(AT.high_pc)) |high_pc_value| {
const pc_end = switch (high_pc_value.*) {
.addr => |value| value,
.udata => |offset| low_pc + offset,
else => return badDwarf(),
};
try di.func_list.append(allocator, .{
.name = fn_name,
.pc_range = .{
.start = low_pc,
.end = pc_end,
},
});
break :blk true;
}
break :blk false;
} else |err| blk: {
if (err != error.MissingDebugInfo) return err;
break :blk false;
};
if (die_obj.getAttr(AT.ranges)) |ranges_value| blk: {
var iter = DebugRangeIterator.init(ranges_value, di, &compile_unit) catch |err| {
if (err != error.MissingDebugInfo) return err;
break :blk;
};
while (try iter.next()) |range| {
range_added = true;
try di.func_list.append(allocator, .{
.name = fn_name,
.pc_range = .{
.start = range.start_addr,
.end = range.end_addr,
},
});
}
}
if (fn_name != null and !range_added) {
try di.func_list.append(allocator, .{
.name = fn_name,
.pc_range = null,
});
}
},
else => {},
}
}
this_unit_offset += next_offset;
}
}
fn scanAllCompileUnits(di: *DwarfInfo, allocator: mem.Allocator) !void {
var fbr: FixedBufferReader = .{ .buf = di.section(.debug_info).?, .endian = di.endian };
var this_unit_offset: u64 = 0;
var attrs_buf = std.ArrayList(Die.Attr).init(allocator);
defer attrs_buf.deinit();
while (this_unit_offset < fbr.buf.len) {
try fbr.seekTo(this_unit_offset);
const unit_header = try readUnitHeader(&fbr);
if (unit_header.unit_length == 0) return;
const next_offset = unit_header.header_length + unit_header.unit_length;
const version = try fbr.readInt(u16);
if (version < 2 or version > 5) return badDwarf();
var address_size: u8 = undefined;
var debug_abbrev_offset: u64 = undefined;
if (version >= 5) {
const unit_type = try fbr.readInt(u8);
if (unit_type != UT.compile) return badDwarf();
address_size = try fbr.readByte();
debug_abbrev_offset = try fbr.readAddress(unit_header.format);
} else {
debug_abbrev_offset = try fbr.readAddress(unit_header.format);
address_size = try fbr.readByte();
}
if (address_size != @sizeOf(usize)) return badDwarf();
const abbrev_table = try di.getAbbrevTable(allocator, debug_abbrev_offset);
var max_attrs: usize = 0;
for (abbrev_table.abbrevs) |abbrev| {
max_attrs = @max(max_attrs, abbrev.attrs.len);
}
try attrs_buf.resize(max_attrs);
var compile_unit_die = (try parseDie(
&fbr,
attrs_buf.items,
abbrev_table,
unit_header.format,
)) orelse return badDwarf();
if (compile_unit_die.tag_id != TAG.compile_unit) return badDwarf();
compile_unit_die.attrs = try allocator.dupe(Die.Attr, compile_unit_die.attrs);
var compile_unit: CompileUnit = .{
.version = version,
.format = unit_header.format,
.pc_range = null,
.die = compile_unit_die,
.str_offsets_base = if (compile_unit_die.getAttr(AT.str_offsets_base)) |fv| try fv.getUInt(usize) else 0,
.addr_base = if (compile_unit_die.getAttr(AT.addr_base)) |fv| try fv.getUInt(usize) else 0,
.rnglists_base = if (compile_unit_die.getAttr(AT.rnglists_base)) |fv| try fv.getUInt(usize) else 0,
.loclists_base = if (compile_unit_die.getAttr(AT.loclists_base)) |fv| try fv.getUInt(usize) else 0,
.frame_base = compile_unit_die.getAttr(AT.frame_base),
};
compile_unit.pc_range = x: {
if (compile_unit_die.getAttrAddr(di, AT.low_pc, compile_unit)) |low_pc| {
if (compile_unit_die.getAttr(AT.high_pc)) |high_pc_value| {
const pc_end = switch (high_pc_value.*) {
.addr => |value| value,
.udata => |offset| low_pc + offset,
else => return badDwarf(),
};
break :x PcRange{
.start = low_pc,
.end = pc_end,
};
} else {
break :x null;
}
} else |err| {
if (err != error.MissingDebugInfo) return err;
break :x null;
}
};
try di.compile_unit_list.append(allocator, compile_unit);
this_unit_offset += next_offset;
}
}
const DebugRangeIterator = struct {
base_address: u64,
section_type: DwarfSection,
di: *const DwarfInfo,
compile_unit: *const CompileUnit,
fbr: FixedBufferReader,
pub fn init(ranges_value: *const FormValue, di: *const DwarfInfo, compile_unit: *const CompileUnit) !@This() {
const section_type = if (compile_unit.version >= 5) DwarfSection.debug_rnglists else DwarfSection.debug_ranges;
const debug_ranges = di.section(section_type) orelse return error.MissingDebugInfo;
const ranges_offset = switch (ranges_value.*) {
.sec_offset, .udata => |off| off,
.rnglistx => |idx| off: {
switch (compile_unit.format) {
.@"32" => {
const offset_loc = @as(usize, @intCast(compile_unit.rnglists_base + 4 * idx));
if (offset_loc + 4 > debug_ranges.len) return badDwarf();
const offset = mem.readInt(u32, debug_ranges[offset_loc..][0..4], di.endian);
break :off compile_unit.rnglists_base + offset;
},
.@"64" => {
const offset_loc = @as(usize, @intCast(compile_unit.rnglists_base + 8 * idx));
if (offset_loc + 8 > debug_ranges.len) return badDwarf();
const offset = mem.readInt(u64, debug_ranges[offset_loc..][0..8], di.endian);
break :off compile_unit.rnglists_base + offset;
},
}
},
else => return badDwarf(),
};
// All the addresses in the list are relative to the value
// specified by DW_AT.low_pc or to some other value encoded
// in the list itself.
// If no starting value is specified use zero.
const base_address = compile_unit.die.getAttrAddr(di, AT.low_pc, compile_unit.*) catch |err| switch (err) {
error.MissingDebugInfo => 0,
else => return err,
};
return .{
.base_address = base_address,
.section_type = section_type,
.di = di,
.compile_unit = compile_unit,
.fbr = .{
.buf = debug_ranges,
.pos = math.cast(usize, ranges_offset) orelse return badDwarf(),
.endian = di.endian,
},
};
}
// Returns the next range in the list, or null if the end was reached.
pub fn next(self: *@This()) !?struct { start_addr: u64, end_addr: u64 } {
switch (self.section_type) {
.debug_rnglists => {
const kind = try self.fbr.readByte();
switch (kind) {
RLE.end_of_list => return null,
RLE.base_addressx => {
const index = try self.fbr.readUleb128(usize);
self.base_address = try self.di.readDebugAddr(self.compile_unit.*, index);
return try self.next();
},
RLE.startx_endx => {
const start_index = try self.fbr.readUleb128(usize);
const start_addr = try self.di.readDebugAddr(self.compile_unit.*, start_index);
const end_index = try self.fbr.readUleb128(usize);
const end_addr = try self.di.readDebugAddr(self.compile_unit.*, end_index);
return .{
.start_addr = start_addr,
.end_addr = end_addr,
};
},
RLE.startx_length => {
const start_index = try self.fbr.readUleb128(usize);
const start_addr = try self.di.readDebugAddr(self.compile_unit.*, start_index);
const len = try self.fbr.readUleb128(usize);
const end_addr = start_addr + len;
return .{
.start_addr = start_addr,
.end_addr = end_addr,
};
},
RLE.offset_pair => {
const start_addr = try self.fbr.readUleb128(usize);
const end_addr = try self.fbr.readUleb128(usize);
// This is the only kind that uses the base address
return .{
.start_addr = self.base_address + start_addr,
.end_addr = self.base_address + end_addr,
};
},
RLE.base_address => {
self.base_address = try self.fbr.readInt(usize);
return try self.next();
},
RLE.start_end => {
const start_addr = try self.fbr.readInt(usize);
const end_addr = try self.fbr.readInt(usize);
return .{
.start_addr = start_addr,
.end_addr = end_addr,
};
},
RLE.start_length => {
const start_addr = try self.fbr.readInt(usize);
const len = try self.fbr.readUleb128(usize);
const end_addr = start_addr + len;
return .{
.start_addr = start_addr,
.end_addr = end_addr,
};
},
else => return badDwarf(),
}
},
.debug_ranges => {
const start_addr = try self.fbr.readInt(usize);
const end_addr = try self.fbr.readInt(usize);
if (start_addr == 0 and end_addr == 0) return null;
// This entry selects a new value for the base address
if (start_addr == math.maxInt(usize)) {
self.base_address = end_addr;
return try self.next();
}
return .{
.start_addr = self.base_address + start_addr,
.end_addr = self.base_address + end_addr,
};
},
else => unreachable,
}
}
};
pub fn findCompileUnit(di: *const DwarfInfo, target_address: u64) !*const CompileUnit {
for (di.compile_unit_list.items) |*compile_unit| {
if (compile_unit.pc_range) |range| {
if (target_address >= range.start and target_address < range.end) return compile_unit;
}
const ranges_value = compile_unit.die.getAttr(AT.ranges) orelse continue;
var iter = DebugRangeIterator.init(ranges_value, di, compile_unit) catch continue;
while (try iter.next()) |range| {
if (target_address >= range.start_addr and target_address < range.end_addr) return compile_unit;
}
}
return missingDwarf();
}
/// Gets an already existing AbbrevTable given the abbrev_offset, or if not found,
/// seeks in the stream and parses it.
fn getAbbrevTable(di: *DwarfInfo, allocator: mem.Allocator, abbrev_offset: u64) !*const Abbrev.Table {
for (di.abbrev_table_list.items) |*table| {
if (table.offset == abbrev_offset) {
return table;
}
}
try di.abbrev_table_list.append(
allocator,
try di.parseAbbrevTable(allocator, abbrev_offset),
);
return &di.abbrev_table_list.items[di.abbrev_table_list.items.len - 1];
}
fn parseAbbrevTable(di: *DwarfInfo, allocator: mem.Allocator, offset: u64) !Abbrev.Table {
var fbr: FixedBufferReader = .{
.buf = di.section(.debug_abbrev).?,
.pos = math.cast(usize, offset) orelse return badDwarf(),
.endian = di.endian,
};
var abbrevs = std.ArrayList(Abbrev).init(allocator);
defer {
for (abbrevs.items) |*abbrev| {
abbrev.deinit(allocator);
}
abbrevs.deinit();
}
var attrs = std.ArrayList(Abbrev.Attr).init(allocator);
defer attrs.deinit();
while (true) {
const code = try fbr.readUleb128(u64);
if (code == 0) break;
const tag_id = try fbr.readUleb128(u64);
const has_children = (try fbr.readByte()) == CHILDREN.yes;
while (true) {
const attr_id = try fbr.readUleb128(u64);
const form_id = try fbr.readUleb128(u64);
if (attr_id == 0 and form_id == 0) break;
try attrs.append(.{
.id = attr_id,
.form_id = form_id,
.payload = switch (form_id) {
FORM.implicit_const => try fbr.readIleb128(i64),
else => undefined,
},
});
}
try abbrevs.append(.{
.code = code,
.tag_id = tag_id,
.has_children = has_children,
.attrs = try attrs.toOwnedSlice(),
});
}
return .{
.offset = offset,
.abbrevs = try abbrevs.toOwnedSlice(),
};
}
fn parseDie(
fbr: *FixedBufferReader,
attrs_buf: []Die.Attr,
abbrev_table: *const Abbrev.Table,
format: Format,
) !?Die {
const abbrev_code = try fbr.readUleb128(u64);
if (abbrev_code == 0) return null;
const table_entry = abbrev_table.get(abbrev_code) orelse return badDwarf();
const attrs = attrs_buf[0..table_entry.attrs.len];
for (attrs, table_entry.attrs) |*result_attr, attr| result_attr.* = Die.Attr{
.id = attr.id,
.value = try parseFormValue(
fbr,
attr.form_id,
format,
attr.payload,
),
};
return .{
.tag_id = table_entry.tag_id,
.has_children = table_entry.has_children,
.attrs = attrs,
};
}
pub fn getLineNumberInfo(
di: *DwarfInfo,
allocator: mem.Allocator,
compile_unit: CompileUnit,
target_address: u64,
) !debug.LineInfo {
const compile_unit_cwd = try compile_unit.die.getAttrString(di, AT.comp_dir, di.section(.debug_line_str), compile_unit);
const line_info_offset = try compile_unit.die.getAttrSecOffset(AT.stmt_list);
var fbr: FixedBufferReader = .{ .buf = di.section(.debug_line).?, .endian = di.endian };
try fbr.seekTo(line_info_offset);
const unit_header = try readUnitHeader(&fbr);
if (unit_header.unit_length == 0) return missingDwarf();
const next_offset = unit_header.header_length + unit_header.unit_length;
const version = try fbr.readInt(u16);
if (version < 2) return badDwarf();
var addr_size: u8 = switch (unit_header.format) {
.@"32" => 4,
.@"64" => 8,
};
var seg_size: u8 = 0;
if (version >= 5) {
addr_size = try fbr.readByte();
seg_size = try fbr.readByte();
}
const prologue_length = try fbr.readAddress(unit_header.format);
const prog_start_offset = fbr.pos + prologue_length;
const minimum_instruction_length = try fbr.readByte();
if (minimum_instruction_length == 0) return badDwarf();
if (version >= 4) {
// maximum_operations_per_instruction
_ = try fbr.readByte();
}
const default_is_stmt = (try fbr.readByte()) != 0;
const line_base = try fbr.readByteSigned();
const line_range = try fbr.readByte();
if (line_range == 0) return badDwarf();
const opcode_base = try fbr.readByte();
const standard_opcode_lengths = try fbr.readBytes(opcode_base - 1);
var include_directories = std.ArrayList(FileEntry).init(allocator);
defer include_directories.deinit();
var file_entries = std.ArrayList(FileEntry).init(allocator);
defer file_entries.deinit();
if (version < 5) {
try include_directories.append(.{ .path = compile_unit_cwd });
while (true) {
const dir = try fbr.readBytesTo(0);
if (dir.len == 0) break;
try include_directories.append(.{ .path = dir });
}
while (true) {
const file_name = try fbr.readBytesTo(0);
if (file_name.len == 0) break;
const dir_index = try fbr.readUleb128(u32);
const mtime = try fbr.readUleb128(u64);
const size = try fbr.readUleb128(u64);
try file_entries.append(.{
.path = file_name,
.dir_index = dir_index,
.mtime = mtime,
.size = size,
});
}
} else {
const FileEntFmt = struct {
content_type_code: u8,
form_code: u16,
};
{
var dir_ent_fmt_buf: [10]FileEntFmt = undefined;
const directory_entry_format_count = try fbr.readByte();
if (directory_entry_format_count > dir_ent_fmt_buf.len) return badDwarf();
for (dir_ent_fmt_buf[0..directory_entry_format_count]) |*ent_fmt| {
ent_fmt.* = .{
.content_type_code = try fbr.readUleb128(u8),
.form_code = try fbr.readUleb128(u16),
};
}
const directories_count = try fbr.readUleb128(usize);
try include_directories.ensureUnusedCapacity(directories_count);
{
var i: usize = 0;
while (i < directories_count) : (i += 1) {
var e: FileEntry = .{ .path = &.{} };
for (dir_ent_fmt_buf[0..directory_entry_format_count]) |ent_fmt| {
const form_value = try parseFormValue(
&fbr,
ent_fmt.form_code,
unit_header.format,
null,
);
switch (ent_fmt.content_type_code) {
LNCT.path => e.path = try form_value.getString(di.*),
LNCT.directory_index => e.dir_index = try form_value.getUInt(u32),
LNCT.timestamp => e.mtime = try form_value.getUInt(u64),
LNCT.size => e.size = try form_value.getUInt(u64),
LNCT.MD5 => e.md5 = switch (form_value) {
.data16 => |data16| data16.*,
else => return badDwarf(),
},
else => continue,
}
}
include_directories.appendAssumeCapacity(e);
}
}
}
var file_ent_fmt_buf: [10]FileEntFmt = undefined;
const file_name_entry_format_count = try fbr.readByte();
if (file_name_entry_format_count > file_ent_fmt_buf.len) return badDwarf();
for (file_ent_fmt_buf[0..file_name_entry_format_count]) |*ent_fmt| {
ent_fmt.* = .{
.content_type_code = try fbr.readUleb128(u8),
.form_code = try fbr.readUleb128(u16),
};
}
const file_names_count = try fbr.readUleb128(usize);
try file_entries.ensureUnusedCapacity(file_names_count);
{
var i: usize = 0;
while (i < file_names_count) : (i += 1) {
var e: FileEntry = .{ .path = &.{} };
for (file_ent_fmt_buf[0..file_name_entry_format_count]) |ent_fmt| {
const form_value = try parseFormValue(
&fbr,
ent_fmt.form_code,
unit_header.format,
null,
);
switch (ent_fmt.content_type_code) {
LNCT.path => e.path = try form_value.getString(di.*),
LNCT.directory_index => e.dir_index = try form_value.getUInt(u32),
LNCT.timestamp => e.mtime = try form_value.getUInt(u64),
LNCT.size => e.size = try form_value.getUInt(u64),
LNCT.MD5 => e.md5 = switch (form_value) {
.data16 => |data16| data16.*,
else => return badDwarf(),
},
else => continue,
}
}
file_entries.appendAssumeCapacity(e);
}
}
}
var prog = LineNumberProgram.init(
default_is_stmt,
include_directories.items,
target_address,
version,
);
try fbr.seekTo(prog_start_offset);
const next_unit_pos = line_info_offset + next_offset;
while (fbr.pos < next_unit_pos) {
const opcode = try fbr.readByte();
if (opcode == LNS.extended_op) {
const op_size = try fbr.readUleb128(u64);
if (op_size < 1) return badDwarf();
const sub_op = try fbr.readByte();
switch (sub_op) {
LNE.end_sequence => {
prog.end_sequence = true;
if (try prog.checkLineMatch(allocator, file_entries.items)) |info| return info;
prog.reset();
},
LNE.set_address => {
const addr = try fbr.readInt(usize);
prog.address = addr;
},
LNE.define_file => {
const path = try fbr.readBytesTo(0);
const dir_index = try fbr.readUleb128(u32);
const mtime = try fbr.readUleb128(u64);
const size = try fbr.readUleb128(u64);
try file_entries.append(.{
.path = path,
.dir_index = dir_index,
.mtime = mtime,
.size = size,
});
},
else => try fbr.seekForward(op_size - 1),
}
} else if (opcode >= opcode_base) {
// special opcodes
const adjusted_opcode = opcode - opcode_base;
const inc_addr = minimum_instruction_length * (adjusted_opcode / line_range);
const inc_line = @as(i32, line_base) + @as(i32, adjusted_opcode % line_range);
prog.line += inc_line;
prog.address += inc_addr;
if (try prog.checkLineMatch(allocator, file_entries.items)) |info| return info;
prog.basic_block = false;
} else {
switch (opcode) {
LNS.copy => {
if (try prog.checkLineMatch(allocator, file_entries.items)) |info| return info;
prog.basic_block = false;
},
LNS.advance_pc => {
const arg = try fbr.readUleb128(usize);
prog.address += arg * minimum_instruction_length;
},
LNS.advance_line => {
const arg = try fbr.readIleb128(i64);
prog.line += arg;
},
LNS.set_file => {
const arg = try fbr.readUleb128(usize);
prog.file = arg;
},
LNS.set_column => {
const arg = try fbr.readUleb128(u64);
prog.column = arg;
},
LNS.negate_stmt => {
prog.is_stmt = !prog.is_stmt;
},
LNS.set_basic_block => {
prog.basic_block = true;
},
LNS.const_add_pc => {
const inc_addr = minimum_instruction_length * ((255 - opcode_base) / line_range);
prog.address += inc_addr;
},
LNS.fixed_advance_pc => {
const arg = try fbr.readInt(u16);
prog.address += arg;
},
LNS.set_prologue_end => {},
else => {
if (opcode - 1 >= standard_opcode_lengths.len) return badDwarf();
try fbr.seekForward(standard_opcode_lengths[opcode - 1]);
},
}
}
}
return missingDwarf();
}
fn getString(di: DwarfInfo, offset: u64) ![:0]const u8 {
return getStringGeneric(di.section(.debug_str), offset);
}
fn getLineString(di: DwarfInfo, offset: u64) ![:0]const u8 {
return getStringGeneric(di.section(.debug_line_str), offset);
}
fn readDebugAddr(di: DwarfInfo, compile_unit: CompileUnit, index: u64) !u64 {
const debug_addr = di.section(.debug_addr) orelse return badDwarf();
// addr_base points to the first item after the header, however we
// need to read the header to know the size of each item. Empirically,
// it may disagree with is_64 on the compile unit.
// The header is 8 or 12 bytes depending on is_64.
if (compile_unit.addr_base < 8) return badDwarf();
const version = mem.readInt(u16, debug_addr[compile_unit.addr_base - 4 ..][0..2], di.endian);
if (version != 5) return badDwarf();
const addr_size = debug_addr[compile_unit.addr_base - 2];
const seg_size = debug_addr[compile_unit.addr_base - 1];
const byte_offset = @as(usize, @intCast(compile_unit.addr_base + (addr_size + seg_size) * index));
if (byte_offset + addr_size > debug_addr.len) return badDwarf();
return switch (addr_size) {
1 => debug_addr[byte_offset],
2 => mem.readInt(u16, debug_addr[byte_offset..][0..2], di.endian),
4 => mem.readInt(u32, debug_addr[byte_offset..][0..4], di.endian),
8 => mem.readInt(u64, debug_addr[byte_offset..][0..8], di.endian),
else => badDwarf(),
};
}
/// If .eh_frame_hdr is present, then only the header needs to be parsed.
///
/// Otherwise, .eh_frame and .debug_frame are scanned and a sorted list
/// of FDEs is built for binary searching during unwinding.
pub fn scanAllUnwindInfo(di: *DwarfInfo, allocator: mem.Allocator, base_address: usize) !void {
if (di.section(.eh_frame_hdr)) |eh_frame_hdr| blk: {
var fbr: FixedBufferReader = .{ .buf = eh_frame_hdr, .endian = native_endian };
const version = try fbr.readByte();
if (version != 1) break :blk;
const eh_frame_ptr_enc = try fbr.readByte();
if (eh_frame_ptr_enc == EH.PE.omit) break :blk;
const fde_count_enc = try fbr.readByte();
if (fde_count_enc == EH.PE.omit) break :blk;
const table_enc = try fbr.readByte();
if (table_enc == EH.PE.omit) break :blk;
const eh_frame_ptr = math.cast(usize, try readEhPointer(&fbr, eh_frame_ptr_enc, @sizeOf(usize), .{
.pc_rel_base = @intFromPtr(&eh_frame_hdr[fbr.pos]),
.follow_indirect = true,
}) orelse return badDwarf()) orelse return badDwarf();
const fde_count = math.cast(usize, try readEhPointer(&fbr, fde_count_enc, @sizeOf(usize), .{
.pc_rel_base = @intFromPtr(&eh_frame_hdr[fbr.pos]),
.follow_indirect = true,
}) orelse return badDwarf()) orelse return badDwarf();
const entry_size = try ExceptionFrameHeader.entrySize(table_enc);
const entries_len = fde_count * entry_size;
if (entries_len > eh_frame_hdr.len - fbr.pos) return badDwarf();
di.eh_frame_hdr = .{
.eh_frame_ptr = eh_frame_ptr,
.table_enc = table_enc,
.fde_count = fde_count,
.entries = eh_frame_hdr[fbr.pos..][0..entries_len],
};
// No need to scan .eh_frame, we have a binary search table already
return;
}
const frame_sections = [2]DwarfSection{ .eh_frame, .debug_frame };
for (frame_sections) |frame_section| {
if (di.section(frame_section)) |section_data| {
var fbr: FixedBufferReader = .{ .buf = section_data, .endian = di.endian };
while (fbr.pos < fbr.buf.len) {
const entry_header = try EntryHeader.read(&fbr, frame_section);
switch (entry_header.type) {
.cie => {
const cie = try CommonInformationEntry.parse(
entry_header.entry_bytes,
di.sectionVirtualOffset(frame_section, base_address).?,
true,
entry_header.format,
frame_section,
entry_header.length_offset,
@sizeOf(usize),
di.endian,
);
try di.cie_map.put(allocator, entry_header.length_offset, cie);
},
.fde => |cie_offset| {
const cie = di.cie_map.get(cie_offset) orelse return badDwarf();
const fde = try FrameDescriptionEntry.parse(
entry_header.entry_bytes,
di.sectionVirtualOffset(frame_section, base_address).?,
true,
cie,
@sizeOf(usize),
di.endian,
);
try di.fde_list.append(allocator, fde);
},
.terminator => break,
}
}
mem.sortUnstable(FrameDescriptionEntry, di.fde_list.items, {}, struct {
fn lessThan(ctx: void, a: FrameDescriptionEntry, b: FrameDescriptionEntry) bool {
_ = ctx;
return a.pc_begin < b.pc_begin;
}
}.lessThan);
}
}
}
/// Unwind a stack frame using DWARF unwinding info, updating the register context.
///
/// If `.eh_frame_hdr` is available, it will be used to binary search for the FDE.
/// Otherwise, a linear scan of `.eh_frame` and `.debug_frame` is done to find the FDE.
///
/// `explicit_fde_offset` is for cases where the FDE offset is known, such as when __unwind_info
/// defers unwinding to DWARF. This is an offset into the `.eh_frame` section.
pub fn unwindFrame(di: *const DwarfInfo, context: *UnwindContext, explicit_fde_offset: ?usize) !usize {
if (!comptime abi.supportsUnwinding(builtin.target)) return error.UnsupportedCpuArchitecture;
if (context.pc == 0) return 0;
// Find the FDE and CIE
var cie: CommonInformationEntry = undefined;
var fde: FrameDescriptionEntry = undefined;
if (explicit_fde_offset) |fde_offset| {
const dwarf_section: DwarfSection = .eh_frame;
const frame_section = di.section(dwarf_section) orelse return error.MissingFDE;
if (fde_offset >= frame_section.len) return error.MissingFDE;
var fbr: FixedBufferReader = .{
.buf = frame_section,
.pos = fde_offset,
.endian = di.endian,
};
const fde_entry_header = try EntryHeader.read(&fbr, dwarf_section);
if (fde_entry_header.type != .fde) return error.MissingFDE;
const cie_offset = fde_entry_header.type.fde;
try fbr.seekTo(cie_offset);
fbr.endian = native_endian;
const cie_entry_header = try EntryHeader.read(&fbr, dwarf_section);
if (cie_entry_header.type != .cie) return badDwarf();
cie = try CommonInformationEntry.parse(
cie_entry_header.entry_bytes,
0,
true,
cie_entry_header.format,
dwarf_section,
cie_entry_header.length_offset,
@sizeOf(usize),
native_endian,
);
fde = try FrameDescriptionEntry.parse(
fde_entry_header.entry_bytes,
0,
true,
cie,
@sizeOf(usize),
native_endian,
);
} else if (di.eh_frame_hdr) |header| {
const eh_frame_len = if (di.section(.eh_frame)) |eh_frame| eh_frame.len else null;
try header.findEntry(
context.isValidMemory,
eh_frame_len,
@intFromPtr(di.section(.eh_frame_hdr).?.ptr),
context.pc,
&cie,
&fde,
);
} else {
const index = std.sort.binarySearch(FrameDescriptionEntry, context.pc, di.fde_list.items, {}, struct {
pub fn compareFn(_: void, pc: usize, mid_item: FrameDescriptionEntry) math.Order {
if (pc < mid_item.pc_begin) return .lt;
const range_end = mid_item.pc_begin + mid_item.pc_range;
if (pc < range_end) return .eq;
return .gt;
}
}.compareFn);
fde = if (index) |i| di.fde_list.items[i] else return error.MissingFDE;
cie = di.cie_map.get(fde.cie_length_offset) orelse return error.MissingCIE;
}
var expression_context: expressions.ExpressionContext = .{
.format = cie.format,
.isValidMemory = context.isValidMemory,
.compile_unit = di.findCompileUnit(fde.pc_begin) catch null,
.thread_context = context.thread_context,
.reg_context = context.reg_context,
.cfa = context.cfa,
};
context.vm.reset();
context.reg_context.eh_frame = cie.version != 4;
context.reg_context.is_macho = di.is_macho;
const row = try context.vm.runToNative(context.allocator, context.pc, cie, fde);
context.cfa = switch (row.cfa.rule) {
.val_offset => |offset| blk: {
const register = row.cfa.register orelse return error.InvalidCFARule;
const value = mem.readInt(usize, (try abi.regBytes(context.thread_context, register, context.reg_context))[0..@sizeOf(usize)], native_endian);
break :blk try call_frame.applyOffset(value, offset);
},
.expression => |expression| blk: {
context.stack_machine.reset();
const value = try context.stack_machine.run(
expression,
context.allocator,
expression_context,
context.cfa,
);
if (value) |v| {
if (v != .generic) return error.InvalidExpressionValue;
break :blk v.generic;
} else return error.NoExpressionValue;
},
else => return error.InvalidCFARule,
};
if (!context.isValidMemory(context.cfa.?)) return error.InvalidCFA;
expression_context.cfa = context.cfa;
// Buffering the modifications is done because copying the thread context is not portable,
// some implementations (ie. darwin) use internal pointers to the mcontext.
var arena = std.heap.ArenaAllocator.init(context.allocator);
defer arena.deinit();
const update_allocator = arena.allocator();
const RegisterUpdate = struct {
// Backed by thread_context
dest: []u8,
// Backed by arena
src: []const u8,
prev: ?*@This(),
};
var update_tail: ?*RegisterUpdate = null;
var has_return_address = true;
for (context.vm.rowColumns(row)) |column| {
if (column.register) |register| {
if (register == cie.return_address_register) {
has_return_address = column.rule != .undefined;
}
const dest = try abi.regBytes(context.thread_context, register, context.reg_context);
const src = try update_allocator.alloc(u8, dest.len);
const prev = update_tail;
update_tail = try update_allocator.create(RegisterUpdate);
update_tail.?.* = .{
.dest = dest,
.src = src,
.prev = prev,
};
try column.resolveValue(
context,
expression_context,
src,
);
}
}
// On all implemented architectures, the CFA is defined as being the previous frame's SP
(try abi.regValueNative(usize, context.thread_context, abi.spRegNum(context.reg_context), context.reg_context)).* = context.cfa.?;
while (update_tail) |tail| {
@memcpy(tail.dest, tail.src);
update_tail = tail.prev;
}
if (has_return_address) {
context.pc = abi.stripInstructionPtrAuthCode(mem.readInt(usize, (try abi.regBytes(
context.thread_context,
cie.return_address_register,
context.reg_context,
))[0..@sizeOf(usize)], native_endian));
} else {
context.pc = 0;
}
(try abi.regValueNative(usize, context.thread_context, abi.ipRegNum(), context.reg_context)).* = context.pc;
// The call instruction will have pushed the address of the instruction that follows the call as the return address.
// This next instruction may be past the end of the function if the caller was `noreturn` (ie. the last instruction in
// the function was the call). If we were to look up an FDE entry using the return address directly, it could end up
// either not finding an FDE at all, or using the next FDE in the program, producing incorrect results. To prevent this,
// we subtract one so that the next lookup is guaranteed to land inside the
//
// The exception to this rule is signal frames, where we return execution would be returned to the instruction
// that triggered the handler.
const return_address = context.pc;
if (context.pc > 0 and !cie.isSignalFrame()) context.pc -= 1;
return return_address;
}
};
/// Returns the DWARF register number for an x86_64 register number found in compact unwind info
fn compactUnwindToDwarfRegNumber(unwind_reg_number: u3) !u8 {
return switch (unwind_reg_number) {
1 => 3, // RBX
2 => 12, // R12
3 => 13, // R13
4 => 14, // R14
5 => 15, // R15
6 => 6, // RBP
else => error.InvalidUnwindRegisterNumber,
};
}
const macho = std.macho;
/// Unwind a frame using MachO compact unwind info (from __unwind_info).
/// If the compact encoding can't encode a way to unwind a frame, it will
/// defer unwinding to DWARF, in which case `.eh_frame` will be used if available.
pub fn unwindFrameMachO(context: *UnwindContext, unwind_info: []const u8, eh_frame: ?[]const u8, module_base_address: usize) !usize {
const header = mem.bytesAsValue(
macho.unwind_info_section_header,
unwind_info[0..@sizeOf(macho.unwind_info_section_header)],
);
const indices = mem.bytesAsSlice(
macho.unwind_info_section_header_index_entry,
unwind_info[header.indexSectionOffset..][0 .. header.indexCount * @sizeOf(macho.unwind_info_section_header_index_entry)],
);
if (indices.len == 0) return error.MissingUnwindInfo;
const mapped_pc = context.pc - module_base_address;
const second_level_index = blk: {
var left: usize = 0;
var len: usize = indices.len;
while (len > 1) {
const mid = left + len / 2;
const offset = indices[mid].functionOffset;
if (mapped_pc < offset) {
len /= 2;
} else {
left = mid;
if (mapped_pc == offset) break;
len -= len / 2;
}
}
// Last index is a sentinel containing the highest address as its functionOffset
if (indices[left].secondLevelPagesSectionOffset == 0) return error.MissingUnwindInfo;
break :blk &indices[left];
};
const common_encodings = mem.bytesAsSlice(
macho.compact_unwind_encoding_t,
unwind_info[header.commonEncodingsArraySectionOffset..][0 .. header.commonEncodingsArrayCount * @sizeOf(macho.compact_unwind_encoding_t)],
);
const start_offset = second_level_index.secondLevelPagesSectionOffset;
const kind = mem.bytesAsValue(
macho.UNWIND_SECOND_LEVEL,
unwind_info[start_offset..][0..@sizeOf(macho.UNWIND_SECOND_LEVEL)],
);
const entry: struct {
function_offset: usize,
raw_encoding: u32,
} = switch (kind.*) {
.REGULAR => blk: {
const page_header = mem.bytesAsValue(
macho.unwind_info_regular_second_level_page_header,
unwind_info[start_offset..][0..@sizeOf(macho.unwind_info_regular_second_level_page_header)],
);
const entries = mem.bytesAsSlice(
macho.unwind_info_regular_second_level_entry,
unwind_info[start_offset + page_header.entryPageOffset ..][0 .. page_header.entryCount * @sizeOf(macho.unwind_info_regular_second_level_entry)],
);
if (entries.len == 0) return error.InvalidUnwindInfo;
var left: usize = 0;
var len: usize = entries.len;
while (len > 1) {
const mid = left + len / 2;
const offset = entries[mid].functionOffset;
if (mapped_pc < offset) {
len /= 2;
} else {
left = mid;
if (mapped_pc == offset) break;
len -= len / 2;
}
}
break :blk .{
.function_offset = entries[left].functionOffset,
.raw_encoding = entries[left].encoding,
};
},
.COMPRESSED => blk: {
const page_header = mem.bytesAsValue(
macho.unwind_info_compressed_second_level_page_header,
unwind_info[start_offset..][0..@sizeOf(macho.unwind_info_compressed_second_level_page_header)],
);
const entries = mem.bytesAsSlice(
macho.UnwindInfoCompressedEntry,
unwind_info[start_offset + page_header.entryPageOffset ..][0 .. page_header.entryCount * @sizeOf(macho.UnwindInfoCompressedEntry)],
);
if (entries.len == 0) return error.InvalidUnwindInfo;
var left: usize = 0;
var len: usize = entries.len;
while (len > 1) {
const mid = left + len / 2;
const offset = second_level_index.functionOffset + entries[mid].funcOffset;
if (mapped_pc < offset) {
len /= 2;
} else {
left = mid;
if (mapped_pc == offset) break;
len -= len / 2;
}
}
const entry = entries[left];
const function_offset = second_level_index.functionOffset + entry.funcOffset;
if (entry.encodingIndex < header.commonEncodingsArrayCount) {
if (entry.encodingIndex >= common_encodings.len) return error.InvalidUnwindInfo;
break :blk .{
.function_offset = function_offset,
.raw_encoding = common_encodings[entry.encodingIndex],
};
} else {
const local_index = try math.sub(
u8,
entry.encodingIndex,
math.cast(u8, header.commonEncodingsArrayCount) orelse return error.InvalidUnwindInfo,
);
const local_encodings = mem.bytesAsSlice(
macho.compact_unwind_encoding_t,
unwind_info[start_offset + page_header.encodingsPageOffset ..][0 .. page_header.encodingsCount * @sizeOf(macho.compact_unwind_encoding_t)],
);
if (local_index >= local_encodings.len) return error.InvalidUnwindInfo;
break :blk .{
.function_offset = function_offset,
.raw_encoding = local_encodings[local_index],
};
}
},
else => return error.InvalidUnwindInfo,
};
if (entry.raw_encoding == 0) return error.NoUnwindInfo;
const reg_context = abi.RegisterContext{
.eh_frame = false,
.is_macho = true,
};
const encoding: macho.CompactUnwindEncoding = @bitCast(entry.raw_encoding);
const new_ip = switch (builtin.cpu.arch) {
.x86_64 => switch (encoding.mode.x86_64) {
.OLD => return error.UnimplementedUnwindEncoding,
.RBP_FRAME => blk: {
const regs: [5]u3 = .{
encoding.value.x86_64.frame.reg0,
encoding.value.x86_64.frame.reg1,
encoding.value.x86_64.frame.reg2,
encoding.value.x86_64.frame.reg3,
encoding.value.x86_64.frame.reg4,
};
const frame_offset = encoding.value.x86_64.frame.frame_offset * @sizeOf(usize);
var max_reg: usize = 0;
inline for (regs, 0..) |reg, i| {
if (reg > 0) max_reg = i;
}
const fp = (try abi.regValueNative(usize, context.thread_context, abi.fpRegNum(reg_context), reg_context)).*;
const new_sp = fp + 2 * @sizeOf(usize);
// Verify the stack range we're about to read register values from
if (!context.isValidMemory(new_sp) or !context.isValidMemory(fp - frame_offset + max_reg * @sizeOf(usize))) return error.InvalidUnwindInfo;
const ip_ptr = fp + @sizeOf(usize);
const new_ip = @as(*const usize, @ptrFromInt(ip_ptr)).*;
const new_fp = @as(*const usize, @ptrFromInt(fp)).*;
(try abi.regValueNative(usize, context.thread_context, abi.fpRegNum(reg_context), reg_context)).* = new_fp;
(try abi.regValueNative(usize, context.thread_context, abi.spRegNum(reg_context), reg_context)).* = new_sp;
(try abi.regValueNative(usize, context.thread_context, abi.ipRegNum(), reg_context)).* = new_ip;
for (regs, 0..) |reg, i| {
if (reg == 0) continue;
const addr = fp - frame_offset + i * @sizeOf(usize);
const reg_number = try compactUnwindToDwarfRegNumber(reg);
(try abi.regValueNative(usize, context.thread_context, reg_number, reg_context)).* = @as(*const usize, @ptrFromInt(addr)).*;
}
break :blk new_ip;
},
.STACK_IMMD,
.STACK_IND,
=> blk: {
const sp = (try abi.regValueNative(usize, context.thread_context, abi.spRegNum(reg_context), reg_context)).*;
const stack_size = if (encoding.mode.x86_64 == .STACK_IMMD)
@as(usize, encoding.value.x86_64.frameless.stack.direct.stack_size) * @sizeOf(usize)
else stack_size: {
// In .STACK_IND, the stack size is inferred from the subq instruction at the beginning of the function.
const sub_offset_addr =
module_base_address +
entry.function_offset +
encoding.value.x86_64.frameless.stack.indirect.sub_offset;
if (!context.isValidMemory(sub_offset_addr)) return error.InvalidUnwindInfo;
// `sub_offset_addr` points to the offset of the literal within the instruction
const sub_operand = @as(*align(1) const u32, @ptrFromInt(sub_offset_addr)).*;
break :stack_size sub_operand + @sizeOf(usize) * @as(usize, encoding.value.x86_64.frameless.stack.indirect.stack_adjust);
};
// Decode the Lehmer-coded sequence of registers.
// For a description of the encoding see lib/libc/include/any-macos.13-any/mach-o/compact_unwind_encoding.h
// Decode the variable-based permutation number into its digits. Each digit represents
// an index into the list of register numbers that weren't yet used in the sequence at
// the time the digit was added.
const reg_count = encoding.value.x86_64.frameless.stack_reg_count;
const ip_ptr = if (reg_count > 0) reg_blk: {
var digits: [6]u3 = undefined;
var accumulator: usize = encoding.value.x86_64.frameless.stack_reg_permutation;
var base: usize = 2;
for (0..reg_count) |i| {
const div = accumulator / base;
digits[digits.len - 1 - i] = @intCast(accumulator - base * div);
accumulator = div;
base += 1;
}
const reg_numbers = [_]u3{ 1, 2, 3, 4, 5, 6 };
var registers: [reg_numbers.len]u3 = undefined;
var used_indices = [_]bool{false} ** reg_numbers.len;
for (digits[digits.len - reg_count ..], 0..) |target_unused_index, i| {
var unused_count: u8 = 0;
const unused_index = for (used_indices, 0..) |used, index| {
if (!used) {
if (target_unused_index == unused_count) break index;
unused_count += 1;
}
} else unreachable;
registers[i] = reg_numbers[unused_index];
used_indices[unused_index] = true;
}
var reg_addr = sp + stack_size - @sizeOf(usize) * @as(usize, reg_count + 1);
if (!context.isValidMemory(reg_addr)) return error.InvalidUnwindInfo;
for (0..reg_count) |i| {
const reg_number = try compactUnwindToDwarfRegNumber(registers[i]);
(try abi.regValueNative(usize, context.thread_context, reg_number, reg_context)).* = @as(*const usize, @ptrFromInt(reg_addr)).*;
reg_addr += @sizeOf(usize);
}
break :reg_blk reg_addr;
} else sp + stack_size - @sizeOf(usize);
const new_ip = @as(*const usize, @ptrFromInt(ip_ptr)).*;
const new_sp = ip_ptr + @sizeOf(usize);
if (!context.isValidMemory(new_sp)) return error.InvalidUnwindInfo;
(try abi.regValueNative(usize, context.thread_context, abi.spRegNum(reg_context), reg_context)).* = new_sp;
(try abi.regValueNative(usize, context.thread_context, abi.ipRegNum(), reg_context)).* = new_ip;
break :blk new_ip;
},
.DWARF => {
return unwindFrameMachODwarf(context, eh_frame orelse return error.MissingEhFrame, @intCast(encoding.value.x86_64.dwarf));
},
},
.aarch64 => switch (encoding.mode.arm64) {
.OLD => return error.UnimplementedUnwindEncoding,
.FRAMELESS => blk: {
const sp = (try abi.regValueNative(usize, context.thread_context, abi.spRegNum(reg_context), reg_context)).*;
const new_sp = sp + encoding.value.arm64.frameless.stack_size * 16;
const new_ip = (try abi.regValueNative(usize, context.thread_context, 30, reg_context)).*;
if (!context.isValidMemory(new_sp)) return error.InvalidUnwindInfo;
(try abi.regValueNative(usize, context.thread_context, abi.spRegNum(reg_context), reg_context)).* = new_sp;
break :blk new_ip;
},
.DWARF => {
return unwindFrameMachODwarf(context, eh_frame orelse return error.MissingEhFrame, @intCast(encoding.value.arm64.dwarf));
},
.FRAME => blk: {
const fp = (try abi.regValueNative(usize, context.thread_context, abi.fpRegNum(reg_context), reg_context)).*;
const new_sp = fp + 16;
const ip_ptr = fp + @sizeOf(usize);
const num_restored_pairs: usize =
@popCount(@as(u5, @bitCast(encoding.value.arm64.frame.x_reg_pairs))) +
@popCount(@as(u4, @bitCast(encoding.value.arm64.frame.d_reg_pairs)));
const min_reg_addr = fp - num_restored_pairs * 2 * @sizeOf(usize);
if (!context.isValidMemory(new_sp) or !context.isValidMemory(min_reg_addr)) return error.InvalidUnwindInfo;
var reg_addr = fp - @sizeOf(usize);
inline for (@typeInfo(@TypeOf(encoding.value.arm64.frame.x_reg_pairs)).Struct.fields, 0..) |field, i| {
if (@field(encoding.value.arm64.frame.x_reg_pairs, field.name) != 0) {
(try abi.regValueNative(usize, context.thread_context, 19 + i, reg_context)).* = @as(*const usize, @ptrFromInt(reg_addr)).*;
reg_addr += @sizeOf(usize);
(try abi.regValueNative(usize, context.thread_context, 20 + i, reg_context)).* = @as(*const usize, @ptrFromInt(reg_addr)).*;
reg_addr += @sizeOf(usize);
}
}
inline for (@typeInfo(@TypeOf(encoding.value.arm64.frame.d_reg_pairs)).Struct.fields, 0..) |field, i| {
if (@field(encoding.value.arm64.frame.d_reg_pairs, field.name) != 0) {
// Only the lower half of the 128-bit V registers are restored during unwinding
@memcpy(
try abi.regBytes(context.thread_context, 64 + 8 + i, context.reg_context),
mem.asBytes(@as(*const usize, @ptrFromInt(reg_addr))),
);
reg_addr += @sizeOf(usize);
@memcpy(
try abi.regBytes(context.thread_context, 64 + 9 + i, context.reg_context),
mem.asBytes(@as(*const usize, @ptrFromInt(reg_addr))),
);
reg_addr += @sizeOf(usize);
}
}
const new_ip = @as(*const usize, @ptrFromInt(ip_ptr)).*;
const new_fp = @as(*const usize, @ptrFromInt(fp)).*;
(try abi.regValueNative(usize, context.thread_context, abi.fpRegNum(reg_context), reg_context)).* = new_fp;
(try abi.regValueNative(usize, context.thread_context, abi.ipRegNum(), reg_context)).* = new_ip;
break :blk new_ip;
},
},
else => return error.UnimplementedArch,
};
context.pc = abi.stripInstructionPtrAuthCode(new_ip);
if (context.pc > 0) context.pc -= 1;
return new_ip;
}
fn unwindFrameMachODwarf(context: *UnwindContext, eh_frame: []const u8, fde_offset: usize) !usize {
var di = DwarfInfo{
.endian = native_endian,
.is_macho = true,
};
defer di.deinit(context.allocator);
di.sections[@intFromEnum(DwarfSection.eh_frame)] = .{
.data = eh_frame,
.owned = false,
};
return di.unwindFrame(context, fde_offset);
}
pub const UnwindContext = struct {
allocator: mem.Allocator,
cfa: ?usize,
pc: usize,
thread_context: *debug.ThreadContext,
reg_context: abi.RegisterContext,
isValidMemory: *const fn (address: usize) bool,
vm: call_frame.VirtualMachine,
stack_machine: expressions.StackMachine(.{ .call_frame_context = true }),
pub fn init(allocator: mem.Allocator, thread_context: *const debug.ThreadContext, isValidMemory: *const fn (address: usize) bool) !UnwindContext {
const pc = abi.stripInstructionPtrAuthCode((try abi.regValueNative(usize, thread_context, abi.ipRegNum(), null)).*);
const context_copy = try allocator.create(debug.ThreadContext);
debug.copyContext(thread_context, context_copy);
return .{
.allocator = allocator,
.cfa = null,
.pc = pc,
.thread_context = context_copy,
.reg_context = undefined,
.isValidMemory = isValidMemory,
.vm = .{},
.stack_machine = .{},
};
}
pub fn deinit(self: *UnwindContext) void {
self.vm.deinit(self.allocator);
self.stack_machine.deinit(self.allocator);
self.allocator.destroy(self.thread_context);
self.* = undefined;
}
pub fn getFp(self: *const UnwindContext) !usize {
return (try abi.regValueNative(usize, self.thread_context, abi.fpRegNum(self.reg_context), self.reg_context)).*;
}
};
/// Initialize DWARF info. The caller has the responsibility to initialize most
/// the DwarfInfo fields before calling. `binary_mem` is the raw bytes of the
/// main binary file (not the secondary debug info file).
pub fn openDwarfDebugInfo(di: *DwarfInfo, allocator: mem.Allocator) !void {
try di.scanAllFunctions(allocator);
try di.scanAllCompileUnits(allocator);
}
/// This function is to make it handy to comment out the return and make it
/// into a crash when working on this file.
fn badDwarf() error{InvalidDebugInfo} {
//if (true) @panic("badDwarf"); // can be handy to uncomment when working on this file
return error.InvalidDebugInfo;
}
fn missingDwarf() error{MissingDebugInfo} {
//if (true) @panic("missingDwarf"); // can be handy to uncomment when working on this file
return error.MissingDebugInfo;
}
fn getStringGeneric(opt_str: ?[]const u8, offset: u64) ![:0]const u8 {
const str = opt_str orelse return badDwarf();
if (offset > str.len) return badDwarf();
const casted_offset = math.cast(usize, offset) orelse return badDwarf();
// Valid strings always have a terminating zero byte
const last = mem.indexOfScalarPos(u8, str, casted_offset, 0) orelse return badDwarf();
return str[casted_offset..last :0];
}
const EhPointerContext = struct {
// The address of the pointer field itself
pc_rel_base: u64,
// Whether or not to follow indirect pointers. This should only be
// used when decoding pointers at runtime using the current process's
// debug info
follow_indirect: bool,
// These relative addressing modes are only used in specific cases, and
// might not be available / required in all parsing contexts
data_rel_base: ?u64 = null,
text_rel_base: ?u64 = null,
function_rel_base: ?u64 = null,
};
fn readEhPointer(fbr: *FixedBufferReader, enc: u8, addr_size_bytes: u8, ctx: EhPointerContext) !?u64 {
if (enc == EH.PE.omit) return null;
const value: union(enum) {
signed: i64,
unsigned: u64,
} = switch (enc & EH.PE.type_mask) {
EH.PE.absptr => .{
.unsigned = switch (addr_size_bytes) {
2 => try fbr.readInt(u16),
4 => try fbr.readInt(u32),
8 => try fbr.readInt(u64),
else => return error.InvalidAddrSize,
},
},
EH.PE.uleb128 => .{ .unsigned = try fbr.readUleb128(u64) },
EH.PE.udata2 => .{ .unsigned = try fbr.readInt(u16) },
EH.PE.udata4 => .{ .unsigned = try fbr.readInt(u32) },
EH.PE.udata8 => .{ .unsigned = try fbr.readInt(u64) },
EH.PE.sleb128 => .{ .signed = try fbr.readIleb128(i64) },
EH.PE.sdata2 => .{ .signed = try fbr.readInt(i16) },
EH.PE.sdata4 => .{ .signed = try fbr.readInt(i32) },
EH.PE.sdata8 => .{ .signed = try fbr.readInt(i64) },
else => return badDwarf(),
};
const base = switch (enc & EH.PE.rel_mask) {
EH.PE.pcrel => ctx.pc_rel_base,
EH.PE.textrel => ctx.text_rel_base orelse return error.PointerBaseNotSpecified,
EH.PE.datarel => ctx.data_rel_base orelse return error.PointerBaseNotSpecified,
EH.PE.funcrel => ctx.function_rel_base orelse return error.PointerBaseNotSpecified,
else => null,
};
const ptr: u64 = if (base) |b| switch (value) {
.signed => |s| @intCast(try math.add(i64, s, @as(i64, @intCast(b)))),
// absptr can actually contain signed values in some cases (aarch64 MachO)
.unsigned => |u| u +% b,
} else switch (value) {
.signed => |s| @as(u64, @intCast(s)),
.unsigned => |u| u,
};
if ((enc & EH.PE.indirect) > 0 and ctx.follow_indirect) {
if (@sizeOf(usize) != addr_size_bytes) {
// See the documentation for `follow_indirect`
return error.NonNativeIndirection;
}
const native_ptr = math.cast(usize, ptr) orelse return error.PointerOverflow;
return switch (addr_size_bytes) {
2, 4, 8 => return @as(*const usize, @ptrFromInt(native_ptr)).*,
else => return error.UnsupportedAddrSize,
};
} else {
return ptr;
}
}
/// This represents the decoded .eh_frame_hdr header
pub const ExceptionFrameHeader = struct {
eh_frame_ptr: usize,
table_enc: u8,
fde_count: usize,
entries: []const u8,
pub fn entrySize(table_enc: u8) !u8 {
return switch (table_enc & EH.PE.type_mask) {
EH.PE.udata2,
EH.PE.sdata2,
=> 4,
EH.PE.udata4,
EH.PE.sdata4,
=> 8,
EH.PE.udata8,
EH.PE.sdata8,
=> 16,
// This is a binary search table, so all entries must be the same length
else => return badDwarf(),
};
}
fn isValidPtr(
self: ExceptionFrameHeader,
ptr: usize,
isValidMemory: *const fn (address: usize) bool,
eh_frame_len: ?usize,
) bool {
if (eh_frame_len) |len| {
return ptr >= self.eh_frame_ptr and ptr < self.eh_frame_ptr + len;
} else {
return isValidMemory(ptr);
}
}
/// Find an entry by binary searching the eh_frame_hdr section.
///
/// Since the length of the eh_frame section (`eh_frame_len`) may not be known by the caller,
/// `isValidMemory` will be called before accessing any memory referenced by
/// the header entries. If `eh_frame_len` is provided, then these checks can be skipped.
pub fn findEntry(
self: ExceptionFrameHeader,
isValidMemory: *const fn (address: usize) bool,
eh_frame_len: ?usize,
eh_frame_hdr_ptr: usize,
pc: usize,
cie: *CommonInformationEntry,
fde: *FrameDescriptionEntry,
) !void {
const entry_size = try entrySize(self.table_enc);
var left: usize = 0;
var len: usize = self.fde_count;
var fbr: FixedBufferReader = .{ .buf = self.entries, .endian = native_endian };
while (len > 1) {
const mid = left + len / 2;
fbr.pos = mid * entry_size;
const pc_begin = try readEhPointer(&fbr, self.table_enc, @sizeOf(usize), .{
.pc_rel_base = @intFromPtr(&self.entries[fbr.pos]),
.follow_indirect = true,
.data_rel_base = eh_frame_hdr_ptr,
}) orelse return badDwarf();
if (pc < pc_begin) {
len /= 2;
} else {
left = mid;
if (pc == pc_begin) break;
len -= len / 2;
}
}
if (len == 0) return badDwarf();
fbr.pos = left * entry_size;
// Read past the pc_begin field of the entry
_ = try readEhPointer(&fbr, self.table_enc, @sizeOf(usize), .{
.pc_rel_base = @intFromPtr(&self.entries[fbr.pos]),
.follow_indirect = true,
.data_rel_base = eh_frame_hdr_ptr,
}) orelse return badDwarf();
const fde_ptr = math.cast(usize, try readEhPointer(&fbr, self.table_enc, @sizeOf(usize), .{
.pc_rel_base = @intFromPtr(&self.entries[fbr.pos]),
.follow_indirect = true,
.data_rel_base = eh_frame_hdr_ptr,
}) orelse return badDwarf()) orelse return badDwarf();
// Verify the length fields of the FDE header are readable
if (!self.isValidPtr(fde_ptr, isValidMemory, eh_frame_len) or fde_ptr < self.eh_frame_ptr) return badDwarf();
var fde_entry_header_len: usize = 4;
if (!self.isValidPtr(fde_ptr + 3, isValidMemory, eh_frame_len)) return badDwarf();
if (self.isValidPtr(fde_ptr + 11, isValidMemory, eh_frame_len)) fde_entry_header_len = 12;
// Even if eh_frame_len is not specified, all ranges accssed are checked by isValidPtr
const eh_frame = @as([*]const u8, @ptrFromInt(self.eh_frame_ptr))[0 .. eh_frame_len orelse math.maxInt(u32)];
const fde_offset = fde_ptr - self.eh_frame_ptr;
var eh_frame_fbr: FixedBufferReader = .{
.buf = eh_frame,
.pos = fde_offset,
.endian = native_endian,
};
const fde_entry_header = try EntryHeader.read(&eh_frame_fbr, .eh_frame);
if (!self.isValidPtr(@intFromPtr(&fde_entry_header.entry_bytes[fde_entry_header.entry_bytes.len - 1]), isValidMemory, eh_frame_len)) return badDwarf();
if (fde_entry_header.type != .fde) return badDwarf();
// CIEs always come before FDEs (the offset is a subtraction), so we can assume this memory is readable
const cie_offset = fde_entry_header.type.fde;
try eh_frame_fbr.seekTo(cie_offset);
const cie_entry_header = try EntryHeader.read(&eh_frame_fbr, .eh_frame);
if (!self.isValidPtr(@intFromPtr(&cie_entry_header.entry_bytes[cie_entry_header.entry_bytes.len - 1]), isValidMemory, eh_frame_len)) return badDwarf();
if (cie_entry_header.type != .cie) return badDwarf();
cie.* = try CommonInformationEntry.parse(
cie_entry_header.entry_bytes,
0,
true,
cie_entry_header.format,
.eh_frame,
cie_entry_header.length_offset,
@sizeOf(usize),
native_endian,
);
fde.* = try FrameDescriptionEntry.parse(
fde_entry_header.entry_bytes,
0,
true,
cie.*,
@sizeOf(usize),
native_endian,
);
}
};
pub const EntryHeader = struct {
/// Offset of the length field in the backing buffer
length_offset: usize,
format: Format,
type: union(enum) {
cie,
/// Value is the offset of the corresponding CIE
fde: u64,
terminator,
},
/// The entry's contents, not including the ID field
entry_bytes: []const u8,
/// The length of the entry including the ID field, but not the length field itself
pub fn entryLength(self: EntryHeader) usize {
return self.entry_bytes.len + @as(u8, if (self.format == .@"64") 8 else 4);
}
/// Reads a header for either an FDE or a CIE, then advances the fbr to the position after the trailing structure.
/// `fbr` must be a FixedBufferReader backed by either the .eh_frame or .debug_frame sections.
pub fn read(fbr: *FixedBufferReader, dwarf_section: DwarfSection) !EntryHeader {
assert(dwarf_section == .eh_frame or dwarf_section == .debug_frame);
const length_offset = fbr.pos;
const unit_header = try readUnitHeader(fbr);
const unit_length = math.cast(usize, unit_header.unit_length) orelse return badDwarf();
if (unit_length == 0) return .{
.length_offset = length_offset,
.format = unit_header.format,
.type = .terminator,
.entry_bytes = &.{},
};
const start_offset = fbr.pos;
const end_offset = start_offset + unit_length;
defer fbr.pos = end_offset;
const id = try fbr.readAddress(unit_header.format);
const entry_bytes = fbr.buf[fbr.pos..end_offset];
const cie_id: u64 = switch (dwarf_section) {
.eh_frame => CommonInformationEntry.eh_id,
.debug_frame => switch (unit_header.format) {
.@"32" => CommonInformationEntry.dwarf32_id,
.@"64" => CommonInformationEntry.dwarf64_id,
},
else => unreachable,
};
return .{
.length_offset = length_offset,
.format = unit_header.format,
.type = if (id == cie_id) .cie else .{ .fde = switch (dwarf_section) {
.eh_frame => try math.sub(u64, start_offset, id),
.debug_frame => id,
else => unreachable,
} },
.entry_bytes = entry_bytes,
};
}
};
pub const CommonInformationEntry = struct {
// Used in .eh_frame
pub const eh_id = 0;
// Used in .debug_frame (DWARF32)
pub const dwarf32_id = math.maxInt(u32);
// Used in .debug_frame (DWARF64)
pub const dwarf64_id = math.maxInt(u64);
// Offset of the length field of this entry in the eh_frame section.
// This is the key that FDEs use to reference CIEs.
length_offset: u64,
version: u8,
address_size: u8,
format: Format,
// Only present in version 4
segment_selector_size: ?u8,
code_alignment_factor: u32,
data_alignment_factor: i32,
return_address_register: u8,
aug_str: []const u8,
aug_data: []const u8,
lsda_pointer_enc: u8,
personality_enc: ?u8,
personality_routine_pointer: ?u64,
fde_pointer_enc: u8,
initial_instructions: []const u8,
pub fn isSignalFrame(self: CommonInformationEntry) bool {
for (self.aug_str) |c| if (c == 'S') return true;
return false;
}
pub fn addressesSignedWithBKey(self: CommonInformationEntry) bool {
for (self.aug_str) |c| if (c == 'B') return true;
return false;
}
pub fn mteTaggedFrame(self: CommonInformationEntry) bool {
for (self.aug_str) |c| if (c == 'G') return true;
return false;
}
/// This function expects to read the CIE starting with the version field.
/// The returned struct references memory backed by cie_bytes.
///
/// See the FrameDescriptionEntry.parse documentation for the description
/// of `pc_rel_offset` and `is_runtime`.
///
/// `length_offset` specifies the offset of this CIE's length field in the
/// .eh_frame / .debug_frame section.
pub fn parse(
cie_bytes: []const u8,
pc_rel_offset: i64,
is_runtime: bool,
format: Format,
dwarf_section: DwarfSection,
length_offset: u64,
addr_size_bytes: u8,
endian: std.builtin.Endian,
) !CommonInformationEntry {
if (addr_size_bytes > 8) return error.UnsupportedAddrSize;
var fbr: FixedBufferReader = .{ .buf = cie_bytes, .endian = endian };
const version = try fbr.readByte();
switch (dwarf_section) {
.eh_frame => if (version != 1 and version != 3) return error.UnsupportedDwarfVersion,
.debug_frame => if (version != 4) return error.UnsupportedDwarfVersion,
else => return error.UnsupportedDwarfSection,
}
var has_eh_data = false;
var has_aug_data = false;
var aug_str_len: usize = 0;
const aug_str_start = fbr.pos;
var aug_byte = try fbr.readByte();
while (aug_byte != 0) : (aug_byte = try fbr.readByte()) {
switch (aug_byte) {
'z' => {
if (aug_str_len != 0) return badDwarf();
has_aug_data = true;
},
'e' => {
if (has_aug_data or aug_str_len != 0) return badDwarf();
if (try fbr.readByte() != 'h') return badDwarf();
has_eh_data = true;
},
else => if (has_eh_data) return badDwarf(),
}
aug_str_len += 1;
}
if (has_eh_data) {
// legacy data created by older versions of gcc - unsupported here
for (0..addr_size_bytes) |_| _ = try fbr.readByte();
}
const address_size = if (version == 4) try fbr.readByte() else addr_size_bytes;
const segment_selector_size = if (version == 4) try fbr.readByte() else null;
const code_alignment_factor = try fbr.readUleb128(u32);
const data_alignment_factor = try fbr.readIleb128(i32);
const return_address_register = if (version == 1) try fbr.readByte() else try fbr.readUleb128(u8);
var lsda_pointer_enc: u8 = EH.PE.omit;
var personality_enc: ?u8 = null;
var personality_routine_pointer: ?u64 = null;
var fde_pointer_enc: u8 = EH.PE.absptr;
var aug_data: []const u8 = &[_]u8{};
const aug_str = if (has_aug_data) blk: {
const aug_data_len = try fbr.readUleb128(usize);
const aug_data_start = fbr.pos;
aug_data = cie_bytes[aug_data_start..][0..aug_data_len];
const aug_str = cie_bytes[aug_str_start..][0..aug_str_len];
for (aug_str[1..]) |byte| {
switch (byte) {
'L' => {
lsda_pointer_enc = try fbr.readByte();
},
'P' => {
personality_enc = try fbr.readByte();
personality_routine_pointer = try readEhPointer(&fbr, personality_enc.?, addr_size_bytes, .{
.pc_rel_base = try pcRelBase(@intFromPtr(&cie_bytes[fbr.pos]), pc_rel_offset),
.follow_indirect = is_runtime,
});
},
'R' => {
fde_pointer_enc = try fbr.readByte();
},
'S', 'B', 'G' => {},
else => return badDwarf(),
}
}
// aug_data_len can include padding so the CIE ends on an address boundary
fbr.pos = aug_data_start + aug_data_len;
break :blk aug_str;
} else &[_]u8{};
const initial_instructions = cie_bytes[fbr.pos..];
return .{
.length_offset = length_offset,
.version = version,
.address_size = address_size,
.format = format,
.segment_selector_size = segment_selector_size,
.code_alignment_factor = code_alignment_factor,
.data_alignment_factor = data_alignment_factor,
.return_address_register = return_address_register,
.aug_str = aug_str,
.aug_data = aug_data,
.lsda_pointer_enc = lsda_pointer_enc,
.personality_enc = personality_enc,
.personality_routine_pointer = personality_routine_pointer,
.fde_pointer_enc = fde_pointer_enc,
.initial_instructions = initial_instructions,
};
}
};
pub const FrameDescriptionEntry = struct {
// Offset into eh_frame where the CIE for this FDE is stored
cie_length_offset: u64,
pc_begin: u64,
pc_range: u64,
lsda_pointer: ?u64,
aug_data: []const u8,
instructions: []const u8,
/// This function expects to read the FDE starting at the PC Begin field.
/// The returned struct references memory backed by `fde_bytes`.
///
/// `pc_rel_offset` specifies an offset to be applied to pc_rel_base values
/// used when decoding pointers. This should be set to zero if fde_bytes is
/// backed by the memory of a .eh_frame / .debug_frame section in the running executable.
/// Otherwise, it should be the relative offset to translate addresses from
/// where the section is currently stored in memory, to where it *would* be
/// stored at runtime: section base addr - backing data base ptr.
///
/// Similarly, `is_runtime` specifies this function is being called on a runtime
/// section, and so indirect pointers can be followed.
pub fn parse(
fde_bytes: []const u8,
pc_rel_offset: i64,
is_runtime: bool,
cie: CommonInformationEntry,
addr_size_bytes: u8,
endian: std.builtin.Endian,
) !FrameDescriptionEntry {
if (addr_size_bytes > 8) return error.InvalidAddrSize;
var fbr: FixedBufferReader = .{ .buf = fde_bytes, .endian = endian };
const pc_begin = try readEhPointer(&fbr, cie.fde_pointer_enc, addr_size_bytes, .{
.pc_rel_base = try pcRelBase(@intFromPtr(&fde_bytes[fbr.pos]), pc_rel_offset),
.follow_indirect = is_runtime,
}) orelse return badDwarf();
const pc_range = try readEhPointer(&fbr, cie.fde_pointer_enc, addr_size_bytes, .{
.pc_rel_base = 0,
.follow_indirect = false,
}) orelse return badDwarf();
var aug_data: []const u8 = &[_]u8{};
const lsda_pointer = if (cie.aug_str.len > 0) blk: {
const aug_data_len = try fbr.readUleb128(usize);
const aug_data_start = fbr.pos;
aug_data = fde_bytes[aug_data_start..][0..aug_data_len];
const lsda_pointer = if (cie.lsda_pointer_enc != EH.PE.omit)
try readEhPointer(&fbr, cie.lsda_pointer_enc, addr_size_bytes, .{
.pc_rel_base = try pcRelBase(@intFromPtr(&fde_bytes[fbr.pos]), pc_rel_offset),
.follow_indirect = is_runtime,
})
else
null;
fbr.pos = aug_data_start + aug_data_len;
break :blk lsda_pointer;
} else null;
const instructions = fde_bytes[fbr.pos..];
return .{
.cie_length_offset = cie.length_offset,
.pc_begin = pc_begin,
.pc_range = pc_range,
.lsda_pointer = lsda_pointer,
.aug_data = aug_data,
.instructions = instructions,
};
}
};
fn pcRelBase(field_ptr: usize, pc_rel_offset: i64) !usize {
if (pc_rel_offset < 0) {
return math.sub(usize, field_ptr, @as(usize, @intCast(-pc_rel_offset)));
} else {
return math.add(usize, field_ptr, @as(usize, @intCast(pc_rel_offset)));
}
}
// Reading debug info needs to be fast, even when compiled in debug mode,
// so avoid using a `std.io.FixedBufferStream` which is too slow.
pub const FixedBufferReader = struct {
buf: []const u8,
pos: usize = 0,
endian: std.builtin.Endian,
pub const Error = error{ EndOfBuffer, Overflow };
fn seekTo(fbr: *FixedBufferReader, pos: u64) Error!void {
if (pos > fbr.buf.len) return error.EndOfBuffer;
fbr.pos = @intCast(pos);
}
fn seekForward(fbr: *FixedBufferReader, amount: u64) Error!void {
if (fbr.buf.len - fbr.pos < amount) return error.EndOfBuffer;
fbr.pos += @intCast(amount);
}
pub inline fn readByte(fbr: *FixedBufferReader) Error!u8 {
if (fbr.pos >= fbr.buf.len) return error.EndOfBuffer;
defer fbr.pos += 1;
return fbr.buf[fbr.pos];
}
fn readByteSigned(fbr: *FixedBufferReader) Error!i8 {
return @bitCast(try fbr.readByte());
}
fn readInt(fbr: *FixedBufferReader, comptime T: type) Error!T {
const size = @divExact(@typeInfo(T).Int.bits, 8);
if (fbr.buf.len - fbr.pos < size) return error.EndOfBuffer;
defer fbr.pos += size;
return mem.readInt(T, fbr.buf[fbr.pos..][0..size], fbr.endian);
}
fn readUleb128(fbr: *FixedBufferReader, comptime T: type) Error!T {
return std.leb.readULEB128(T, fbr);
}
fn readIleb128(fbr: *FixedBufferReader, comptime T: type) Error!T {
return std.leb.readILEB128(T, fbr);
}
fn readAddress(fbr: *FixedBufferReader, format: Format) Error!u64 {
return switch (format) {
.@"32" => try fbr.readInt(u32),
.@"64" => try fbr.readInt(u64),
};
}
fn readBytes(fbr: *FixedBufferReader, len: usize) Error![]const u8 {
if (fbr.buf.len - fbr.pos < len) return error.EndOfBuffer;
defer fbr.pos += len;
return fbr.buf[fbr.pos..][0..len];
}
fn readBytesTo(fbr: *FixedBufferReader, comptime sentinel: u8) Error![:sentinel]const u8 {
const end = @call(.always_inline, mem.indexOfScalarPos, .{
u8,
fbr.buf,
fbr.pos,
sentinel,
}) orelse return error.EndOfBuffer;
defer fbr.pos = end + 1;
return fbr.buf[fbr.pos..end :sentinel];
}
};
test {
std.testing.refAllDecls(@This());
}
Reference in New Issue View Git Blame Copy Permalink