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dwarf: add support for .debug_frame and CIE version 4

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This commit is contained in:
kcbanner 2023-06-26 00:58:42 -04:00
parent 41832aa1e6
commit a9b6f2d929
1 changed files with 78 additions and 48 deletions
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56
lib/std/dwarf.zig
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@ -7,6 +7,7 @@ const os = std.os;
const mem = std.mem;
const math = std.math;
const leb = @import("leb128.zig");
const assert = std.debug.assert;
pub const TAG = @import("dwarf/TAG.zig");
pub const AT = @import("dwarf/AT.zig");
@ -1530,16 +1531,19 @@ pub const DwarfInfo = struct {
return;
}
if (di.section(.eh_frame)) |eh_frame| {
const frame_sections = [2]DwarfSection{ .eh_frame, .debug_frame };
for (frame_sections) |frame_section| {
if (di.section(frame_section)) |eh_frame| {
var stream = io.fixedBufferStream(eh_frame);
while (stream.pos < stream.buffer.len) {
const entry_header = try EntryHeader.read(&stream, di.endian);
const entry_header = try EntryHeader.read(&stream, frame_section, di.endian);
switch (entry_header.type) {
.cie => {
const cie = try CommonInformationEntry.parse(
entry_header.entry_bytes,
-@as(i64, @intCast(@intFromPtr(binary_mem.ptr))),
true,
frame_section,
entry_header.length_offset,
@sizeOf(usize),
di.endian,
@ -1571,6 +1575,7 @@ pub const DwarfInfo = struct {
}.lessThan);
}
}
}
pub fn unwindFrame(di: *const DwarfInfo, allocator: mem.Allocator, context: *UnwindContext, module_base_address: usize) !void {
if (!comptime abi.isSupportedArch(builtin.target.cpu.arch)) return error.UnsupportedCpuArchitecture;
@ -1905,14 +1910,14 @@ pub const ExceptionFrameHeader = struct {
var eh_frame_stream = io.fixedBufferStream(eh_frame);
try eh_frame_stream.seekTo(fde_offset);
const fde_entry_header = try EntryHeader.read(&eh_frame_stream, builtin.cpu.arch.endian());
const fde_entry_header = try EntryHeader.read(&eh_frame_stream, .eh_frame, builtin.cpu.arch.endian());
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 subtration), so we can assume this memory is readable
const cie_offset = fde_entry_header.type.fde;
try eh_frame_stream.seekTo(cie_offset);
const cie_entry_header = try EntryHeader.read(&eh_frame_stream, builtin.cpu.arch.endian());
const cie_entry_header = try EntryHeader.read(&eh_frame_stream, .eh_frame, builtin.cpu.arch.endian());
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();
@ -1920,6 +1925,7 @@ pub const ExceptionFrameHeader = struct {
cie_entry_header.entry_bytes,
0,
true,
.eh_frame,
cie_entry_header.length_offset,
@sizeOf(usize),
builtin.cpu.arch.endian(),
@ -1937,7 +1943,7 @@ pub const ExceptionFrameHeader = struct {
};
pub const EntryHeader = struct {
/// Offset of the length in the backing buffer
/// Offset of the length field in the backing buffer
length_offset: usize,
is_64: bool,
type: union(enum) {
@ -1950,8 +1956,10 @@ pub const EntryHeader = struct {
entry_bytes: []const u8,
/// Reads a header for either an FDE or a CIE, then advances the stream to the position after the trailing structure.
/// `stream` must be a stream backed by the .eh_frame section.
pub fn read(stream: *std.io.FixedBufferStream([]const u8), endian: std.builtin.Endian) !EntryHeader {
/// `stream` must be a stream backed by either the .eh_frame or .debug_frame sections.
pub fn read(stream: *std.io.FixedBufferStream([]const u8), dwarf_section: DwarfSection, endian: std.builtin.Endian) !EntryHeader {
assert(dwarf_section == .eh_frame or dwarf_section == .debug_frame);
const reader = stream.reader();
const length_offset = stream.pos;
@ -1967,14 +1975,21 @@ pub const EntryHeader = struct {
const id_len = @as(u8, if (is_64) 8 else 4);
const id = if (is_64) try reader.readInt(u64, endian) else try reader.readInt(u32, endian);
const entry_bytes = stream.buffer[stream.pos..][0 .. length - id_len];
const cie_id: u64 = switch (dwarf_section) {
.eh_frame => CommonInformationEntry.eh_id,
.debug_frame => if (is_64) CommonInformationEntry.dwarf64_id else CommonInformationEntry.dwarf32_id,
else => unreachable,
};
const result = EntryHeader{
.length_offset = length_offset,
.is_64 = is_64,
.type = switch (id) {
0 => .{ .cie = {} },
// TODO: Support CommonInformationEntry.dwarf32_id, CommonInformationEntry.dwarf64_id
else => .{ .fde = stream.pos - id_len - id },
.type = if (id == cie_id) .{ .cie = {} } else .{
.fde = switch (dwarf_section) {
.eh_frame => stream.pos - id_len - id,
.debug_frame => id,
else => unreachable,
},
},
.entry_bytes = entry_bytes,
};
@ -2004,6 +2019,11 @@ pub const CommonInformationEntry = struct {
length_offset: u64,
version: u8,
address_size: u8,
// Only present in version 4
segment_selector_size: ?u8,
code_alignment_factor: u32,
data_alignment_factor: i32,
return_address_register: u8,
@ -2038,11 +2058,12 @@ pub const CommonInformationEntry = struct {
/// of `pc_rel_offset` and `is_runtime`.
///
/// `length_offset` specifies the offset of this CIE's length field in the
/// .eh_frame section.
/// .eh_frame / .debug_framesection.
pub fn parse(
cie_bytes: []const u8,
pc_rel_offset: i64,
is_runtime: bool,
dwarf_section: DwarfSection,
length_offset: u64,
addr_size_bytes: u8,
endian: std.builtin.Endian,
@ -2053,7 +2074,11 @@ pub const CommonInformationEntry = struct {
const reader = stream.reader();
const version = try reader.readByte();
if (version != 1 and version != 3) return error.UnsupportedDwarfVersion;
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;
@ -2083,6 +2108,9 @@ pub const CommonInformationEntry = struct {
for (0..addr_size_bytes) |_| _ = try reader.readByte();
}
const address_size = if (version == 4) try reader.readByte() else addr_size_bytes;
const segment_selector_size = if (version == 4) try reader.readByte() else null;
const code_alignment_factor = try leb.readULEB128(u32, reader);
const data_alignment_factor = try leb.readILEB128(i32, reader);
const return_address_register = if (version == 1) try reader.readByte() else try leb.readULEB128(u8, reader);
@ -2134,6 +2162,8 @@ pub const CommonInformationEntry = struct {
return .{
.length_offset = length_offset,
.version = version,
.address_size = address_size,
.segment_selector_size = segment_selector_size,
.code_alignment_factor = code_alignment_factor,
.data_alignment_factor = data_alignment_factor,
.return_address_register = return_address_register,