authorgravatar for kcbanner@gmail.comCasey Banner <kcbanner@gmail.com> 2023-06-26 00:58:42-04:00
committergravatar for kcbanner@gmail.comCasey Banner <kcbanner@gmail.com> 2023-07-20 22:58:14-04:00
loga9b6f2d92984e1b4d4a9fe2b0ba0b14ec8b812c5
tree614a4c9b1b8dddeb8574a01d19f916aa0e882829
parent41832aa1e651a4a19f3ab275a54c28ed27180cd5

dwarf: add support for .debug_frame and CIE version 4

1 files changed, 78 insertions(+), 48 deletions(-)

lib/std/dwarf.zig+78-48
......@@ -7,6 +7,7 @@ const os = std.os;
77const mem = std.mem;
88const math = std.math;
99const leb = @import("leb128.zig");
10const assert = std.debug.assert;
1011
1112pub const TAG = @import("dwarf/TAG.zig");
1213pub const AT = @import("dwarf/AT.zig");
......@@ -1530,45 +1531,49 @@ pub const DwarfInfo = struct {
15301531 return;
15311532 }
15321533
1533 if (di.section(.eh_frame)) |eh_frame| {
1534 var stream = io.fixedBufferStream(eh_frame);
1535 while (stream.pos < stream.buffer.len) {
1536 const entry_header = try EntryHeader.read(&stream, di.endian);
1537 switch (entry_header.type) {
1538 .cie => {
1539 const cie = try CommonInformationEntry.parse(
1540 entry_header.entry_bytes,
1541 -@as(i64, @intCast(@intFromPtr(binary_mem.ptr))),
1542 true,
1543 entry_header.length_offset,
1544 @sizeOf(usize),
1545 di.endian,
1546 );
1547 try di.cie_map.put(allocator, entry_header.length_offset, cie);
1548 },
1549 .fde => |cie_offset| {
1550 const cie = di.cie_map.get(cie_offset) orelse return badDwarf();
1551 const fde = try FrameDescriptionEntry.parse(
1552 entry_header.entry_bytes,
1553 -@as(i64, @intCast(@intFromPtr(binary_mem.ptr))),
1554 true,
1555 cie,
1556 @sizeOf(usize),
1557 di.endian,
1558 );
1559 try di.fde_list.append(allocator, fde);
1560 },
1561 .terminator => break,
1534 const frame_sections = [2]DwarfSection{ .eh_frame, .debug_frame };
1535 for (frame_sections) |frame_section| {
1536 if (di.section(frame_section)) |eh_frame| {
1537 var stream = io.fixedBufferStream(eh_frame);
1538 while (stream.pos < stream.buffer.len) {
1539 const entry_header = try EntryHeader.read(&stream, frame_section, di.endian);
1540 switch (entry_header.type) {
1541 .cie => {
1542 const cie = try CommonInformationEntry.parse(
1543 entry_header.entry_bytes,
1544 -@as(i64, @intCast(@intFromPtr(binary_mem.ptr))),
1545 true,
1546 frame_section,
1547 entry_header.length_offset,
1548 @sizeOf(usize),
1549 di.endian,
1550 );
1551 try di.cie_map.put(allocator, entry_header.length_offset, cie);
1552 },
1553 .fde => |cie_offset| {
1554 const cie = di.cie_map.get(cie_offset) orelse return badDwarf();
1555 const fde = try FrameDescriptionEntry.parse(
1556 entry_header.entry_bytes,
1557 -@as(i64, @intCast(@intFromPtr(binary_mem.ptr))),
1558 true,
1559 cie,
1560 @sizeOf(usize),
1561 di.endian,
1562 );
1563 try di.fde_list.append(allocator, fde);
1564 },
1565 .terminator => break,
1566 }
15621567 }
1563 }
15641568
1565 // TODO: Avoiding sorting if has_eh_frame_hdr exists
1566 std.mem.sort(FrameDescriptionEntry, di.fde_list.items, {}, struct {
1567 fn lessThan(ctx: void, a: FrameDescriptionEntry, b: FrameDescriptionEntry) bool {
1568 _ = ctx;
1569 return a.pc_begin < b.pc_begin;
1570 }
1571 }.lessThan);
1569 // TODO: Avoiding sorting if has_eh_frame_hdr exists
1570 std.mem.sort(FrameDescriptionEntry, di.fde_list.items, {}, struct {
1571 fn lessThan(ctx: void, a: FrameDescriptionEntry, b: FrameDescriptionEntry) bool {
1572 _ = ctx;
1573 return a.pc_begin < b.pc_begin;
1574 }
1575 }.lessThan);
1576 }
15721577 }
15731578 }
15741579
......@@ -1905,14 +1910,14 @@ pub const ExceptionFrameHeader = struct {
19051910 var eh_frame_stream = io.fixedBufferStream(eh_frame);
19061911 try eh_frame_stream.seekTo(fde_offset);
19071912
1908 const fde_entry_header = try EntryHeader.read(&eh_frame_stream, builtin.cpu.arch.endian());
1913 const fde_entry_header = try EntryHeader.read(&eh_frame_stream, .eh_frame, builtin.cpu.arch.endian());
19091914 if (!self.isValidPtr(@intFromPtr(&fde_entry_header.entry_bytes[fde_entry_header.entry_bytes.len - 1]), isValidMemory, eh_frame_len)) return badDwarf();
19101915 if (fde_entry_header.type != .fde) return badDwarf();
19111916
19121917 // CIEs always come before FDEs (the offset is a subtration), so we can assume this memory is readable
19131918 const cie_offset = fde_entry_header.type.fde;
19141919 try eh_frame_stream.seekTo(cie_offset);
1915 const cie_entry_header = try EntryHeader.read(&eh_frame_stream, builtin.cpu.arch.endian());
1920 const cie_entry_header = try EntryHeader.read(&eh_frame_stream, .eh_frame, builtin.cpu.arch.endian());
19161921 if (!self.isValidPtr(@intFromPtr(&cie_entry_header.entry_bytes[cie_entry_header.entry_bytes.len - 1]), isValidMemory, eh_frame_len)) return badDwarf();
19171922 if (cie_entry_header.type != .cie) return badDwarf();
19181923
......@@ -1920,6 +1925,7 @@ pub const ExceptionFrameHeader = struct {
19201925 cie_entry_header.entry_bytes,
19211926 0,
19221927 true,
1928 .eh_frame,
19231929 cie_entry_header.length_offset,
19241930 @sizeOf(usize),
19251931 builtin.cpu.arch.endian(),
......@@ -1937,7 +1943,7 @@ pub const ExceptionFrameHeader = struct {
19371943};
19381944
19391945pub const EntryHeader = struct {
1940 /// Offset of the length in the backing buffer
1946 /// Offset of the length field in the backing buffer
19411947 length_offset: usize,
19421948 is_64: bool,
19431949 type: union(enum) {
......@@ -1950,8 +1956,10 @@ pub const EntryHeader = struct {
19501956 entry_bytes: []const u8,
19511957
19521958 /// Reads a header for either an FDE or a CIE, then advances the stream to the position after the trailing structure.
1953 /// `stream` must be a stream backed by the .eh_frame section.
1954 pub fn read(stream: *std.io.FixedBufferStream([]const u8), endian: std.builtin.Endian) !EntryHeader {
1959 /// `stream` must be a stream backed by either the .eh_frame or .debug_frame sections.
1960 pub fn read(stream: *std.io.FixedBufferStream([]const u8), dwarf_section: DwarfSection, endian: std.builtin.Endian) !EntryHeader {
1961 assert(dwarf_section == .eh_frame or dwarf_section == .debug_frame);
1962
19551963 const reader = stream.reader();
19561964 const length_offset = stream.pos;
19571965
......@@ -1967,14 +1975,21 @@ pub const EntryHeader = struct {
19671975 const id_len = @as(u8, if (is_64) 8 else 4);
19681976 const id = if (is_64) try reader.readInt(u64, endian) else try reader.readInt(u32, endian);
19691977 const entry_bytes = stream.buffer[stream.pos..][0 .. length - id_len];
1978 const cie_id: u64 = switch (dwarf_section) {
1979 .eh_frame => CommonInformationEntry.eh_id,
1980 .debug_frame => if (is_64) CommonInformationEntry.dwarf64_id else CommonInformationEntry.dwarf32_id,
1981 else => unreachable,
1982 };
19701983
19711984 const result = EntryHeader{
19721985 .length_offset = length_offset,
19731986 .is_64 = is_64,
1974 .type = switch (id) {
1975 0 => .{ .cie = {} },
1976 // TODO: Support CommonInformationEntry.dwarf32_id, CommonInformationEntry.dwarf64_id
1977 else => .{ .fde = stream.pos - id_len - id },
1987 .type = if (id == cie_id) .{ .cie = {} } else .{
1988 .fde = switch (dwarf_section) {
1989 .eh_frame => stream.pos - id_len - id,
1990 .debug_frame => id,
1991 else => unreachable,
1992 },
19781993 },
19791994 .entry_bytes = entry_bytes,
19801995 };
......@@ -2004,6 +2019,11 @@ pub const CommonInformationEntry = struct {
20042019 length_offset: u64,
20052020 version: u8,
20062021
2022 address_size: u8,
2023
2024 // Only present in version 4
2025 segment_selector_size: ?u8,
2026
20072027 code_alignment_factor: u32,
20082028 data_alignment_factor: i32,
20092029 return_address_register: u8,
......@@ -2038,11 +2058,12 @@ pub const CommonInformationEntry = struct {
20382058 /// of `pc_rel_offset` and `is_runtime`.
20392059 ///
20402060 /// `length_offset` specifies the offset of this CIE's length field in the
2041 /// .eh_frame section.
2061 /// .eh_frame / .debug_framesection.
20422062 pub fn parse(
20432063 cie_bytes: []const u8,
20442064 pc_rel_offset: i64,
20452065 is_runtime: bool,
2066 dwarf_section: DwarfSection,
20462067 length_offset: u64,
20472068 addr_size_bytes: u8,
20482069 endian: std.builtin.Endian,
......@@ -2053,7 +2074,11 @@ pub const CommonInformationEntry = struct {
20532074 const reader = stream.reader();
20542075
20552076 const version = try reader.readByte();
2056 if (version != 1 and version != 3) return error.UnsupportedDwarfVersion;
2077 switch (dwarf_section) {
2078 .eh_frame => if (version != 1 and version != 3) return error.UnsupportedDwarfVersion,
2079 .debug_frame => if (version != 4) return error.UnsupportedDwarfVersion,
2080 else => return error.UnsupportedDwarfSection,
2081 }
20572082
20582083 var has_eh_data = false;
20592084 var has_aug_data = false;
......@@ -2083,6 +2108,9 @@ pub const CommonInformationEntry = struct {
20832108 for (0..addr_size_bytes) |_| _ = try reader.readByte();
20842109 }
20852110
2111 const address_size = if (version == 4) try reader.readByte() else addr_size_bytes;
2112 const segment_selector_size = if (version == 4) try reader.readByte() else null;
2113
20862114 const code_alignment_factor = try leb.readULEB128(u32, reader);
20872115 const data_alignment_factor = try leb.readILEB128(i32, reader);
20882116 const return_address_register = if (version == 1) try reader.readByte() else try leb.readULEB128(u8, reader);
......@@ -2134,6 +2162,8 @@ pub const CommonInformationEntry = struct {
21342162 return .{
21352163 .length_offset = length_offset,
21362164 .version = version,
2165 .address_size = address_size,
2166 .segment_selector_size = segment_selector_size,
21372167 .code_alignment_factor = code_alignment_factor,
21382168 .data_alignment_factor = data_alignment_factor,
21392169 .return_address_register = return_address_register,