Commit b1d86db7b4
lib/std/debug.zig
@@ -648,7 +648,7 @@ pub const StackIterator = struct {
// __unwind_info is a requirement for unwinding on Darwin. It may fall back to DWARF, but unwinding
// via DWARF before attempting to use the compact unwind info will produce incorrect results.
if (module.unwind_info) |unwind_info| {
- if (macho.unwindFrame(&unwind_state.dwarf_context, unwind_info, module.eh_frame, module.base_address)) |return_address| {
+ if (DW.unwindFrameMachO(&unwind_state.dwarf_context, unwind_info, module.eh_frame, module.base_address)) |return_address| {
return return_address;
} else |err| {
if (err != error.RequiresDWARFUnwind) return err;
lib/std/dwarf.zig
@@ -1841,6 +1841,365 @@ pub const DwarfInfo = struct {
}
};
+/// 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 std.math.sub(
+ u8,
+ entry.encodingIndex,
+ std.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 = builtin.cpu.arch.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,
@@ -2166,7 +2525,7 @@ pub const EntryHeader = struct {
.is_64 = is_64,
.type = if (id == cie_id) .{ .cie = {} } else .{
.fde = switch (dwarf_section) {
- .eh_frame => stream.pos - id_len - id,
+ .eh_frame => try std.math.sub(u64, stream.pos - id_len, id),
.debug_frame => id,
else => unreachable,
},
lib/std/macho.zig
@@ -2125,360 +2125,3 @@ pub const CompactUnwindEncoding = packed struct(u32) {
has_lsda: u1,
start: u1,
};
-
-/// Returns the DWARF register number for an x86_64 register number found in compact unwind info
-fn dwarfRegNumber(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 dwarf = std.dwarf;
-const abi = dwarf.abi;
-
-pub fn unwindFrame(context: *dwarf.UnwindContext, unwind_info: []const u8, eh_frame: ?[]const u8, module_base_address: usize) !usize {
- const header = mem.bytesAsValue(
- unwind_info_section_header,
- unwind_info[0..@sizeOf(unwind_info_section_header)],
- );
- const indices = mem.bytesAsSlice(
- unwind_info_section_header_index_entry,
- unwind_info[header.indexSectionOffset..][0 .. header.indexCount * @sizeOf(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(
- compact_unwind_encoding_t,
- unwind_info[header.commonEncodingsArraySectionOffset..][0 .. header.commonEncodingsArrayCount * @sizeOf(compact_unwind_encoding_t)],
- );
-
- const start_offset = second_level_index.secondLevelPagesSectionOffset;
- const kind = mem.bytesAsValue(
- UNWIND_SECOND_LEVEL,
- unwind_info[start_offset..][0..@sizeOf(UNWIND_SECOND_LEVEL)],
- );
-
- const entry: struct {
- function_offset: usize,
- raw_encoding: u32,
- } = switch (kind.*) {
- .REGULAR => blk: {
- const page_header = mem.bytesAsValue(
- unwind_info_regular_second_level_page_header,
- unwind_info[start_offset..][0..@sizeOf(unwind_info_regular_second_level_page_header)],
- );
-
- const entries = mem.bytesAsSlice(
- unwind_info_regular_second_level_entry,
- unwind_info[start_offset + page_header.entryPageOffset ..][0 .. page_header.entryCount * @sizeOf(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(
- unwind_info_compressed_second_level_page_header,
- unwind_info[start_offset..][0..@sizeOf(unwind_info_compressed_second_level_page_header)],
- );
-
- const entries = mem.bytesAsSlice(
- UnwindInfoCompressedEntry,
- unwind_info[start_offset + page_header.entryPageOffset ..][0 .. page_header.entryCount * @sizeOf(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 std.math.sub(
- u8,
- entry.encodingIndex,
- std.math.cast(u8, header.commonEncodingsArrayCount) orelse return error.InvalidUnwindInfo,
- );
- const local_encodings = mem.bytesAsSlice(
- compact_unwind_encoding_t,
- unwind_info[start_offset + page_header.encodingsPageOffset ..][0 .. page_header.encodingsCount * @sizeOf(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 = dwarf.abi.RegisterContext{
- .eh_frame = false,
- .is_macho = true,
- };
-
- const encoding: 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 dwarfRegNumber(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 dwarfRegNumber(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 unwindFrameDwarf(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 unwindFrameDwarf(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 = dwarf.abi.stripInstructionPtrAuthCode(new_ip);
- if (context.pc > 0) context.pc -= 1;
- return new_ip;
-}
-
-fn unwindFrameDwarf(context: *dwarf.UnwindContext, eh_frame: []const u8, fde_offset: usize) !usize {
- var di = dwarf.DwarfInfo{
- .endian = builtin.cpu.arch.endian(),
- .is_macho = true,
- };
- defer di.deinit(context.allocator);
-
- di.sections[@intFromEnum(dwarf.DwarfSection.eh_frame)] = .{
- .data = eh_frame,
- .owned = false,
- };
-
- return di.unwindFrame(context, fde_offset);
-}