Commit b32f5ee932
Changed files (6)
src/link/MachO/dead_strip.zig
@@ -88,7 +88,7 @@ fn collectRoots(zld: *Zld, roots: *AtomTable) !void {
source_sym.n_sect - 1
else sect_id: {
const nbase = @intCast(u32, object.in_symtab.?.len);
- const sect_id = @intCast(u16, atom.sym_index - nbase);
+ const sect_id = @intCast(u8, atom.sym_index - nbase);
break :sect_id sect_id;
};
const source_sect = object.getSourceSection(sect_id);
@@ -223,7 +223,7 @@ fn mark(zld: *Zld, roots: AtomTable, alive: *AtomTable) !void {
source_sym.n_sect - 1
else blk: {
const nbase = @intCast(u32, object.in_symtab.?.len);
- const sect_id = @intCast(u16, atom.sym_index - nbase);
+ const sect_id = @intCast(u8, atom.sym_index - nbase);
break :blk sect_id;
};
const source_sect = object.getSourceSection(sect_id);
@@ -350,8 +350,9 @@ fn markEhFrameRecord(zld: *Zld, object_id: u32, atom_index: AtomIndex, alive: *A
}
},
.x86_64 => {
+ const sect = object.getSourceSection(object.eh_frame_sect_id.?);
const lsda_ptr = try fde.getLsdaPointer(cie, .{
- .base_addr = object.eh_frame_sect.?.addr,
+ .base_addr = sect.addr,
.base_offset = fde_offset,
});
if (lsda_ptr) |lsda_address| {
src/link/MachO/eh_frame.zig
@@ -171,8 +171,9 @@ pub fn write(zld: *Zld, unwind_info: *UnwindInfo) !void {
const cie_record = eh_records.get(
eh_frame_offset + 4 - fde_record.getCiePointer(),
).?;
+ const eh_frame_sect = object.getSourceSection(object.eh_frame_sect_id.?);
const source_lsda_ptr = try fde_record.getLsdaPointer(cie_record, .{
- .base_addr = object.eh_frame_sect.?.addr,
+ .base_addr = eh_frame_sect.addr,
.base_offset = fde_record_offset,
});
if (source_lsda_ptr) |ptr| {
@@ -552,16 +553,12 @@ pub fn EhFrameRecord(comptime is_mutable: bool) type {
};
}
-pub fn getRelocs(
- zld: *Zld,
- object_id: u32,
- source_offset: u32,
-) []align(1) const macho.relocation_info {
+pub fn getRelocs(zld: *Zld, object_id: u32, source_offset: u32) []const macho.relocation_info {
const object = &zld.objects.items[object_id];
assert(object.hasEhFrameRecords());
const urel = object.eh_frame_relocs_lookup.get(source_offset) orelse
return &[0]macho.relocation_info{};
- const all_relocs = object.getRelocs(object.eh_frame_sect.?);
+ const all_relocs = object.getRelocs(object.eh_frame_sect_id.?);
return all_relocs[urel.reloc.start..][0..urel.reloc.len];
}
src/link/MachO/Object.zig
@@ -60,14 +60,20 @@ globals_lookup: []i64 = undefined,
/// Can be undefined as set together with in_symtab.
relocs_lookup: []RelocEntry = undefined,
+/// All relocations sorted and flatened.
+relocations: std.ArrayListUnmanaged(macho.relocation_info) = .{},
+/// Beginning index to the relocations array for each input section
+/// defined within this Object file.
+section_relocs_lookup: std.ArrayListUnmanaged(u32) = .{},
+
atoms: std.ArrayListUnmanaged(AtomIndex) = .{},
exec_atoms: std.ArrayListUnmanaged(AtomIndex) = .{},
-eh_frame_sect: ?macho.section_64 = null,
+eh_frame_sect_id: ?u8 = null,
eh_frame_relocs_lookup: std.AutoArrayHashMapUnmanaged(u32, Record) = .{},
eh_frame_records_lookup: std.AutoArrayHashMapUnmanaged(AtomIndex, u32) = .{},
-unwind_info_sect: ?macho.section_64 = null,
+unwind_info_sect_id: ?u8 = null,
unwind_relocs_lookup: []Record = undefined,
unwind_records_lookup: std.AutoHashMapUnmanaged(AtomIndex, u32) = .{},
@@ -100,6 +106,8 @@ pub fn deinit(self: *Object, gpa: Allocator) void {
gpa.free(self.unwind_relocs_lookup);
}
self.unwind_records_lookup.deinit(gpa);
+ self.relocations.deinit(gpa);
+ self.section_relocs_lookup.deinit(gpa);
}
pub fn parse(self: *Object, allocator: Allocator, cpu_arch: std.Target.Cpu.Arch) !void {
@@ -137,15 +145,18 @@ pub fn parse(self: *Object, allocator: Allocator, cpu_arch: std.Target.Cpu.Arch)
.buffer = self.contents[@sizeOf(macho.mach_header_64)..][0..self.header.sizeofcmds],
};
const nsects = self.getSourceSections().len;
+
+ // Prepopulate relocations per section lookup table.
+ try self.section_relocs_lookup.resize(allocator, nsects);
+ mem.set(u32, self.section_relocs_lookup.items, 0);
+
+ // Parse symtab.
const symtab = while (it.next()) |cmd| switch (cmd.cmd()) {
.SYMTAB => break cmd.cast(macho.symtab_command).?,
else => {},
} else return;
- self.in_symtab = @ptrCast(
- [*]const macho.nlist_64,
- @alignCast(@alignOf(macho.nlist_64), &self.contents[symtab.symoff]),
- )[0..symtab.nsyms];
+ self.in_symtab = @ptrCast([*]align(1) const macho.nlist_64, self.contents.ptr + symtab.symoff)[0..symtab.nsyms];
self.in_strtab = self.contents[symtab.stroff..][0..symtab.strsize];
self.symtab = try allocator.alloc(macho.nlist_64, self.in_symtab.?.len + nsects);
@@ -212,10 +223,10 @@ pub fn parse(self: *Object, allocator: Allocator, cpu_arch: std.Target.Cpu.Arch)
}
// Parse __TEXT,__eh_frame header if one exists
- self.eh_frame_sect = self.getSourceSectionByName("__TEXT", "__eh_frame");
+ self.eh_frame_sect_id = self.getSourceSectionIndexByName("__TEXT", "__eh_frame");
// Parse __LD,__compact_unwind header if one exists
- self.unwind_info_sect = self.getSourceSectionByName("__LD", "__compact_unwind");
+ self.unwind_info_sect_id = self.getSourceSectionIndexByName("__LD", "__compact_unwind");
if (self.hasUnwindRecords()) {
self.unwind_relocs_lookup = try allocator.alloc(Record, self.getUnwindRecords().len);
mem.set(Record, self.unwind_relocs_lookup, .{
@@ -452,6 +463,8 @@ pub fn splitRegularSections(self: *Object, zld: *Zld, object_id: u32) !void {
zld.sections.items(.header)[out_sect_id].sectName(),
});
+ try self.parseRelocs(gpa, section.id);
+
const cpu_arch = zld.options.target.cpu.arch;
const sect_loc = filterSymbolsBySection(symtab[sect_sym_index..], sect_id + 1);
const sect_start_index = sect_sym_index + sect_loc.index;
@@ -623,25 +636,36 @@ fn filterRelocs(
return .{ .start = @intCast(u32, start), .len = @intCast(u32, len) };
}
+/// Parse all relocs for the input section, and sort in descending order.
+/// Previously, I have wrongly assumed the compilers output relocations for each
+/// section in a sorted manner which is simply not true.
+fn parseRelocs(self: *Object, gpa: Allocator, sect_id: u8) !void {
+ const section = self.getSourceSection(sect_id);
+ const start = @intCast(u32, self.relocations.items.len);
+ if (self.getSourceRelocs(section)) |relocs| {
+ try self.relocations.ensureUnusedCapacity(gpa, relocs.len);
+ self.relocations.appendUnalignedSliceAssumeCapacity(relocs);
+ std.sort.sort(macho.relocation_info, self.relocations.items[start..], {}, relocGreaterThan);
+ }
+ self.section_relocs_lookup.items[sect_id] = start;
+}
+
fn cacheRelocs(self: *Object, zld: *Zld, atom_index: AtomIndex) !void {
const atom = zld.getAtom(atom_index);
- const source_sect = if (self.getSourceSymbol(atom.sym_index)) |source_sym| blk: {
- const source_sect = self.getSourceSection(source_sym.n_sect - 1);
- assert(!source_sect.isZerofill());
- break :blk source_sect;
+ const source_sect_id = if (self.getSourceSymbol(atom.sym_index)) |source_sym| blk: {
+ break :blk source_sym.n_sect - 1;
} else blk: {
// If there was no matching symbol present in the source symtab, this means
// we are dealing with either an entire section, or part of it, but also
// starting at the beginning.
const nbase = @intCast(u32, self.in_symtab.?.len);
- const sect_id = @intCast(u16, atom.sym_index - nbase);
- const source_sect = self.getSourceSection(sect_id);
- assert(!source_sect.isZerofill());
- break :blk source_sect;
+ const sect_id = @intCast(u8, atom.sym_index - nbase);
+ break :blk sect_id;
};
-
- const relocs = self.getRelocs(source_sect);
+ const source_sect = self.getSourceSection(source_sect_id);
+ assert(!source_sect.isZerofill());
+ const relocs = self.getRelocs(source_sect_id);
self.relocs_lookup[atom.sym_index] = if (self.getSourceSymbol(atom.sym_index)) |source_sym| blk: {
const offset = source_sym.n_value - source_sect.addr;
@@ -649,8 +673,14 @@ fn cacheRelocs(self: *Object, zld: *Zld, atom_index: AtomIndex) !void {
} else filterRelocs(relocs, 0, atom.size);
}
+fn relocGreaterThan(ctx: void, lhs: macho.relocation_info, rhs: macho.relocation_info) bool {
+ _ = ctx;
+ return lhs.r_address > rhs.r_address;
+}
+
fn parseEhFrameSection(self: *Object, zld: *Zld, object_id: u32) !void {
- const sect = self.eh_frame_sect orelse return;
+ const sect_id = self.eh_frame_sect_id orelse return;
+ const sect = self.getSourceSection(sect_id);
log.debug("parsing __TEXT,__eh_frame section", .{});
@@ -660,7 +690,8 @@ fn parseEhFrameSection(self: *Object, zld: *Zld, object_id: u32) !void {
const gpa = zld.gpa;
const cpu_arch = zld.options.target.cpu.arch;
- const relocs = self.getRelocs(sect);
+ try self.parseRelocs(gpa, sect_id);
+ const relocs = self.getRelocs(sect_id);
var it = self.getEhFrameRecordsIterator();
var record_count: u32 = 0;
@@ -728,12 +759,12 @@ fn parseEhFrameSection(self: *Object, zld: *Zld, object_id: u32) !void {
}
fn parseUnwindInfo(self: *Object, zld: *Zld, object_id: u32) !void {
- const sect = self.unwind_info_sect orelse {
+ const sect_id = self.unwind_info_sect_id orelse {
// If it so happens that the object had `__eh_frame` section defined but no `__compact_unwind`,
// we will try fully synthesising unwind info records to somewhat match Apple ld's
// approach. However, we will only synthesise DWARF records and nothing more. For this reason,
// we still create the output `__TEXT,__unwind_info` section.
- if (self.eh_frame_sect != null) {
+ if (self.hasEhFrameRecords()) {
if (zld.getSectionByName("__TEXT", "__unwind_info") == null) {
_ = try zld.initSection("__TEXT", "__unwind_info", .{});
}
@@ -758,15 +789,15 @@ fn parseUnwindInfo(self: *Object, zld: *Zld, object_id: u32) !void {
if (UnwindInfo.UnwindEncoding.isDwarf(record.compactUnwindEncoding, cpu_arch)) break true;
} else false;
- if (needs_eh_frame) {
- if (self.eh_frame_sect == null) {
- log.err("missing __TEXT,__eh_frame section", .{});
- log.err(" in object {s}", .{self.name});
- return error.MissingSection;
- }
+ if (needs_eh_frame and !self.hasEhFrameRecords()) {
+ log.err("missing __TEXT,__eh_frame section", .{});
+ log.err(" in object {s}", .{self.name});
+ return error.MissingSection;
}
- const relocs = self.getRelocs(sect);
+ try self.parseRelocs(gpa, sect_id);
+ const relocs = self.getRelocs(sect_id);
+
for (unwind_records) |record, record_id| {
const offset = record_id * @sizeOf(macho.compact_unwind_entry);
const rel_pos = filterRelocs(
@@ -806,25 +837,23 @@ pub fn getSourceSymbol(self: Object, index: u32) ?macho.nlist_64 {
return symtab[mapped_index];
}
-pub fn getSourceSection(self: Object, index: u16) macho.section_64 {
+pub fn getSourceSection(self: Object, index: u8) macho.section_64 {
const sections = self.getSourceSections();
assert(index < sections.len);
return sections[index];
}
pub fn getSourceSectionByName(self: Object, segname: []const u8, sectname: []const u8) ?macho.section_64 {
+ const index = self.getSourceSectionIndexByName(segname, sectname) orelse return null;
const sections = self.getSourceSections();
- for (sections) |sect| {
- if (mem.eql(u8, segname, sect.segName()) and mem.eql(u8, sectname, sect.sectName()))
- return sect;
- } else return null;
+ return sections[index];
}
pub fn getSourceSectionIndexByName(self: Object, segname: []const u8, sectname: []const u8) ?u8 {
const sections = self.getSourceSections();
for (sections) |sect, i| {
if (mem.eql(u8, segname, sect.segName()) and mem.eql(u8, sectname, sect.sectName()))
- return @intCast(u8, i + 1);
+ return @intCast(u8, i);
} else return null;
}
@@ -914,11 +943,18 @@ pub fn getSectionAliasSymbolPtr(self: *Object, sect_id: u8) *macho.nlist_64 {
return &self.symtab[self.getSectionAliasSymbolIndex(sect_id)];
}
-pub fn getRelocs(self: Object, sect: macho.section_64) []align(1) const macho.relocation_info {
- if (sect.nreloc == 0) return &[0]macho.relocation_info{};
+fn getSourceRelocs(self: Object, sect: macho.section_64) ?[]align(1) const macho.relocation_info {
+ if (sect.nreloc == 0) return null;
return @ptrCast([*]align(1) const macho.relocation_info, self.contents.ptr + sect.reloff)[0..sect.nreloc];
}
+pub fn getRelocs(self: Object, sect_id: u8) []const macho.relocation_info {
+ const sect = self.getSourceSection(sect_id);
+ const start = self.section_relocs_lookup.items[sect_id];
+ const len = sect.nreloc;
+ return self.relocations.items[start..][0..len];
+}
+
pub fn getSymbolName(self: Object, index: u32) []const u8 {
const strtab = self.in_strtab.?;
const sym = self.symtab[index];
@@ -976,22 +1012,24 @@ pub fn getAtomIndexForSymbol(self: Object, sym_index: u32) ?AtomIndex {
}
pub fn hasUnwindRecords(self: Object) bool {
- return self.unwind_info_sect != null;
+ return self.unwind_info_sect_id != null;
}
pub fn getUnwindRecords(self: Object) []align(1) const macho.compact_unwind_entry {
- const sect = self.unwind_info_sect orelse return &[0]macho.compact_unwind_entry{};
+ const sect_id = self.unwind_info_sect_id orelse return &[0]macho.compact_unwind_entry{};
+ const sect = self.getSourceSection(sect_id);
const data = self.getSectionContents(sect);
const num_entries = @divExact(data.len, @sizeOf(macho.compact_unwind_entry));
return @ptrCast([*]align(1) const macho.compact_unwind_entry, data)[0..num_entries];
}
pub fn hasEhFrameRecords(self: Object) bool {
- return self.eh_frame_sect != null;
+ return self.eh_frame_sect_id != null;
}
pub fn getEhFrameRecordsIterator(self: Object) eh_frame.Iterator {
- const sect = self.eh_frame_sect orelse return .{ .data = &[0]u8{} };
+ const sect_id = self.eh_frame_sect_id orelse return .{ .data = &[0]u8{} };
+ const sect = self.getSourceSection(sect_id);
const data = self.getSectionContents(sect);
return .{ .data = data };
}
src/link/MachO/UnwindInfo.zig
@@ -703,15 +703,11 @@ pub fn parseRelocTarget(
} else return sym_loc;
}
-fn getRelocs(
- zld: *Zld,
- object_id: u32,
- record_id: usize,
-) []align(1) const macho.relocation_info {
+fn getRelocs(zld: *Zld, object_id: u32, record_id: usize) []const macho.relocation_info {
const object = &zld.objects.items[object_id];
assert(object.hasUnwindRecords());
const rel_pos = object.unwind_relocs_lookup[record_id].reloc;
- const relocs = object.getRelocs(object.unwind_info_sect.?);
+ const relocs = object.getRelocs(object.unwind_info_sect_id.?);
return relocs[rel_pos.start..][0..rel_pos.len];
}
src/link/MachO/zld.zig
@@ -2406,7 +2406,7 @@ pub const Zld = struct {
source_sym.n_value
else blk: {
const nbase = @intCast(u32, object.in_symtab.?.len);
- const source_sect_id = @intCast(u16, atom.sym_index - nbase);
+ const source_sect_id = @intCast(u8, atom.sym_index - nbase);
break :blk object.getSourceSection(source_sect_id).addr;
};
const filtered_dice = filterDataInCode(dice, source_addr, source_addr + atom.size);
src/link/MachO/ZldAtom.zig
@@ -143,7 +143,7 @@ pub fn calcInnerSymbolOffset(zld: *Zld, atom_index: AtomIndex, sym_index: u32) u
sym.n_value
else blk: {
const nbase = @intCast(u32, object.in_symtab.?.len);
- const sect_id = @intCast(u16, atom.sym_index - nbase);
+ const sect_id = @intCast(u8, atom.sym_index - nbase);
const source_sect = object.getSourceSection(sect_id);
break :blk source_sect.addr;
};
@@ -180,7 +180,7 @@ pub fn getRelocContext(zld: *Zld, atom_index: AtomIndex) RelocContext {
};
}
const nbase = @intCast(u32, object.in_symtab.?.len);
- const sect_id = @intCast(u16, atom.sym_index - nbase);
+ const sect_id = @intCast(u8, atom.sym_index - nbase);
const source_sect = object.getSourceSection(sect_id);
return .{
.base_addr = source_sect.addr,
@@ -724,7 +724,7 @@ fn resolveRelocsArm64(
if (rel.r_extern == 0) {
const base_addr = if (target.sym_index > object.source_address_lookup.len)
- @intCast(i64, object.getSourceSection(@intCast(u16, rel.r_symbolnum - 1)).addr)
+ @intCast(i64, object.getSourceSection(@intCast(u8, rel.r_symbolnum - 1)).addr)
else
object.source_address_lookup[target.sym_index];
ptr_addend -= base_addr;
@@ -861,7 +861,7 @@ fn resolveRelocsX86(
if (rel.r_extern == 0) {
const base_addr = if (target.sym_index > object.source_address_lookup.len)
- @intCast(i64, object.getSourceSection(@intCast(u16, rel.r_symbolnum - 1)).addr)
+ @intCast(i64, object.getSourceSection(@intCast(u8, rel.r_symbolnum - 1)).addr)
else
object.source_address_lookup[target.sym_index];
addend += @intCast(i32, @intCast(i64, context.base_addr) + rel.r_address + 4 -
@@ -884,7 +884,7 @@ fn resolveRelocsX86(
if (rel.r_extern == 0) {
const base_addr = if (target.sym_index > object.source_address_lookup.len)
- @intCast(i64, object.getSourceSection(@intCast(u16, rel.r_symbolnum - 1)).addr)
+ @intCast(i64, object.getSourceSection(@intCast(u8, rel.r_symbolnum - 1)).addr)
else
object.source_address_lookup[target.sym_index];
addend -= base_addr;
@@ -928,7 +928,7 @@ pub fn getAtomCode(zld: *Zld, atom_index: AtomIndex) []const u8 {
// we are dealing with either an entire section, or part of it, but also
// starting at the beginning.
const nbase = @intCast(u32, object.in_symtab.?.len);
- const sect_id = @intCast(u16, atom.sym_index - nbase);
+ const sect_id = @intCast(u8, atom.sym_index - nbase);
const source_sect = object.getSourceSection(sect_id);
assert(!source_sect.isZerofill());
const code = object.getSectionContents(source_sect);
@@ -943,28 +943,25 @@ pub fn getAtomCode(zld: *Zld, atom_index: AtomIndex) []const u8 {
return code[offset..][0..code_len];
}
-pub fn getAtomRelocs(zld: *Zld, atom_index: AtomIndex) []align(1) const macho.relocation_info {
+pub fn getAtomRelocs(zld: *Zld, atom_index: AtomIndex) []const macho.relocation_info {
const atom = zld.getAtom(atom_index);
assert(atom.getFile() != null); // Synthetic atom shouldn't need to unique for relocs.
const object = zld.objects.items[atom.getFile().?];
const cache = object.relocs_lookup[atom.sym_index];
- const source_sect = if (object.getSourceSymbol(atom.sym_index)) |source_sym| blk: {
- const source_sect = object.getSourceSection(source_sym.n_sect - 1);
- assert(!source_sect.isZerofill());
- break :blk source_sect;
+ const source_sect_id = if (object.getSourceSymbol(atom.sym_index)) |source_sym| blk: {
+ break :blk source_sym.n_sect - 1;
} else blk: {
// If there was no matching symbol present in the source symtab, this means
// we are dealing with either an entire section, or part of it, but also
// starting at the beginning.
const nbase = @intCast(u32, object.in_symtab.?.len);
- const sect_id = @intCast(u16, atom.sym_index - nbase);
- const source_sect = object.getSourceSection(sect_id);
- assert(!source_sect.isZerofill());
- break :blk source_sect;
+ const sect_id = @intCast(u8, atom.sym_index - nbase);
+ break :blk sect_id;
};
-
- const relocs = object.getRelocs(source_sect);
+ const source_sect = object.getSourceSection(source_sect_id);
+ assert(!source_sect.isZerofill());
+ const relocs = object.getRelocs(source_sect_id);
return relocs[cache.start..][0..cache.len];
}