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macho: write all atoms in flush so that we can resolve relocs

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This commit is contained in:
Jakub Konka
2021-08-26 14:23:28 +02:00
parent 432fb7054d
commit 570c75cb74
2 changed files with 59 additions and 87 deletions
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107
src/link/MachO.zig
View File

@@ -788,6 +788,7 @@ pub fn flush(self: *MachO, comp: *Compilation) !void {
try self.allocateTextBlocks();
try self.flushZld();
} else {
try self.writeAtoms();
try self.flushModule(comp);
}
}
@@ -1901,8 +1902,7 @@ pub fn allocateAtom(self: *MachO, atom: *TextBlock, match: MatchingSection) !u64
const last_atom_sym = self.locals.items[last.local_sym_index];
break :blk last_atom_sym.n_value + last.size;
} else sect.addr;
// const atom_alignment = try math.powi(u32, 2, atom.alignment); TODO
const atom_alignment = math.powi(u32, 2, atom.alignment) catch unreachable;
const atom_alignment = try math.powi(u32, 2, atom.alignment);
const vaddr = mem.alignForwardGeneric(u64, base_addr, atom_alignment);
log.debug("allocating atom for symbol {s} at address 0x{x}", .{ self.getString(sym.n_strx), vaddr });
@@ -1954,6 +1954,20 @@ pub fn allocateAtomStage1(self: *MachO, atom: *TextBlock, match: MatchingSection
}
}
fn writeAtoms(self: *MachO) !void {
var it = self.blocks.iterator();
while (it.next()) |entry| {
const match = entry.key_ptr.*;
var atom: *TextBlock = entry.value_ptr.*;
while (atom.prev) |prev| {
try self.writeAtom(atom, match);
atom = prev;
}
try self.writeAtom(atom, match);
}
}
pub fn createGotAtom(self: *MachO, key: GotIndirectionKey) !*TextBlock {
const local_sym_index = @intCast(u32, self.locals.items.len);
try self.locals.append(self.base.allocator, .{
@@ -2588,21 +2602,17 @@ fn resolveSymbols(self: *MachO) !void {
if (!use_stage1) {
{
const atom = try self.createDyldPrivateAtom();
const match = MatchingSection{
_ = try self.allocateAtom(atom, .{
.seg = self.data_segment_cmd_index.?,
.sect = self.data_section_index.?,
};
_ = try self.allocateAtom(atom, match);
try self.writeAtom(atom, match);
});
}
{
const atom = try self.createStubHelperPreambleAtom();
const match = MatchingSection{
_ = try self.allocateAtom(atom, .{
.seg = self.text_segment_cmd_index.?,
.sect = self.stub_helper_section_index.?,
};
_ = try self.allocateAtom(atom, match);
try self.writeAtom(atom, match);
});
}
}
@@ -2634,12 +2644,10 @@ fn resolveSymbols(self: *MachO) !void {
if (self.stubs_map.contains(resolv.where_index)) break :outer_blk;
const stub_helper_atom = blk: {
const atom = try self.createStubHelperAtom();
const match = MatchingSection{
_ = try self.allocateAtom(atom, .{
.seg = self.text_segment_cmd_index.?,
.sect = self.stub_helper_section_index.?,
};
_ = try self.allocateAtom(atom, match);
try self.writeAtom(atom, match);
});
break :blk atom;
};
const laptr_atom = blk: {
@@ -2647,22 +2655,18 @@ fn resolveSymbols(self: *MachO) !void {
stub_helper_atom.local_sym_index,
resolv.where_index,
);
const match = MatchingSection{
_ = try self.allocateAtom(atom, .{
.seg = self.data_segment_cmd_index.?,
.sect = self.la_symbol_ptr_section_index.?,
};
_ = try self.allocateAtom(atom, match);
try self.writeAtom(atom, match);
});
break :blk atom;
};
const stub_atom = blk: {
const atom = try self.createStubAtom(laptr_atom.local_sym_index);
const match = MatchingSection{
_ = try self.allocateAtom(atom, .{
.seg = self.text_segment_cmd_index.?,
.sect = self.stubs_section_index.?,
};
_ = try self.allocateAtom(atom, match);
try self.writeAtom(atom, match);
});
break :blk atom;
};
try self.stubs_map.putNoClobber(self.base.allocator, resolv.where_index, stub_atom);
@@ -2793,7 +2797,6 @@ fn resolveDyldStubBinder(self: *MachO) !void {
// TODO remove once we can incrementally update in stage1 too.
if (!(build_options.is_stage1 and self.base.options.use_stage1)) {
_ = try self.allocateAtom(atom, match);
try self.writeAtom(atom, match);
} else {
try self.allocateAtomStage1(atom, match);
}
@@ -3480,10 +3483,6 @@ pub fn allocateDeclIndexes(self: *MachO, decl: *Module.Decl) !void {
.where_index = decl.link.macho.local_sym_index,
};
const got_atom = try self.createGotAtom(key);
_ = try self.allocateAtom(got_atom, .{
.seg = self.data_const_segment_cmd_index.?,
.sect = self.got_section_index.?,
});
try self.got_entries_map.put(self.base.allocator, key, got_atom);
self.rebase_info_dirty = true;
}
@@ -3549,9 +3548,7 @@ pub fn updateFunc(self: *MachO, module: *Module, func: *Module.Fn, air: Air, liv
},
}
const symbol = try self.placeDecl(decl, decl.link.macho.code.items.len);
try self.writeCode(symbol, decl.link.macho.code.items);
_ = try self.placeDecl(decl, decl.link.macho.code.items.len);
if (debug_buffers) |db| {
try self.d_sym.?.commitDeclDebugInfo(
@@ -3642,9 +3639,7 @@ pub fn updateDecl(self: *MachO, module: *Module, decl: *Module.Decl) !void {
},
}
};
const symbol = try self.placeDecl(decl, code.len);
try self.writeCode(symbol, code);
_ = try self.placeDecl(decl, code.len);
// Since we updated the vaddr and the size, each corresponding export symbol also
// needs to be updated.
@@ -3667,16 +3662,14 @@ fn placeDecl(self: *MachO, decl: *Module.Decl, code_len: usize) !*macho.nlist_64
if (vaddr != symbol.n_value) {
log.debug(" (writing new GOT entry)", .{});
const match = MatchingSection{
.seg = self.data_const_segment_cmd_index.?,
.sect = self.got_section_index.?,
};
const got_atom = self.got_entries_map.get(.{
.where = .local,
.where_index = decl.link.macho.local_sym_index,
}) orelse unreachable;
// _ = try self.allocateAtom(got_atom, match);
try self.writeAtom(got_atom, match);
_ = try self.allocateAtom(got_atom, .{
.seg = self.data_const_segment_cmd_index.?,
.sect = self.got_section_index.?,
});
}
symbol.n_value = vaddr;
@@ -3714,40 +3707,29 @@ fn placeDecl(self: *MachO, decl: *Module.Decl, code_len: usize) !*macho.nlist_64
.n_desc = 0,
.n_value = addr,
};
const match = MatchingSection{
.seg = self.data_const_segment_cmd_index.?,
.sect = self.got_section_index.?,
};
const got_atom = self.got_entries_map.get(.{
.where = .local,
.where_index = decl.link.macho.local_sym_index,
}) orelse unreachable;
// _ = try self.allocateAtom(got_atom, match);
try self.writeAtom(got_atom, match);
_ = try self.allocateAtom(got_atom, .{
.seg = self.data_const_segment_cmd_index.?,
.sect = self.got_section_index.?,
});
try self.writeLocalSymbol(decl.link.macho.local_sym_index);
if (self.d_sym) |*ds|
try ds.writeLocalSymbol(decl.link.macho.local_sym_index);
}
// Resolve relocations
try decl.link.macho.resolveRelocs(self);
// TODO this requires further investigation: should we dispose of resolved relocs, or keep them
// so that we can reapply them when moving/growing sections?
decl.link.macho.relocs.clearAndFree(self.base.allocator);
// // Resolve relocations
// try decl.link.macho.resolveRelocs(self);
// // TODO this requires further investigation: should we dispose of resolved relocs, or keep them
// // so that we can reapply them when moving/growing sections?
// decl.link.macho.relocs.clearAndFree(self.base.allocator);
return symbol;
}
fn writeCode(self: *MachO, symbol: *macho.nlist_64, code: []const u8) !void {
const text_segment = &self.load_commands.items[self.text_segment_cmd_index.?].Segment;
const text_section = text_segment.sections.items[self.text_section_index.?];
const section_offset = symbol.n_value - text_section.addr;
const file_offset = text_section.offset + section_offset;
log.debug("writing code for symbol {s} at file offset 0x{x}", .{ self.getString(symbol.n_strx), file_offset });
try self.base.file.?.pwriteAll(code, file_offset);
}
pub fn updateDeclLineNumber(self: *MachO, module: *Module, decl: *const Module.Decl) !void {
if (self.d_sym) |*ds| {
try ds.updateDeclLineNumber(module, decl);
@@ -3983,7 +3965,7 @@ pub fn populateMissingMetadata(self: *MachO) !void {
.aarch64 => 3 * @sizeOf(u32),
else => unreachable, // unhandled architecture type
};
const needed_size = @sizeOf(u64) * self.base.options.symbol_count_hint;
const needed_size = stub_size * self.base.options.symbol_count_hint;
const off = text_segment.findFreeSpace(needed_size, @alignOf(u64), self.header_pad);
assert(off + needed_size <= text_segment.inner.fileoff + text_segment.inner.filesize); // TODO Must expand __TEXT segment.
@@ -4739,8 +4721,9 @@ fn writeLocalSymbol(self: *MachO, index: usize) !void {
try self.relocateSymbolTable();
const symtab = &self.load_commands.items[self.symtab_cmd_index.?].Symtab;
const off = symtab.symoff + @sizeOf(macho.nlist_64) * index;
log.debug("writing local symbol {} at 0x{x}", .{ index, off });
try self.base.file.?.pwriteAll(mem.asBytes(&self.locals.items[index]), off);
const sym = self.locals.items[index];
log.debug("writing local symbol {s}: {} at 0x{x}", .{ self.getString(sym.n_strx), sym, off });
try self.base.file.?.pwriteAll(mem.asBytes(&sym), off);
}
fn writeAllGlobalAndUndefSymbols(self: *MachO) !void {

39
src/link/MachO/TextBlock.zig
View File

@@ -75,6 +75,8 @@ dbg_info_off: u32,
/// Size of the .debug_info tag for this Decl, not including padding.
dbg_info_len: u32,
dirty: bool = true,
pub const SymbolAtOffset = struct {
local_sym_index: u32,
offset: u64,
@@ -843,7 +845,6 @@ pub fn parseRelocs(self: *TextBlock, relocs: []macho.relocation_info, context: R
};
if (!(build_options.is_stage1 and context.macho_file.base.options.use_stage1)) {
_ = try context.macho_file.allocateAtom(atom, match);
try context.macho_file.writeAtom(atom, match);
} else {
try context.macho_file.allocateAtomStage1(atom, match);
}
@@ -924,30 +925,18 @@ pub fn parseRelocs(self: *TextBlock, relocs: []macho.relocation_info, context: R
.sect = context.macho_file.stubs_section_index.?,
});
} else {
{
const match = MachO.MatchingSection{
.seg = context.macho_file.text_segment_cmd_index.?,
.sect = context.macho_file.stub_helper_section_index.?,
};
_ = try context.macho_file.allocateAtom(stub_helper_atom, match);
try context.macho_file.writeAtom(stub_helper_atom, match);
}
{
const match = MachO.MatchingSection{
.seg = context.macho_file.data_segment_cmd_index.?,
.sect = context.macho_file.la_symbol_ptr_section_index.?,
};
_ = try context.macho_file.allocateAtom(laptr_atom, match);
try context.macho_file.writeAtom(laptr_atom, match);
}
{
const match = MachO.MatchingSection{
.seg = context.macho_file.text_segment_cmd_index.?,
.sect = context.macho_file.stubs_section_index.?,
};
_ = try context.macho_file.allocateAtom(stub_atom, match);
try context.macho_file.writeAtom(stub_atom, match);
}
_ = try context.macho_file.allocateAtom(stub_helper_atom, .{
.seg = context.macho_file.text_segment_cmd_index.?,
.sect = context.macho_file.stub_helper_section_index.?,
});
_ = try context.macho_file.allocateAtom(laptr_atom, .{
.seg = context.macho_file.data_segment_cmd_index.?,
.sect = context.macho_file.la_symbol_ptr_section_index.?,
});
_ = try context.macho_file.allocateAtom(stub_atom, .{
.seg = context.macho_file.text_segment_cmd_index.?,
.sect = context.macho_file.stubs_section_index.?,
});
}
}
}