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macho: prealloc DATA_CONST and DATA segments

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This commit is contained in:
Jakub Konka 2021-01-05 21:58:33 +01:00
parent 5487dd13ea
commit 3d07f057b1
1 changed files with 68 additions and 9 deletions
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77
src/link/MachO.zig
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@ -52,6 +52,8 @@ load_commands: std.ArrayListUnmanaged(LoadCommand) = .{},
pagezero_segment_cmd_index: ?u16 = null,
/// __TEXT segment
text_segment_cmd_index: ?u16 = null,
/// __DATA_CONST segment
data_const_segment_cmd_index: ?u16 = null,
/// __DATA segment
data_segment_cmd_index: ?u16 = null,
/// __LINKEDIT segment
@ -1519,6 +1521,64 @@ pub fn populateMissingMetadata(self: *MachO) !void {
self.header_dirty = true;
self.load_commands_dirty = true;
}
if (self.data_const_segment_cmd_index == null) {
self.data_const_segment_cmd_index = @intCast(u16, self.load_commands.items.len);
const maxprot = macho.VM_PROT_READ | macho.VM_PROT_WRITE | macho.VM_PROT_EXECUTE;
const initprot = macho.VM_PROT_READ | macho.VM_PROT_WRITE;
const address_and_offset = self.nextSegmentAddressAndOffset();
const ideal_size = @sizeOf(u64) * self.base.options.symbol_count_hint;
const needed_size = mem.alignForwardGeneric(u64, satMul(ideal_size, alloc_num) / alloc_den, self.page_size);
log.debug("found __DATA_CONST segment free space 0x{x} to 0x{x}", .{ address_and_offset.offset, address_and_offset.offset + needed_size });
try self.load_commands.append(self.base.allocator, .{
.Segment = SegmentCommand.empty(.{
.cmd = macho.LC_SEGMENT_64,
.cmdsize = @sizeOf(macho.segment_command_64),
.segname = makeStaticString("__DATA_CONST"),
.vmaddr = address_and_offset.address,
.vmsize = needed_size,
.fileoff = address_and_offset.offset,
.filesize = needed_size,
.maxprot = maxprot,
.initprot = initprot,
.nsects = 0,
.flags = 0,
}),
});
self.header_dirty = true;
self.load_commands_dirty = true;
}
if (self.data_segment_cmd_index == null) {
self.data_segment_cmd_index = @intCast(u16, self.load_commands.items.len);
const maxprot = macho.VM_PROT_READ | macho.VM_PROT_WRITE | macho.VM_PROT_EXECUTE;
const initprot = macho.VM_PROT_READ | macho.VM_PROT_WRITE;
const address_and_offset = self.nextSegmentAddressAndOffset();
const ideal_size = @sizeOf(u64) * self.base.options.symbol_count_hint;
const needed_size = mem.alignForwardGeneric(u64, satMul(ideal_size, alloc_num) / alloc_den, self.page_size);
log.debug("found __DATA segment free space 0x{x} to 0x{x}", .{ address_and_offset.offset, address_and_offset.offset + needed_size });
try self.load_commands.append(self.base.allocator, .{
.Segment = SegmentCommand.empty(.{
.cmd = macho.LC_SEGMENT_64,
.cmdsize = @sizeOf(macho.segment_command_64),
.segname = makeStaticString("__DATA"),
.vmaddr = address_and_offset.address,
.vmsize = needed_size,
.fileoff = address_and_offset.offset,
.filesize = needed_size,
.maxprot = maxprot,
.initprot = initprot,
.nsects = 0,
.flags = 0,
}),
});
self.header_dirty = true;
self.load_commands_dirty = true;
}
if (self.linkedit_segment_cmd_index == null) {
self.linkedit_segment_cmd_index = @intCast(u16, self.load_commands.items.len);
@ -1907,16 +1967,13 @@ const NextSegmentAddressAndOffset = struct {
};
fn nextSegmentAddressAndOffset(self: *MachO) NextSegmentAddressAndOffset {
const prev_segment_idx = blk: {
if (self.data_segment_cmd_index) |idx| {
break :blk idx;
} else if (self.text_segment_cmd_index) |idx| {
break :blk idx;
} else {
unreachable; // unhandled LC_SEGMENT_64 load command before __TEXT
var prev_segment_idx: ?usize = null; // We use optional here for safety.
for (self.load_commands.items) |cmd, i| {
if (cmd == .Segment) {
prev_segment_idx = i;
}
};
const prev_segment = self.load_commands.items[prev_segment_idx].Segment;
}
const prev_segment = self.load_commands.items[prev_segment_idx.?].Segment;
const address = prev_segment.inner.vmaddr + prev_segment.inner.vmsize;
const offset = prev_segment.inner.fileoff + prev_segment.inner.filesize;
return .{
@ -2464,6 +2521,8 @@ fn parseFromFile(self: *MachO, file: fs.File) !void {
}
} else if (parseAndCmpName(&x.inner.segname, "__DATA")) {
self.data_segment_cmd_index = i;
} else if (parseAndCmpName(&x.inner.segname, "__DATA_CONST")) {
self.data_const_segment_cmd_index = i;
}
},
macho.LC_DYLD_INFO_ONLY => {