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zld: map __DATA,__common as __DATA_CONST,__common

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This commit is contained in:
Jakub Konka 2021-04-20 07:23:21 +02:00
parent e5b83056ae
commit 7bc6554a58
1 changed files with 55 additions and 16 deletions
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71
src/link/MachO/Zld.zig
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@ -64,6 +64,7 @@ got_section_index: ?u16 = null,
mod_init_func_section_index: ?u16 = null,
mod_term_func_section_index: ?u16 = null,
data_const_section_index: ?u16 = null,
common_section_index: ?u16 = null,
// __DATA segment sections
tlv_section_index: ?u16 = null,
@ -483,23 +484,43 @@ fn updateMetadata(self: *Zld) !void {
},
macho.S_ZEROFILL => {
if (!mem.eql(u8, segname, "__DATA")) continue;
if (self.bss_section_index != null) continue;
if (mem.eql(u8, sectname, "__common")) {
if (self.common_section_index != null) continue;
self.bss_section_index = @intCast(u16, data_seg.sections.items.len);
try data_seg.addSection(self.allocator, .{
.sectname = makeStaticString("__bss"),
.segname = makeStaticString("__DATA"),
.addr = 0,
.size = 0,
.offset = 0,
.@"align" = 0,
.reloff = 0,
.nreloc = 0,
.flags = macho.S_ZEROFILL,
.reserved1 = 0,
.reserved2 = 0,
.reserved3 = 0,
});
self.common_section_index = @intCast(u16, data_const_seg.sections.items.len);
try data_const_seg.addSection(self.allocator, .{
.sectname = makeStaticString("__common"),
.segname = makeStaticString("__DATA_CONST"),
.addr = 0,
.size = 0,
.offset = 0,
.@"align" = 0,
.reloff = 0,
.nreloc = 0,
.flags = macho.S_ZEROFILL,
.reserved1 = 0,
.reserved2 = 0,
.reserved3 = 0,
});
} else {
if (self.bss_section_index != null) continue;
self.bss_section_index = @intCast(u16, data_seg.sections.items.len);
try data_seg.addSection(self.allocator, .{
.sectname = makeStaticString("__bss"),
.segname = makeStaticString("__DATA"),
.addr = 0,
.size = 0,
.offset = 0,
.@"align" = 0,
.reloff = 0,
.nreloc = 0,
.flags = macho.S_ZEROFILL,
.reserved1 = 0,
.reserved2 = 0,
.reserved3 = 0,
});
}
},
macho.S_THREAD_LOCAL_VARIABLES => {
if (!mem.eql(u8, segname, "__DATA")) continue;
@ -586,7 +607,9 @@ fn updateMetadata(self: *Zld) !void {
const segname = parseName(&source_sect.segname);
const sectname = parseName(&source_sect.sectname);
log.debug("section '{s}/{s}' will be unmapped", .{ segname, sectname });
try self.unhandled_sections.putNoClobber(self.allocator, .{
.object_id = object_id,
.source_sect_id = source_sect_id,
@ -603,6 +626,7 @@ const MatchingSection = struct {
fn getMatchingSection(self: *Zld, section: macho.section_64) ?MatchingSection {
const segname = parseName(&section.segname);
const sectname = parseName(&section.sectname);
const res: ?MatchingSection = blk: {
switch (section.flags) {
macho.S_4BYTE_LITERALS, macho.S_8BYTE_LITERALS, macho.S_16BYTE_LITERALS => {
@ -630,6 +654,12 @@ fn getMatchingSection(self: *Zld, section: macho.section_64) ?MatchingSection {
};
},
macho.S_ZEROFILL => {
if (mem.eql(u8, sectname, "__common")) {
break :blk .{
.seg = self.data_const_segment_cmd_index.?,
.sect = self.common_section_index.?,
};
}
break :blk .{
.seg = self.data_segment_cmd_index.?,
.sect = self.bss_section_index.?,
@ -685,6 +715,7 @@ fn getMatchingSection(self: *Zld, section: macho.section_64) ?MatchingSection {
},
}
};
return res;
}
@ -733,6 +764,7 @@ fn sortSections(self: *Zld) !void {
&self.mod_init_func_section_index,
&self.mod_term_func_section_index,
&self.data_const_section_index,
&self.common_section_index,
};
for (indices) |maybe_index| {
const new_index: u16 = if (maybe_index.*) |index| blk: {
@ -1634,6 +1666,7 @@ fn resolveRelocsAndWriteSections(self: *Zld) !void {
target_sect_off,
target_sect_off + sect.code.len,
});
// Zero-out the space
var zeroes = try self.allocator.alloc(u8, sect.code.len);
defer self.allocator.free(zeroes);
@ -2118,6 +2151,12 @@ fn populateMetadata(self: *Zld) !void {
}
fn flush(self: *Zld) !void {
if (self.common_section_index) |index| {
const seg = &self.load_commands.items[self.data_const_segment_cmd_index.?].Segment;
const sect = &seg.sections.items[index];
sect.offset = 0;
}
if (self.bss_section_index) |index| {
const seg = &self.load_commands.items[self.data_segment_cmd_index.?].Segment;
const sect = &seg.sections.items[index];