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zld: handle __eh_frame section

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This commit is contained in:
Jakub Konka 2021-06-14 16:01:58 +02:00
parent 5fc25ee8e4
commit 0ca0e88463
4 changed files with 87 additions and 22 deletions
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56
src/link/MachO/Zld.zig
View File

@ -65,9 +65,9 @@ stub_helper_section_index: ?u16 = null,
text_const_section_index: ?u16 = null,
cstring_section_index: ?u16 = null,
ustring_section_index: ?u16 = null,
gcc_except_tab: ?u16 = null,
unwind_info: ?u16 = null,
eh_frame: ?u16 = null,
gcc_except_tab_section_index: ?u16 = null,
unwind_info_section_index: ?u16 = null,
eh_frame_section_index: ?u16 = null,
// __DATA_CONST segment sections
got_section_index: ?u16 = null,
@ -412,7 +412,7 @@ fn mapAndUpdateSections(
const offset = mem.alignForwardGeneric(u64, target_sect.size, alignment);
const size = mem.alignForwardGeneric(u64, source_sect.inner.size, alignment);
log.warn("{s}: '{s},{s}' mapped to '{s},{s}' from 0x{x} to 0x{x}", .{
log.debug("{s}: '{s},{s}' mapped to '{s},{s}' from 0x{x} to 0x{x}", .{
object.name.?,
parseName(&source_sect.inner.segname),
parseName(&source_sect.inner.sectname),
@ -625,8 +625,24 @@ fn updateMetadata(self: *Zld) !void {
},
macho.S_COALESCED => {
if (mem.eql(u8, "__TEXT", segname) and mem.eql(u8, "__eh_frame", sectname)) {
log.debug("TODO __eh_frame section: type 0x{x}, name '{s},{s}'", .{
sect.flags(), segname, sectname,
// TODO I believe __eh_frame is currently part of __unwind_info section
// in the latest ld64 output.
if (self.eh_frame_section_index != null) continue;
self.eh_frame_section_index = @intCast(u16, text_seg.sections.items.len);
try text_seg.addSection(self.allocator, .{
.sectname = makeStaticString("__eh_frame"),
.segname = makeStaticString("__TEXT"),
.addr = 0,
.size = 0,
.offset = 0,
.@"align" = 0,
.reloff = 0,
.nreloc = 0,
.flags = macho.S_REGULAR,
.reserved1 = 0,
.reserved2 = 0,
.reserved3 = 0,
});
continue;
}
@ -682,9 +698,9 @@ fn updateMetadata(self: *Zld) !void {
.reserved3 = 0,
});
} else if (mem.eql(u8, sectname, "__gcc_except_tab")) {
if (self.gcc_except_tab != null) continue;
if (self.gcc_except_tab_section_index != null) continue;
self.gcc_except_tab = @intCast(u16, text_seg.sections.items.len);
self.gcc_except_tab_section_index = @intCast(u16, text_seg.sections.items.len);
try text_seg.addSection(self.allocator, .{
.sectname = makeStaticString("__gcc_except_tab"),
.segname = makeStaticString("__TEXT"),
@ -818,7 +834,7 @@ fn updateMetadata(self: *Zld) !void {
try self.mapAndUpdateSections(object, @intCast(u16, sect_id), res.seg, res.sect);
continue;
}
log.warn("section '{s},{s}' will be unmapped", .{ sect.segname(), sect.sectname() });
log.debug("section '{s},{s}' will be unmapped", .{ sect.segname(), sect.sectname() });
}
}
@ -976,7 +992,13 @@ fn getMatchingSection(self: *Zld, sect: Object.Section) ?MatchingSection {
};
},
macho.S_COALESCED => {
// TODO coalesced sections
if (mem.eql(u8, "__TEXT", segname) and mem.eql(u8, "__eh_frame", sectname)) {
break :blk .{
.seg = self.text_segment_cmd_index.?,
.sect = self.eh_frame_section_index.?,
};
}
break :blk null;
},
macho.S_REGULAR => {
@ -1000,7 +1022,7 @@ fn getMatchingSection(self: *Zld, sect: Object.Section) ?MatchingSection {
} else if (mem.eql(u8, sectname, "__gcc_except_tab")) {
break :blk .{
.seg = self.text_segment_cmd_index.?,
.sect = self.gcc_except_tab.?,
.sect = self.gcc_except_tab_section_index.?,
};
} else {
break :blk .{
@ -1058,10 +1080,11 @@ fn sortSections(self: *Zld) !void {
&self.text_section_index,
&self.stubs_section_index,
&self.stub_helper_section_index,
&self.gcc_except_tab,
&self.text_const_section_index,
&self.gcc_except_tab_section_index,
&self.cstring_section_index,
&self.ustring_section_index,
&self.text_const_section_index,
&self.eh_frame_section_index,
};
for (indices) |maybe_index| {
const new_index: u16 = if (maybe_index.*) |index| blk: {
@ -1846,7 +1869,7 @@ fn resolveStubsAndGotEntries(self: *Zld) !void {
for (relocs) |rel| {
switch (rel.@"type") {
.unsigned => continue,
.got_page, .got_page_off, .got_load, .got => {
.got_page, .got_page_off, .got_load, .got, .pointer_to_got => {
const sym = rel.target.symbol.getTopmostAlias();
if (sym.got_index != null) continue;
@ -1864,9 +1887,6 @@ fn resolveStubsAndGotEntries(self: *Zld) !void {
if (sym.stubs_index != null) continue;
if (sym.@"type" != .proxy) continue;
// if (sym.cast(Symbol.Regular)) |reg| {
// if (!reg.weak_ref) continue;
// }
const index = @intCast(u32, self.stubs.items.len);
sym.stubs_index = index;
@ -1977,7 +1997,7 @@ fn resolveRelocsAndWriteSections(self: *Zld) !void {
});
}
},
.got_page, .got_page_off, .got_load, .got => {
.got_page, .got_page_off, .got_load, .got, .pointer_to_got => {
const dc_seg = self.load_commands.items[self.data_const_segment_cmd_index.?].Segment;
const got = dc_seg.sections.items[self.got_section_index.?];
const final = rel.target.symbol.getTopmostAlias();

2
src/link/MachO/reloc.zig
View File

@ -52,6 +52,7 @@ pub const Relocation = struct {
.page_off => @fieldParentPtr(aarch64.PageOff, "base", base).resolve(args),
.got_page => @fieldParentPtr(aarch64.GotPage, "base", base).resolve(args),
.got_page_off => @fieldParentPtr(aarch64.GotPageOff, "base", base).resolve(args),
.pointer_to_got => @fieldParentPtr(aarch64.PointerToGot, "base", base).resolve(args),
.tlvp_page => @fieldParentPtr(aarch64.TlvpPage, "base", base).resolve(args),
.tlvp_page_off => @fieldParentPtr(aarch64.TlvpPageOff, "base", base).resolve(args),
.branch_x86_64 => @fieldParentPtr(x86_64.Branch, "base", base).resolve(args),
@ -70,6 +71,7 @@ pub const Relocation = struct {
got_page,
got_page_off,
tlvp_page,
pointer_to_got,
tlvp_page_off,
branch_x86_64,
signed,

43
src/link/MachO/reloc/aarch64.zig
View File

@ -141,6 +141,20 @@ pub const GotPageOff = struct {
}
};
pub const PointerToGot = struct {
base: Relocation,
pub const base_type: Relocation.Type = .pointer_to_got;
pub fn resolve(ptr_to_got: PointerToGot, args: Relocation.ResolveArgs) !void {
const result = try math.cast(i32, @intCast(i64, args.target_addr) - @intCast(i64, args.source_addr));
log.debug(" | calculated value 0x{x}", .{result});
mem.writeIntLittle(u32, ptr_to_got.base.code[0..4], @bitCast(u32, result));
}
};
pub const TlvpPage = struct {
base: Relocation,
/// Always .PCRelativeAddress
@ -228,9 +242,7 @@ pub const Parser = struct {
try parser.parseTlvpLoadPageOff(rel);
},
.ARM64_RELOC_POINTER_TO_GOT => {
// TODO Handle pointer to GOT. This reloc seems to appear in
// __LD,__compact_unwind section which we currently don't handle.
log.debug("Unhandled relocation ARM64_RELOC_POINTER_TO_GOT", .{});
try parser.parsePointerToGot(rel);
},
}
}
@ -583,6 +595,31 @@ pub const Parser = struct {
log.debug(" | emitting {}", .{unsigned});
try parser.parsed.append(&unsigned.base);
}
fn parsePointerToGot(parser: *Parser, rel: macho.relocation_info) !void {
const rel_type = @intToEnum(macho.reloc_type_arm64, rel.r_type);
assert(rel_type == .ARM64_RELOC_POINTER_TO_GOT);
assert(rel.r_pcrel == 1);
assert(rel.r_length == 2);
var ptr_to_got = try parser.allocator.create(PointerToGot);
errdefer parser.allocator.destroy(ptr_to_got);
const target = Relocation.Target.from_reloc(rel, parser.symbols);
const offset = @intCast(u32, rel.r_address);
ptr_to_got.* = .{
.base = .{
.@"type" = .pointer_to_got,
.code = parser.code[offset..][0..4],
.offset = offset,
.target = target,
},
};
log.debug(" | emitting {}", .{ptr_to_got});
try parser.parsed.append(&ptr_to_got.base);
}
};
inline fn isArithmeticOp(inst: *const [4]u8) bool {

8
src/link/MachO/reloc/x86_64.zig
View File

@ -66,11 +66,15 @@ pub const GotLoad = struct {
pub const Got = struct {
base: Relocation,
addend: i32,
pub const base_type: Relocation.Type = .got;
pub fn resolve(got: Got, args: Relocation.ResolveArgs) !void {
const displacement = try math.cast(i32, @intCast(i64, args.target_addr) - @intCast(i64, args.source_addr) - 4);
const displacement = try math.cast(
i32,
@intCast(i64, args.target_addr) - @intCast(i64, args.source_addr) - 4 + got.addend,
);
log.debug(" | displacement 0x{x}", .{displacement});
mem.writeIntLittle(u32, got.base.code[0..4], @bitCast(u32, displacement));
}
@ -237,6 +241,7 @@ pub const Parser = struct {
const offset = @intCast(u32, rel.r_address);
const inst = parser.code[offset..][0..4];
const target = Relocation.Target.from_reloc(rel, parser.symbols);
const addend = mem.readIntLittle(i32, inst);
var got = try parser.allocator.create(Got);
errdefer parser.allocator.destroy(got);
@ -248,6 +253,7 @@ pub const Parser = struct {
.offset = offset,
.target = target,
},
.addend = addend,
};
log.debug(" | emitting {}", .{got});