authorgravatar for kubkon@jakubkonka.comJakub Konka <kubkon@jakubkonka.com> 2023-09-12 17:35:56+02:00
committergravatar for kubkon@jakubkonka.comJakub Konka <kubkon@jakubkonka.com> 2023-09-12 17:35:56+02:00
log472d326a8c88570f629d58539b9829c69730a96b
tree754ec0aa4c6d9018d44cf3ade1d6d0d1235bee8e
parent44e84af874bc01fe0657d20548f69801cf18dccd

elf: set output section index when parsing objects

2 files changed, 64 insertions(+), 25 deletions(-)

src/link/Elf.zig+9-2
......@@ -1043,14 +1043,17 @@ pub fn flushModule(self: *Elf, comp: *Compilation, prog_node: *std.Progress.Node
10431043 self.linker_defined_index = index;
10441044 }
10451045
1046 // Symbol resolution happens here
10461047 try self.addLinkerDefinedSymbols();
1047
1048 // Resolve symbols
10491048 self.resolveSymbols();
10501049 self.markImportsExports();
10511050 self.claimUnresolved();
1051
1052 // Scan and create missing synthetic entries such as GOT indirection
10521053 try self.scanRelocs();
10531054
1055 // Allocate atoms parsed from input object files
1056 self.allocateObjects();
10541057 self.allocateLinkerDefinedSymbols();
10551058
10561059 // Beyond this point, everything has been allocated a virtual address and we can resolve
......@@ -1402,6 +1405,10 @@ fn scanRelocs(self: *Elf) !void {
14021405 }
14031406}
14041407
1408fn allocateObjects(self: *Elf) void {
1409 _ = self;
1410}
1411
14051412fn linkWithLLD(self: *Elf, comp: *Compilation, prog_node: *std.Progress.Node) !void {
14061413 const tracy = trace(@src());
14071414 defer tracy.end();
src/link/Elf/Object.zig+55-23
......@@ -17,7 +17,6 @@ comdat_groups: std.ArrayListUnmanaged(Elf.ComdatGroup.Index) = .{},
1717fdes: std.ArrayListUnmanaged(Fde) = .{},
1818cies: std.ArrayListUnmanaged(Cie) = .{},
1919
20needs_exec_stack: bool = false,
2120alive: bool = true,
2221num_dynrelocs: u32 = 0,
2322
......@@ -80,12 +79,12 @@ pub fn parse(self: *Object, elf_file: *Elf) !void {
8079 try self.initAtoms(elf_file);
8180 try self.initSymtab(elf_file);
8281
83 for (self.shdrs.items, 0..) |shdr, i| {
84 const atom = elf_file.atom(self.atoms.items[i]) orelse continue;
85 if (!atom.alive) continue;
86 if (shdr.sh_type == elf.SHT_X86_64_UNWIND or mem.eql(u8, atom.name(elf_file), ".eh_frame"))
87 try self.parseEhFrame(@as(u16, @intCast(i)), elf_file);
88 }
82 // for (self.shdrs.items, 0..) |shdr, i| {
83 // const atom = elf_file.atom(self.atoms.items[i]) orelse continue;
84 // if (!atom.alive) continue;
85 // if (shdr.sh_type == elf.SHT_X86_64_UNWIND or mem.eql(u8, atom.name(elf_file), ".eh_frame"))
86 // try self.parseEhFrame(@as(u16, @intCast(i)), elf_file);
87 // }
8988}
9089
9190fn initAtoms(self: *Object, elf_file: *Elf) !void {
......@@ -148,20 +147,6 @@ fn initAtoms(self: *Object, elf_file: *Elf) !void {
148147 else => {
149148 const name = self.strings.getAssumeExists(shdr.sh_name);
150149 const shndx = @as(u16, @intCast(i));
151
152 // if (mem.eql(u8, ".note.GNU-stack", name)) {
153 // if (shdr.sh_flags & elf.SHF_EXECINSTR != 0) {
154 // if (!elf_file.options.z_execstack or !elf_file.options.z_execstack_if_needed) {
155 // elf_file.base.warn(
156 // "{}: may cause segmentation fault as this file requested executable stack",
157 // .{self.fmtPath()},
158 // );
159 // }
160 // self.needs_exec_stack = true;
161 // }
162 // continue;
163 // }
164
165150 if (self.skipShdr(shndx, elf_file)) continue;
166151 try self.addAtom(shdr, shndx, name, elf_file);
167152 },
......@@ -187,6 +172,7 @@ fn addAtom(self: *Object, shdr: elf.Elf64_Shdr, shndx: u16, name: [:0]const u8,
187172 atom.name_offset = try elf_file.strtab.insert(elf_file.base.allocator, name);
188173 atom.file_index = self.index;
189174 atom.input_section_index = shndx;
175 atom.output_section_index = self.getOutputSectionIndex(elf_file, shdr);
190176 atom.alive = true;
191177 self.atoms.items[shndx] = atom_index;
192178
......@@ -201,15 +187,61 @@ fn addAtom(self: *Object, shdr: elf.Elf64_Shdr, shndx: u16, name: [:0]const u8,
201187 }
202188}
203189
190fn getOutputSectionIndex(self: *Object, elf_file: *Elf, shdr: elf.Elf64_Shdr) u16 {
191 const name = blk: {
192 const name = self.strings.getAssumeExists(shdr.sh_name);
193 // if (shdr.sh_flags & elf.SHF_MERGE != 0) break :blk name;
194 const sh_name_prefixes: []const [:0]const u8 = &.{
195 ".text", ".data.rel.ro", ".data", ".rodata", ".bss.rel.ro", ".bss",
196 ".init_array", ".fini_array", ".tbss", ".tdata", ".gcc_except_table", ".ctors",
197 ".dtors", ".gnu.warning",
198 };
199 inline for (sh_name_prefixes) |prefix| {
200 if (std.mem.eql(u8, name, prefix) or std.mem.startsWith(u8, name, prefix ++ ".")) {
201 break :blk prefix;
202 }
203 }
204 break :blk name;
205 };
206 const @"type" = switch (shdr.sh_type) {
207 elf.SHT_NULL => unreachable,
208 elf.SHT_PROGBITS => blk: {
209 if (std.mem.eql(u8, name, ".init_array") or std.mem.startsWith(u8, name, ".init_array."))
210 break :blk elf.SHT_INIT_ARRAY;
211 if (std.mem.eql(u8, name, ".fini_array") or std.mem.startsWith(u8, name, ".fini_array."))
212 break :blk elf.SHT_FINI_ARRAY;
213 break :blk shdr.sh_type;
214 },
215 elf.SHT_X86_64_UNWIND => elf.SHT_PROGBITS,
216 else => shdr.sh_type,
217 };
218 const flags = blk: {
219 const flags = shdr.sh_flags & ~@as(u64, elf.SHF_COMPRESSED | elf.SHF_GROUP | elf.SHF_GNU_RETAIN);
220 break :blk switch (@"type") {
221 elf.SHT_INIT_ARRAY, elf.SHT_FINI_ARRAY => flags | elf.SHF_WRITE,
222 else => flags,
223 };
224 };
225 _ = flags;
226 const out_shndx = elf_file.sectionByName(name) orelse {
227 log.err("{}: output section {s} not found", .{ self.fmtPath(), name });
228 @panic("TODO: missing output section!");
229 };
230 return out_shndx;
231}
232
204233fn skipShdr(self: *Object, index: u16, elf_file: *Elf) bool {
234 _ = elf_file;
205235 const shdr = self.shdrs.items[index];
206236 const name = self.strings.getAssumeExists(shdr.sh_name);
207237 const ignore = blk: {
208238 if (mem.startsWith(u8, name, ".note")) break :blk true;
209239 if (mem.startsWith(u8, name, ".comment")) break :blk true;
210240 if (mem.startsWith(u8, name, ".llvm_addrsig")) break :blk true;
211 if (elf_file.base.options.strip and shdr.sh_flags & elf.SHF_ALLOC == 0 and
212 mem.startsWith(u8, name, ".debug")) break :blk true;
241 if (mem.startsWith(u8, name, ".eh_frame")) break :blk true;
242 // if (elf_file.base.options.strip and shdr.sh_flags & elf.SHF_ALLOC == 0 and
243 // mem.startsWith(u8, name, ".debug")) break :blk true;
244 if (shdr.sh_flags & elf.SHF_ALLOC == 0 and mem.startsWith(u8, name, ".debug")) break :blk true;
213245 break :blk false;
214246 };
215247 return ignore;