Commit 2ef3e30e2d

@@ -288,6 +288,13 @@ pub fn calcEhFrameHdrSize(elf_file: *Elf) usize {
 
 pub fn calcEhFrameRelocs(elf_file: *Elf) usize {
     var count: usize = 0;
+    if (elf_file.zigObjectPtr()) |zo| zo: {
+        const sym_index = zo.eh_frame_index orelse break :zo;
+        const sym = zo.symbol(sym_index);
+        const atom_ptr = zo.atom(sym.ref.index).?;
+        if (!atom_ptr.alive) break :zo;
+        count += atom_ptr.relocs(elf_file).len;
+    }
     for (elf_file.objects.items) |index| {
         const object = elf_file.file(index).?.object;
         for (object.cies.items) |cie| {
@@ -416,9 +423,9 @@ pub fn writeEhFrameRelocatable(elf_file: *Elf, writer: anytype) !void {
     }
 }
 
-fn emitReloc(elf_file: *Elf, rec: anytype, sym: *const Symbol, rel: elf.Elf64_Rela) elf.Elf64_Rela {
+fn emitReloc(elf_file: *Elf, base_offset: u64, sym: *const Symbol, rel: elf.Elf64_Rela) elf.Elf64_Rela {
     const cpu_arch = elf_file.getTarget().cpu.arch;
-    const r_offset = rec.address(elf_file) + rel.r_offset - rec.offset;
+    const r_offset = base_offset + rel.r_offset;
     const r_type = rel.r_type();
     var r_addend = rel.r_addend;
     var r_sym: u32 = 0;
@@ -452,6 +459,19 @@ pub fn writeEhFrameRelocs(elf_file: *Elf, writer: anytype) !void {
         elf_file.sections.items(.shdr)[elf_file.eh_frame_section_index.?].sh_addr,
     });
 
+    if (elf_file.zigObjectPtr()) |zo| zo: {
+        const sym_index = zo.eh_frame_index orelse break :zo;
+        const sym = zo.symbol(sym_index);
+        const atom_ptr = zo.atom(sym.ref.index).?;
+        if (!atom_ptr.alive) break :zo;
+        for (atom_ptr.relocs(elf_file)) |rel| {
+            const ref = zo.resolveSymbol(rel.r_sym(), elf_file);
+            const target = elf_file.symbol(ref).?;
+            const out_rel = emitReloc(elf_file, 0, target, rel);
+            try writer.writeStruct(out_rel);
+        }
+    }
+
     for (elf_file.objects.items) |index| {
         const object = elf_file.file(index).?.object;
 
@@ -460,7 +480,8 @@ pub fn writeEhFrameRelocs(elf_file: *Elf, writer: anytype) !void {
             for (cie.relocs(elf_file)) |rel| {
                 const ref = object.resolveSymbol(rel.r_sym(), elf_file);
                 const sym = elf_file.symbol(ref).?;
-                const out_rel = emitReloc(elf_file, cie, sym, rel);
+                const offset = cie.address(elf_file) - cie.offset;
+                const out_rel = emitReloc(elf_file, offset, sym, rel);
                 try writer.writeStruct(out_rel);
             }
         }
@@ -470,7 +491,8 @@ pub fn writeEhFrameRelocs(elf_file: *Elf, writer: anytype) !void {
             for (fde.relocs(elf_file)) |rel| {
                 const ref = object.resolveSymbol(rel.r_sym(), elf_file);
                 const sym = elf_file.symbol(ref).?;
-                const out_rel = emitReloc(elf_file, fde, sym, rel);
+                const offset = fde.address(elf_file) - fde.offset;
+                const out_rel = emitReloc(elf_file, offset, sym, rel);
                 try writer.writeStruct(out_rel);
             }
         }

@@ -391,15 +391,24 @@ fn parseEhFrame(self: *Object, allocator: Allocator, handle: std.fs.File, shndx:
                 .input_section_index = shndx,
                 .file_index = self.index,
             }),
-            .fde => try self.fdes.append(allocator, .{
-                .offset = data_start + rec.offset,
-                .size = rec.size,
-                .cie_index = undefined,
-                .rel_index = rel_start + @as(u32, @intCast(rel_range.start)),
-                .rel_num = @as(u32, @intCast(rel_range.len)),
-                .input_section_index = shndx,
-                .file_index = self.index,
-            }),
+            .fde => {
+                if (rel_range.len == 0) {
+                    // No relocs for an FDE means we cannot associate this FDE to an Atom
+                    // so we skip it. According to mold source code
+                    // (https://github.com/rui314/mold/blob/a3e69502b0eaf1126d6093e8ea5e6fdb95219811/src/input-files.cc#L525-L528)
+                    // this can happen for object files built with -r flag by the linker.
+                    continue;
+                }
+                try self.fdes.append(allocator, .{
+                    .offset = data_start + rec.offset,
+                    .size = rec.size,
+                    .cie_index = undefined,
+                    .rel_index = rel_start + @as(u32, @intCast(rel_range.start)),
+                    .rel_num = @as(u32, @intCast(rel_range.len)),
+                    .input_section_index = shndx,
+                    .file_index = self.index,
+                });
+            },
         }
     }
 
@@ -1106,6 +1115,7 @@ pub fn addAtomsToRelaSections(self: *Object, elf_file: *Elf) !void {
     for (self.atoms_indexes.items) |atom_index| {
         const atom_ptr = self.atom(atom_index) orelse continue;
         if (!atom_ptr.alive) continue;
+        if (atom_ptr.output_section_index == elf_file.eh_frame_section_index) continue;
         const shndx = blk: {
             const shndx = atom_ptr.relocsShndx() orelse continue;
             const shdr = self.shdrs.items[shndx];

@@ -424,8 +424,9 @@ fn writeSyntheticSections(elf_file: *Elf) !void {
     const gpa = elf_file.base.comp.gpa;
     const slice = elf_file.sections.slice();
 
-    for (slice.items(.shdr), slice.items(.atom_list)) |shdr, atom_list| {
+    for (slice.items(.shdr), slice.items(.atom_list), 0..) |shdr, atom_list, shndx| {
         if (shdr.sh_type != elf.SHT_RELA) continue;
+        if (@as(u32, @intCast(shndx)) == elf_file.eh_frame_rela_section_index) continue;
         if (atom_list.items.len == 0) continue;
 
         const num_relocs = math.cast(usize, @divExact(shdr.sh_size, shdr.sh_entsize)) orelse

@@ -808,6 +808,7 @@ pub fn addAtomsToRelaSections(self: *ZigObject, elf_file: *Elf) !void {
     for (self.atoms_indexes.items) |atom_index| {
         const atom_ptr = self.atom(atom_index) orelse continue;
         if (!atom_ptr.alive) continue;
+        if (atom_ptr.output_section_index == elf_file.eh_frame_section_index) continue;
         const rela_shndx = atom_ptr.relocsShndx() orelse continue;
         // TODO this check will become obsolete when we rework our relocs mechanism at the ZigObject level
         if (self.relocs.items[rela_shndx].items.len == 0) continue;

@@ -3388,34 +3388,36 @@ fn shdrRank(self: *Elf, shndx: u32) u8 {
         elf.SHT_PREINIT_ARRAY,
         elf.SHT_INIT_ARRAY,
         elf.SHT_FINI_ARRAY,
-        => return 0xf2,
+        => return 0xf1,
 
-        elf.SHT_DYNAMIC => return 0xf3,
+        elf.SHT_DYNAMIC => return 0xf2,
 
         elf.SHT_RELA, elf.SHT_GROUP => return 0xf,
 
         elf.SHT_PROGBITS => if (flags & elf.SHF_ALLOC != 0) {
             if (flags & elf.SHF_EXECINSTR != 0) {
-                return 0xf1;
+                return 0xf0;
             } else if (flags & elf.SHF_WRITE != 0) {
-                return if (flags & elf.SHF_TLS != 0) 0xf4 else 0xf6;
+                return if (flags & elf.SHF_TLS != 0) 0xf3 else 0xf5;
             } else if (mem.eql(u8, name, ".interp")) {
                 return 1;
+            } else if (mem.startsWith(u8, name, ".eh_frame")) {
+                return 0xe1;
             } else {
-                return 0xf0;
+                return 0xe0;
             }
         } else {
             if (mem.startsWith(u8, name, ".debug")) {
-                return 0xf8;
+                return 0xf7;
             } else {
-                return 0xf9;
+                return 0xf8;
             }
         },
-        elf.SHT_X86_64_UNWIND => return 0xf0,
+        elf.SHT_X86_64_UNWIND => return 0xe1,
 
-        elf.SHT_NOBITS => return if (flags & elf.SHF_TLS != 0) 0xf5 else 0xf7,
-        elf.SHT_SYMTAB => return 0xfa,
-        elf.SHT_STRTAB => return if (mem.eql(u8, name, ".dynstr")) 0x4 else 0xfb,
+        elf.SHT_NOBITS => return if (flags & elf.SHF_TLS != 0) 0xf4 else 0xf6,
+        elf.SHT_SYMTAB => return 0xf9,
+        elf.SHT_STRTAB => return if (mem.eql(u8, name, ".dynstr")) 0x4 else 0xfa,
         else => return 0xff,
     }
 }