elf: dynamically allocate remaining alloc sections (and segments)

2 files changed, 76 insertions, 22 deletions

diff --git a/src/link/Elf.zig b/src/link/Elf.zig
index 68101ae964..15aacffc82 100644
--- a/src/link/Elf.zig
+++ b/src/link/Elf.zig
@@ -409,16 +409,24 @@ fn findFreeSpace(self: *Elf, object_size: u64, min_alignment: u64) u64 {
 }
 
 const AllocateSegmentOpts = struct {
-    addr: u64, // TODO find free VM space
     size: u64,
     alignment: u64,
+    addr: ?u64 = null, // TODO find free VM space
     flags: u32 = elf.PF_R,
 };
 
-fn allocateSegment(self: *Elf, opts: AllocateSegmentOpts) error{OutOfMemory}!u16 {
+pub fn allocateSegment(self: *Elf, opts: AllocateSegmentOpts) error{OutOfMemory}!u16 {
     const index = @as(u16, @intCast(self.phdrs.items.len));
     try self.phdrs.ensureUnusedCapacity(self.base.allocator, 1);
     const off = self.findFreeSpace(opts.size, opts.alignment);
+    // Memory is always allocated in sequence.
+    // TODO is this correct? Or should we implement something similar to `findFreeSpace`?
+    // How would that impact HCS?
+    const addr = opts.addr orelse blk: {
+        assert(self.phdr_table_load_index != null);
+        const phdr = &self.phdrs.items[index - 1];
+        break :blk mem.alignForward(u64, phdr.p_vaddr + phdr.p_memsz, opts.alignment);
+    };
     log.debug("allocating phdr({d})({c}{c}{c}) from 0x{x} to 0x{x} (0x{x} - 0x{x})", .{
         index,
         if (opts.flags & elf.PF_R != 0) @as(u8, 'R') else '_',
@@ -426,15 +434,15 @@ fn allocateSegment(self: *Elf, opts: AllocateSegmentOpts) error{OutOfMemory}!u16
         if (opts.flags & elf.PF_X != 0) @as(u8, 'X') else '_',
         off,
         off + opts.size,
-        opts.addr,
-        opts.addr + opts.size,
+        addr,
+        addr + opts.size,
     });
     self.phdrs.appendAssumeCapacity(.{
         .p_type = elf.PT_LOAD,
         .p_offset = off,
         .p_filesz = opts.size,
-        .p_vaddr = opts.addr,
-        .p_paddr = opts.addr,
+        .p_vaddr = addr,
+        .p_paddr = addr,
         .p_memsz = opts.size,
         .p_align = opts.alignment,
         .p_flags = opts.flags,
@@ -446,12 +454,12 @@ fn allocateSegment(self: *Elf, opts: AllocateSegmentOpts) error{OutOfMemory}!u16
 const AllocateAllocSectionOpts = struct {
     name: [:0]const u8,
     phdr_index: u16,
-    alignment: u16 = 1,
-    flags: u16 = elf.SHF_ALLOC,
+    alignment: u64 = 1,
+    flags: u64 = elf.SHF_ALLOC,
     type: u32 = elf.SHT_PROGBITS,
 };
 
-fn allocateAllocSection(self: *Elf, opts: AllocateAllocSectionOpts) error{OutOfMemory}!u16 {
+pub fn allocateAllocSection(self: *Elf, opts: AllocateAllocSectionOpts) error{OutOfMemory}!u16 {
     const gpa = self.base.allocator;
     const phdr = &self.phdrs.items[opts.phdr_index];
     const index = @as(u16, @intCast(self.shdrs.items.len));
@@ -622,6 +630,7 @@ pub fn populateMissingMetadata(self: *Elf) !void {
         });
         const phdr = &self.phdrs.items[self.phdr_load_zerofill_index.?];
         phdr.p_offset = self.phdrs.items[self.phdr_load_rw_index.?].p_offset; // .bss overlaps .data
+        phdr.p_memsz = 1024;
     }
 
     if (self.shstrtab_section_index == null) {
@@ -994,6 +1003,12 @@ pub fn flushModule(self: *Elf, comp: *Compilation, prog_node: *std.Progress.Node
         try positionals.append(.{ .path = key.status.success.object_path });
     }
 
+    // csu prelude
+    var csu = try CsuObjects.init(arena, self.base.options, comp);
+    if (csu.crt0) |v| try positionals.append(.{ .path = v });
+    if (csu.crti) |v| try positionals.append(.{ .path = v });
+    if (csu.crtbegin) |v| try positionals.append(.{ .path = v });
+
     for (positionals.items) |obj| {
         const in_file = try std.fs.cwd().openFile(obj.path, .{});
         defer in_file.close();
@@ -1039,18 +1054,29 @@ pub fn flushModule(self: *Elf, comp: *Compilation, prog_node: *std.Progress.Node
             try self.handleAndReportParseError(lib.path, err, &parse_ctx);
     }
 
-    // Finally, as the last input object add compiler_rt if any.
+    // Finally, as the last input objects we add compiler_rt and CSU postlude (if any).
+    positionals.clearRetainingCapacity();
+
+    // compiler-rt. Since compiler_rt exports symbols like `memset`, it needs
+    // to be after the shared libraries, so they are picked up from the shared
+    // libraries, not libcompiler_rt.
     const compiler_rt_path: ?[]const u8 = blk: {
         if (comp.compiler_rt_lib) |x| break :blk x.full_object_path;
         if (comp.compiler_rt_obj) |x| break :blk x.full_object_path;
         break :blk null;
     };
-    if (compiler_rt_path) |path| {
-        const in_file = try std.fs.cwd().openFile(path, .{});
+    if (compiler_rt_path) |path| try positionals.append(.{ .path = path });
+
+    // csu postlude
+    if (csu.crtend) |v| try positionals.append(.{ .path = v });
+    if (csu.crtn) |v| try positionals.append(.{ .path = v });
+
+    for (positionals.items) |obj| {
+        const in_file = try std.fs.cwd().openFile(obj.path, .{});
         defer in_file.close();
         var parse_ctx: ParseErrorCtx = .{ .detected_cpu_arch = undefined };
-        self.parsePositional(in_file, path, false, &parse_ctx) catch |err|
-            try self.handleAndReportParseError(path, err, &parse_ctx);
+        self.parsePositional(in_file, obj.path, obj.must_link, &parse_ctx) catch |err|
+            try self.handleAndReportParseError(obj.path, err, &parse_ctx);
     }
 
     // Handle any lazy symbols that were emitted by incremental compilation.
diff --git a/src/link/Elf/Object.zig b/src/link/Elf/Object.zig
index 7402bb4f59..8ee37b7676 100644
--- a/src/link/Elf/Object.zig
+++ b/src/link/Elf/Object.zig
@@ -136,7 +136,7 @@ fn initAtoms(self: *Object, elf_file: *Elf) !void {
                 try self.comdat_groups.append(elf_file.base.allocator, comdat_group_index);
             },
 
-            elf.SHT_SYMTAB_SHNDX => @panic("TODO"),
+            elf.SHT_SYMTAB_SHNDX => @panic("TODO SHT_SYMTAB_SHNDX"),
 
             elf.SHT_NULL,
             elf.SHT_REL,
@@ -166,14 +166,20 @@ fn initAtoms(self: *Object, elf_file: *Elf) !void {
     };
 }
 
-fn addAtom(self: *Object, shdr: elf.Elf64_Shdr, shndx: u16, name: [:0]const u8, elf_file: *Elf) !void {
+fn addAtom(
+    self: *Object,
+    shdr: elf.Elf64_Shdr,
+    shndx: u16,
+    name: [:0]const u8,
+    elf_file: *Elf,
+) error{ OutOfMemory, Overflow }!void {
     const atom_index = try elf_file.addAtom();
     const atom = elf_file.atom(atom_index).?;
     atom.atom_index = atom_index;
     atom.name_offset = try elf_file.strtab.insert(elf_file.base.allocator, name);
     atom.file_index = self.index;
     atom.input_section_index = shndx;
-    atom.output_section_index = self.getOutputSectionIndex(elf_file, shdr);
+    atom.output_section_index = try self.getOutputSectionIndex(elf_file, shdr);
     atom.alive = true;
     self.atoms.items[shndx] = atom_index;
 
@@ -188,7 +194,7 @@ fn addAtom(self: *Object, shdr: elf.Elf64_Shdr, shndx: u16, name: [:0]const u8,
     }
 }
 
-fn getOutputSectionIndex(self: *Object, elf_file: *Elf, shdr: elf.Elf64_Shdr) u16 {
+fn getOutputSectionIndex(self: *Object, elf_file: *Elf, shdr: elf.Elf64_Shdr) error{OutOfMemory}!u16 {
     const name = blk: {
         const name = self.strings.getAssumeExists(shdr.sh_name);
         // if (shdr.sh_flags & elf.SHF_MERGE != 0) break :blk name;
@@ -223,10 +229,32 @@ fn getOutputSectionIndex(self: *Object, elf_file: *Elf, shdr: elf.Elf64_Shdr) u1
             else => flags,
         };
     };
-    _ = flags;
-    const out_shndx = elf_file.sectionByName(name) orelse {
-        log.err("{}: output section {s} not found", .{ self.fmtPath(), name });
-        @panic("TODO: missing output section!");
+    const out_shndx = elf_file.sectionByName(name) orelse blk: {
+        const is_alloc = flags & elf.SHF_ALLOC != 0;
+        const is_write = flags & elf.SHF_WRITE != 0;
+        const is_exec = flags & elf.SHF_EXECINSTR != 0;
+        const is_tls = flags & elf.SHF_TLS != 0;
+        if (!is_alloc or is_tls) {
+            log.err("{}: output section {s} not found", .{ self.fmtPath(), name });
+            @panic("TODO: missing output section!");
+        }
+        var phdr_flags: u32 = elf.PF_R;
+        if (is_write) phdr_flags |= elf.PF_W;
+        if (is_exec) phdr_flags |= elf.PF_X;
+        const phdr_index = try elf_file.allocateSegment(.{
+            .size = Elf.padToIdeal(shdr.sh_size),
+            .alignment = if (is_tls) shdr.sh_addralign else elf_file.page_size,
+            .flags = phdr_flags,
+        });
+        const shndx = try elf_file.allocateAllocSection(.{
+            .name = name,
+            .phdr_index = phdr_index,
+            .alignment = shdr.sh_addralign,
+            .flags = flags,
+            .type = @"type",
+        });
+        try elf_file.last_atom_and_free_list_table.putNoClobber(elf_file.base.allocator, shndx, .{});
+        break :blk shndx;
     };
     return out_shndx;
 }