elf: make zig jump table indirection implicit via Symbol.address

3 files changed, 35 insertions, 38 deletions

diff --git a/src/link/Elf/Atom.zig b/src/link/Elf/Atom.zig
index 32583b39d7..e067e53c10 100644
--- a/src/link/Elf/Atom.zig
+++ b/src/link/Elf/Atom.zig
@@ -750,8 +750,6 @@ pub fn resolveRelocsAlloc(self: Atom, elf_file: *Elf, code: []u8) RelocError!voi
         const S = target.address(.{}, elf_file);
         // Address of the global offset table.
         const GOT = elf_file.gotAddress();
-        // Address of the zig jump table entry if any.
-        const ZJT = target.zigJumpTableAddress(elf_file);
         // Relative offset to the start of the global offset table.
         const G = target.gotAddress(elf_file) - GOT;
         // // Address of the thread pointer.
@@ -759,19 +757,18 @@ pub fn resolveRelocsAlloc(self: Atom, elf_file: *Elf, code: []u8) RelocError!voi
         // Address of the dynamic thread pointer.
         const DTP = elf_file.dtpAddress();
 
-        relocs_log.debug("  {s}: {x}: [{x} => {x}] GOT({x}) ZJT({x}) ({s})", .{
+        relocs_log.debug("  {s}: {x}: [{x} => {x}] GOT({x}) ({s})", .{
             relocation.fmtRelocType(rel.r_type(), cpu_arch),
             r_offset,
             P,
             S + A,
             G + GOT + A,
-            ZJT + A,
             target.name(elf_file),
         });
 
         try stream.seekTo(r_offset);
 
-        const args = ResolveArgs{ P, A, S, GOT, G, TP, DTP, ZJT };
+        const args = ResolveArgs{ P, A, S, GOT, G, TP, DTP };
 
         switch (cpu_arch) {
             .x86_64 => x86_64.resolveRelocAlloc(self, elf_file, rel, target, args, &it, code, &stream) catch |err| switch (err) {
@@ -956,7 +953,7 @@ pub fn resolveRelocsNonAlloc(self: Atom, elf_file: *Elf, code: []u8, undefs: any
         // Address of the dynamic thread pointer.
         const DTP = elf_file.dtpAddress();
 
-        const args = ResolveArgs{ P, A, S, GOT, 0, 0, DTP, 0 };
+        const args = ResolveArgs{ P, A, S, GOT, 0, 0, DTP };
 
         relocs_log.debug("  {}: {x}: [{x} => {x}] ({s})", .{
             relocation.fmtRelocType(rel.r_type(), cpu_arch),
@@ -1200,7 +1197,7 @@ const x86_64 = struct {
 
         const cwriter = stream.writer();
 
-        const P, const A, const S, const GOT, const G, const TP, const DTP, const ZJT = args;
+        const P, const A, const S, const GOT, const G, const TP, const DTP = args;
 
         switch (r_type) {
             .NONE => unreachable,
@@ -1215,10 +1212,7 @@ const x86_64 = struct {
                 );
             },
 
-            .PLT32 => {
-                const S_ = if (target.flags.zig_jump_table) ZJT else S;
-                try cwriter.writeInt(i32, @as(i32, @intCast(S_ + A - P)), .little);
-            },
+            .PLT32 => try cwriter.writeInt(i32, @as(i32, @intCast(S + A - P)), .little),
             .PC32 => try cwriter.writeInt(i32, @as(i32, @intCast(S + A - P)), .little),
 
             .GOTPCREL => try cwriter.writeInt(i32, @as(i32, @intCast(G + GOT + A - P)), .little),
@@ -1243,10 +1237,7 @@ const x86_64 = struct {
                 try cwriter.writeInt(i32, @as(i32, @intCast(G + GOT + A - P)), .little);
             },
 
-            .@"32" => {
-                const S_ = if (target.flags.zig_jump_table) ZJT else S;
-                try cwriter.writeInt(u32, @as(u32, @truncate(@as(u64, @intCast(S_ + A)))), .little);
-            },
+            .@"32" => try cwriter.writeInt(u32, @as(u32, @truncate(@as(u64, @intCast(S + A)))), .little),
             .@"32S" => try cwriter.writeInt(i32, @as(i32, @truncate(S + A)), .little),
 
             .TPOFF32 => try cwriter.writeInt(i32, @as(i32, @truncate(S + A - TP)), .little),
@@ -1345,7 +1336,7 @@ const x86_64 = struct {
         const r_type: elf.R_X86_64 = @enumFromInt(rel.r_type());
         const cwriter = stream.writer();
 
-        _, const A, const S, const GOT, _, _, const DTP, _ = args;
+        _, const A, const S, const GOT, _, _, const DTP = args;
 
         switch (r_type) {
             .NONE => unreachable,
@@ -1728,9 +1719,8 @@ const aarch64 = struct {
         const code = code_buffer[r_offset..][0..4];
         const file_ptr = atom.file(elf_file).?;
 
-        const P, const A, const S, const GOT, const G, const TP, const DTP, const ZJT = args;
+        const P, const A, const S, const GOT, const G, const TP, const DTP = args;
         _ = DTP;
-        _ = ZJT;
 
         switch (r_type) {
             .NONE => unreachable,
@@ -1932,7 +1922,7 @@ const aarch64 = struct {
         const r_type: elf.R_AARCH64 = @enumFromInt(rel.r_type());
         const cwriter = stream.writer();
 
-        _, const A, const S, _, _, _, _, _ = args;
+        _, const A, const S, _, _, _, _ = args;
 
         switch (r_type) {
             .NONE => unreachable,
@@ -2012,10 +2002,9 @@ const riscv = struct {
         const r_offset = std.math.cast(usize, rel.r_offset) orelse return error.Overflow;
         const cwriter = stream.writer();
 
-        const P, const A, const S, const GOT, const G, const TP, const DTP, const ZJT = args;
+        const P, const A, const S, const GOT, const G, const TP, const DTP = args;
         _ = TP;
         _ = DTP;
-        _ = ZJT;
 
         switch (r_type) {
             .NONE => unreachable,
@@ -2167,7 +2156,7 @@ const riscv = struct {
         const r_offset = std.math.cast(usize, rel.r_offset) orelse return error.Overflow;
         const cwriter = stream.writer();
 
-        _, const A, const S, const GOT, _, _, const DTP, _ = args;
+        _, const A, const S, const GOT, _, _, const DTP = args;
         _ = GOT;
         _ = DTP;
 
@@ -2203,7 +2192,7 @@ const riscv = struct {
     const riscv_util = @import("../riscv.zig");
 };
 
-const ResolveArgs = struct { i64, i64, i64, i64, i64, i64, i64, i64 };
+const ResolveArgs = struct { i64, i64, i64, i64, i64, i64, i64 };
 
 const RelocError = error{
     Overflow,
diff --git a/src/link/Elf/Symbol.zig b/src/link/Elf/Symbol.zig
index 38ef6bb8f7..8b30f0ab03 100644
--- a/src/link/Elf/Symbol.zig
+++ b/src/link/Elf/Symbol.zig
@@ -101,7 +101,7 @@ pub fn symbolRank(symbol: Symbol, elf_file: *Elf) u32 {
     return file_ptr.symbolRank(sym, in_archive);
 }
 
-pub fn address(symbol: Symbol, opts: struct { plt: bool = true }, elf_file: *Elf) i64 {
+pub fn address(symbol: Symbol, opts: struct { plt: bool = true, zjt: bool = true }, elf_file: *Elf) i64 {
     if (symbol.mergeSubsection(elf_file)) |msub| {
         if (!msub.alive) return 0;
         return msub.address(elf_file) + symbol.value;
@@ -109,6 +109,9 @@ pub fn address(symbol: Symbol, opts: struct { plt: bool = true }, elf_file: *Elf
     if (symbol.flags.has_copy_rel) {
         return symbol.copyRelAddress(elf_file);
     }
+    if (symbol.flags.has_zjt and opts.zjt) {
+        return symbol.zjtAddress(elf_file);
+    }
     if (symbol.flags.has_plt and opts.plt) {
         if (!symbol.flags.is_canonical and symbol.flags.has_got) {
             // We have a non-lazy bound function pointer, use that!
@@ -217,12 +220,12 @@ pub fn tlsDescAddress(symbol: Symbol, elf_file: *Elf) i64 {
     return entry.address(elf_file);
 }
 
-pub fn zigJumpTableAddress(symbol: Symbol, elf_file: *Elf) i64 {
-    if (!symbol.flags.zig_jump_table) return 0;
+pub fn zjtAddress(symbol: Symbol, elf_file: *Elf) i64 {
+    if (!symbol.flags.has_zjt) return 0;
     const zo = elf_file.zigObjectPtr().?;
     const jump_table = zo.jumpTablePtr().?;
-    const jt_index = symbol.extra(elf_file).zig_jump_table;
-    return jump_table.entryAddress(jt_index, zo, elf_file);
+    const index = symbol.extra(elf_file).zjt;
+    return jump_table.entryAddress(index, zo, elf_file);
 }
 
 pub fn dsoAlignment(symbol: Symbol, elf_file: *Elf) !u64 {
@@ -248,7 +251,7 @@ const AddExtraOpts = struct {
     tlsgd: ?u32 = null,
     gottp: ?u32 = null,
     tlsdesc: ?u32 = null,
-    zig_jump_table: ?u32 = null,
+    zjt: ?u32 = null,
 };
 
 pub fn addExtra(symbol: *Symbol, opts: AddExtraOpts, elf_file: *Elf) void {
@@ -377,7 +380,7 @@ fn format2(
     try writer.print("%{d} : {s} : @{x}", .{
         symbol.esym_index,
         symbol.fmtName(elf_file),
-        symbol.address(.{}, elf_file),
+        symbol.address(.{ .plt = false, .zjt = false }, elf_file),
     });
     if (symbol.file(elf_file)) |file_ptr| {
         if (symbol.isAbs(elf_file)) {
@@ -454,7 +457,7 @@ pub const Flags = packed struct {
     merge_subsection: bool = false,
 
     /// Whether the symbol has __zig_jump_table indirection.
-    zig_jump_table: bool = false,
+    has_zjt: bool = false,
 };
 
 pub const Extra = struct {
@@ -468,7 +471,7 @@ pub const Extra = struct {
     gottp: u32 = 0,
     tlsdesc: u32 = 0,
     merge_section: u32 = 0,
-    zig_jump_table: u32 = 0,
+    zjt: u32 = 0,
 };
 
 pub const Index = u32;
diff --git a/src/link/Elf/ZigObject.zig b/src/link/Elf/ZigObject.zig
index 596ed781ca..9069e180a3 100644
--- a/src/link/Elf/ZigObject.zig
+++ b/src/link/Elf/ZigObject.zig
@@ -918,7 +918,7 @@ fn updateNavCode(
                 if (stt_bits == elf.STT_FUNC) {
                     const extra = sym.extra(elf_file);
                     const jump_table = self.jumpTablePtr().?;
-                    jump_table.entries.items(.dirty)[extra.zig_jump_table] = true;
+                    jump_table.entries.items(.dirty)[extra.zjt] = true;
                 }
             }
         } else if (code.len < old_size) {
@@ -1045,10 +1045,10 @@ pub fn updateFunc(
 
     {
         const sym = self.symbol(sym_index);
-        if (!sym.flags.zig_jump_table) {
+        if (!sym.flags.has_zjt) {
             const index = try jump_table.addSymbol(gpa, sym_index);
-            sym.flags.zig_jump_table = true;
-            sym.addExtra(.{ .zig_jump_table = index }, elf_file);
+            sym.flags.has_zjt = true;
+            sym.addExtra(.{ .zjt = index }, elf_file);
             try jump_table.updateSize(self, elf_file);
             const old_vaddr = jump_table.address(self, elf_file);
             try self.symbol(jump_table.sym_index).atom(elf_file).?.allocate(elf_file);
@@ -1108,7 +1108,7 @@ pub fn updateFunc(
         }
     } else {
         const sym = self.symbol(sym_index);
-        const jt_index = sym.extra(elf_file).zig_jump_table;
+        const jt_index = sym.extra(elf_file).zjt;
         var jt_entry = jump_table.entries.get(jt_index);
         if (jt_entry.dirty) {
             try jump_table.writeEntry(jt_index, self, elf_file);
@@ -1896,7 +1896,12 @@ pub const JumpTable = struct {
         try writer.print("  @{x} : size({x})\n", .{ jt.address(zo, ef), jt.size(zo, ef) });
         for (jt.entries.items(.sym_index), jt.entries.items(.dirty)) |sym_index, dirty| {
             const sym = zo.symbol(sym_index);
-            try writer.print("    %{d} : {s} : @{x}", .{ sym_index, sym.name(ef), sym.address(.{}, ef) });
+            try writer.print("    {x} => {x} : %{d} : {s}", .{
+                sym.address(.{}, ef),
+                sym.address(.{ .zjt = false }, ef),
+                sym_index,
+                sym.name(ef),
+            });
             if (dirty) try writer.writeAll(" : [!]");
             try writer.writeByte('\n');
         }