From 04624c10801cd9d10971a634f3b25db3d3def87e Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Alex=20R=C3=B8nne=20Petersen?= <alex@alexrp.com>
Date: Mon, 12 Oct 2026 10:43:26 +0200
Subject: [PATCH] std.os.linux.tls: manual backport of
 https://codeberg.org/ziglang/zig/pulls/37186

---
 lib/std/os/linux/tls.zig | 77 ++++++++++++++++++++++------------------
 1 file changed, 42 insertions(+), 35 deletions(-)

diff --git a/lib/std/os/linux/tls.zig b/lib/std/os/linux/tls.zig
index aed76fc0cb2ee83318e5c0e2d72b0016cf44eb91..a804115344259e58e5300c8c30868f3548aff487 100644
--- a/lib/std/os/linux/tls.zig
+++ b/lib/std/os/linux/tls.zig
@@ -142,30 +142,14 @@ const current_dtv_offset = switch (native_arch) {
 
 /// Per-thread storage for the ELF TLS ABI.
 const AbiTcb = switch (current_variant) {
-    .I_original, .I_modified => switch (native_arch) {
-        .aarch64,
-        .aarch64_be,
-        .alpha,
-        .arm,
-        .armeb,
-        .hppa,
-        .microblaze,
-        .microblazeel,
-        .sh,
-        .sheb,
-        .thumb,
-        .thumbeb,
-        .xtensa,
-        .xtensaeb,
-        => extern struct {
-            /// This is offset by `current_dtv_offset`.
-            dtv: usize,
-            _reserved: ?*anyopaque,
-        },
-        else => extern struct {
-            /// This is offset by `current_dtv_offset`.
-            dtv: usize,
-        },
+    .I_original => extern struct {
+        /// This is offset by `current_dtv_offset`.
+        dtv: usize,
+        _reserved: ?*anyopaque,
+    },
+    .I_modified => extern struct {
+        /// This is offset by `current_dtv_offset`.
+        dtv: usize,
     },
     .II => extern struct {
         /// This is self-referential.
@@ -500,7 +484,7 @@ fn computeAreaDesc(phdrs: []elf.ElfN.Phdr) void {
     var block_size: usize = undefined;
 
     if (tls_phdr) |phdr| {
-        align_factor = phdr.@"align";
+        align_factor = @max(phdr.@"align", 1);
 
         // The effective size in memory is represented by `memsz`; the length of the data stored
         // in the `PT.TLS` segment is `filesz` and may be less than the former.
@@ -727,6 +711,11 @@ comptime {
         // the linker should be able to relax every TLS access to the LE model and therefore
         // eliminate all calls to this function, but that isn't guaranteed.
         const Fns = struct {
+            fn __m68k_read_tp() callconv(.c) ?*anyopaque {
+                comptime assert(native_arch == .m68k);
+
+                return @ptrFromInt(getThreadPointer());
+            }
             const TlsIndex = switch (native_arch) {
                 .x86_64 => extern struct { module: u64, offset: u64 }, // Even for x32...
                 else => extern struct { module: usize, offset: usize }, // ...but not MIPS N32!
@@ -736,14 +725,25 @@ comptime {
 
                 assert(ti.module == 1); // The executable's module ID is always 1
                 const tp = getThreadPointer();
-                const block: [*]u8 = switch (current_variant) {
-                    .I_original => @ptrFromInt(tp -% area_desc.abi_tcb.offset +% area_desc.block.offset),
-                    .I_modified => @ptrFromInt(tp -% current_tp_offset),
+                const block = switch (current_variant) {
+                    .I_original => tp -% area_desc.abi_tcb.offset +% area_desc.block.offset,
+                    .I_modified => tp -% current_tp_offset,
                     // The `.I_original` approach would also work for `.II`, but there is an
                     // alternative strategy which is one less operation:
-                    .II => @ptrFromInt(tp -% area_desc.block.size),
+                    .II => tp -% area_desc.abi_tcb.offset,
                 };
-                return block[@intCast(ti.offset)..];
+                return @ptrFromInt(block +% current_dtv_offset +% @as(usize, @intCast(ti.offset)));
+            }
+            fn ___tls_get_addr() callconv(.naked) *anyopaque {
+                comptime assert(native_arch == .x86);
+
+                // We receive the `TlsIndex` pointer in eax.
+                comptime assert(@sizeOf(AbiTcb) + @sizeOf(ZigTcb) + @offsetOf(Dtv, "tls_block") == 12);
+                asm volatile (
+                    \\ mov 4(%%eax), %%eax
+                    \\ add %%gs:12, %%eax
+                    \\ ret
+                );
             }
             fn __tls_get_offset() callconv(.naked) noreturn {
                 comptime assert(native_arch == .s390x);
@@ -752,18 +752,25 @@ comptime {
                 asm volatile (
                     \\ la %%r1, 0(%%r12, %%r2)
                     \\ lg %%r2, 8(%%r1)
-                    \\ lgrl %%r0, %[block_size]
+                    \\ lgrl %%r0, %[abi_tcb_offset]
                     \\ sgr %%r2, %%r0
                     \\ br %%r14
                     :
-                    : [block_size] "s" (&area_desc.block.size),
+                    : [abi_tcb_offset] "s" (&area_desc.abi_tcb.offset),
                 );
             }
         };
 
-        if (native_arch == .s390x)
-            @export(&Fns.__tls_get_offset, .{ .name = "__tls_get_offset" })
-        else
+        if (native_arch == .s390x) {
+            @export(&Fns.__tls_get_offset, .{ .name = "__tls_get_offset" });
+        } else {
             @export(&Fns.__tls_get_addr, .{ .name = "__tls_get_addr" });
+            if (native_arch == .m68k) {
+                @export(&Fns.__m68k_read_tp, .{ .name = "__m68k_read_tp" });
+	        }
+	        if (native_arch == .x86) {
+                @export(&Fns.___tls_get_addr, .{ .name = "___tls_get_addr" });
+	        }
+        }
     }
 }
-- 
2.54.0