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std: Minor changes to TLS handling

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* Always allocate an info block per-thread so that libc can store
  important stuff there.
* Respect ABI-mandated alignment in more places.
* Nicer code, use slices/pointers instead of raw addresses whenever
  possible.
This commit is contained in:
LemonBoy
2020-03-25 12:08:50 +01:00
parent cbaede7f55
commit a34f67aa66
3 changed files with 142 additions and 136 deletions
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33
lib/std/thread.zig
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@@ -286,11 +286,10 @@ pub const Thread = struct {
}
// Finally, the Thread Local Storage, if any.
if (!Thread.use_pthreads) {
if (os.linux.tls.tls_image) |tls_img| {
l = mem.alignForward(l, @alignOf(usize));
tls_start_offset = l;
l += tls_img.alloc_size;
}
// XXX: Is this alignment enough?
l = mem.alignForward(l, @alignOf(usize));
tls_start_offset = l;
l += os.linux.tls.tls_image.alloc_size;
}
break :blk l;
};
@@ -349,18 +348,21 @@ pub const Thread = struct {
else => return os.unexpectedErrno(@intCast(usize, err)),
}
} else if (std.Target.current.os.tag == .linux) {
var flags: u32 = os.CLONE_VM | os.CLONE_FS | os.CLONE_FILES | os.CLONE_SIGHAND |
os.CLONE_THREAD | os.CLONE_SYSVSEM | os.CLONE_PARENT_SETTID | os.CLONE_CHILD_CLEARTID |
os.CLONE_DETACHED;
var newtls: usize = undefined;
const flags: u32 = os.CLONE_VM | os.CLONE_FS | os.CLONE_FILES |
os.CLONE_SIGHAND | os.CLONE_THREAD | os.CLONE_SYSVSEM |
os.CLONE_PARENT_SETTID | os.CLONE_CHILD_CLEARTID |
os.CLONE_DETACHED | os.CLONE_SETTLS;
// This structure is only needed when targeting i386
var user_desc: if (std.Target.current.cpu.arch == .i386) os.linux.user_desc else void = undefined;
if (os.linux.tls.tls_image) |tls_img| {
const tls_area = mmap_slice[tls_start_offset..];
const tp_value = os.linux.tls.prepareTLS(tls_area);
var newtls = blk: {
if (std.Target.current.cpu.arch == .i386) {
user_desc = os.linux.user_desc{
.entry_number = tls_img.gdt_entry_number,
.base_addr = os.linux.tls.copyTLS(mmap_addr + tls_start_offset),
.entry_number = os.linux.tls.tls_image.gdt_entry_number,
.base_addr = tp_value,
.limit = 0xfffff,
.seg_32bit = 1,
.contents = 0, // Data
@@ -369,12 +371,11 @@ pub const Thread = struct {
.seg_not_present = 0,
.useable = 1,
};
newtls = @ptrToInt(&user_desc);
break :blk @ptrToInt(&user_desc);
} else {
newtls = os.linux.tls.copyTLS(mmap_addr + tls_start_offset);
break :blk tp_value;
}
flags |= os.CLONE_SETTLS;
}
};
const rc = os.linux.clone(
MainFuncs.linuxThreadMain,