From 3ba7b3831f91dc7a297446458efd811fbe46d3dc Mon Sep 17 00:00:00 2001
From: Roland McGrath <roland@gnu.org>
Date: Wed, 27 Oct 2004 07:48:08 +0000
Subject: * sysdeps/mach/hurd/i386/tls.h (HURD_TLS_DESC_DECL): New macro.

	(_hurd_tls_init): Use it.
	(_hurd_tls_fork): New function.
	* sysdeps/mach/hurd/fork.c (__fork) [USE_TLS]: Call it.
---
 sysdeps/mach/hurd/fork.c     | 10 ++++++++-
 sysdeps/mach/hurd/i386/tls.h | 50 +++++++++++++++++++++++++++++++++-----------
 2 files changed, 47 insertions(+), 13 deletions(-)

(limited to 'sysdeps/mach/hurd')

diff --git a/sysdeps/mach/hurd/fork.c b/sysdeps/mach/hurd/fork.c
index c3f8a1a86b..8728596915 100644
--- a/sysdeps/mach/hurd/fork.c
+++ b/sysdeps/mach/hurd/fork.c
@@ -1,4 +1,4 @@
-/* Copyright (C) 1994,95,96,97,99,2001,02 Free Software Foundation, Inc.
+/* Copyright (C) 1994,95,96,97,99,2001,02, 04 Free Software Foundation, Inc.
    This file is part of the GNU C Library.
 
    The GNU C Library is free software; you can redistribute it and/or
@@ -26,6 +26,7 @@
 #include "set-hooks.h"
 #include <assert.h>
 #include "hurdmalloc.h"		/* XXX */
+#include <tls.h>
 
 #undef __fork
 
@@ -529,6 +530,13 @@ __fork (void)
 
       /* Set the child user thread up to return 1 from the setjmp above.  */
       _hurd_longjmp_thread_state (&state, env, 1);
+
+#if USE_TLS
+      /* Do special thread setup for TLS if needed.  */
+      if (err = _hurd_tls_fork (thread, &state))
+	LOSE;
+#endif
+
       if (err = __thread_set_state (thread, MACHINE_THREAD_STATE_FLAVOR,
 				    (natural_t *) &state, statecount))
 	LOSE;
diff --git a/sysdeps/mach/hurd/i386/tls.h b/sysdeps/mach/hurd/i386/tls.h
index 910834687f..a7c291c53f 100644
--- a/sysdeps/mach/hurd/i386/tls.h
+++ b/sysdeps/mach/hurd/i386/tls.h
@@ -45,21 +45,24 @@
 # include <errno.h>
 # include <assert.h>
 
+#define HURD_TLS_DESC_DECL(desc, tcb)					      \
+  struct descriptor desc =						      \
+    {				/* low word: */				      \
+      0xffff			/* limit 0..15 */			      \
+      | (((unsigned int) (tcb)) << 16) /* base 0..15 */			      \
+      ,				/* high word: */			      \
+      ((((unsigned int) (tcb)) >> 16) & 0xff) /* base 16..23 */		      \
+      | ((0x12 | 0x60 | 0x80) << 8) /* access = ACC_DATA_W|ACC_PL_U|ACC_P */  \
+      | (0xf << 16)		/* limit 16..19 */			      \
+      | ((4 | 8) << 20)		/* granularity = SZ_32|SZ_G */		      \
+      | (((unsigned int) (tcb)) & 0xff000000) /* base 24..31 */		      \
+    }
+
+
 static inline const char * __attribute__ ((unused))
 _hurd_tls_init (tcbhead_t *tcb, int secondcall)
 {
-  const unsigned int base = (unsigned int) tcb;
-  struct descriptor desc =
-    {				/* low word: */
-      0xffff			/* limit 0..15 */
-      | (base << 16)		/* base 0..15 */
-      ,				/* high word: */
-      ((base >> 16) & 0xff)	/* base 16..23 */
-      | ((0x12 | 0x60 | 0x80) << 8) /* access = ACC_DATA_W|ACC_PL_U|ACC_P */
-      | (0xf << 16)		/* limit 16..19 */
-      | ((4 | 8) << 20)		/* granularity = SZ_32|SZ_G */
-      | (base & 0xff000000)	/* base 24..31 */
-    };
+  HURD_TLS_DESC_DECL (desc, tcb);
 
   if (!secondcall)
     {
@@ -140,6 +143,29 @@ _hurd_tls_init (tcbhead_t *tcb, int secondcall)
      asm ("movl %%gs:%P1,%0" : "=q" (_dtv) : "i" (offsetof (tcbhead_t, dtv)));\
      _dtv; })
 
+/* Set up TLS in the new thread of a fork child, copying from our own.  */
+static inline error_t __attribute__ ((unused))
+_hurd_tls_fork (thread_t child, struct machine_thread_state *state)
+{
+  /* Fetch the selector set by _hurd_tls_init.  */
+  int sel;
+  asm ("mov %%gs, %w0" : "=q" (sel));
+  if (sel == state->ds)		/* _hurd_tls_init was never called.  */
+    return 0;
+
+  tcbhead_t *const tcb = THREAD_SELF;
+  HURD_TLS_DESC_DECL (desc, tcb);
+  error_t err;
+
+  if (__builtin_expect (sel, 0x50) & 4) /* LDT selector */
+    err = __i386_set_ldt (child, sel, &desc, 1);
+  else
+    err = __i386_set_gdt (child, &sel, desc);
+
+  state->gs = sel;
+  return err;
+}
+
 # endif	/* !ASSEMBLER */
 #endif /* HAVE_TLS_SUPPORT */
 
-- 
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