* 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.

1 files changed, 38 insertions, 12 deletions

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 */