[PATCH v2 3/4] hurd: Implement TLS for x86_64

[Sergey Bugaev]

Signed-off-by: Sergey Bugaev <bugaevc@gmail.com>
---
 sysdeps/mach/hurd/x86/init-first.c |  14 +-
 sysdeps/mach/hurd/x86_64/tls.h     | 215 +++++++++++++++++++++++++++++
 2 files changed, 228 insertions(+), 1 deletion(-)
 create mode 100644 sysdeps/mach/hurd/x86_64/tls.h

diff --git a/sysdeps/mach/hurd/x86/init-first.c 
b/sysdeps/mach/hurd/x86/init-first.c
index a187af82..04480ed3 100644
--- a/sysdeps/mach/hurd/x86/init-first.c
+++ b/sysdeps/mach/hurd/x86/init-first.c
@@ -41,8 +41,14 @@ extern char **__libc_argv attribute_hidden;
 extern char **_dl_argv;
 
 #ifndef SHARED
-unsigned short __init1_desc;
 static tcbhead_t __init1_tcbhead;
+# ifndef __x86_64__
+unsigned short __init1_desc;
+# endif
+#endif
+
+#ifdef __x86_64__
+unsigned char __libc_tls_initialized;
 #endif
 
 /* Things that want to be run before _hurd_init or much anything else.
@@ -174,7 +180,13 @@ first_init (void)
   /* In the static case, we need to set up TLS early so that the stack
      protection guard can be read at gs:0x14 by the gcc-generated snippets.  */
   _hurd_tls_init (&__init1_tcbhead);
+
+  /* Make sure __LIBC_NO_TLS () keeps evaluating to 1.  */
+# ifdef __x86_64__
+  __libc_tls_initialized = 0;
+# else
   asm ("movw %%gs,%w0" : "=m" (__init1_desc));
+# endif
 #endif
 
   RUN_RELHOOK (_hurd_preinit_hook, ());
diff --git a/sysdeps/mach/hurd/x86_64/tls.h b/sysdeps/mach/hurd/x86_64/tls.h
new file mode 100644
index 00000000..cf74e1f4
--- /dev/null
+++ b/sysdeps/mach/hurd/x86_64/tls.h
@@ -0,0 +1,215 @@
+/* Definitions for thread-local data handling.  Hurd/x86_64 version.
+   Copyright (C) 2003-2023 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
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <https://www.gnu.org/licenses/>.  */
+
+#ifndef _X86_64_TLS_H
+#define _X86_64_TLS_H
+
+
+/* Some things really need not be machine-dependent.  */
+#include <sysdeps/mach/hurd/tls.h>
+
+
+#ifndef __ASSEMBLER__
+# include <dl-dtv.h>
+# include <mach/machine/thread_status.h>
+# include <errno.h>
+# include <assert.h>
+
+/* Type of the TCB.  */
+typedef struct
+{
+  void *tcb;                   /* Points to this structure.  */
+  dtv_t *dtv;                  /* Vector of pointers to TLS data.  */
+  thread_t self;               /* This thread's control port.  */
+  int __glibc_padding1;
+  int multiple_threads;
+  int gscope_flag;
+  uintptr_t sysinfo;
+  uintptr_t stack_guard;
+  uintptr_t pointer_guard;
+  long __glibc_padding2[2];
+  int private_futex;
+  int __glibc_padding3;
+  /* Reservation of some values for the TM ABI.  */
+  void *__private_tm[4];
+  /* GCC split stack support.  */
+  void *__private_ss;
+  /* The lowest address of shadow stack.  */
+  unsigned long long int ssp_base;
+
+  /* Keep these fields last, so offsets of fields above can continue being
+     compatible with the x86_64 NPTL version.  */
+  mach_port_t reply_port;      /* This thread's reply port.  */
+  struct hurd_sigstate *_hurd_sigstate;
+
+  /* Used by the exception handling implementation in the dynamic loader.  */
+  struct rtld_catch *rtld_catch;
+} tcbhead_t;
+
+/* GCC generates %fs:0x28 to access the stack guard.  */
+_Static_assert (offsetof (tcbhead_t, stack_guard) == 0x28,
+                "stack guard offset");
+/* libgcc uses %fs:0x70 to access the split stack pointer.  */
+_Static_assert (offsetof (tcbhead_t, __private_ss) == 0x70,
+                "split stack pointer offset");
+
+extern unsigned char __libc_tls_initialized;
+
+# define __LIBC_NO_TLS() __builtin_expect (!__libc_tls_initialized, 0)
+
+/* The TCB can have any size and the memory following the address the
+   thread pointer points to is unspecified.  Allocate the TCB there.  */
+# define TLS_TCB_AT_TP 1
+# define TLS_DTV_AT_TP 0
+
+/* Alignment requirement for TCB.
+
+   Some processors such as Intel Atom pay a big penalty on every
+   access using a segment override if that segment's base is not
+   aligned to the size of a cache line.  (See Intel 64 and IA-32
+   Architectures Optimization Reference Manual, section 13.3.3.3,
+   "Segment Base".)  On such machines, a cache line is 64 bytes.  */
+# define TCB_ALIGNMENT 64
+
+
+# define TLS_INIT_TP(descr) _hurd_tls_init ((tcbhead_t *) (descr))
+
+# define THREAD_SELF                                                   \
+  (*(tcbhead_t * __seg_fs *) offsetof (tcbhead_t, tcb))
+/* Read member of the thread descriptor directly.  */
+# define THREAD_GETMEM(descr, member)                                  \
+  (*(__typeof (descr->member) __seg_fs *) offsetof (tcbhead_t, member))
+/* Write member of the thread descriptor directly.  */
+# define THREAD_SETMEM(descr, member, value)                           \
+  (*(__typeof (descr->member) __seg_fs *) offsetof (tcbhead_t, member) = value)
+
+
+/* Return the TCB address of a thread given its state.
+   Note: this is expensive.  */
+static inline tcbhead_t * __attribute__ ((unused))
+THREAD_TCB (thread_t thread,
+            const void *all_state __attribute__ ((unused)))
+{
+  error_t err;
+  /* Fetch the target thread's state.  */
+  struct i386_fsgs_base_state state;
+  mach_msg_type_number_t state_count = i386_FSGS_BASE_STATE_COUNT;
+  err = __thread_get_state (thread, i386_FSGS_BASE_STATE,
+                            (thread_state_t) &state,
+                            &state_count);
+  assert_perror (err);
+  assert (state_count == i386_FSGS_BASE_STATE_COUNT);
+  return (tcbhead_t *) state.fs_base;
+}
+
+/* Install new dtv for current thread.  */
+# define INSTALL_NEW_DTV(dtvp) THREAD_SETMEM (THREAD_SELF, dtv, dtvp)
+
+/* Return the address of the dtv for the current thread.  */
+# define THREAD_DTV() THREAD_GETMEM (THREAD_SELF, dtv)
+
+
+/* Set the stack guard field in TCB head.  */
+# define THREAD_SET_STACK_GUARD(value)                                 \
+  THREAD_SETMEM (THREAD_SELF, stack_guard, value)
+# define THREAD_COPY_STACK_GUARD(descr)                                        
\
+  ((descr)->stack_guard                                                        
\
+   = THREAD_GETMEM (THREAD_SELF, stack_guard))
+
+/* Set the pointer guard field in the TCB head.  */
+# define THREAD_SET_POINTER_GUARD(value)                               \
+  THREAD_SETMEM (THREAD_SELF, pointer_guard, value)
+# define THREAD_COPY_POINTER_GUARD(descr)                              \
+  ((descr)->pointer_guard                                              \
+   = THREAD_GETMEM (THREAD_SELF, pointer_guard))
+
+/* Set up TLS in the new thread of a fork child, copying from the original.  */
+static inline kern_return_t __attribute__ ((unused))
+_hurd_tls_fork (thread_t child, thread_t orig,
+                void *machine_state __attribute__ ((unused)))
+{
+  error_t err;
+  struct i386_fsgs_base_state state;
+  mach_msg_type_number_t state_count = i386_FSGS_BASE_STATE_COUNT;
+  err = __thread_get_state (orig, i386_FSGS_BASE_STATE,
+                            (thread_state_t) &state,
+                            &state_count);
+  if (err)
+    return err;
+  assert (state_count == i386_FSGS_BASE_STATE_COUNT);
+
+  return __thread_set_state (child, i386_FSGS_BASE_STATE,
+                             (thread_state_t) &state,
+                             state_count);
+}
+
+static inline kern_return_t __attribute__ ((unused))
+_hurd_tls_new (thread_t child, tcbhead_t *tcb)
+{
+  struct i386_fsgs_base_state state;
+
+  tcb->tcb = tcb;
+  tcb->self = child;
+
+  /* Install the TCB address into FS base.  */
+  state.fs_base = (uintptr_t) tcb;
+  state.gs_base = 0;
+  return __thread_set_state (child, i386_FSGS_BASE_STATE,
+                             (thread_state_t) &state,
+                             i386_FSGS_BASE_STATE_COUNT);
+}
+
+static inline bool __attribute__ ((unused))
+_hurd_tls_init (tcbhead_t *tcb)
+{
+  error_t err;
+  thread_t self = __mach_thread_self ();
+
+  /* We always at least start the sigthread anyway.  */
+  tcb->multiple_threads = 1;
+
+  err = _hurd_tls_new (self, tcb);
+  __mach_port_deallocate (__mach_task_self (), self);
+  __libc_tls_initialized = 1;
+  return err == 0;
+}
+
+
+/* Global scope switch support.  */
+# define THREAD_GSCOPE_FLAG_UNUSED 0
+# define THREAD_GSCOPE_FLAG_USED   1
+# define THREAD_GSCOPE_FLAG_WAIT   2
+
+# define THREAD_GSCOPE_SET_FLAG() \
+  THREAD_SETMEM (THREAD_SELF, gscope_flag, THREAD_GSCOPE_FLAG_USED)
+
+# define THREAD_GSCOPE_RESET_FLAG() \
+  ({                                                                   \
+    int __flag;                                                                
\
+    asm volatile ("xchgl %0, %%fs:%P1"                                 \
+                  : "=r" (__flag)                                      \
+                  : "i" (offsetof (tcbhead_t, gscope_flag)),           \
+                    "0" (THREAD_GSCOPE_FLAG_UNUSED));                  \
+    if (__flag == THREAD_GSCOPE_FLAG_WAIT)                             \
+      lll_wake (THREAD_SELF->gscope_flag, LLL_PRIVATE);                        
\
+  })
+
+
+
+#endif /* __ASSEMBLER__ */
+#endif /* x86_64/tls.h */
-- 
2.39.2