[PATCH 08/10] hurd: Fix setting up pthreads

[Sergey Bugaev]

On x86_64, we have to pass function arguments in registers, not on the
stack. We also have to align the stack pointer in a specific way. Since
sharing the logic with i386 does not bring much benefit, split the file
back into i386- and x86_64-specific versions, and fix the x86_64 version
to set up the thread properly.

Bonus: i386 keeps doing the extra RPC inside __thread_set_pcsptp to
fetch the state of the thread before setting it; but x86_64 no lnoger
does that.

Checked on x86_64-gnu and i686-gnu.

Fixes be6d002ca277ffc90058d382396150cb0e785b9c
"hurd: Set up the basic tree for x86_64-gnu"

Signed-off-by: Sergey Bugaev <bugaevc@gmail.com>
---
__thread_set_pcsptp is also used by pthread_cancel (), which suffers
from the same issue. Eventually I'd like to remove __thread_set_pcsptp
entirely.

 .../mach/hurd/{x86 => i386}/htl/pt-setup.c    |  2 +-
 sysdeps/mach/hurd/x86_64/htl/pt-setup.c       | 93 +++++++++++++++++++
 2 files changed, 94 insertions(+), 1 deletion(-)
 rename sysdeps/mach/hurd/{x86 => i386}/htl/pt-setup.c (98%)
 create mode 100644 sysdeps/mach/hurd/x86_64/htl/pt-setup.c

diff --git a/sysdeps/mach/hurd/x86/htl/pt-setup.c 
b/sysdeps/mach/hurd/i386/htl/pt-setup.c
similarity index 98%
rename from sysdeps/mach/hurd/x86/htl/pt-setup.c
rename to sysdeps/mach/hurd/i386/htl/pt-setup.c
index 686124d7..ba108b96 100644
--- a/sysdeps/mach/hurd/x86/htl/pt-setup.c
+++ b/sysdeps/mach/hurd/i386/htl/pt-setup.c
@@ -1,4 +1,4 @@
-/* Setup thread stack.  Hurd/x86 version.
+/* Setup thread stack.  Hurd/i386 version.
    Copyright (C) 2000-2023 Free Software Foundation, Inc.
    This file is part of the GNU C Library.
 
diff --git a/sysdeps/mach/hurd/x86_64/htl/pt-setup.c 
b/sysdeps/mach/hurd/x86_64/htl/pt-setup.c
new file mode 100644
index 00000000..7dc62912
--- /dev/null
+++ b/sysdeps/mach/hurd/x86_64/htl/pt-setup.c
@@ -0,0 +1,93 @@
+/* Setup thread stack.  Hurd/x86_64 version.
+   Copyright (C) 2000-2023 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/>.  */
+
+#include <stdint.h>
+#include <assert.h>
+#include <mach.h>
+#include <hurd.h>
+
+#include <thread_state.h>
+#include <pt-internal.h>
+
+/* Set up the stack for THREAD.  Return the stack pointer
+   for the new thread.  */
+static void *
+stack_setup (struct __pthread *thread)
+{
+  error_t err;
+  uintptr_t bottom, top;
+
+  /* Calculate the top of the new stack.  */
+  bottom = (uintptr_t) thread->stackaddr;
+  top = bottom + thread->stacksize + round_page (thread->guardsize);
+
+  if (thread->guardsize)
+    {
+      err = __vm_protect (__mach_task_self (), (vm_address_t) bottom,
+                         thread->guardsize, 0, 0);
+      assert_perror (err);
+    }
+
+  return (void *) PTR_ALIGN_DOWN_8_16 (top);
+}
+
+int
+__pthread_setup (struct __pthread *thread,
+                void (*entry_point) (struct __pthread *, void *(*)(void *),
+                                     void *), void *(*start_routine) (void *),
+                void *arg)
+{
+  error_t err;
+  struct i386_thread_state state;
+  struct i386_fsgs_base_state fsgs_state;
+
+  if (thread->kernel_thread == hurd_thread_self ())
+    /* Fix up the TCB for the main thread.  The C library has already
+       installed a TCB, which we want to keep using.  This TCB must not
+       be freed so don't register it in the thread structure.  On the
+       other hand, it's not yet possible to reliably release a TCB.
+       Leave the unused one registered so that it doesn't leak.  */
+    return 0;
+
+
+  thread->mcontext.pc = entry_point;
+  thread->mcontext.sp = stack_setup (thread);
+
+  /* Set up the state to call entry_point (thread, start_routine, arg) */
+  memset (&state, 0, sizeof (state));
+  state.ursp = (uintptr_t) thread->mcontext.sp;
+  state.rip = (uintptr_t) thread->mcontext.pc;
+  state.rdi = (uintptr_t) thread;
+  state.rsi = (uintptr_t) start_routine;
+  state.rdx = (uintptr_t) arg;
+
+  err = __thread_set_state (thread->kernel_thread, i386_THREAD_STATE,
+                           (thread_state_t) &state,
+                           i386_THREAD_STATE_COUNT);
+  assert_perror (err);
+
+  /* Set fs_base to the TCB pointer for the thread.  */
+  memset (&fsgs_state, 0, sizeof (fsgs_state));
+  fsgs_state.fs_base = (uintptr_t) thread->tcb;
+  err = __thread_set_state (thread->kernel_thread, i386_FSGS_BASE_STATE,
+                           (thread_state_t) &fsgs_state,
+                           i386_FSGS_BASE_STATE_COUNT);
+  assert_perror (err);
+
+  return 0;
+}
-- 
2.40.1