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

[Samuel Thibault]

Applied, thanks!

Sergey Bugaev, le mer. 17 mai 2023 22:14:34 +0300, a ecrit:
> 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
> 
> 

-- 
Samuel
---
Pour une évaluation indépendante, transparente et rigoureuse !
Je soutiens la Commission d'Évaluation de l'Inria.