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74 lines
3.1 KiB
C
74 lines
3.1 KiB
C
/* Pthread cancellation syscall bridge. Default Linux version.
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Copyright (C) 2023-2025 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version.
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The GNU C Library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with the GNU C Library; if not, see
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<http://www.gnu.org/licenses/>. */
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#include <sysdep.h>
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#include <pthreadP.h>
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#warning "This implementation should be use just as reference or for bootstrapping"
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/* This is the generic version of the cancellable syscall code which
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adds the label guards (__syscall_cancel_arch_{start,end}) used on SIGCANCEL
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handler to check if the cancelled syscall have side-effects that need to be
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returned to the caller.
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This implementation should be used as a reference one to document the
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implementation constraints:
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1. The __syscall_cancel_arch_start should point just before the test
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that thread is already cancelled,
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2. The __syscall_cancel_arch_end should point to the immediate next
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instruction after the syscall one.
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3. It should return the syscall value or a negative result if is has
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failed, similar to INTERNAL_SYSCALL_CALL.
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The __syscall_cancel_arch_end one is because the kernel will signal
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interrupted syscall with side effects by setting the signal frame program
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counter (on the ucontext_t third argument from SA_SIGINFO signal handler)
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right after the syscall instruction.
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For some architecture, the INTERNAL_SYSCALL_NCS macro use more instructions
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to get the error condition from kernel (as for powerpc and sparc that
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checks for the conditional register), or uses an out of the line helper
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(ARM thumb), or uses a kernel helper gate (i686 or ia64). In this case
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the architecture should either adjust the macro or provide a custom
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__syscall_cancel_arch implementation. */
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long int
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__syscall_cancel_arch (volatile int *ch, __syscall_arg_t nr,
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__syscall_arg_t a1, __syscall_arg_t a2,
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__syscall_arg_t a3, __syscall_arg_t a4,
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__syscall_arg_t a5, __syscall_arg_t a6
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__SYSCALL_CANCEL7_ARG_DEF)
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{
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#define ADD_LABEL(__label) \
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asm volatile ( \
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".global " __label "\t\n" \
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__label ":\n");
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ADD_LABEL ("__syscall_cancel_arch_start");
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if (__glibc_unlikely (*ch & CANCELED_BITMASK))
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__syscall_do_cancel();
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long int result = INTERNAL_SYSCALL_NCS_CALL (nr, a1, a2, a3, a4, a5, a6
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__SYSCALL_CANCEL7_ARG7);
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ADD_LABEL ("__syscall_cancel_arch_end");
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if (__glibc_unlikely (INTERNAL_SYSCALL_ERROR_P (result)))
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return -INTERNAL_SYSCALL_ERRNO (result);
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return result;
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}
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