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hurd: Implement sigreturn for x86_64
Signed-off-by: Sergey Bugaev <bugaevc@gmail.com> Message-Id: <20230429201822.2605207-2-bugaevc@gmail.com>
This commit is contained in:
Sergey Bugaev
Samuel Thibault
parent
6b25b6ca4e
commit
b574ae0a28
162
sysdeps/mach/hurd/x86_64/sigreturn.c
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162
sysdeps/mach/hurd/x86_64/sigreturn.c
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/* Copyright (C) 1991-2023 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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<https://www.gnu.org/licenses/>. */
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#include <hurd.h>
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#include <hurd/signal.h>
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#include <hurd/msg.h>
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#include <stdlib.h>
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/* This is run on the thread stack after restoring it, to be able to
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unlock SS off sigstack. */
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void
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__sigreturn2 (struct hurd_sigstate *ss, uintptr_t *usp,
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struct sigcontext *scp)
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{
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mach_port_t reply_port;
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_hurd_sigstate_unlock (ss);
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/* Destroy the MiG reply port used by the signal handler, and restore the
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reply port in use by the thread when interrupted.
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We cannot use the original reply port for our RPCs that we do here, since
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we could unexpectedly receive/consume a reply message meant for the user
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(in particular, msg_sig_post_reply), and also since we would deallocate
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the port if *our* RPC fails, which we don't want to do since the user
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still has the old name. And so, temporarily set MACH_PORT_DEAD as our
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reply name, and make sure destroying the port is the very last RPC we
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do. */
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reply_port = THREAD_GETMEM (THREAD_SELF, reply_port);
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THREAD_SETMEM (THREAD_SELF, reply_port, MACH_PORT_DEAD);
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if (__glibc_likely (MACH_PORT_VALID (reply_port)))
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(void) __mach_port_mod_refs (__mach_task_self (), reply_port,
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MACH_PORT_RIGHT_RECEIVE, -1);
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THREAD_SETMEM (THREAD_SELF, reply_port, scp->sc_reply_port);
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asm volatile (
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/* Point the stack to the register dump. */
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"movq %0, %%rsp\n"
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/* Pop off the registers. */
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"popq %%r8\n"
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"popq %%r9\n"
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"popq %%r10\n"
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"popq %%r11\n"
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"popq %%r12\n"
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"popq %%r13\n"
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"popq %%r14\n"
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"popq %%r15\n"
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"popq %%rdi\n"
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"popq %%rsi\n"
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"popq %%rbp\n"
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"popq %%rbx\n"
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"popq %%rdx\n"
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"popq %%rcx\n"
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"popq %%rax\n"
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"popfq\n"
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/* Restore %rip and %rsp with a single instruction. */
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"retq $128" :
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: "rm" (usp));
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__builtin_unreachable ();
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}
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int
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__sigreturn (struct sigcontext *scp)
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{
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struct hurd_sigstate *ss;
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struct hurd_userlink *link = (void *) &scp[1];
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if (__glibc_unlikely (scp == NULL || (scp->sc_mask & _SIG_CANT_MASK)))
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{
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errno = EINVAL;
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return -1;
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}
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ss = _hurd_self_sigstate ();
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_hurd_sigstate_lock (ss);
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/* Remove the link on the `active resources' chain added by
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_hurd_setup_sighandler. Its purpose was to make sure
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that we got called; now we have, it is done. */
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_hurd_userlink_unlink (link);
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/* Restore the set of blocked signals, and the intr_port slot. */
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ss->blocked = scp->sc_mask;
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ss->intr_port = scp->sc_intr_port;
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/* Check for pending signals that were blocked by the old set. */
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if (_hurd_sigstate_pending (ss) & ~ss->blocked)
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{
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/* There are pending signals that just became unblocked. Wake up the
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signal thread to deliver them. But first, squirrel away SCP where
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the signal thread will notice it if it runs another handler, and
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arrange to have us called over again in the new reality. */
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ss->context = scp;
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_hurd_sigstate_unlock (ss);
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__msg_sig_post (_hurd_msgport, 0, 0, __mach_task_self ());
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/* If a pending signal was handled, sig_post never returned.
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If it did return, the pending signal didn't run a handler;
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proceed as usual. */
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_hurd_sigstate_lock (ss);
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ss->context = NULL;
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}
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if (scp->sc_onstack)
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ss->sigaltstack.ss_flags &= ~SS_ONSTACK;
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if (scp->sc_fpused)
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/* Restore the FPU state. Mach conveniently stores the state
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in the format the i387 `frstor' instruction uses to restore it. */
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asm volatile ("frstor %0" : : "m" (scp->sc_fpsave));
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{
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/* There are convenient instructions to pop state off the stack, so we
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copy the registers onto the user's stack, switch there, pop and
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return. */
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uintptr_t *usp = (uintptr_t *) scp->sc_ursp - 128;
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*--usp = scp->sc_rip;
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*--usp = scp->sc_rfl;
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*--usp = scp->sc_rax;
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*--usp = scp->sc_rcx;
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*--usp = scp->sc_rdx;
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*--usp = scp->sc_rbx;
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*--usp = scp->sc_rbp;
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*--usp = scp->sc_rsi;
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*--usp = scp->sc_rdi;
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*--usp = scp->sc_r15;
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*--usp = scp->sc_r14;
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*--usp = scp->sc_r13;
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*--usp = scp->sc_r12;
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*--usp = scp->sc_r11;
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*--usp = scp->sc_r10;
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*--usp = scp->sc_r9;
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*--usp = scp->sc_r8;
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/* Switch to the user's stack that we have just prepared, and call
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__sigreturn2. Clobber "memory" to make sure GCC flushes the stack
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setup to actual memory. We align the stack as per the ABI, but pass
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the original usp to __sigreturn2 as an argument. */
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asm volatile ("movq %1, %%rsp\n"
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"andq $-16, %%rsp\n"
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"call __sigreturn2" :
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: "D" (ss), "S" (usp), "d" (scp)
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: "memory");
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__builtin_unreachable ();
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}
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}
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weak_alias (__sigreturn, sigreturn)
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