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/* Set thread_state for sighandler, and sigcontext to recover. i386 version.
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Copyright (C) 1994,1995,1996,1997,1998,1999,2005,2008
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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 <hurd/signal.h>
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#include <hurd/userlink.h>
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#include <thread_state.h>
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#include <mach/machine/eflags.h>
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#include "hurdfault.h"
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_hurd_setup_sighandler (struct hurd_sigstate *ss, __sighandler_t handler,
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int signo, struct hurd_signal_detail *detail,
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volatile int rpc_wait,
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struct machine_thread_all_state *state)
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void trampoline (void);
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void rpc_wait_trampoline (void);
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extern const void _hurd_intr_rpc_msg_in_trap;
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extern const void _hurd_intr_rpc_msg_cx_sp;
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extern const void _hurd_intr_rpc_msg_sp_restored;
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struct sigcontext *scp;
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struct sigcontext *scp; /* Points to ctx, below. */
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void *sigreturn_returns_here;
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struct sigcontext *return_scp; /* Same; arg to sigreturn. */
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struct sigcontext ctx;
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struct hurd_userlink link;
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/* We have a previous sigcontext that sigreturn was about
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to restore when another signal arrived. We will just base
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if (! _hurdsig_catch_memory_fault (ss->context))
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memcpy (&state->basic, &ss->context->sc_i386_thread_state,
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sizeof (state->basic));
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memcpy (&state->fpu, &ss->context->sc_i386_float_state,
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state->set |= (1 << i386_THREAD_STATE) | (1 << i386_FLOAT_STATE);
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if (! machine_get_basic_state (ss->thread, state))
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/* Save the original SP in the gratuitous `esp' slot.
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We may need to reset the SP (the `uesp' slot) to avoid clobbering an
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interrupted RPC frame. */
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state->basic.esp = state->basic.uesp;
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if ((ss->actions[signo].sa_flags & SA_ONSTACK) &&
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!(ss->sigaltstack.ss_flags & (SS_DISABLE|SS_ONSTACK)))
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sigsp = ss->sigaltstack.ss_sp + ss->sigaltstack.ss_size;
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ss->sigaltstack.ss_flags |= SS_ONSTACK;
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/* XXX need to set up base of new stack for
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per-thread variables, cthreads. */
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/* This code has intimate knowledge of the special mach_msg system call
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done in intr-msg.c; that code does (see intr-msg.h):
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_hurd_intr_rpc_msg_cx_sp: movl $-25, %eax
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_hurd_intr_rpc_msg_do_trap: lcall $7, $0
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_hurd_intr_rpc_msg_in_trap: movl %ecx, %esp
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_hurd_intr_rpc_msg_sp_restored:
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We must check for the window during which %esp points at the
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mach_msg arguments. The space below until %ecx is used by
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the _hurd_intr_rpc_mach_msg frame, and must not be clobbered. */
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else if (state->basic.eip >= (int) &_hurd_intr_rpc_msg_cx_sp &&
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state->basic.eip < (int) &_hurd_intr_rpc_msg_sp_restored)
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/* The SP now points at the mach_msg args, but there is more stack
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space used below it. The real SP is saved in %ecx; we must push the
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new frame below there, and restore that value as the SP on
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sigsp = (char *) (state->basic.uesp = state->basic.ecx);
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sigsp = (char *) state->basic.uesp;
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/* Push the arguments to call `trampoline' on the stack. */
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sigsp -= sizeof (*stackframe);
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if (_hurdsig_catch_memory_fault (stackframe))
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/* We got a fault trying to write the stack frame.
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We cannot set up the signal handler.
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Returning NULL tells our caller, who will nuke us with a SIGILL. */
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extern void _hurdsig_longjmp_from_handler (void *, jmp_buf, int);
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/* Add a link to the thread's active-resources list. We mark this as
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the only user of the "resource", so the cleanup function will be
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called by any longjmp which is unwinding past the signal frame.
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The cleanup function (in sigunwind.c) will make sure that all the
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appropriate cleanups done by sigreturn are taken care of. */
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stackframe->link.cleanup = &_hurdsig_longjmp_from_handler;
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stackframe->link.cleanup_data = &stackframe->ctx;
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stackframe->link.resource.next = NULL;
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stackframe->link.resource.prevp = NULL;
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stackframe->link.thread.next = ss->active_resources;
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stackframe->link.thread.prevp = &ss->active_resources;
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if (stackframe->link.thread.next)
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stackframe->link.thread.next->thread.prevp
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= &stackframe->link.thread.next;
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ss->active_resources = &stackframe->link;
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/* Set up the arguments for the signal handler. */
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stackframe->signo = signo;
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stackframe->sigcode = detail->code;
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stackframe->scp = stackframe->return_scp = scp = &stackframe->ctx;
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stackframe->sigreturn_addr = &__sigreturn;
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stackframe->sigreturn_returns_here = firewall; /* Crash on return. */
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/* Set up the sigcontext from the current state of the thread. */
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scp->sc_onstack = ss->sigaltstack.ss_flags & SS_ONSTACK ? 1 : 0;
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/* struct sigcontext is laid out so that starting at sc_gs mimics a
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struct i386_thread_state. */
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memcpy (&scp->sc_i386_thread_state,
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&state->basic, sizeof (state->basic));
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/* struct sigcontext is laid out so that starting at sc_fpkind mimics
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a struct i386_float_state. */
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ok = machine_get_state (ss->thread, state, i386_FLOAT_STATE,
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&state->fpu, &scp->sc_i386_float_state,
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sizeof (state->fpu));
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_hurdsig_end_catch_fault ();
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/* Modify the thread state to call the trampoline code on the new stack. */
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/* The signalee thread was blocked in a mach_msg_trap system call,
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still waiting for a reply. We will have it run the special
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trampoline code which retries the message receive before running
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To do this we change the OPTION argument on its stack to enable only
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message reception, since the request message has already been
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struct mach_msg_trap_args *args = (void *) state->basic.esp;
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if (_hurdsig_catch_memory_fault (args))
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/* Faulted accessing ARGS. Bomb. */
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assert (args->option & MACH_RCV_MSG);
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/* Disable the message-send, since it has already completed. The
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calls we retry need only wait to receive the reply message. */
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args->option &= ~MACH_SEND_MSG;
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/* Limit the time to receive the reply message, in case the server
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claimed that `interrupt_operation' succeeded but in fact the RPC
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args->option |= MACH_RCV_TIMEOUT;
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args->timeout = _hurd_interrupted_rpc_timeout;
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_hurdsig_end_catch_fault ();
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state->basic.eip = (int) rpc_wait_trampoline;
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/* The reply-receiving trampoline code runs initially on the original
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user stack. We pass it the signal stack pointer in %ebx. */
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state->basic.uesp = state->basic.esp; /* Restore mach_msg syscall SP. */
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state->basic.ebx = (int) sigsp;
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/* After doing the message receive, the trampoline code will need to
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update the %eax value to be restored by sigreturn. To simplify
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the assembly code, we pass the address of its slot in SCP to the
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trampoline code in %ecx. */
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state->basic.ecx = (int) &scp->sc_eax;
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state->basic.eip = (int) trampoline;
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state->basic.uesp = (int) sigsp;
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/* We pass the handler function to the trampoline code in %edx. */
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state->basic.edx = (int) handler;
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/* The x86 ABI says the DF bit is clear on entry to any function. */
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state->basic.efl &= ~EFL_DF;
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/* The trampoline code follows. This used to be located inside
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_hurd_setup_sighandler, but was optimized away by gcc 2.95. */
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asm ("rpc_wait_trampoline:\n");
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/* This is the entry point when we have an RPC reply message to receive
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before running the handler. The MACH_MSG_SEND bit has already been
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cleared in the OPTION argument on our stack. The interrupted user
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stack pointer has not been changed, so the system call can find its
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arguments; the signal stack pointer is in %ebx. For our convenience,
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%ecx points to the sc_eax member of the sigcontext. */
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asm (/* Retry the interrupted mach_msg system call. */
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"movl $-25, %eax\n" /* mach_msg_trap */
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/* When the sigcontext was saved, %eax was MACH_RCV_INTERRUPTED. But
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now the message receive has completed and the original caller of
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the RPC (i.e. the code running when the signal arrived) needs to
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see the final return value of the message receive in %eax. So
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store the new %eax value into the sc_eax member of the sigcontext
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(whose address is in %ecx to make this code simpler). */
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"movl %eax, (%ecx)\n"
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/* Switch to the signal stack. */
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"movl %ebx, %esp\n");
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asm ("trampoline:\n");
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/* Entry point for running the handler normally. The arguments to the
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handler function are already on the top of the stack:
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asm ("call *%edx\n" /* Call the handler function. */
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"addl $12, %esp\n" /* Pop its args. */
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/* The word at the top of stack is &__sigreturn; following are a dummy
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word to fill the slot for the address for __sigreturn to return to,
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and a copy of SCP for __sigreturn's argument. "Return" to calling
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__sigreturn (SCP); this call never returns. */