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Roland McGrath 1994-11-09 12:23:25 +00:00
parent eacddc0a20
commit 1db9e43738
1 changed files with 253 additions and 0 deletions
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253
sysdeps/mach/hurd/alpha/trampoline.c Normal file
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/* Set thread_state for sighandler, and sigcontext to recover. Alpha version.
Copyright (C) 1994 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 Library General Public License as
published by the Free Software Foundation; either version 2 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
Library General Public License for more details.
You should have received a copy of the GNU Library General Public
License along with the GNU C Library; see the file COPYING.LIB. If
not, write to the Free Software Foundation, Inc., 675 Mass Ave,
Cambridge, MA 02139, USA. */
#include <hurd/signal.h>
#include "thread_state.h"
struct mach_msg_trap_args
{
/* This is the order of arguments to mach_msg_trap. */
mach_msg_header_t *msg;
mach_msg_option_t option;
mach_msg_size_t send_size;
mach_msg_size_t rcv_size;
mach_port_t rcv_name;
mach_msg_timeout_t timeout;
mach_port_t notify;
};
struct sigcontext *
_hurd_setup_sighandler (struct hurd_sigstate *ss, __sighandler_t handler,
int signo, int sigcode,
int rpc_wait,
struct machine_thread_all_state *state)
{
__label__ trampoline, rpc_wait_trampoline;
void *sigsp;
struct sigcontext *scp;
if (ss->context)
{
/* We have a previous sigcontext that sigreturn was about
to restore when another signal arrived. We will just base
our setup on that. */
if (! setjmp (_hurd_sigthread_fault_env))
{
memcpy (&state->basic, &ss->context->sc_alpha_thread_state,
sizeof (state->basic));
state->set = (1 << ALPHA_THREAD_STATE);
if (1) /* if fpu used XXX */
{
memcpy (&state->fpu, &ss->context->sc_alpha_float_state,
sizeof (state->fpu));
state->set |= (1 << ALPHA_FLOAT_STATE);
}
assert (! rpc_wait);
/* The intr_port slot was cleared before sigreturn sent us the
sig_post that made us notice this pending signal, so
_hurd_internal_post_signal wouldn't do interrupt_operation.
After we return, our caller will set SCP->sc_intr_port (in the
new context) from SS->intr_port and clear SS->intr_port. Now
that we are restoring this old context recorded by sigreturn,
we want to restore its intr_port too; so store it in
SS->intr_port now, so it will end up in SCP->sc_intr_port
later. */
ss->intr_port = ss->context->sc_intr_port;
}
/* If the sigreturn context was bogus, just ignore it. */
ss->context = NULL;
}
else if (! machine_get_basic_state (ss->thread, state))
return NULL;
if ((ss->actions[signo].sa_flags & SA_ONSTACK) &&
!(ss->sigaltstack.ss_flags & (SA_DISABLE|SA_ONSTACK)))
{
sigsp = ss->sigaltstack.ss_sp + ss->sigaltstack.ss_size;
ss->sigaltstack.ss_flags |= SA_ONSTACK;
/* XXX need to set up base of new stack for
per-thread variables, cthreads. */
}
else
sigsp = (char *) state->basic.r29;
/* Set up the sigcontext structure on the stack. This is all the stack
needs, since the args are passed in registers (below). */
sigsp -= sizeof (*scp);
scp = sigsp;
if (! setjmp (_hurd_sigthread_fault_env))
{
/* Set up the sigcontext from the current state of the thread. */
scp->sc_onstack = ss->sigaltstack.ss_flags & SA_ONSTACK ? 1 : 0;
/* struct sigcontext is laid out so that starting at sc_regs
mimics a struct alpha_thread_state. */
memcpy (&scp->sc_alpha_thread_state,
&state->basic, sizeof (state->basic));
if (1 && /* XXX fpu used */
/* struct sigcontext is laid out so that starting at sc_fpregs
mimics a struct alpha_float_state. This state
is only meaningful if the coprocessor was used. */
! machine_get_state (ss->thread, state, ALPHA_FLOAT_STATE,
&state->fpu,
&scp->sc_alpha_float_state,
sizeof (state->fpu)))
return NULL;
}
else
/* We got a fault trying to write the stack frame.
We cannot set up the signal handler.
Returning NULL tells our caller, who will nuke us with a SIGILL. */
return NULL;
/* Modify the thread state to call the trampoline code on the new stack. */
if (rpc_wait)
{
/* The signalee thread was blocked in a mach_msg_trap system call,
still waiting for a reply. We will have it run the special
trampoline code which retries the message receive before running
the signal handler.
To do this we change the OPTION argument in its registers to
enable only message reception, since the request message has
already been sent. */
/* The system call arguments are stored in consecutive registers
starting with a0 ($16). */
struct mach_msg_trap_args *args = (void *) &state->basic.r16;
assert (args->option & MACH_RCV_MSG);
/* Disable the message-send, since it has already completed. The
calls we retry need only wait to receive the reply message. */
args->option &= ~MACH_SEND_MSG;
state->basic.pc = (long int) &&rpc_wait_trampoline;
/* After doing the message receive, the trampoline code will need to
update the v0 ($0) value to be restored by sigreturn. To simplify
the assembly code, we pass the address of its slot in SCP to the
trampoline code in at ($28). */
state->basic.r28 = (long int) &scp->sc_regs[0];
/* We must preserve the mach_msg_trap args in a0..a5 and t0
($16..$21, $1). Pass the handler args to the trampoline code in
t8..t10 ($22.$24). */
state->basic.r22 = signo;
state->basic.r23 = sigcode;
state->basic.r24 = (long int) scp;
}
else
{
state->basic.pc = (long int) &&trampoline;
state->basic.r16 = signo;
state->basic.r17 = sigcode;
state->basic.r18 = (long int) scp;
}
state->basic.r30 = (long int) sigsp; /* $30 is the stack pointer. */
/* We pass the handler function to the trampoline code in ra ($26). */
state->basic.r26 = (long int) handler;
/* In the callee-saved register t12 ($27), we save the SCP value to pass
to __sigreturn after the handler returns. */
state->basic.r27 = (long int) scp;
return scp;
/* The trampoline code follows. This is not actually executed as part of
this function, it is just convenient to write it that way. */
rpc_wait_trampoline:
/* This is the entry point when we have an RPC reply message to receive
before running the handler. The MACH_MSG_SEND bit has already been
cleared in the OPTION argument in our registers. For our convenience,
$3 points to the sc_gpr[1] member of the sigcontext (saved v0 ($2)). */
asm volatile
(".set noat; .set noreorder; .set nomacro\n"
/* Retry the interrupted mach_msg system call. */
"ldiq $0, -25\n" /* mach_msg_trap */
"call_pal PAL_callsys\n"
/* When the sigcontext was saved, v0 was MACH_RCV_INTERRUPTED. But
now the message receive has completed and the original caller of
the RPC (i.e. the code running when the signal arrived) needs to
see the final return value of the message receive in v0. So
store the new v0 value into the sc_regs[0] member of the sigcontext
(whose address is in at to make this code simpler). */
"stq v0, 0(at)\n"
/* Since the argument registers needed to have the mach_msg_trap
arguments, we've stored the arguments to the handler function
in registers t8..t10 ($22..$24). */
"mov t8, a0\n"
"mov t9, a1\n"
"mov t10, a2\n");
trampoline:
/* Entry point for running the handler normally. The arguments to the
handler function are already in the standard registers:
a0 SIGNO
a1 SIGCODE
a2 SCP
*/
asm volatile
("br at, 0f;0: ldgp gp, 0(at)\n" /* Reset GP (???). */
/* Call the handler function. */
"jsr ra, ra; ldgp gp, 0(ra)\n"
/* Call __sigreturn (SCP); this cannot return. */
"mov t12, a0\n"
"jsr ra, %0; ldgp gp, 0(ra)\n"
: : "i" (&__sigreturn));
/* NOTREACHED */
asm volatile (".set reorder; .set at; .set macro");
return NULL;
}
/* STATE describes a thread that had intr_port set (meaning it was inside
HURD_EINTR_RPC), after it has been thread_abort'd. It it looks to have
just completed a mach_msg_trap system call that returned
MACH_RCV_INTERRUPTED, return nonzero and set *PORT to the receive right
being waited on. */
int
_hurdsig_rcv_interrupted_p (struct machine_thread_all_state *state,
mach_port_t *port)
{
if (! setjmp (_hurd_sigthread_fault_env))
{
const unsigned int *pc = (void *) state->basic.pc;
if (state->basic.r2 == MACH_RCV_INTERRUPTED &&
pc[-1] == 0xc) /* XXX ???? syscall */
{
/* We did just return from a mach_msg_trap system call
doing a message receive that was interrupted.
Examine the parameters to find the receive right. */
struct mach_msg_trap_args *args = (void *) &state->basic.r16;
*port = args->rcv_name;
return 1;
}
}
return 0;
}