struct sigcontext *
_hurd_setup_sighandler (struct hurd_sigstate *ss, __sighandler_t handler,
int signo, struct hurd_signal_detail *detail,
volatile int rpc_wait,
struct machine_thread_all_state *state)
{
void trampoline (void);
void rpc_wait_trampoline (void);
void firewall (void);
extern const void _hurd_intr_rpc_msg_in_trap;
extern const void _hurd_intr_rpc_msg_cx_sp;
extern const void _hurd_intr_rpc_msg_sp_restored;
void *volatile sigsp;
struct sigcontext *scp;
struct
{
int signo;
long int sigcode;
struct sigcontext *scp; /* Points to ctx, below. */
void *sigreturn_addr;
void *sigreturn_returns_here;
struct sigcontext *return_scp; /* Same; arg to sigreturn. */
struct sigcontext ctx;
struct hurd_userlink link;
} *stackframe;
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 (! _hurdsig_catch_memory_fault (ss->context))
{
memcpy (&state->basic, &ss->context->sc_i386_thread_state,
sizeof (state->basic));
memcpy (&state->fpu, &ss->context->sc_i386_float_state,
sizeof (state->fpu));
state->set |= (1 << i386_REGS_SEGS_STATE) | (1 << i386_FLOAT_STATE);
}
}
if (! machine_get_basic_state (ss->thread, state))
return NULL;
/* Save the original SP in the gratuitous `esp' slot.
We may need to reset the SP (the `uesp' slot) to avoid clobbering an
interrupted RPC frame. */
state->basic.esp = state->basic.uesp;
/* XXX what if handler != action->handler (for instance, if a signal
* preemptor took over) ? */
action = & _hurd_sigstate_actions (ss) [signo];
if ((action->sa_flags & SA_ONSTACK) &&
!(ss->sigaltstack.ss_flags & (SS_DISABLE|SS_ONSTACK)))
{
sigsp = ss->sigaltstack.ss_sp + ss->sigaltstack.ss_size;
ss->sigaltstack.ss_flags |= SS_ONSTACK;
/* XXX need to set up base of new stack for
per-thread variables, cthreads. */
}
/* This code has intimate knowledge of the special mach_msg system call
done in intr-msg.c; that code does (see intr-msg.h):
movl %esp, %ecx
leal ARGS, %esp
_hurd_intr_rpc_msg_cx_sp: movl $-25, %eax
_hurd_intr_rpc_msg_do_trap: lcall $7, $0
_hurd_intr_rpc_msg_in_trap: movl %ecx, %esp
_hurd_intr_rpc_msg_sp_restored:
We must check for the window during which %esp points at the
mach_msg arguments. The space below until %ecx is used by
the _hurd_intr_rpc_mach_msg frame, and must not be clobbered. */
else if (state->basic.eip >= (int) &_hurd_intr_rpc_msg_cx_sp &&
state->basic.eip < (int) &_hurd_intr_rpc_msg_sp_restored)
/* The SP now points at the mach_msg args, but there is more stack
space used below it. The real SP is saved in %ecx; we must push the
new frame below there, and restore that value as the SP on
sigreturn. */
sigsp = (char *) (state->basic.uesp = state->basic.ecx);
else
sigsp = (char *) state->basic.uesp;
/* Push the arguments to call `trampoline' on the stack. */
sigsp -= sizeof (*stackframe);
stackframe = sigsp;
if (_hurdsig_catch_memory_fault (stackframe))
{
/* 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;
}
else
{
int ok;
extern void _hurdsig_longjmp_from_handler (void *, jmp_buf, int);
/* Add a link to the thread's active-resources list. We mark this as
the only user of the "resource", so the cleanup function will be
called by any longjmp which is unwinding past the signal frame.
The cleanup function (in sigunwind.c) will make sure that all the
appropriate cleanups done by sigreturn are taken care of. */
stackframe->link.cleanup = &_hurdsig_longjmp_from_handler;
stackframe->link.cleanup_data = &stackframe->ctx;
stackframe->link.resource.next = NULL;
stackframe->link.resource.prevp = NULL;
stackframe->link.thread.next = ss->active_resources;
stackframe->link.thread.prevp = &ss->active_resources;
if (stackframe->link.thread.next)
stackframe->link.thread.next->thread.prevp
= &stackframe->link.thread.next;
ss->active_resources = &stackframe->link;
/* Set up the arguments for the signal handler. */
stackframe->signo = signo;
stackframe->sigcode = detail->code;
stackframe->scp = stackframe->return_scp = scp = &stackframe->ctx;
stackframe->sigreturn_addr = &__sigreturn;
stackframe->sigreturn_returns_here = firewall; /* Crash on return. */
/* Set up the sigcontext from the current state of the thread. */
scp->sc_onstack = ss->sigaltstack.ss_flags & SS_ONSTACK ? 1 : 0;
/* struct sigcontext is laid out so that starting at sc_gs mimics a
struct i386_thread_state. */
memcpy (&scp->sc_i386_thread_state,
&state->basic, sizeof (state->basic));
/* struct sigcontext is laid out so that starting at sc_fpkind mimics
a struct i386_float_state. */
ok = machine_get_state (ss->thread, state, i386_FLOAT_STATE,
&state->fpu, &scp->sc_i386_float_state,
sizeof (state->fpu));
_hurdsig_end_catch_fault ();
if (! ok)
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 on its stack to enable only
message reception, since the request message has already been
sent. */
struct mach_msg_trap_args *args = (void *) state->basic.esp;
if (_hurdsig_catch_memory_fault (args))
{
/* Faulted accessing ARGS. Bomb. */
return NULL;
}
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;
/* Limit the time to receive the reply message, in case the server
claimed that `interrupt_operation' succeeded but in fact the RPC
is hung. */
args->option |= MACH_RCV_TIMEOUT;
args->timeout = _hurd_interrupted_rpc_timeout;
_hurdsig_end_catch_fault ();
state->basic.eip = (int) rpc_wait_trampoline;
/* The reply-receiving trampoline code runs initially on the original
user stack. We pass it the signal stack pointer in %ebx. */
state->basic.uesp = state->basic.esp; /* Restore mach_msg syscall SP. */
state->basic.ebx = (int) sigsp;
/* After doing the message receive, the trampoline code will need to
update the %eax 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 %ecx. */
state->basic.ecx = (int) &scp->sc_eax;
}
else
{
state->basic.eip = (int) trampoline;
state->basic.uesp = (int) sigsp;
}
/* We pass the handler function to the trampoline code in %edx. */
state->basic.edx = (int) handler;
/* The x86 ABI says the DF bit is clear on entry to any function. */
state->basic.efl &= ~EFL_DF;
return scp;
}
mach_port_t
_hurdsig_abort_rpcs (struct hurd_sigstate *ss, int signo, int sigthread,
struct machine_thread_all_state *state, int *state_change,
void (*reply) (void))
{
extern const void _hurd_intr_rpc_msg_in_trap;
mach_port_t rcv_port = MACH_PORT_NULL;
mach_port_t intr_port;
*state_change = 0;
intr_port = ss->intr_port;
if (intr_port == MACH_PORT_NULL)
/* No interruption needs done. */
return MACH_PORT_NULL;
/* Abort the thread's kernel context, so any pending message send or
receive completes immediately or aborts. */
abort_thread (ss, state, reply);
if (state->basic.PC < (natural_t) &_hurd_intr_rpc_msg_in_trap)
{
/* The thread is about to do the RPC, but hasn't yet entered
mach_msg. Mutate the thread's state so it knows not to try
the RPC. */
INTR_MSG_BACK_OUT (&state->basic);
MACHINE_THREAD_STATE_SET_PC (&state->basic,
&_hurd_intr_rpc_msg_in_trap);
state->basic.SYSRETURN = MACH_SEND_INTERRUPTED;
*state_change = 1;
}
else if (state->basic.PC == (natural_t) &_hurd_intr_rpc_msg_in_trap &&
/* The thread was blocked in the system call. After thread_abort,
the return value register indicates what state the RPC was in
when interrupted. */
state->basic.SYSRETURN == MACH_RCV_INTERRUPTED)
{
/* The RPC request message was sent and the thread was waiting for
the reply message; now the message receive has been aborted, so
the mach_msg call will return MACH_RCV_INTERRUPTED. We must tell
the server to interrupt the pending operation. The thread must
wait for the reply message before running the signal handler (to
guarantee that the operation has finished being interrupted), so
our nonzero return tells the trampoline code to finish the message
receive operation before running the handler. */
mach_port_t *reply = interrupted_reply_port_location (ss->thread,
state,
sigthread);
error_t err = __interrupt_operation (intr_port, _hurdsig_interrupt_timeout);
if (err)
{
if (reply)
{
/* The interrupt didn't work.
Destroy the receive right the thread is blocked on. */
__mach_port_destroy (__mach_task_self (), *reply);
*reply = MACH_PORT_NULL;
}
/* The system call return value register now contains
MACH_RCV_INTERRUPTED; when mach_msg resumes, it will retry the
call. Since we have just destroyed the receive right, the
retry will fail with MACH_RCV_INVALID_NAME. Instead, just
change the return value here to EINTR so mach_msg will not
retry and the EINTR error code will propagate up. */
state->basic.SYSRETURN = EINTR;
*state_change = 1;
}
else if (reply)
rcv_port = *reply;
/* All threads whose RPCs were interrupted by the interrupt_operation
call above will retry their RPCs unless we clear SS->intr_port.
So we clear it for the thread taking a signal when SA_RESTART is
clear, so that its call returns EINTR. */
if (! signo || !(_hurd_sigstate_actions (ss) [signo].sa_flags & SA_RESTART))
ss->intr_port = MACH_PORT_NULL;
}
return rcv_port;
}
