new file mode 100644
@@ -0,0 +1,96 @@
+/* Machine-dependent signal context structure for GNU Hurd. aarch64 version.
+ Copyright (C) 1991-2024 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 Lesser General Public
+ License as published by the Free Software Foundation; either
+ version 2.1 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
+ Lesser General Public License for more details.
+
+ You should have received a copy of the GNU Lesser General Public
+ License along with the GNU C Library; if not, see
+ <https://www.gnu.org/licenses/>. */
+
+#ifndef _BITS_SIGCONTEXT_H
+#define _BITS_SIGCONTEXT_H 1
+
+#if !defined _SIGNAL_H && !defined _SYS_UCONTEXT_H
+# error "Never use <bits/sigcontext.h> directly; include <signal.h> instead."
+#endif
+
+/* Signal handlers are actually called:
+ void handler (int sig, int code, struct sigcontext *scp); */
+
+#include <bits/types/__sigset_t.h>
+#include <mach/machine/fp_reg.h>
+
+/* State of this thread when the signal was taken. */
+struct sigcontext
+ {
+ /* These first members are machine-independent. */
+
+ int sc_onstack; /* Nonzero if running on sigstack. */
+ __sigset_t sc_mask; /* Blocked signals to restore. */
+
+ /* MiG reply port this thread is using. */
+ unsigned int sc_reply_port;
+
+ /* Port this thread is doing an interruptible RPC on. */
+ unsigned int sc_intr_port;
+
+ /* Error code associated with this signal (interpreted as `error_t'). */
+ int sc_error;
+
+ /* Make sure the below members are properly aligned, and not packed
+ together with sc_error -- otherwise the layout won't match that of
+ aarch64_thread_state. */
+ int sc_pad1;
+
+ /* All following members are machine-dependent. The rest of this
+ structure is written to be laid out identically to:
+ {
+ struct aarch64_thread_state basic;
+ struct aarch64_float_state fpu;
+ }
+ trampoline.c knows this, so it must be changed if this changes. */
+
+#define sc_aarch64_thread_state sc_x[0] /* Beginning of correspondence. */
+ long sc_x[31];
+ long sc_sp;
+ long sc_pc;
+ long sc_tpidr_el0;
+ int sc_cpsr;
+
+#define sc_aarch64_float_state sc_v[0]
+ __int128_t sc_v[32];
+ int sc_fpsr;
+ int sc_fpcr;
+ };
+
+/* Traditional BSD names for some members. */
+#define sc_fp sc_x[29] /* Frame pointer. */
+#define sc_ps sc_cpsr
+
+
+/* The deprecated sigcode values below are passed as an extra, non-portable
+ argument to regular signal handlers. You should use SA_SIGINFO handlers
+ instead, which use the standard POSIX signal codes. */
+
+/* Codes for SIGFPE. */
+#define FPE_INTOVF_TRAP 0x1 /* integer overflow */
+#define FPE_INTDIV_FAULT 0x2 /* integer divide by zero */
+#define FPE_FLTOVF_FAULT 0x3 /* floating overflow */
+#define FPE_FLTDIV_FAULT 0x4 /* floating divide by zero */
+#define FPE_FLTUND_FAULT 0x5 /* floating underflow */
+#define FPE_SUBRNG_FAULT 0x7 /* BOUNDS instruction failed */
+#define FPE_FLTDNR_FAULT 0x8 /* denormalized operand */
+#define FPE_FLTINX_FAULT 0x9 /* floating loss of precision */
+#define FPE_EMERR_FAULT 0xa /* mysterious emulation error 33 */
+#define FPE_EMBND_FAULT 0xb /* emulation BOUNDS instruction failed */
+
+#endif /* bits/sigcontext.h */
new file mode 100644
@@ -0,0 +1,119 @@
+/* Translate Mach exception codes into signal numbers. aarch64 version.
+ Copyright (C) 1991-2024 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 Lesser General Public
+ License as published by the Free Software Foundation; either
+ version 2.1 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
+ Lesser General Public License for more details.
+
+ You should have received a copy of the GNU Lesser General Public
+ License along with the GNU C Library; if not, see
+ <https://www.gnu.org/licenses/>. */
+
+#include <hurd.h>
+#include <hurd/signal.h>
+#include <mach/exception.h>
+
+/* Translate the Mach exception codes, as received in an `exception_raise' RPC,
+ into a signal number and signal subcode. */
+
+static void
+exception2signal (struct hurd_signal_detail *detail, int *signo, int posix)
+{
+ detail->error = 0;
+
+ switch (detail->exc)
+ {
+ default:
+ *signo = SIGIOT;
+ detail->code = detail->exc;
+ break;
+
+ case EXC_BAD_ACCESS:
+ switch (detail->exc_code)
+ {
+ case KERN_INVALID_ADDRESS:
+ case KERN_MEMORY_FAILURE:
+ *signo = SIGSEGV;
+ detail->code = posix ? SEGV_MAPERR : detail->exc_subcode;
+ break;
+
+ case KERN_PROTECTION_FAILURE:
+ case KERN_WRITE_PROTECTION_FAILURE:
+ *signo = SIGSEGV;
+ detail->code = posix ? SEGV_ACCERR : detail->exc_subcode;
+ break;
+
+ default:
+ *signo = SIGBUS;
+ detail->code = posix ? BUS_ADRERR : detail->exc_subcode;
+ break;
+ }
+ detail->error = detail->exc_code;
+ break;
+
+ case EXC_BAD_INSTRUCTION:
+ *signo = SIGILL;
+ detail->code = posix ? ILL_ILLOPC : 0;
+ break;
+
+ case EXC_ARITHMETIC:
+ *signo = SIGFPE;
+ switch (detail->exc_code)
+ {
+ case EXC_AARCH64_FP_ID:
+ detail->code = posix ? FPE_FLTIDO : 0;
+ case EXC_AARCH64_FP_IX:
+ detail->code = posix ? FPE_FLTRES : FPE_FLTINX_FAULT;
+ break;
+ case EXC_AARCH64_FP_UF:
+ detail->code = posix ? FPE_FLTUND : FPE_FLTDNR_FAULT;
+ break;
+ case EXC_AARCH64_FP_OF:
+ detail->code = posix ? FPE_FLTOVF : FPE_FLTOVF_FAULT;
+ break;
+ case EXC_AARCH64_FP_DZ:
+ detail->code = posix ? FPE_FLTDIV : FPE_FLTDIV_FAULT;
+ break;
+ case EXC_AARCH64_FP_IO:
+ /* NB: We used to send SIGILL here but we can't distinguish
+ POSIX vs. legacy with respect to what signal we send. */
+ detail->code = posix ? FPE_FLTINV : 0 /*ILL_FPEOPR_FAULT*/;
+ break;
+ default:
+ detail->code = 0;
+ }
+ break;
+
+ case EXC_EMULATION:
+ case EXC_SOFTWARE:
+ *signo = SIGEMT;
+ detail->code = 0;
+ break;
+
+
+ case EXC_BREAKPOINT:
+ *signo = SIGTRAP;
+ detail->code = posix ? TRAP_BRKPT : 0;
+ break;
+ }
+}
+libc_hidden_def (_hurd_exception2signal)
+
+void
+_hurd_exception2signal (struct hurd_signal_detail *detail, int *signo)
+{
+ exception2signal (detail, signo, 1);
+}
+
+void
+_hurd_exception2signal_legacy (struct hurd_signal_detail *detail, int *signo)
+{
+ exception2signal (detail, signo, 0);
+}
new file mode 100644
@@ -0,0 +1,123 @@
+/* Machine-dependent details of interruptible RPC messaging. aarch64 version.
+ Copyright (C) 1995-2024 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 Lesser General Public
+ License as published by the Free Software Foundation; either
+ version 2.1 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
+ Lesser General Public License for more details.
+
+ You should have received a copy of the GNU Lesser General Public
+ License along with the GNU C Library; if not, see
+ <https://www.gnu.org/licenses/>. */
+
+
+/* Note that we must mark OPTION and TIMEOUT as outputs of this operation,
+ to indicate that the signal thread might mutate them as part
+ of sending us to a signal handler. */
+
+#define INTR_MSG_TRAP(msg, option, send_size, rcv_size, rcv_name, timeout, notify, cancel_p, intr_port_p) \
+({ \
+ register uintptr_t /* error_t */ err asm ("x0"); \
+ register uintptr_t option_x1 asm ("x1") = option; \
+ register uintptr_t send_size_x2 asm ("x2") = send_size; \
+ register uintptr_t rcv_size_x3 asm ("x3") = rcv_size; \
+ register uintptr_t rcv_name_x4 asm ("x4") = rcv_name; \
+ register uintptr_t timeout_x5 asm ("x5") = timeout; \
+ register uintptr_t notify_x6 asm ("x6") = notify; \
+ register void *msg_x9 asm ("x9") = msg; /* used by trampoline.c */ \
+ asm volatile ("\n" \
+ ".globl _hurd_intr_rpc_msg_about_to\n" \
+ ".globl _hurd_intr_rpc_msg_setup_done\n" \
+ ".globl _hurd_intr_rpc_msg_in_trap\n" \
+ /* Clear x0 before we do the check for cancel below. This is to
+ detect x0 being set to non-zero (actually MACH_SEND_INTERRUPTED)
+ from the outside (namely, _hurdsig_abort_rpcs), which signals us
+ to skip the trap we were about to enter. */ \
+ " mov %[err], #0\n" \
+ "_hurd_intr_rpc_msg_about_to:\n" \
+ /* We need to make a last check of cancel, in case we got interrupted
+ right before _hurd_intr_rpc_msg_about_to. */ \
+ " ldr w8, %[cancel]\n" \
+ " cbz w8, _hurd_intr_rpc_msg_do\n" \
+ /* We got interrupted, note so and return EINTR. */ \
+ " str wzr, %[intr_port]\n" \
+ " mov %[err], %[eintr_lo]\n" \
+ " movk %[err], %[eintr_hi], lsl 16\n" \
+ " b _hurd_intr_rpc_msg_sp_restored\n" \
+ "_hurd_intr_rpc_msg_do:\n" \
+ /* Ok, prepare the mach_msg_trap arguments. We pass all the 7 args
+ in registers. */ \
+ "_hurd_intr_rpc_msg_setup_done:\n" \
+ /* From here on, it is safe to make us jump over the syscall. Now
+ check if we have been told to skip the syscall while running
+ the above. */ \
+ " cbnz %[err], _hurd_intr_rpc_msg_in_trap\n" \
+ /* Do the actual syscall. */ \
+ " mov %[err], %[msg]\n" \
+ " mov x8, #-25\n" \
+ "_hurd_intr_rpc_msg_do_trap:\n" \
+ " svc #0\n" /* status in %[err] */ \
+ "_hurd_intr_rpc_msg_in_trap:\n" \
+ "_hurd_intr_rpc_msg_sp_restored:\n" \
+ : [err] "=r" (err), "+r" (option_x1), \
+ [intr_port] "=m" (*intr_port_p), \
+ "+r" (timeout_x5) \
+ : [msg] "r" (msg_x9), "r" (send_size_x2), "r" (rcv_size_x3), \
+ "r" (rcv_name_x4), "r" (notify_x6), \
+ [cancel] "m" (*cancel_p), \
+ [eintr_lo] "i" (EINTR & 0xffff), [eintr_hi] "i" (EINTR >> 16)); \
+ option = option_x1; \
+ timeout = timeout_x5; \
+ err; \
+})
+
+#include "hurdfault.h"
+
+/* This cannot be an inline function because it calls setjmp. */
+#define SYSCALL_EXAMINE(state, callno) \
+({ \
+ int result; \
+ unsigned int *p = (unsigned int *) (state)->pc - 4; \
+ if (_hurdsig_catch_memory_fault (p)) \
+ return 0; \
+ if (result = (*p == 0xd4000001)) \
+ /* The PC is just after a "svc #0" instruction.
+ This is a system call in progress; x8 holds the call number. */ \
+ *(callno) = (state)->x[8]; \
+ _hurdsig_end_catch_fault (); \
+ result; \
+})
+
+
+/* This cannot be an inline function because it calls setjmp. */
+#define MSG_EXAMINE(state, msgid, rcvname, send_name, opt, tmout) \
+({ \
+ int ret = 0; \
+ const struct machine_thread_state *s = (state); \
+ const mach_msg_header_t *msg = (const void *) s->x[0]; \
+ *(opt) = s->x[1]; \
+ *(rcvname) = s->x[4]; \
+ *(tmout) = s->x[5]; \
+ if (msg == 0) \
+ { \
+ *(send_name) = MACH_PORT_NULL; \
+ *(msgid) = 0; \
+ } \
+ else \
+ { \
+ ret = _hurdsig_catch_memory_fault (msg) ? -1 : 0; \
+ if (ret == 0) \
+ { \
+ *(send_name) = msg->msgh_remote_port; \
+ *(msgid) = msg->msgh_id; \
+ _hurdsig_end_catch_fault (); \
+ } \
+ } \
+ ret; \
+})
new file mode 100644
@@ -0,0 +1,327 @@
+/* Set thread_state for sighandler, and sigcontext to recover. aarch64 version.
+ Copyright (C) 1994-2024 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 Lesser General Public
+ License as published by the Free Software Foundation; either
+ version 2.1 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
+ Lesser General Public License for more details.
+
+ You should have received a copy of the GNU Lesser General Public
+ License along with the GNU C Library; if not, see
+ <https://www.gnu.org/licenses/>. */
+
+#include <hurd/signal.h>
+#include <hurd/userlink.h>
+#include <thread_state.h>
+#include <mach/exception.h>
+//#include <mach/machine/eflags.h>
+#include <assert.h>
+#include <errno.h>
+#include "hurdfault.h"
+//#include <intr-msg.h>
+#include <sys/ucontext.h>
+
+
+/* Fill in a siginfo_t structure for SA_SIGINFO-enabled handlers. */
+static void fill_siginfo (siginfo_t *si, int signo,
+ const struct hurd_signal_detail *detail,
+ const struct machine_thread_all_state *state)
+{
+ si->si_signo = signo;
+ si->si_errno = detail->error;
+ si->si_code = detail->code;
+
+ /* XXX We would need a protocol change for sig_post to include
+ * this information. */
+ si->si_pid = -1;
+ si->si_uid = -1;
+
+ /* Address of the faulting instruction or memory access. */
+ if (detail->exc == EXC_BAD_ACCESS)
+ si->si_addr = (void *) detail->exc_subcode;
+ else
+ si->si_addr = (void *) state->basic.pc;
+
+ /* XXX On SIGCHLD, this should be the exit status of the child
+ * process. We would need a protocol change for the proc server
+ * to send this information along with the signal. */
+ si->si_status = 0;
+
+ si->si_band = 0; /* SIGPOLL is not supported yet. */
+ si->si_value.sival_int = 0; /* sigqueue() is not supported yet. */
+}
+
+/* Fill in a ucontext_t structure SA_SIGINFO-enabled handlers. */
+static void fill_ucontext (ucontext_t *uc, const struct sigcontext *sc)
+{
+ uc->uc_flags = 0;
+ uc->uc_link = NULL;
+ uc->uc_sigmask = sc->sc_mask;
+ uc->uc_stack.ss_sp = (__ptr_t) sc->sc_sp;
+ uc->uc_stack.ss_size = 0;
+ uc->uc_stack.ss_flags = 0;
+
+ /* Registers. */
+ memcpy (&uc->uc_mcontext.gregs.x[0], &sc->sc_x[0],
+ (const unsigned char *) &sc->sc_aarch64_float_state
+ - (const unsigned char *) &sc->sc_aarch64_thread_state);
+ /* XXX FPU state. */
+ memset (&uc->uc_mcontext.fpregs, 0, sizeof (fpregset_t));
+}
+
+struct sigcontext *
+_hurd_setup_sighandler (struct hurd_sigstate *ss, const struct sigaction *action,
+ __sighandler_t handler,
+ int signo, struct hurd_signal_detail *detail,
+ int rpc_wait,
+ struct machine_thread_all_state *state)
+{
+ void trampoline (void) attribute_hidden;
+ void rpc_wait_trampoline (void) attribute_hidden;
+ void *sigsp;
+ struct sigcontext *scp;
+ struct
+ {
+ union
+ {
+ int signo;
+ /* Make sure signo takes up a pointer-sized slot on the stack.
+ (This should already be the case considering the siginfop
+ pointer below, but better be explicit.) */
+ void *_pointer_sized;
+ };
+ union
+ {
+ /* Extra arguments for traditional signal handlers */
+ struct
+ {
+ long int sigcode;
+ struct sigcontext *scp; /* Points to ctx, below. */
+ } legacy;
+
+ /* Extra arguments for SA_SIGINFO handlers */
+ struct
+ {
+ siginfo_t *siginfop; /* Points to siginfo, below. */
+ ucontext_t *uctxp; /* Points to uctx, below. */
+ } posix;
+ };
+
+ void *_pad;
+ void *sigreturn_addr;
+ struct sigcontext *return_scp; /* Argument to sigreturn. */
+
+ /* NB: sigreturn assumes link is next to ctx. */
+ struct sigcontext ctx;
+ struct hurd_userlink link;
+ ucontext_t ucontext;
+ siginfo_t siginfo;
+ } *stackframe;
+
+ _Static_assert (offsetof (typeof (*stackframe), sigreturn_addr) % 16 == 0,
+ "sigreturn_addr must be 16-byte aligned");
+ _Static_assert (sizeof (*stackframe) % 16 == 0,
+ "stackframe size must be a multiple of 16");
+
+ 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_aarch64_thread_state,
+ sizeof (state->basic));
+ memcpy (&state->fpu, &ss->context->sc_aarch64_float_state,
+ sizeof (state->fpu));
+ state->set |= (1 << AARCH64_THREAD_STATE) | (1 << AARCH64_FLOAT_STATE);
+ }
+ }
+
+ if (! machine_get_basic_state (ss->thread, state))
+ return NULL;
+
+ 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;
+ }
+ else
+ /* No red zone on aarch64-gnu. */
+ sigsp = (char *) state->basic.sp;
+
+ /* 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 sigcontext from the current state of the thread. */
+
+ scp = &stackframe->ctx;
+ scp->sc_onstack = ss->sigaltstack.ss_flags & SS_ONSTACK ? 1 : 0;
+
+ /* struct sigcontext is laid out so that starting at sc_x[0] mimics a
+ struct aarch64_thread_state. */
+ _Static_assert (offsetof (struct sigcontext, sc_aarch64_thread_state)
+ % __alignof__ (struct aarch64_thread_state) == 0,
+ "sc_aarch64_thread_state layout mismatch");
+ memcpy (&scp->sc_aarch64_thread_state,
+ &state->basic, sizeof (state->basic));
+
+ /* struct sigcontext is laid out so that starting at sc_v[0] mimics
+ a struct aarch64_float_state. */
+ _Static_assert (offsetof (struct sigcontext, sc_aarch64_float_state)
+ % __alignof__ (struct aarch64_float_state) == 0,
+ "sc_aarch64_float_state layout mismatch");
+ ok = machine_get_state (ss->thread, state, AARCH64_FLOAT_STATE,
+ &state->fpu, &scp->sc_aarch64_float_state,
+ sizeof (state->fpu));
+
+ /* Set up the arguments for the signal handler. */
+ stackframe->signo = signo;
+ if (action->sa_flags & SA_SIGINFO)
+ {
+ stackframe->posix.siginfop = &stackframe->siginfo;
+ stackframe->posix.uctxp = &stackframe->ucontext;
+ fill_siginfo (&stackframe->siginfo, signo, detail, state);
+ fill_ucontext (&stackframe->ucontext, scp);
+ }
+ else
+ {
+ if (detail->exc)
+ {
+ int nsigno;
+ _hurd_exception2signal_legacy (detail, &nsigno);
+ assert (nsigno == signo);
+ }
+ else
+ detail->code = 0;
+
+ stackframe->legacy.sigcode = detail->code;
+ stackframe->legacy.scp = &stackframe->ctx;
+ }
+
+ /* Set up the bottom of the stack. */
+ stackframe->sigreturn_addr = &__sigreturn;
+ stackframe->return_scp = &stackframe->ctx;
+
+ _hurdsig_end_catch_fault ();
+
+ if (! ok)
+ return NULL;
+ }
+
+ /* Modify the thread state to call the trampoline code on the new stack. */
+ state->basic.sp = (uintptr_t) sigsp;
+
+ 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 x1) to enable only
+ message reception, since the request message has already been
+ sent. */
+
+ assert (state->basic.x[1] & MACH_RCV_MSG);
+ /* Disable the message-send, since it has already completed. The
+ calls we retry need only wait to receive the reply message. */
+ state->basic.x[1] &= ~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. */
+ state->basic.x[1] |= MACH_RCV_TIMEOUT;
+ state->basic.x[5] = _hurd_interrupted_rpc_timeout;
+
+ state->basic.pc = (uintptr_t) rpc_wait_trampoline;
+ /* After doing the message receive, the trampoline code will need to
+ update the x0 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 x21. */
+ state->basic.x[21] = (uintptr_t) &scp->sc_x[0];
+ }
+ else
+ state->basic.pc = (uintptr_t) trampoline;
+
+ /* We pass the handler function to the trampoline code in x20. */
+ state->basic.x[20] = (uintptr_t) handler;
+
+ return scp;
+}
+
+asm ("rpc_wait_trampoline:\n"
+ /* 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 x1. For our convenience, x21
+ points to the sc_x[0] member of the sigcontext.
+
+ When the sigcontext was saved, x0 was MACH_RCV_INTERRUPTED. To repeat
+ the message call, we need to restore the original message buffer
+ pointer; intr-msg.h keeps a backup copy of it in x9 specifically for
+ this purpose. */
+ "mov x0, x9\n"
+ "svc #0\n"
+ /* 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 x0. So store
+ the new x0 value into the sc_x[0] member of the sigcontext (whose
+ address is in x21 to make this code simpler). */
+ "str x0, [x21]\n"
+
+ "trampoline:\n"
+ /* Entry point for running the handler normally. The arguments to the
+ handler function are on the top of the stack:
+
+ [sp] SIGNO
+ [sp, #8] SIGCODE
+ [sp, #16] SCP
+ [sp, #24] _pad
+
+ Pop them off to the registers, to pass as arguments to the handler.
+ */
+ "ldp x0, x1, [sp], 16\n"
+ "ldr x2, [sp], 16\n"
+ "blr x20\n" /* Call handler (signo, sigcode, scp). */
+ /* The word at the top of stack is &__sigreturn, following it is a copy
+ of SCP for __sigreturn's argument. Load the SCP as for a call, and
+ "return" to calling __sigreturn (SCP); this call never returns. */
+ "ldp x30, x0, [sp], 16\n"
+ "ret");