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-rw-r--r--sysdeps/mach/hurd/mips/trampoline.c292
1 files changed, 292 insertions, 0 deletions
diff --git a/sysdeps/mach/hurd/mips/trampoline.c b/sysdeps/mach/hurd/mips/trampoline.c
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+/* Set thread_state for sighandler, and sigcontext to recover. MIPS version.
+ Copyright (C) 1996, 1997, 1998 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, write to the Free
+ Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
+ 02111-1307 USA. */
+
+#include <hurd/signal.h>
+#include <hurd/userlink.h>
+#include "thread_state.h"
+#include <assert.h>
+#include <errno.h>
+#include "hurdfault.h"
+#include "intr-msg.h"
+
+
+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)
+{
+ __label__ trampoline, rpc_wait_trampoline, firewall;
+ 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_mips_thread_state,
+ sizeof (state->basic));
+ memcpy (&state->exc, &ss->context->sc_mips_exc_state,
+ sizeof (state->exc));
+ state->set = (1 << MIPS_THREAD_STATE) | (1 << MIPS_EXC_STATE);
+ if (state->exc.coproc_state & SC_COPROC_USE_FPU)
+ {
+ memcpy (&state->fpu, &ss->context->sc_mips_float_state,
+ sizeof (state->fpu));
+ state->set |= (1 << MIPS_FLOAT_STATE);
+ }
+ }
+ }
+
+ if (! machine_get_basic_state (ss->thread, state))
+ return NULL;
+
+ /* Save the original SP in the gratuitous s0 ($16) slot.
+ We may need to reset the SP (the `r29' slot) to avoid clobbering an
+ interrupted RPC frame. */
+ state->basic.r16 = state->basic.r29;
+
+ if ((ss->actions[signo].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. */
+ }
+ else
+ sigsp = (char *) state->basic.r29;
+
+ /* 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_gpr
+ mimics a struct mips_thread_state. */
+ memcpy (&scp->sc_mips_thread_state,
+ &state->basic, sizeof (state->basic));
+
+ /* struct sigcontext is laid out so that starting at sc_cause
+ mimics a struct mips_exc_state. */
+ ok = machine_get_state (ss->thread, state, MIPS_EXC_STATE,
+ &state->exc, &scp->sc_cause,
+ sizeof (state->exc));
+
+ if (ok && (scp->sc_coproc_used & SC_COPROC_USE_FPU))
+ /* struct sigcontext is laid out so that starting at sc_fpr
+ mimics a struct mips_float_state. This state
+ is only meaningful if the coprocessor was used. */
+ ok = machine_get_state (ss->thread, state, MIPS_FLOAT_STATE,
+ &state->fpu, &scp->sc_mips_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 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 ($4). */
+ struct mach_msg_trap_args *args = (void *) &state->basic.r4;
+
+ 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.pc = (int) &&rpc_wait_trampoline;
+ /* The reply-receiving trampoline code runs initially on the original
+ user stack. We pass it the signal stack pointer in s4 ($20). */
+ state->basic.r29 = state->basic.r16; /* Restore mach_msg syscall SP. */
+ state->basic.r20 = (int) sigsp;
+ /* After doing the message receive, the trampoline code will need to
+ update the v0 ($2) 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 s5 ($21). */
+ state->basic.r21 = (int) &scp->sc_gpr[1];
+ /* We must preserve the mach_msg_trap args in a0..t2 ($4..$10).
+ Pass the handler args to the trampoline code in s1..s3 ($17..$19). */
+ state->basic.r17 = signo;
+ state->basic.r18 = detail->code;
+ state->basic.r19 = (int) scp;
+ }
+ else
+ {
+ state->basic.pc = (int) &&trampoline;
+ state->basic.r29 = (int) sigsp;
+ state->basic.r4 = signo;
+ state->basic.r5 = detail->code;
+ state->basic.r6 = (int) scp;
+ }
+
+ /* We pass the handler function to the trampoline code in s6 ($22). */
+ state->basic.r22 = (int) handler;
+ /* In the callee-saved register s0 ($16), we save the SCP value to pass
+ to __sigreturn after the handler returns. */
+ state->basic.r16 = (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. */
+#ifdef __mips64
+ "dli $2, -25\n" /* mach_msg_trap */
+#else
+ "li $2, -25\n" /* mach_msg_trap */
+#endif
+ "syscall\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_gpr[1] member of the sigcontext
+ (whose address is in s5 to make this code simpler). */
+#ifdef __mips64
+ "sd $2, ($21)\n"
+#else
+ "sw $2, ($21)\n"
+#endif
+ /* Since the argument registers needed to have the mach_msg_trap
+ arguments, we've stored the arguments to the handler function
+ in registers s1..s3 ($17..$19). */
+ "move $4, $17\n"
+ "move $5, $18\n"
+ "move $6, $19\n"
+ /* Switch to the signal stack. */
+ "move $29, $20\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
+ ("move $25, $22\n" /* Copy s6 to t9 for MIPS ABI. */
+ "jal $25; nop\n" /* Call the handler function. */
+ /* Call __sigreturn (SCP); this cannot return. */
+#ifdef __mips64
+ "dla $1,%0\n"
+#else
+ "la $1,%0\n"
+#endif
+ "j $1\n"
+ "move $4, $16" /* Set up arg from saved SCP in delay slot. */
+ : : "i" (&__sigreturn));
+
+ /* NOTREACHED */
+ asm volatile (".set reorder; .set at; .set macro");
+
+ firewall:
+ asm volatile ("hlt: j hlt");
+
+ return NULL;
+}
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