diff options
Diffstat (limited to 'sysdeps/mach/hurd/mips/trampoline.c')
| -rw-r--r-- | sysdeps/mach/hurd/mips/trampoline.c | 292 |
1 files changed, 292 insertions, 0 deletions
diff --git a/sysdeps/mach/hurd/mips/trampoline.c b/sysdeps/mach/hurd/mips/trampoline.c new file mode 100644 index 0000000000..dd42dfc1c6 --- /dev/null +++ b/sysdeps/mach/hurd/mips/trampoline.c @@ -0,0 +1,292 @@ +/* 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; +} |