diff options
Diffstat (limited to 'sysdeps/mach/hurd/powerpc/trampoline.c')
| -rw-r--r-- | sysdeps/mach/hurd/powerpc/trampoline.c | 256 |
1 files changed, 256 insertions, 0 deletions
diff --git a/sysdeps/mach/hurd/powerpc/trampoline.c b/sysdeps/mach/hurd/powerpc/trampoline.c new file mode 100644 index 0000000..4e5d675 --- /dev/null +++ b/sysdeps/mach/hurd/powerpc/trampoline.c @@ -0,0 +1,256 @@ +/* Set thread_state for sighandler, and sigcontext to recover. For PowerPC. + Copyright (C) 1994,95,96,97,98,99,2001 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) +{ + void trampoline (void); + void rpc_wait_trampoline (void); + void *volatile 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 (! _hurdsig_catch_memory_fault (ss->context)) + { + memcpy (&state->basic, &ss->context->sc_ppc_thread_state, + sizeof (state->basic)); + memcpy (&state->exc, &ss->context->sc_ppc_exc_state, + sizeof (state->exc)); + memcpy (&state->fpu, &ss->context->sc_ppc_float_state, + sizeof (state->fpu)); + state->set = (1 << PPC_THREAD_STATE) | (1 << PPC_EXCEPTION_STATE) + | (1 << PPC_FLOAT_STATE); + } + } + + if (! machine_get_basic_state (ss->thread, state)) + return NULL; + + 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.SP; + + /* 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; + sigsp -= 16; /* Reserve some space for a stack frame. */ + + if (_hurdsig_catch_memory_fault (scp)) + { + /* 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; + + /* 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_srr0 + mimics a struct ppc_thread_state. */ + memcpy (&scp->sc_ppc_thread_state, + &state->basic, sizeof (state->basic)); + + /* struct sigcontext is laid out so that starting at sc_dar + mimics a struct ppc_exc_state. */ + ok = machine_get_state (ss->thread, state, PPC_EXCEPTION_STATE, + &state->exc, &scp->sc_ppc_exc_state, + sizeof (state->exc)); + + /* struct sigcontext is laid out so that starting at sc_fprs[0] + mimics a struct ppc_float_state. */ + if (ok) + ok = machine_get_state (ss->thread, state, PPC_FLOAT_STATE, + &state->fpu, &scp->sc_ppc_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 r3. */ + struct mach_msg_trap_args *args = (void *) &state->basic.r3; + + 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; + /* After doing the message receive, the trampoline code will need to + update the r3 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 r10. */ + state->basic.r10 = (long int) &scp->sc_gprs[3]; + /* We must preserve the mach_msg_trap args in r3..r9. + Pass the handler args to the trampoline code in r11..r13. */ + state->basic.r11 = signo; + state->basic.r12 = detail->code; + state->basic.r13 = (int) scp; + } + else + { + state->basic.PC = (int) trampoline; + state->basic.r3 = signo; + state->basic.r4 = detail->code; + state->basic.r5 = (int) scp; + } + + state->basic.r1 = (int) sigsp; /* r1 is the stack pointer. */ + + /* We pass the handler function to the trampoline code in ctr. */ + state->basic.ctr = (int) handler; + /* In r15, we store the address of __sigreturn itself, + for the trampoline code to use. */ + state->basic.r15 = (int) &__sigreturn; + /* In r16, we save the SCP value to pass to __sigreturn + after the handler returns. */ + state->basic.r16 = (int) scp; + + /* In r3, we store a pointer to the registers in STATE so that the + trampoline code can load the registers from that. For some reason, + thread_set_state doesn't set all registers. */ + state->basic.r17 = state->basic.r3; /* Store the real r3 in r17. */ + state->basic.r3 = (int) &state->basic.r0; + + return scp; +} + +/* The trampoline code follows. This used to be located inside + _hurd_setup_sighandler, but was optimized away by gcc 2.95. */ + +/* This function sets some registers which the trampoline code uses + and which are not automatically set by thread_set_state. + In r3 we have a pointer to the registers in STATE. */ +asm ("trampoline_load_registers:\n" + "lwz 17,68(3)\n" /* The real r3. */ + "lwz 4,16(3)\n" + "lwz 5,20(3)\n" + "lwz 6,24(3)\n" + "lwz 7,28(3)\n" + "lwz 8,32(3)\n" + "lwz 9,36(3)\n" + "lwz 10,40(3)\n" + "lwz 11,44(3)\n" + "lwz 12,48(3)\n" + "lwz 13,52(3)\n" + "lwz 14,56(3)\n" + "lwz 15,60(3)\n" + "lwz 16,64(3)\n" + "mr 3,17\n" + "blr\n"); + +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 registers. For our convenience, + r10 points to the sc_regs[3] member of the sigcontext (saved r3). */ + +asm (/* Retry the interrupted mach_msg system call. */ + "bl trampoline_load_registers\n" + "li 0, -25\n" /* mach_msg_trap */ + "sc\n" + /* When the sigcontext was saved, r3 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 r3. So + store the new r3 value into the sc_regs[3] member of the sigcontext + (whose address is in r10 to make this code simpler). */ + "stw 3, 0(10)\n" + /* Since the argument registers needed to have the mach_msg_trap + arguments, we've stored the arguments to the handler function + in registers r11..r13 of the state structure. */ + "mr 3,11\n" + "mr 4,12\n" + "mr 5,13\n"); + +asm ("trampoline:\n"); + /* Entry point for running the handler normally. The arguments to the + handler function are already in the standard registers: + + r3 SIGNO + r4 SIGCODE + r5 SCP + + r16 also contains SCP; this value is callee-saved (and so should not get + clobbered by running the handler). We use this saved value to pass to + __sigreturn, so the handler can clobber the argument registers if it + likes. */ +asm ("bl trampoline_load_registers\n" + "bctrl\n" /* Call the handler function. */ + "mtctr 15\n" /* Copy &__sigreturn to CTR. */ + "mr 3,16\n" /* Copy the saved SCP to r3. */ + "bctr\n" /* Call __sigreturn (SCP). */ + ); |