linux-user/sh4/signal.c - qemu - Git at Google

 /*
  *  Emulation of Linux signals
  *
  *  Copyright (c) 2003 Fabrice Bellard
  *
  *  This program is free software; you can redistribute it and/or modify
  *  it under the terms of the GNU General Public License as published by
  *  the Free Software Foundation; either version 2 of the License, or
  *  (at your option) any later version.
  *
  *  This program 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 General Public License for more details.
  *
  *  You should have received a copy of the GNU General Public License
  *  along with this program; if not, see <http://www.gnu.org/licenses/>.
  */
 #include "qemu/osdep.h"
 #include "qemu.h"
 #include "user-internals.h"
 #include "signal-common.h"
 #include "linux-user/trace.h"

 /*
  * code and data structures from linux kernel:
  * include/asm-sh/sigcontext.h
  * arch/sh/kernel/signal.c
  */

 struct target_sigcontext {
     target_ulong  oldmask;

     /* CPU registers */
     target_ulong  sc_gregs[16];
     target_ulong  sc_pc;
     target_ulong  sc_pr;
     target_ulong  sc_sr;
     target_ulong  sc_gbr;
     target_ulong  sc_mach;
     target_ulong  sc_macl;

     /* FPU registers */
     target_ulong  sc_fpregs[16];
     target_ulong  sc_xfpregs[16];
     unsigned int sc_fpscr;
     unsigned int sc_fpul;
     unsigned int sc_ownedfp;
 };

 struct target_sigframe
 {
     struct target_sigcontext sc;
     target_ulong extramask[TARGET_NSIG_WORDS-1];
 };


 struct target_ucontext {
     target_ulong tuc_flags;
     struct target_ucontext *tuc_link;
     target_stack_t tuc_stack;
     struct target_sigcontext tuc_mcontext;
     target_sigset_t tuc_sigmask;        /* mask last for extensibility */
 };

 struct target_rt_sigframe
 {
     struct target_siginfo info;
     struct target_ucontext uc;
 };


 #define MOVW(n)  (0x9300|((n)-2)) /* Move mem word at PC+n to R3 */
 #define TRAP_NOARG 0xc310         /* Syscall w/no args (NR in R3) SH3/4 */

 static abi_ulong get_sigframe(struct target_sigaction *ka,
                               unsigned long sp, size_t frame_size)
 {
     sp = target_sigsp(sp, ka);

     return (sp - frame_size) & -8ul;
 }

 /*
  * Notice when we're in the middle of a gUSA region and reset.
  * Note that this will only occur when #CF_PARALLEL is unset, as we
  * will translate such sequences differently in a parallel context.
  */
 static void unwind_gusa(CPUSH4State *regs)
 {
     /* If the stack pointer is sufficiently negative, and we haven't
        completed the sequence, then reset to the entry to the region.  */
     /* ??? The SH4 kernel checks for and address above 0xC0000000.
        However, the page mappings in qemu linux-user aren't as restricted
        and we wind up with the normal stack mapped above 0xF0000000.
        That said, there is no reason why the kernel should be allowing
        a gUSA region that spans 1GB.  Use a tighter check here, for what
        can actually be enabled by the immediate move.  */
     if (regs->gregs[15] >= -128u && regs->pc < regs->gregs[0]) {
         /* Reset the PC to before the gUSA region, as computed from
            R0 = region end, SP = -(region size), plus one more for the
            insn that actually initializes SP to the region size.  */
         regs->pc = regs->gregs[0] + regs->gregs[15] - 2;

         /* Reset the SP to the saved version in R1.  */
         regs->gregs[15] = regs->gregs[1];
     } else if (regs->gregs[15] >= -128u && regs->pc == regs->gregs[0]) {
         /* If we are on the last instruction of a gUSA region, we must reset
            the SP, otherwise we would be pushing the signal context to
            invalid memory.  */
         regs->gregs[15] = regs->gregs[1];
     } else if (regs->flags & TB_FLAG_DELAY_SLOT) {
         /* If we are in a delay slot, push the previous instruction.  */
         regs->pc -= 2;
     }
 }

 static void setup_sigcontext(struct target_sigcontext *sc,
                              CPUSH4State *regs, unsigned long mask)
 {
     int i;

 #define COPY(x)         __put_user(regs->x, &sc->sc_##x)
     COPY(gregs[0]); COPY(gregs[1]);
     COPY(gregs[2]); COPY(gregs[3]);
     COPY(gregs[4]); COPY(gregs[5]);
     COPY(gregs[6]); COPY(gregs[7]);
     COPY(gregs[8]); COPY(gregs[9]);
     COPY(gregs[10]); COPY(gregs[11]);
     COPY(gregs[12]); COPY(gregs[13]);
     COPY(gregs[14]); COPY(gregs[15]);
     COPY(gbr); COPY(mach);
     COPY(macl); COPY(pr);
     COPY(sr); COPY(pc);
 #undef COPY

     for (i=0; i<16; i++) {
         __put_user(regs->fregs[i], &sc->sc_fpregs[i]);
     }
     __put_user(regs->fpscr, &sc->sc_fpscr);
     __put_user(regs->fpul, &sc->sc_fpul);

     /* non-iBCS2 extensions.. */
     __put_user(mask, &sc->oldmask);
 }

 static void restore_sigcontext(CPUSH4State *regs, struct target_sigcontext *sc)
 {
     int i;

 #define COPY(x)         __get_user(regs->x, &sc->sc_##x)
     COPY(gregs[0]); COPY(gregs[1]);
     COPY(gregs[2]); COPY(gregs[3]);
     COPY(gregs[4]); COPY(gregs[5]);
     COPY(gregs[6]); COPY(gregs[7]);
     COPY(gregs[8]); COPY(gregs[9]);
     COPY(gregs[10]); COPY(gregs[11]);
     COPY(gregs[12]); COPY(gregs[13]);
     COPY(gregs[14]); COPY(gregs[15]);
     COPY(gbr); COPY(mach);
     COPY(macl); COPY(pr);
     COPY(sr); COPY(pc);
 #undef COPY

     for (i=0; i<16; i++) {
         __get_user(regs->fregs[i], &sc->sc_fpregs[i]);
     }
     __get_user(regs->fpscr, &sc->sc_fpscr);
     __get_user(regs->fpul, &sc->sc_fpul);

     regs->tra = -1;         /* disable syscall checks */
     regs->flags = 0;
 }

 void setup_frame(int sig, struct target_sigaction *ka,
                  target_sigset_t *set, CPUSH4State *regs)
 {
     struct target_sigframe *frame;
     abi_ulong frame_addr;
     int i;

     unwind_gusa(regs);

     frame_addr = get_sigframe(ka, regs->gregs[15], sizeof(*frame));
     trace_user_setup_frame(regs, frame_addr);
     if (!lock_user_struct(VERIFY_WRITE, frame, frame_addr, 0)) {
         goto give_sigsegv;
     }

     setup_sigcontext(&frame->sc, regs, set->sig[0]);

     for (i = 0; i < TARGET_NSIG_WORDS - 1; i++) {
         __put_user(set->sig[i + 1], &frame->extramask[i]);
     }

     /* Set up to return from userspace.  If provided, use a stub
        already in userspace.  */
     if (ka->sa_flags & TARGET_SA_RESTORER) {
         regs->pr = ka->sa_restorer;
     } else {
         regs->pr = default_sigreturn;
     }

     /* Set up registers for signal handler */
     regs->gregs[15] = frame_addr;
     regs->gregs[4] = sig; /* Arg for signal handler */
     regs->gregs[5] = 0;
     regs->gregs[6] = frame_addr += offsetof(typeof(*frame), sc);
     regs->pc = (unsigned long) ka->_sa_handler;
     regs->flags &= ~(TB_FLAG_DELAY_SLOT_MASK | TB_FLAG_GUSA_MASK);

     unlock_user_struct(frame, frame_addr, 1);
     return;

 give_sigsegv:
     unlock_user_struct(frame, frame_addr, 1);
     force_sigsegv(sig);
 }

 void setup_rt_frame(int sig, struct target_sigaction *ka,
                     target_siginfo_t *info,
                     target_sigset_t *set, CPUSH4State *regs)
 {
     struct target_rt_sigframe *frame;
     abi_ulong frame_addr;
     int i;

     unwind_gusa(regs);

     frame_addr = get_sigframe(ka, regs->gregs[15], sizeof(*frame));
     trace_user_setup_rt_frame(regs, frame_addr);
     if (!lock_user_struct(VERIFY_WRITE, frame, frame_addr, 0)) {
         goto give_sigsegv;
     }

     frame->info = *info;

     /* Create the ucontext.  */
     __put_user(0, &frame->uc.tuc_flags);
     __put_user(0, (unsigned long *)&frame->uc.tuc_link);
     target_save_altstack(&frame->uc.tuc_stack, regs);
     setup_sigcontext(&frame->uc.tuc_mcontext,
                      regs, set->sig[0]);
     for(i = 0; i < TARGET_NSIG_WORDS; i++) {
         __put_user(set->sig[i], &frame->uc.tuc_sigmask.sig[i]);
     }

     /* Set up to return from userspace.  If provided, use a stub
        already in userspace.  */
     if (ka->sa_flags & TARGET_SA_RESTORER) {
         regs->pr = ka->sa_restorer;
     } else {
         regs->pr = default_rt_sigreturn;
     }

     /* Set up registers for signal handler */
     regs->gregs[15] = frame_addr;
     regs->gregs[4] = sig; /* Arg for signal handler */
     regs->gregs[5] = frame_addr + offsetof(typeof(*frame), info);
     regs->gregs[6] = frame_addr + offsetof(typeof(*frame), uc);
     regs->pc = (unsigned long) ka->_sa_handler;
     regs->flags &= ~(TB_FLAG_DELAY_SLOT_MASK | TB_FLAG_GUSA_MASK);

     unlock_user_struct(frame, frame_addr, 1);
     return;

 give_sigsegv:
     unlock_user_struct(frame, frame_addr, 1);
     force_sigsegv(sig);
 }

 long do_sigreturn(CPUSH4State *regs)
 {
     struct target_sigframe *frame;
     abi_ulong frame_addr;
     sigset_t blocked;
     target_sigset_t target_set;
     int i;

     frame_addr = regs->gregs[15];
     trace_user_do_sigreturn(regs, frame_addr);
     if (!lock_user_struct(VERIFY_READ, frame, frame_addr, 1)) {
         goto badframe;
     }

     __get_user(target_set.sig[0], &frame->sc.oldmask);
     for(i = 1; i < TARGET_NSIG_WORDS; i++) {
         __get_user(target_set.sig[i], &frame->extramask[i - 1]);
     }

     target_to_host_sigset_internal(&blocked, &target_set);
     set_sigmask(&blocked);

     restore_sigcontext(regs, &frame->sc);

     unlock_user_struct(frame, frame_addr, 0);
     return -QEMU_ESIGRETURN;

 badframe:
     unlock_user_struct(frame, frame_addr, 0);
     force_sig(TARGET_SIGSEGV);
     return -QEMU_ESIGRETURN;
 }

 long do_rt_sigreturn(CPUSH4State *regs)
 {
     struct target_rt_sigframe *frame;
     abi_ulong frame_addr;
     sigset_t blocked;

     frame_addr = regs->gregs[15];
     trace_user_do_rt_sigreturn(regs, frame_addr);
     if (!lock_user_struct(VERIFY_READ, frame, frame_addr, 1)) {
         goto badframe;
     }

     target_to_host_sigset(&blocked, &frame->uc.tuc_sigmask);
     set_sigmask(&blocked);

     restore_sigcontext(regs, &frame->uc.tuc_mcontext);
     target_restore_altstack(&frame->uc.tuc_stack, regs);

     unlock_user_struct(frame, frame_addr, 0);
     return -QEMU_ESIGRETURN;

 badframe:
     unlock_user_struct(frame, frame_addr, 0);
     force_sig(TARGET_SIGSEGV);
     return -QEMU_ESIGRETURN;
 }

 void setup_sigtramp(abi_ulong sigtramp_page)
 {
     uint16_t *tramp = lock_user(VERIFY_WRITE, sigtramp_page, 2 * 6, 0);
     assert(tramp != NULL);

     default_sigreturn = sigtramp_page;
     __put_user(MOVW(2), &tramp[0]);
     __put_user(TRAP_NOARG, &tramp[1]);
     __put_user(TARGET_NR_sigreturn, &tramp[2]);

     default_rt_sigreturn = sigtramp_page + 6;
     __put_user(MOVW(2), &tramp[3]);
     __put_user(TRAP_NOARG, &tramp[4]);
     __put_user(TARGET_NR_rt_sigreturn, &tramp[5]);

     unlock_user(tramp, sigtramp_page, 2 * 6);
 }
	/*
	* Emulation of Linux signals
	*
	* Copyright (c) 2003 Fabrice Bellard
	*
	* This program is free software; you can redistribute it and/or modify
	* it under the terms of the GNU General Public License as published by
	* the Free Software Foundation; either version 2 of the License, or
	* (at your option) any later version.
	*
	* This program 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 General Public License for more details.
	*
	* You should have received a copy of the GNU General Public License
	* along with this program; if not, see <http://www.gnu.org/licenses/>.
	*/
	#include "qemu/osdep.h"
	#include "qemu.h"
	#include "user-internals.h"
	#include "signal-common.h"
	#include "linux-user/trace.h"

	/*
	* code and data structures from linux kernel:
	* include/asm-sh/sigcontext.h
	* arch/sh/kernel/signal.c
	*/

	struct target_sigcontext {
	target_ulong oldmask;

	/* CPU registers */
	target_ulong sc_gregs[16];
	target_ulong sc_pc;
	target_ulong sc_pr;
	target_ulong sc_sr;
	target_ulong sc_gbr;
	target_ulong sc_mach;
	target_ulong sc_macl;

	/* FPU registers */
	target_ulong sc_fpregs[16];
	target_ulong sc_xfpregs[16];
	unsigned int sc_fpscr;
	unsigned int sc_fpul;
	unsigned int sc_ownedfp;
	};

	struct target_sigframe
	{
	struct target_sigcontext sc;
	target_ulong extramask[TARGET_NSIG_WORDS-1];
	};


	struct target_ucontext {
	target_ulong tuc_flags;
	struct target_ucontext *tuc_link;
	target_stack_t tuc_stack;
	struct target_sigcontext tuc_mcontext;
	target_sigset_t tuc_sigmask; /* mask last for extensibility */
	};

	struct target_rt_sigframe
	{
	struct target_siginfo info;
	struct target_ucontext uc;
	};


	#define MOVW(n) (0x9300\|((n)-2)) /* Move mem word at PC+n to R3 */
	#define TRAP_NOARG 0xc310 /* Syscall w/no args (NR in R3) SH3/4 */

	static abi_ulong get_sigframe(struct target_sigaction *ka,
	unsigned long sp, size_t frame_size)
	{
	sp = target_sigsp(sp, ka);

	return (sp - frame_size) & -8ul;
	}

	/*
	* Notice when we're in the middle of a gUSA region and reset.
	* Note that this will only occur when #CF_PARALLEL is unset, as we
	* will translate such sequences differently in a parallel context.
	*/
	static void unwind_gusa(CPUSH4State *regs)
	{
	/* If the stack pointer is sufficiently negative, and we haven't
	completed the sequence, then reset to the entry to the region. */
	/* ??? The SH4 kernel checks for and address above 0xC0000000.
	However, the page mappings in qemu linux-user aren't as restricted
	and we wind up with the normal stack mapped above 0xF0000000.
	That said, there is no reason why the kernel should be allowing
	a gUSA region that spans 1GB. Use a tighter check here, for what
	can actually be enabled by the immediate move. */
	if (regs->gregs[15] >= -128u && regs->pc < regs->gregs[0]) {
	/* Reset the PC to before the gUSA region, as computed from
	R0 = region end, SP = -(region size), plus one more for the
	insn that actually initializes SP to the region size. */
	regs->pc = regs->gregs[0] + regs->gregs[15] - 2;

	/* Reset the SP to the saved version in R1. */
	regs->gregs[15] = regs->gregs[1];
	} else if (regs->gregs[15] >= -128u && regs->pc == regs->gregs[0]) {
	/* If we are on the last instruction of a gUSA region, we must reset
	the SP, otherwise we would be pushing the signal context to
	invalid memory. */
	regs->gregs[15] = regs->gregs[1];
	} else if (regs->flags & TB_FLAG_DELAY_SLOT) {
	/* If we are in a delay slot, push the previous instruction. */
	regs->pc -= 2;
	}
	}

	static void setup_sigcontext(struct target_sigcontext *sc,
	CPUSH4State *regs, unsigned long mask)
	{
	int i;

	#define COPY(x) __put_user(regs->x, &sc->sc_##x)
	COPY(gregs[0]); COPY(gregs[1]);
	COPY(gregs[2]); COPY(gregs[3]);
	COPY(gregs[4]); COPY(gregs[5]);
	COPY(gregs[6]); COPY(gregs[7]);
	COPY(gregs[8]); COPY(gregs[9]);
	COPY(gregs[10]); COPY(gregs[11]);
	COPY(gregs[12]); COPY(gregs[13]);
	COPY(gregs[14]); COPY(gregs[15]);
	COPY(gbr); COPY(mach);
	COPY(macl); COPY(pr);
	COPY(sr); COPY(pc);
	#undef COPY

	for (i=0; i<16; i++) {
	__put_user(regs->fregs[i], &sc->sc_fpregs[i]);
	}
	__put_user(regs->fpscr, &sc->sc_fpscr);
	__put_user(regs->fpul, &sc->sc_fpul);

	/* non-iBCS2 extensions.. */
	__put_user(mask, &sc->oldmask);
	}

	static void restore_sigcontext(CPUSH4State regs, struct target_sigcontext sc)
	{
	int i;

	#define COPY(x) __get_user(regs->x, &sc->sc_##x)
	COPY(gregs[0]); COPY(gregs[1]);
	COPY(gregs[2]); COPY(gregs[3]);
	COPY(gregs[4]); COPY(gregs[5]);
	COPY(gregs[6]); COPY(gregs[7]);
	COPY(gregs[8]); COPY(gregs[9]);
	COPY(gregs[10]); COPY(gregs[11]);
	COPY(gregs[12]); COPY(gregs[13]);
	COPY(gregs[14]); COPY(gregs[15]);
	COPY(gbr); COPY(mach);
	COPY(macl); COPY(pr);
	COPY(sr); COPY(pc);
	#undef COPY

	for (i=0; i<16; i++) {
	__get_user(regs->fregs[i], &sc->sc_fpregs[i]);
	}
	__get_user(regs->fpscr, &sc->sc_fpscr);
	__get_user(regs->fpul, &sc->sc_fpul);

	regs->tra = -1; /* disable syscall checks */
	regs->flags = 0;
	}

	void setup_frame(int sig, struct target_sigaction *ka,
	target_sigset_t set, CPUSH4State regs)
	{
	struct target_sigframe *frame;
	abi_ulong frame_addr;
	int i;

	unwind_gusa(regs);

	frame_addr = get_sigframe(ka, regs->gregs[15], sizeof(*frame));
	trace_user_setup_frame(regs, frame_addr);
	if (!lock_user_struct(VERIFY_WRITE, frame, frame_addr, 0)) {
	goto give_sigsegv;
	}

	setup_sigcontext(&frame->sc, regs, set->sig[0]);

	for (i = 0; i < TARGET_NSIG_WORDS - 1; i++) {
	__put_user(set->sig[i + 1], &frame->extramask[i]);
	}

	/* Set up to return from userspace. If provided, use a stub
	already in userspace. */
	if (ka->sa_flags & TARGET_SA_RESTORER) {
	regs->pr = ka->sa_restorer;
	} else {
	regs->pr = default_sigreturn;
	}

	/* Set up registers for signal handler */
	regs->gregs[15] = frame_addr;
	regs->gregs[4] = sig; /* Arg for signal handler */
	regs->gregs[5] = 0;
	regs->gregs[6] = frame_addr += offsetof(typeof(*frame), sc);
	regs->pc = (unsigned long) ka->_sa_handler;
	regs->flags &= ~(TB_FLAG_DELAY_SLOT_MASK \| TB_FLAG_GUSA_MASK);

	unlock_user_struct(frame, frame_addr, 1);
	return;

	give_sigsegv:
	unlock_user_struct(frame, frame_addr, 1);
	force_sigsegv(sig);
	}

	void setup_rt_frame(int sig, struct target_sigaction *ka,
	target_siginfo_t *info,
	target_sigset_t set, CPUSH4State regs)
	{
	struct target_rt_sigframe *frame;
	abi_ulong frame_addr;
	int i;

	unwind_gusa(regs);

	frame_addr = get_sigframe(ka, regs->gregs[15], sizeof(*frame));
	trace_user_setup_rt_frame(regs, frame_addr);
	if (!lock_user_struct(VERIFY_WRITE, frame, frame_addr, 0)) {
	goto give_sigsegv;
	}

	frame->info = *info;

	/* Create the ucontext. */
	__put_user(0, &frame->uc.tuc_flags);
	__put_user(0, (unsigned long *)&frame->uc.tuc_link);
	target_save_altstack(&frame->uc.tuc_stack, regs);
	setup_sigcontext(&frame->uc.tuc_mcontext,
	regs, set->sig[0]);
	for(i = 0; i < TARGET_NSIG_WORDS; i++) {
	__put_user(set->sig[i], &frame->uc.tuc_sigmask.sig[i]);
	}

	/* Set up to return from userspace. If provided, use a stub
	already in userspace. */
	if (ka->sa_flags & TARGET_SA_RESTORER) {
	regs->pr = ka->sa_restorer;
	} else {
	regs->pr = default_rt_sigreturn;
	}

	/* Set up registers for signal handler */
	regs->gregs[15] = frame_addr;
	regs->gregs[4] = sig; /* Arg for signal handler */
	regs->gregs[5] = frame_addr + offsetof(typeof(*frame), info);
	regs->gregs[6] = frame_addr + offsetof(typeof(*frame), uc);
	regs->pc = (unsigned long) ka->_sa_handler;
	regs->flags &= ~(TB_FLAG_DELAY_SLOT_MASK \| TB_FLAG_GUSA_MASK);

	unlock_user_struct(frame, frame_addr, 1);
	return;

	give_sigsegv:
	unlock_user_struct(frame, frame_addr, 1);
	force_sigsegv(sig);
	}

	long do_sigreturn(CPUSH4State *regs)
	{
	struct target_sigframe *frame;
	abi_ulong frame_addr;
	sigset_t blocked;
	target_sigset_t target_set;
	int i;

	frame_addr = regs->gregs[15];
	trace_user_do_sigreturn(regs, frame_addr);
	if (!lock_user_struct(VERIFY_READ, frame, frame_addr, 1)) {
	goto badframe;
	}

	__get_user(target_set.sig[0], &frame->sc.oldmask);
	for(i = 1; i < TARGET_NSIG_WORDS; i++) {
	__get_user(target_set.sig[i], &frame->extramask[i - 1]);
	}

	target_to_host_sigset_internal(&blocked, &target_set);
	set_sigmask(&blocked);

	restore_sigcontext(regs, &frame->sc);

	unlock_user_struct(frame, frame_addr, 0);
	return -QEMU_ESIGRETURN;

	badframe:
	unlock_user_struct(frame, frame_addr, 0);
	force_sig(TARGET_SIGSEGV);
	return -QEMU_ESIGRETURN;
	}

	long do_rt_sigreturn(CPUSH4State *regs)
	{
	struct target_rt_sigframe *frame;
	abi_ulong frame_addr;
	sigset_t blocked;

	frame_addr = regs->gregs[15];
	trace_user_do_rt_sigreturn(regs, frame_addr);
	if (!lock_user_struct(VERIFY_READ, frame, frame_addr, 1)) {
	goto badframe;
	}

	target_to_host_sigset(&blocked, &frame->uc.tuc_sigmask);
	set_sigmask(&blocked);

	restore_sigcontext(regs, &frame->uc.tuc_mcontext);
	target_restore_altstack(&frame->uc.tuc_stack, regs);

	unlock_user_struct(frame, frame_addr, 0);
	return -QEMU_ESIGRETURN;

	badframe:
	unlock_user_struct(frame, frame_addr, 0);
	force_sig(TARGET_SIGSEGV);
	return -QEMU_ESIGRETURN;
	}

	void setup_sigtramp(abi_ulong sigtramp_page)
	{
	uint16_t tramp = lock_user(VERIFY_WRITE, sigtramp_page, 2 6, 0);
	assert(tramp != NULL);

	default_sigreturn = sigtramp_page;
	__put_user(MOVW(2), &tramp[0]);
	__put_user(TRAP_NOARG, &tramp[1]);
	__put_user(TARGET_NR_sigreturn, &tramp[2]);

	default_rt_sigreturn = sigtramp_page + 6;
	__put_user(MOVW(2), &tramp[3]);
	__put_user(TRAP_NOARG, &tramp[4]);
	__put_user(TARGET_NR_rt_sigreturn, &tramp[5]);

	unlock_user(tramp, sigtramp_page, 2 * 6);
	}