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linux_machdep.c revision 1.23.10.1
      1 /*	$NetBSD: linux_machdep.c,v 1.23.10.1 2007/10/06 15:30:13 yamt Exp $ */
      2 
      3 /*-
      4  * Copyright (c) 2005 Emmanuel Dreyfus, all rights reserved.
      5  *
      6  * Redistribution and use in source and binary forms, with or without
      7  * modification, are permitted provided that the following conditions
      8  * are met:
      9  * 1. Redistributions of source code must retain the above copyright
     10  *    notice, this list of conditions and the following disclaimer.
     11  * 2. Redistributions in binary form must reproduce the above copyright
     12  *    notice, this list of conditions and the following disclaimer in the
     13  *    documentation and/or other materials provided with the distribution.
     14  * 3. All advertising materials mentioning features or use of this software
     15  *    must display the following acknowledgement:
     16  *	This product includes software developed by Emmanuel Dreyfus
     17  * 4. The name of the author may not be used to endorse or promote
     18  *    products derived from this software without specific prior written
     19  *    permission.
     20  *
     21  * THIS SOFTWARE IS PROVIDED BY THE THE AUTHOR AND CONTRIBUTORS ``AS IS''
     22  * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
     23  * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
     24  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS
     25  * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
     26  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
     27  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
     28  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
     29  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
     30  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
     31  * POSSIBILITY OF SUCH DAMAGE.
     32  */
     33 
     34 #include <sys/cdefs.h>
     35 
     36 __KERNEL_RCSID(0, "$NetBSD: linux_machdep.c,v 1.23.10.1 2007/10/06 15:30:13 yamt Exp $");
     37 
     38 #include <sys/param.h>
     39 #include <sys/types.h>
     40 #include <sys/systm.h>
     41 #include <sys/signal.h>
     42 #include <sys/exec.h>
     43 #include <sys/proc.h>
     44 #include <sys/ptrace.h> /* for process_read_fpregs() */
     45 #include <sys/user.h>
     46 #include <sys/wait.h>
     47 #include <sys/ucontext.h>
     48 #include <sys/conf.h>
     49 
     50 #include <machine/reg.h>
     51 #include <machine/pcb.h>
     52 #include <machine/fpu.h>
     53 #include <machine/mcontext.h>
     54 #include <machine/specialreg.h>
     55 #include <machine/vmparam.h>
     56 
     57 /*
     58  * To see whether wscons is configured (for virtual console ioctl calls).
     59  */
     60 #if defined(_KERNEL_OPT)
     61 #include "wsdisplay.h"
     62 #endif
     63 #if (NWSDISPLAY > 0)
     64 #include <dev/wscons/wsconsio.h>
     65 #include <dev/wscons/wsdisplay_usl_io.h>
     66 #endif
     67 
     68 
     69 #include <compat/linux/common/linux_signal.h>
     70 #include <compat/linux/common/linux_errno.h>
     71 #include <compat/linux/common/linux_exec.h>
     72 #include <compat/linux/common/linux_ioctl.h>
     73 #include <compat/linux/common/linux_prctl.h>
     74 #include <compat/linux/common/linux_machdep.h>
     75 #include <compat/linux/linux_syscall.h>
     76 #include <compat/linux/linux_syscallargs.h>
     77 
     78 static void linux_buildcontext(struct lwp *, void *, void *);
     79 
     80 void
     81 linux_setregs(l, epp, stack)
     82         struct lwp *l;
     83 	struct exec_package *epp;
     84 	u_long stack;
     85 {
     86 	struct pcb *pcb = &l->l_addr->u_pcb;
     87 	struct trapframe *tf;
     88 
     89 	/* If we were using the FPU, forget about it. */
     90 	if (l->l_addr->u_pcb.pcb_fpcpu != NULL)
     91 		fpusave_lwp(l, 0);
     92 
     93 	l->l_md.md_flags &= ~MDP_USEDFPU;
     94 	pcb->pcb_flags = 0;
     95 	pcb->pcb_savefpu.fp_fxsave.fx_fcw = __NetBSD_NPXCW__;
     96 	pcb->pcb_savefpu.fp_fxsave.fx_mxcsr = __INITIAL_MXCSR__;
     97 	pcb->pcb_savefpu.fp_fxsave.fx_mxcsr_mask = __INITIAL_MXCSR_MASK__;
     98 	pcb->pcb_fs = 0;
     99 	pcb->pcb_gs = 0;
    100 
    101 	l->l_proc->p_flag &= ~PK_32;
    102 
    103 	tf = l->l_md.md_regs;
    104 	tf->tf_rax = 0;
    105 	tf->tf_rbx = 0;
    106 	tf->tf_rcx = epp->ep_entry;
    107 	tf->tf_rdx = 0;
    108 	tf->tf_rsi = 0;
    109 	tf->tf_rdi = 0;
    110 	tf->tf_rbp = 0;
    111 	tf->tf_rsp = stack;
    112 	tf->tf_r8 = 0;
    113 	tf->tf_r9 = 0;
    114 	tf->tf_r10 = 0;
    115 	tf->tf_r11 = 0;
    116 	tf->tf_r12 = 0;
    117 	tf->tf_r13 = 0;
    118 	tf->tf_r14 = 0;
    119 	tf->tf_r15 = 0;
    120 	tf->tf_rip = epp->ep_entry;
    121 	tf->tf_rflags = PSL_USERSET;
    122 	tf->tf_cs = GSEL(GUCODE_SEL, SEL_UPL);
    123 	tf->tf_ss = GSEL(GUDATA_SEL, SEL_UPL);
    124 	tf->tf_ds = 0;
    125 	tf->tf_es = 0;
    126 	tf->tf_fs = 0;
    127 	tf->tf_gs = 0;
    128 
    129 	return;
    130 }
    131 
    132 void
    133 linux_sendsig(ksi, mask)
    134 	const ksiginfo_t *ksi;
    135 	const sigset_t *mask;
    136 {
    137 	struct lwp *l = curlwp;
    138 	struct proc *p = l->l_proc;
    139 	struct sigacts *ps = p->p_sigacts;
    140 	int onstack, error;
    141 	int sig = ksi->ksi_signo;
    142 	struct linux_rt_sigframe *sfp, sigframe;
    143 	struct linux__fpstate *fpsp, fpstate;
    144 	struct fpreg fpregs;
    145 	struct trapframe *tf = l->l_md.md_regs;
    146 	sig_t catcher = SIGACTION(p, sig).sa_handler;
    147 	linux_sigset_t lmask;
    148 	char *sp;
    149 
    150 	/* Do we need to jump onto the signal stack? */
    151 	onstack =
    152 	    (l->l_sigstk.ss_flags & (SS_DISABLE | SS_ONSTACK)) == 0 &&
    153 	    (SIGACTION(p, sig).sa_flags & SA_ONSTACK) != 0;
    154 
    155 	/* Allocate space for the signal handler context. */
    156 	if (onstack)
    157 		sp = ((char *)l->l_sigstk.ss_sp +
    158 		    l->l_sigstk.ss_size);
    159 	else
    160 		sp = (char *)tf->tf_rsp - 128;
    161 
    162 	/*
    163 	 * Save FPU state, if any
    164 	 */
    165 	if (l->l_md.md_flags & MDP_USEDFPU) {
    166 		sp = (char *)
    167 		    (((long)sp - sizeof(struct linux__fpstate)) & ~0xfUL);
    168 		fpsp = (struct linux__fpstate *)sp;
    169 	} else
    170 		fpsp = NULL;
    171 
    172 	/*
    173 	 * Populate the rt_sigframe
    174 	 */
    175 	sp = (char *)
    176 	    ((((long)sp - sizeof(struct linux_rt_sigframe)) & ~0xfUL) - 8);
    177 	sfp = (struct linux_rt_sigframe *)sp;
    178 
    179 	bzero(&sigframe, sizeof(sigframe));
    180 	if (ps->sa_sigdesc[sig].sd_vers != 0)
    181 		sigframe.pretcode =
    182 		    (char *)(u_long)ps->sa_sigdesc[sig].sd_tramp;
    183 	else
    184 		sigframe.pretcode = NULL;
    185 
    186 	/*
    187 	 * The user context
    188 	 */
    189 	sigframe.uc.luc_flags = 0;
    190 	sigframe.uc.luc_link = NULL;
    191 
    192 	/* This is used regardless of SA_ONSTACK in Linux */
    193 	sigframe.uc.luc_stack.ss_sp = l->l_sigstk.ss_sp;
    194 	sigframe.uc.luc_stack.ss_size = l->l_sigstk.ss_size;
    195 	sigframe.uc.luc_stack.ss_flags = 0;
    196 	if (l->l_sigstk.ss_flags & SS_ONSTACK)
    197 		sigframe.uc.luc_stack.ss_flags |= LINUX_SS_ONSTACK;
    198 	if (l->l_sigstk.ss_flags & SS_DISABLE)
    199 		sigframe.uc.luc_stack.ss_flags |= LINUX_SS_DISABLE;
    200 
    201 	sigframe.uc.luc_mcontext.r8 = tf->tf_r8;
    202 	sigframe.uc.luc_mcontext.r9 = tf->tf_r9;
    203 	sigframe.uc.luc_mcontext.r10 = tf->tf_r10;
    204 	sigframe.uc.luc_mcontext.r11 = tf->tf_r11;
    205 	sigframe.uc.luc_mcontext.r12 = tf->tf_r12;
    206 	sigframe.uc.luc_mcontext.r13 = tf->tf_r13;
    207 	sigframe.uc.luc_mcontext.r14 = tf->tf_r14;
    208 	sigframe.uc.luc_mcontext.r15 = tf->tf_r15;
    209 	sigframe.uc.luc_mcontext.rdi = tf->tf_rdi;
    210 	sigframe.uc.luc_mcontext.rsi = tf->tf_rsi;
    211 	sigframe.uc.luc_mcontext.rbp = tf->tf_rbp;
    212 	sigframe.uc.luc_mcontext.rbx = tf->tf_rbx;
    213 	sigframe.uc.luc_mcontext.rdx = tf->tf_rdx;
    214 	sigframe.uc.luc_mcontext.rax = tf->tf_rax;
    215 	sigframe.uc.luc_mcontext.rcx = tf->tf_rcx;
    216 	sigframe.uc.luc_mcontext.rsp = tf->tf_rsp;
    217 	sigframe.uc.luc_mcontext.rip = tf->tf_rip;
    218 	sigframe.uc.luc_mcontext.eflags = tf->tf_rflags;
    219 	sigframe.uc.luc_mcontext.cs = tf->tf_cs;
    220 	sigframe.uc.luc_mcontext.gs = tf->tf_gs;
    221 	sigframe.uc.luc_mcontext.fs = tf->tf_fs;
    222 	sigframe.uc.luc_mcontext.err = tf->tf_err;
    223 	sigframe.uc.luc_mcontext.trapno = tf->tf_trapno;
    224 	native_to_linux_sigset(&lmask, mask);
    225 	sigframe.uc.luc_mcontext.oldmask = lmask.sig[0];
    226 	sigframe.uc.luc_mcontext.cr2 = (long)l->l_addr->u_pcb.pcb_onfault;
    227 	sigframe.uc.luc_mcontext.fpstate = fpsp;
    228 	native_to_linux_sigset(&sigframe.uc.luc_sigmask, mask);
    229 
    230 	/*
    231 	 * the siginfo structure
    232 	 */
    233 	sigframe.info.lsi_signo = native_to_linux_signo[sig];
    234 	sigframe.info.lsi_errno = native_to_linux_errno[ksi->ksi_errno];
    235 	sigframe.info.lsi_code = ksi->ksi_code;
    236 
    237 	/* XXX This is a rought conversion, taken from i386 code */
    238 	switch (sigframe.info.lsi_signo) {
    239 	case LINUX_SIGILL:
    240 	case LINUX_SIGFPE:
    241 	case LINUX_SIGSEGV:
    242 	case LINUX_SIGBUS:
    243 	case LINUX_SIGTRAP:
    244 		sigframe.info._sifields._sigfault._addr = ksi->ksi_addr;
    245 		break;
    246 	case LINUX_SIGCHLD:
    247 		sigframe.info._sifields._sigchld._pid = ksi->ksi_pid;
    248 		sigframe.info._sifields._sigchld._uid = ksi->ksi_uid;
    249 		sigframe.info._sifields._sigchld._utime = ksi->ksi_utime;
    250 		sigframe.info._sifields._sigchld._stime = ksi->ksi_stime;
    251 
    252 		if (WCOREDUMP(ksi->ksi_status)) {
    253 			sigframe.info.lsi_code = LINUX_CLD_DUMPED;
    254 			sigframe.info._sifields._sigchld._status =
    255 			    _WSTATUS(ksi->ksi_status);
    256 		} else if (_WSTATUS(ksi->ksi_status)) {
    257 			sigframe.info.lsi_code = LINUX_CLD_KILLED;
    258 			sigframe.info._sifields._sigchld._status =
    259 			    _WSTATUS(ksi->ksi_status);
    260 		} else {
    261 			sigframe.info.lsi_code = LINUX_CLD_EXITED;
    262 			sigframe.info._sifields._sigchld._status =
    263 			    ((ksi->ksi_status & 0xff00U) >> 8);
    264 		}
    265 		break;
    266 	case LINUX_SIGIO:
    267 		sigframe.info._sifields._sigpoll._band = ksi->ksi_band;
    268 		sigframe.info._sifields._sigpoll._fd = ksi->ksi_fd;
    269 		break;
    270 	default:
    271 		sigframe.info._sifields._sigchld._pid = ksi->ksi_pid;
    272 		sigframe.info._sifields._sigchld._uid = ksi->ksi_uid;
    273 		if ((sigframe.info.lsi_signo == LINUX_SIGALRM) ||
    274 		    (sigframe.info.lsi_signo >= LINUX_SIGRTMIN))
    275 			sigframe.info._sifields._timer._sigval.sival_ptr =
    276 			     ksi->ksi_value.sival_ptr;
    277 		break;
    278 	}
    279 
    280 	sendsig_reset(l, sig);
    281 	mutex_exit(&p->p_smutex);
    282 	error = 0;
    283 
    284 	/*
    285 	 * Save FPU state, if any
    286 	 */
    287 	if (fpsp != NULL) {
    288 		(void)process_read_fpregs(l, &fpregs);
    289 		bzero(&fpstate, sizeof(fpstate));
    290 		fpstate.cwd = fpregs.fp_fcw;
    291 		fpstate.swd = fpregs.fp_fsw;
    292 		fpstate.twd = fpregs.fp_ftw;
    293 		fpstate.fop = fpregs.fp_fop;
    294 		fpstate.rip = fpregs.fp_rip;
    295 		fpstate.rdp = fpregs.fp_rdp;
    296 		fpstate.mxcsr = fpregs.fp_mxcsr;
    297 		fpstate.mxcsr_mask = fpregs.fp_mxcsr_mask;
    298 		memcpy(&fpstate.st_space, &fpregs.fp_st,
    299 		    sizeof(fpstate.st_space));
    300 		memcpy(&fpstate.xmm_space, &fpregs.fp_xmm,
    301 		    sizeof(fpstate.xmm_space));
    302 		error = copyout(&fpstate, fpsp, sizeof(fpstate));
    303 	}
    304 
    305 	if (error == 0)
    306 		error = copyout(&sigframe, sp, sizeof(sigframe));
    307 
    308 	mutex_enter(&p->p_smutex);
    309 
    310 	if (error != 0) {
    311 		sigexit(l, SIGILL);
    312 		return;
    313 	}
    314 
    315 	linux_buildcontext(l, catcher, sp);
    316 	tf->tf_rdi = sigframe.info.lsi_signo;
    317 	tf->tf_rax = 0;
    318 	tf->tf_rsi = (long)&sfp->info;
    319 	tf->tf_rdx = (long)&sfp->uc;
    320 
    321 	/*
    322 	 * Remember we use signal stack
    323 	 */
    324 	if (onstack)
    325 		l->l_sigstk.ss_flags |= SS_ONSTACK;
    326 	return;
    327 }
    328 
    329 int
    330 linux_sys_modify_ldt(l, v, retval)
    331         struct lwp *l;
    332         void *v;
    333         register_t *retval;
    334 {
    335 	printf("linux_sys_modify_ldt\n");
    336 	return 0;
    337 }
    338 
    339 int
    340 linux_sys_iopl(l, v, retval)
    341         struct lwp *l;
    342         void *v;
    343         register_t *retval;
    344 {
    345 	return 0;
    346 }
    347 
    348 int
    349 linux_sys_ioperm(l, v, retval)
    350         struct lwp *l;
    351         void *v;
    352         register_t *retval;
    353 {
    354 	return 0;
    355 }
    356 
    357 dev_t
    358 linux_fakedev(dev, raw)
    359         dev_t dev;
    360 	int raw;
    361 {
    362 
    363        extern const struct cdevsw ptc_cdevsw, pts_cdevsw;
    364        const struct cdevsw *cd = cdevsw_lookup(dev);
    365 
    366        if (raw) {
    367 #if (NWSDISPLAY > 0)
    368 	       extern const struct cdevsw wsdisplay_cdevsw;
    369 	       if (cd == &wsdisplay_cdevsw)
    370 		       return makedev(LINUX_CONS_MAJOR, (minor(dev) + 1));
    371 #endif
    372        }
    373 
    374        if (cd == &ptc_cdevsw)
    375 	       return makedev(LINUX_PTC_MAJOR, minor(dev));
    376        if (cd == &pts_cdevsw)
    377 	       return makedev(LINUX_PTS_MAJOR, minor(dev));
    378 
    379 	return ((minor(dev) & 0xff) | ((major(dev) & 0xfff) << 8)
    380 	    | (((unsigned long long int) (minor(dev) & ~0xff)) << 12)
    381 	    | (((unsigned long long int) (major(dev) & ~0xfff)) << 32));
    382 }
    383 
    384 int
    385 linux_machdepioctl(l, v, retval)
    386         struct lwp *l;
    387         void *v;
    388         register_t *retval;
    389 {
    390 	return 0;
    391 }
    392 
    393 int
    394 linux_sys_rt_sigreturn(l, v, retval)
    395         struct lwp *l;
    396         void *v;
    397         register_t *retval;
    398 {
    399 	struct linux_ucontext *luctx;
    400 	struct trapframe *tf = l->l_md.md_regs;
    401 	struct linux_sigcontext *lsigctx;
    402 	struct linux__fpstate fpstate;
    403 	struct linux_rt_sigframe frame, *fp;
    404 	ucontext_t uctx;
    405 	mcontext_t *mctx;
    406 	struct fxsave64 *fxarea;
    407 	int error;
    408 
    409 	fp = (struct linux_rt_sigframe *)(tf->tf_rsp - 8);
    410 	if ((error = copyin(fp, &frame, sizeof(frame))) != 0) {
    411 		mutex_enter(&l->l_proc->p_smutex);
    412 		sigexit(l, SIGILL);
    413 		return error;
    414 	}
    415 	luctx = &frame.uc;
    416 	lsigctx = &luctx->luc_mcontext;
    417 
    418 	bzero(&uctx, sizeof(uctx));
    419 	mctx = (mcontext_t *)&uctx.uc_mcontext;
    420 	fxarea = (struct fxsave64 *)&mctx->__fpregs;
    421 
    422 	/*
    423 	 * Set the flags. Linux always have CPU, stack and signal state,
    424 	 * FPU is optional. uc_flags is not used to tell what we have.
    425 	 */
    426 	uctx.uc_flags = (_UC_SIGMASK|_UC_CPU|_UC_STACK|_UC_CLRSTACK);
    427 	if (lsigctx->fpstate != NULL)
    428 		uctx.uc_flags |= _UC_FPU;
    429 	uctx.uc_link = NULL;
    430 
    431 	/*
    432 	 * Signal set
    433 	 */
    434 	linux_to_native_sigset(&uctx.uc_sigmask, &luctx->luc_sigmask);
    435 
    436 	/*
    437 	 * CPU state
    438 	 */
    439 	mctx->__gregs[_REG_R8] = lsigctx->r8;
    440 	mctx->__gregs[_REG_R9] = lsigctx->r9;
    441 	mctx->__gregs[_REG_R10] = lsigctx->r10;
    442 	mctx->__gregs[_REG_R11] = lsigctx->r11;
    443 	mctx->__gregs[_REG_R12] = lsigctx->r12;
    444 	mctx->__gregs[_REG_R13] = lsigctx->r13;
    445 	mctx->__gregs[_REG_R14] = lsigctx->r14;
    446 	mctx->__gregs[_REG_R15] = lsigctx->r15;
    447 	mctx->__gregs[_REG_RDI] = lsigctx->rdi;
    448 	mctx->__gregs[_REG_RSI] = lsigctx->rsi;
    449 	mctx->__gregs[_REG_RBP] = lsigctx->rbp;
    450 	mctx->__gregs[_REG_RBX] = lsigctx->rbx;
    451 	mctx->__gregs[_REG_RAX] = lsigctx->rax;
    452 	mctx->__gregs[_REG_RDX] = lsigctx->rdx;
    453 	mctx->__gregs[_REG_RCX] = lsigctx->rcx;
    454 	mctx->__gregs[_REG_RIP] = lsigctx->rip;
    455 	mctx->__gregs[_REG_RFL] = lsigctx->eflags;
    456 	mctx->__gregs[_REG_CS] = lsigctx->cs;
    457 	mctx->__gregs[_REG_GS] = lsigctx->gs;
    458 	mctx->__gregs[_REG_FS] = lsigctx->fs;
    459 	mctx->__gregs[_REG_ERR] = lsigctx->err;
    460 	mctx->__gregs[_REG_TRAPNO] = lsigctx->trapno;
    461 	mctx->__gregs[_REG_ES] = tf->tf_es;
    462 	mctx->__gregs[_REG_DS] = tf->tf_ds;
    463 	mctx->__gregs[_REG_URSP] = lsigctx->rsp; /* XXX */
    464 	mctx->__gregs[_REG_SS] = tf->tf_ss;
    465 
    466 	/*
    467 	 * FPU state
    468 	 */
    469 	if (lsigctx->fpstate != NULL) {
    470 		error = copyin(lsigctx->fpstate, &fpstate, sizeof(fpstate));
    471 		if (error != 0) {
    472 			mutex_enter(&l->l_proc->p_smutex);
    473 			sigexit(l, SIGILL);
    474 			return error;
    475 		}
    476 
    477 		fxarea->fx_fcw = fpstate.cwd;
    478 		fxarea->fx_fsw = fpstate.swd;
    479 		fxarea->fx_ftw = fpstate.twd;
    480 		fxarea->fx_fop = fpstate.fop;
    481 		fxarea->fx_rip = fpstate.rip;
    482 		fxarea->fx_rdp = fpstate.rdp;
    483 		fxarea->fx_mxcsr = fpstate.mxcsr;
    484 		fxarea->fx_mxcsr_mask = fpstate.mxcsr_mask;
    485 		memcpy(&fxarea->fx_st, &fpstate.st_space,
    486 		    sizeof(fxarea->fx_st));
    487 		memcpy(&fxarea->fx_xmm, &fpstate.xmm_space,
    488 		    sizeof(fxarea->fx_xmm));
    489 	}
    490 
    491 	/*
    492 	 * And the stack
    493 	 */
    494 	uctx.uc_stack.ss_flags = 0;
    495 	if (luctx->luc_stack.ss_flags & LINUX_SS_ONSTACK);
    496 		uctx.uc_stack.ss_flags = SS_ONSTACK;
    497 
    498 	if (luctx->luc_stack.ss_flags & LINUX_SS_DISABLE);
    499 		uctx.uc_stack.ss_flags = SS_DISABLE;
    500 
    501 	uctx.uc_stack.ss_sp = luctx->luc_stack.ss_sp;
    502 	uctx.uc_stack.ss_size = luctx->luc_stack.ss_size;
    503 
    504 	/*
    505 	 * And let setucontext deal with that.
    506 	 */
    507 	mutex_enter(&l->l_proc->p_smutex);
    508 	error = setucontext(l, &uctx);
    509 	mutex_exit(&l->l_proc->p_smutex);
    510 	if (error)
    511 		return error;
    512 
    513 	return EJUSTRETURN;
    514 }
    515 
    516 int
    517 linux_sys_arch_prctl(l, v, retval)
    518 	struct lwp *l;
    519 	void *v;
    520 	register_t *retval;
    521 {
    522 	struct linux_sys_arch_prctl_args /* {
    523 		syscallarg(int) code;
    524 		syscallarg(unsigned long) addr;
    525 	} */ *uap = v;
    526 	struct pcb *pcb = &l->l_addr->u_pcb;
    527 	struct trapframe *tf = l->l_md.md_regs;
    528 	int error;
    529 	uint64_t taddr;
    530 
    531 	switch(SCARG(uap, code)) {
    532 	case LINUX_ARCH_SET_GS:
    533 		taddr = SCARG(uap, addr);
    534 		if (taddr >= VM_MAXUSER_ADDRESS)
    535 			return EINVAL;
    536 		pcb->pcb_gs = taddr;
    537 		pcb->pcb_flags |= PCB_GS64;
    538 		if (l == curlwp)
    539 			wrmsr(MSR_KERNELGSBASE, taddr);
    540 		break;
    541 
    542 	case LINUX_ARCH_GET_GS:
    543 		if (pcb->pcb_flags & PCB_GS64)
    544 			taddr = pcb->pcb_gs;
    545 		else {
    546 			error = memseg_baseaddr(l, tf->tf_fs, NULL, 0, &taddr);
    547 			if (error != 0)
    548 				return error;
    549 		}
    550 		error = copyout(&taddr, (char *)SCARG(uap, addr), 8);
    551 		if (error != 0)
    552 			return error;
    553 		break;
    554 
    555 	case LINUX_ARCH_SET_FS:
    556 		taddr = SCARG(uap, addr);
    557 		if (taddr >= VM_MAXUSER_ADDRESS)
    558 			return EINVAL;
    559 		pcb->pcb_fs = taddr;
    560 		pcb->pcb_flags |= PCB_FS64;
    561 		if (l == curlwp)
    562 			wrmsr(MSR_FSBASE, taddr);
    563 		break;
    564 
    565 	case LINUX_ARCH_GET_FS:
    566 		if (pcb->pcb_flags & PCB_FS64)
    567 			taddr = pcb->pcb_fs;
    568 		else {
    569 			error = memseg_baseaddr(l, tf->tf_fs, NULL, 0, &taddr);
    570 			if (error != 0)
    571 				return error;
    572 		}
    573 		error = copyout(&taddr, (char *)SCARG(uap, addr), 8);
    574 		if (error != 0)
    575 			return error;
    576 		break;
    577 
    578 	default:
    579 #ifdef DEBUG_LINUX
    580 		printf("linux_sys_arch_prctl: unexpected code %d\n",
    581 		    SCARG(uap, code));
    582 #endif
    583 		return EINVAL;
    584 	}
    585 
    586 	return 0;
    587 }
    588 
    589 const int linux_vsyscall_to_syscall[] = {
    590 	LINUX_SYS_gettimeofday,
    591 	LINUX_SYS_time,
    592 	LINUX_SYS_nosys,
    593 	LINUX_SYS_nosys,
    594 };
    595 
    596 int
    597 linux_usertrap(struct lwp *l, vaddr_t trapaddr, void *arg)
    598 {
    599 	struct trapframe *tf = arg;
    600 	uint64_t retaddr;
    601 	int vsyscallnr;
    602 
    603 	/*
    604 	 * Check for a vsyscall. %rip must be the fault address,
    605 	 * and the address must be in the Linux vsyscall area.
    606 	 * Also, vsyscalls are only done at 1024-byte boundaries.
    607 	 */
    608 
    609 	if (__predict_true(trapaddr < LINUX_VSYSCALL_START))
    610 		return 0;
    611 
    612 	if (trapaddr != tf->tf_rip)
    613 		return 0;
    614 
    615 	if ((tf->tf_rip & (LINUX_VSYSCALL_SIZE - 1)) != 0)
    616 		return 0;
    617 
    618 	vsyscallnr = (tf->tf_rip - LINUX_VSYSCALL_START) / LINUX_VSYSCALL_SIZE;
    619 
    620 	if (vsyscallnr > LINUX_VSYSCALL_MAXNR)
    621 		return 0;
    622 
    623 	/*
    624 	 * Get the return address from the top of the stack,
    625 	 * and fix up the return address.
    626 	 * This assumes the faulting instruction was callq *reg,
    627 	 * which is the only way that vsyscalls are ever entered.
    628 	 */
    629 	if (copyin((void *)tf->tf_rsp, &retaddr, sizeof retaddr) != 0)
    630 		return 0;
    631 	tf->tf_rip = retaddr;
    632 	tf->tf_rax = linux_vsyscall_to_syscall[vsyscallnr];
    633 	tf->tf_rsp += 8;	/* "pop" the return address */
    634 
    635 #if 0
    636 	printf("usertrap: rip %p rsp %p retaddr %p vsys %d sys %d\n",
    637 	    (void *)tf->tf_rip, (void *)tf->tf_rsp, (void *)retaddr,
    638 	    vsyscallnr, (int)tf->tf_rax);
    639 #endif
    640 
    641 	(*l->l_proc->p_md.md_syscall)(tf);
    642 
    643 	return 1;
    644 }
    645 
    646 static void
    647 linux_buildcontext(struct lwp *l, void *catcher, void *f)
    648 {
    649 	struct trapframe *tf = l->l_md.md_regs;
    650 
    651 	tf->tf_ds = GSEL(GUDATA_SEL, SEL_UPL);
    652 	tf->tf_rip = (u_int64_t)catcher;
    653 	tf->tf_cs = GSEL(GUCODE_SEL, SEL_UPL);
    654 	tf->tf_rflags &= ~(PSL_T|PSL_VM|PSL_AC);
    655 	tf->tf_rsp = (u_int64_t)f;
    656 	tf->tf_ss = GSEL(GUDATA_SEL, SEL_UPL);
    657 }
    658 
    659 void *
    660 linux_get_newtls(l)
    661 	struct lwp *l;
    662 {
    663 	struct trapframe *tf = l->l_md.md_regs;
    664 
    665 	return (void *)tf->tf_r8;
    666 }
    667 
    668 int
    669 linux_set_newtls(l, tls)
    670 	struct lwp *l;
    671 	void *tls;
    672 {
    673 	struct linux_sys_arch_prctl_args cup;
    674 	register_t retval;
    675 
    676 	SCARG(&cup, code) = LINUX_ARCH_SET_FS;
    677 	SCARG(&cup, addr) = (unsigned long)tls;
    678 
    679 	return linux_sys_arch_prctl(l, &cup, &retval);
    680 }
    681