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linux_machdep.c revision 1.29.2.5
      1 /*	$NetBSD: linux_machdep.c,v 1.29.2.5 2010/08/11 22:53:04 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 1.29.2.5 2010/08/11 22:53:04 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/ucontext.h>
     46 #include <sys/conf.h>
     47 
     48 #include <machine/reg.h>
     49 #include <machine/pcb.h>
     50 #include <machine/fpu.h>
     51 #include <machine/mcontext.h>
     52 #include <machine/specialreg.h>
     53 #include <machine/vmparam.h>
     54 #include <machine/cpufunc.h>
     55 
     56 /*
     57  * To see whether wscons is configured (for virtual console ioctl calls).
     58  */
     59 #if defined(_KERNEL_OPT)
     60 #include "wsdisplay.h"
     61 #endif
     62 #if (NWSDISPLAY > 0)
     63 #include <dev/wscons/wsconsio.h>
     64 #include <dev/wscons/wsdisplay_usl_io.h>
     65 #endif
     66 
     67 
     68 #include <compat/linux/common/linux_signal.h>
     69 #include <compat/linux/common/linux_errno.h>
     70 #include <compat/linux/common/linux_exec.h>
     71 #include <compat/linux/common/linux_ioctl.h>
     72 #include <compat/linux/common/linux_prctl.h>
     73 #include <compat/linux/common/linux_machdep.h>
     74 #include <compat/linux/common/linux_ipc.h>
     75 #include <compat/linux/common/linux_sem.h>
     76 #include <compat/linux/linux_syscall.h>
     77 #include <compat/linux/linux_syscallargs.h>
     78 
     79 static void linux_buildcontext(struct lwp *, void *, void *);
     80 
     81 void
     82 linux_setregs(struct lwp *l, struct exec_package *epp, vaddr_t stack)
     83 {
     84 	struct pcb *pcb = lwp_getpcb(l);
     85 	struct trapframe *tf;
     86 
     87 	/* If we were using the FPU, forget about it. */
     88 	if (pcb->pcb_fpcpu != NULL)
     89 		fpusave_lwp(l, 0);
     90 
     91 	l->l_md.md_flags &= ~MDP_USEDFPU;
     92 	pcb->pcb_flags = 0;
     93 	pcb->pcb_savefpu.fp_fxsave.fx_fcw = __NetBSD_NPXCW__;
     94 	pcb->pcb_savefpu.fp_fxsave.fx_mxcsr = __INITIAL_MXCSR__;
     95 	pcb->pcb_savefpu.fp_fxsave.fx_mxcsr_mask = __INITIAL_MXCSR_MASK__;
     96 
     97 	l->l_proc->p_flag &= ~PK_32;
     98 
     99 	tf = l->l_md.md_regs;
    100 	tf->tf_rax = 0;
    101 	tf->tf_rbx = 0;
    102 	tf->tf_rcx = epp->ep_entry;
    103 	tf->tf_rdx = 0;
    104 	tf->tf_rsi = 0;
    105 	tf->tf_rdi = 0;
    106 	tf->tf_rbp = 0;
    107 	tf->tf_rsp = stack;
    108 	tf->tf_r8 = 0;
    109 	tf->tf_r9 = 0;
    110 	tf->tf_r10 = 0;
    111 	tf->tf_r11 = 0;
    112 	tf->tf_r12 = 0;
    113 	tf->tf_r13 = 0;
    114 	tf->tf_r14 = 0;
    115 	tf->tf_r15 = 0;
    116 	tf->tf_rip = epp->ep_entry;
    117 	tf->tf_rflags = PSL_USERSET;
    118 	tf->tf_cs = GSEL(GUCODE_SEL, SEL_UPL);
    119 	tf->tf_ss = GSEL(GUDATA_SEL, SEL_UPL);
    120 	tf->tf_ds = 0;
    121 	tf->tf_es = 0;
    122 	cpu_fsgs_zero(l);
    123 
    124 	return;
    125 }
    126 
    127 void
    128 linux_sendsig(const ksiginfo_t *ksi, const sigset_t *mask)
    129 {
    130 	struct lwp *l = curlwp;
    131 	struct proc *p = l->l_proc;
    132 	struct pcb *pcb = lwp_getpcb(l);
    133 	struct sigacts *ps = p->p_sigacts;
    134 	int onstack, error;
    135 	int sig = ksi->ksi_signo;
    136 	struct linux_rt_sigframe *sfp, sigframe;
    137 	struct linux__fpstate *fpsp, fpstate;
    138 	struct fpreg fpregs;
    139 	struct trapframe *tf = l->l_md.md_regs;
    140 	sig_t catcher = SIGACTION(p, sig).sa_handler;
    141 	linux_sigset_t lmask;
    142 	char *sp;
    143 
    144 	/* Do we need to jump onto the signal stack? */
    145 	onstack =
    146 	    (l->l_sigstk.ss_flags & (SS_DISABLE | SS_ONSTACK)) == 0 &&
    147 	    (SIGACTION(p, sig).sa_flags & SA_ONSTACK) != 0;
    148 
    149 	/* Allocate space for the signal handler context. */
    150 	if (onstack)
    151 		sp = ((char *)l->l_sigstk.ss_sp +
    152 		    l->l_sigstk.ss_size);
    153 	else
    154 		sp = (char *)tf->tf_rsp - 128;
    155 
    156 	/*
    157 	 * Save FPU state, if any
    158 	 */
    159 	if (l->l_md.md_flags & MDP_USEDFPU) {
    160 		sp = (char *)
    161 		    (((long)sp - sizeof(struct linux__fpstate)) & ~0xfUL);
    162 		fpsp = (struct linux__fpstate *)sp;
    163 	} else
    164 		fpsp = NULL;
    165 
    166 	/*
    167 	 * Populate the rt_sigframe
    168 	 */
    169 	sp = (char *)
    170 	    ((((long)sp - sizeof(struct linux_rt_sigframe)) & ~0xfUL) - 8);
    171 	sfp = (struct linux_rt_sigframe *)sp;
    172 
    173 	memset(&sigframe, 0, sizeof(sigframe));
    174 	if (ps->sa_sigdesc[sig].sd_vers != 0)
    175 		sigframe.pretcode =
    176 		    (char *)(u_long)ps->sa_sigdesc[sig].sd_tramp;
    177 	else
    178 		sigframe.pretcode = NULL;
    179 
    180 	/*
    181 	 * The user context
    182 	 */
    183 	sigframe.uc.luc_flags = 0;
    184 	sigframe.uc.luc_link = NULL;
    185 
    186 	/* This is used regardless of SA_ONSTACK in Linux */
    187 	sigframe.uc.luc_stack.ss_sp = l->l_sigstk.ss_sp;
    188 	sigframe.uc.luc_stack.ss_size = l->l_sigstk.ss_size;
    189 	sigframe.uc.luc_stack.ss_flags = 0;
    190 	if (l->l_sigstk.ss_flags & SS_ONSTACK)
    191 		sigframe.uc.luc_stack.ss_flags |= LINUX_SS_ONSTACK;
    192 	if (l->l_sigstk.ss_flags & SS_DISABLE)
    193 		sigframe.uc.luc_stack.ss_flags |= LINUX_SS_DISABLE;
    194 
    195 	sigframe.uc.luc_mcontext.r8 = tf->tf_r8;
    196 	sigframe.uc.luc_mcontext.r9 = tf->tf_r9;
    197 	sigframe.uc.luc_mcontext.r10 = tf->tf_r10;
    198 	sigframe.uc.luc_mcontext.r11 = tf->tf_r11;
    199 	sigframe.uc.luc_mcontext.r12 = tf->tf_r12;
    200 	sigframe.uc.luc_mcontext.r13 = tf->tf_r13;
    201 	sigframe.uc.luc_mcontext.r14 = tf->tf_r14;
    202 	sigframe.uc.luc_mcontext.r15 = tf->tf_r15;
    203 	sigframe.uc.luc_mcontext.rdi = tf->tf_rdi;
    204 	sigframe.uc.luc_mcontext.rsi = tf->tf_rsi;
    205 	sigframe.uc.luc_mcontext.rbp = tf->tf_rbp;
    206 	sigframe.uc.luc_mcontext.rbx = tf->tf_rbx;
    207 	sigframe.uc.luc_mcontext.rdx = tf->tf_rdx;
    208 	sigframe.uc.luc_mcontext.rax = tf->tf_rax;
    209 	sigframe.uc.luc_mcontext.rcx = tf->tf_rcx;
    210 	sigframe.uc.luc_mcontext.rsp = tf->tf_rsp;
    211 	sigframe.uc.luc_mcontext.rip = tf->tf_rip;
    212 	sigframe.uc.luc_mcontext.eflags = tf->tf_rflags;
    213 	sigframe.uc.luc_mcontext.cs = tf->tf_cs;
    214 	sigframe.uc.luc_mcontext.gs = tf->tf_gs;
    215 	sigframe.uc.luc_mcontext.fs = tf->tf_fs;
    216 	sigframe.uc.luc_mcontext.err = tf->tf_err;
    217 	sigframe.uc.luc_mcontext.trapno = tf->tf_trapno;
    218 	native_to_linux_sigset(&lmask, mask);
    219 	sigframe.uc.luc_mcontext.oldmask = lmask.sig[0];
    220 	sigframe.uc.luc_mcontext.cr2 = (long)pcb->pcb_onfault;
    221 	sigframe.uc.luc_mcontext.fpstate = fpsp;
    222 	native_to_linux_sigset(&sigframe.uc.luc_sigmask, mask);
    223 
    224 	/*
    225 	 * the siginfo structure
    226 	 */
    227 	sigframe.info.lsi_signo = native_to_linux_signo[sig];
    228 	sigframe.info.lsi_errno = native_to_linux_errno[ksi->ksi_errno];
    229 	sigframe.info.lsi_code = native_to_linux_si_code(ksi->ksi_code);
    230 
    231 	/* XXX This is a rought conversion, taken from i386 code */
    232 	switch (sigframe.info.lsi_signo) {
    233 	case LINUX_SIGILL:
    234 	case LINUX_SIGFPE:
    235 	case LINUX_SIGSEGV:
    236 	case LINUX_SIGBUS:
    237 	case LINUX_SIGTRAP:
    238 		sigframe.info._sifields._sigfault._addr = ksi->ksi_addr;
    239 		break;
    240 	case LINUX_SIGCHLD:
    241 		sigframe.info._sifields._sigchld._pid = ksi->ksi_pid;
    242 		sigframe.info._sifields._sigchld._uid = ksi->ksi_uid;
    243 		sigframe.info._sifields._sigchld._utime = ksi->ksi_utime;
    244 		sigframe.info._sifields._sigchld._stime = ksi->ksi_stime;
    245 		sigframe.info._sifields._sigchld._status =
    246 		    native_to_linux_si_status(ksi->ksi_code, ksi->ksi_status);
    247 		break;
    248 	case LINUX_SIGIO:
    249 		sigframe.info._sifields._sigpoll._band = ksi->ksi_band;
    250 		sigframe.info._sifields._sigpoll._fd = ksi->ksi_fd;
    251 		break;
    252 	default:
    253 		sigframe.info._sifields._sigchld._pid = ksi->ksi_pid;
    254 		sigframe.info._sifields._sigchld._uid = ksi->ksi_uid;
    255 		if ((sigframe.info.lsi_signo == LINUX_SIGALRM) ||
    256 		    (sigframe.info.lsi_signo >= LINUX_SIGRTMIN))
    257 			sigframe.info._sifields._timer._sigval.sival_ptr =
    258 			     ksi->ksi_value.sival_ptr;
    259 		break;
    260 	}
    261 
    262 	sendsig_reset(l, sig);
    263 	mutex_exit(p->p_lock);
    264 	error = 0;
    265 
    266 	/*
    267 	 * Save FPU state, if any
    268 	 */
    269 	if (fpsp != NULL) {
    270 		(void)process_read_fpregs(l, &fpregs);
    271 		memset(&fpstate, 0, sizeof(fpstate));
    272 		fpstate.cwd = fpregs.fp_fcw;
    273 		fpstate.swd = fpregs.fp_fsw;
    274 		fpstate.twd = fpregs.fp_ftw;
    275 		fpstate.fop = fpregs.fp_fop;
    276 		fpstate.rip = fpregs.fp_rip;
    277 		fpstate.rdp = fpregs.fp_rdp;
    278 		fpstate.mxcsr = fpregs.fp_mxcsr;
    279 		fpstate.mxcsr_mask = fpregs.fp_mxcsr_mask;
    280 		memcpy(&fpstate.st_space, &fpregs.fp_st,
    281 		    sizeof(fpstate.st_space));
    282 		memcpy(&fpstate.xmm_space, &fpregs.fp_xmm,
    283 		    sizeof(fpstate.xmm_space));
    284 		error = copyout(&fpstate, fpsp, sizeof(fpstate));
    285 	}
    286 
    287 	if (error == 0)
    288 		error = copyout(&sigframe, sp, sizeof(sigframe));
    289 
    290 	mutex_enter(p->p_lock);
    291 
    292 	if (error != 0) {
    293 		sigexit(l, SIGILL);
    294 		return;
    295 	}
    296 
    297 	linux_buildcontext(l, catcher, sp);
    298 	tf->tf_rdi = sigframe.info.lsi_signo;
    299 	tf->tf_rax = 0;
    300 	tf->tf_rsi = (long)&sfp->info;
    301 	tf->tf_rdx = (long)&sfp->uc;
    302 
    303 	/*
    304 	 * Remember we use signal stack
    305 	 */
    306 	if (onstack)
    307 		l->l_sigstk.ss_flags |= SS_ONSTACK;
    308 	return;
    309 }
    310 
    311 int
    312 linux_sys_modify_ldt(struct lwp *l, const struct linux_sys_modify_ldt_args *v, register_t *retval)
    313 {
    314 	printf("linux_sys_modify_ldt\n");
    315 	return 0;
    316 }
    317 
    318 int
    319 linux_sys_iopl(struct lwp *l, const struct linux_sys_iopl_args *v, register_t *retval)
    320 {
    321 	return 0;
    322 }
    323 
    324 int
    325 linux_sys_ioperm(struct lwp *l, const struct linux_sys_ioperm_args *v, register_t *retval)
    326 {
    327 	return 0;
    328 }
    329 
    330 dev_t
    331 linux_fakedev(dev_t dev, int raw)
    332 {
    333 
    334        extern const struct cdevsw ptc_cdevsw, pts_cdevsw;
    335        const struct cdevsw *cd = cdevsw_lookup(dev);
    336 
    337        if (raw) {
    338 #if (NWSDISPLAY > 0)
    339 	       extern const struct cdevsw wsdisplay_cdevsw;
    340 	       if (cd == &wsdisplay_cdevsw)
    341 		       return makedev(LINUX_CONS_MAJOR, (minor(dev) + 1));
    342 #endif
    343        }
    344 
    345        if (cd == &ptc_cdevsw)
    346 	       return makedev(LINUX_PTC_MAJOR, minor(dev));
    347        if (cd == &pts_cdevsw)
    348 	       return makedev(LINUX_PTS_MAJOR, minor(dev));
    349 
    350 	return ((minor(dev) & 0xff) | ((major(dev) & 0xfff) << 8)
    351 	    | (((unsigned long long int) (minor(dev) & ~0xff)) << 12)
    352 	    | (((unsigned long long int) (major(dev) & ~0xfff)) << 32));
    353 }
    354 
    355 int
    356 linux_machdepioctl(struct lwp *l, const struct linux_sys_ioctl_args *v, register_t *retval)
    357 {
    358 	return 0;
    359 }
    360 
    361 int
    362 linux_sys_rt_sigreturn(struct lwp *l, const void *v, register_t *retval)
    363 {
    364 	struct linux_ucontext *luctx;
    365 	struct trapframe *tf = l->l_md.md_regs;
    366 	struct linux_sigcontext *lsigctx;
    367 	struct linux__fpstate fpstate;
    368 	struct linux_rt_sigframe frame, *fp;
    369 	ucontext_t uctx;
    370 	mcontext_t *mctx;
    371 	struct fxsave64 *fxarea;
    372 	int error;
    373 
    374 	fp = (struct linux_rt_sigframe *)(tf->tf_rsp - 8);
    375 	if ((error = copyin(fp, &frame, sizeof(frame))) != 0) {
    376 		mutex_enter(l->l_proc->p_lock);
    377 		sigexit(l, SIGILL);
    378 		return error;
    379 	}
    380 	luctx = &frame.uc;
    381 	lsigctx = &luctx->luc_mcontext;
    382 
    383 	memset(&uctx, 0, sizeof(uctx));
    384 	mctx = (mcontext_t *)&uctx.uc_mcontext;
    385 	fxarea = (struct fxsave64 *)&mctx->__fpregs;
    386 
    387 	/*
    388 	 * Set the flags. Linux always have CPU, stack and signal state,
    389 	 * FPU is optional. uc_flags is not used to tell what we have.
    390 	 */
    391 	uctx.uc_flags = (_UC_SIGMASK|_UC_CPU|_UC_STACK|_UC_CLRSTACK);
    392 	if (lsigctx->fpstate != NULL)
    393 		uctx.uc_flags |= _UC_FPU;
    394 	uctx.uc_link = NULL;
    395 
    396 	/*
    397 	 * Signal set
    398 	 */
    399 	linux_to_native_sigset(&uctx.uc_sigmask, &luctx->luc_sigmask);
    400 
    401 	/*
    402 	 * CPU state
    403 	 */
    404 	mctx->__gregs[_REG_R8] = lsigctx->r8;
    405 	mctx->__gregs[_REG_R9] = lsigctx->r9;
    406 	mctx->__gregs[_REG_R10] = lsigctx->r10;
    407 	mctx->__gregs[_REG_R11] = lsigctx->r11;
    408 	mctx->__gregs[_REG_R12] = lsigctx->r12;
    409 	mctx->__gregs[_REG_R13] = lsigctx->r13;
    410 	mctx->__gregs[_REG_R14] = lsigctx->r14;
    411 	mctx->__gregs[_REG_R15] = lsigctx->r15;
    412 	mctx->__gregs[_REG_RDI] = lsigctx->rdi;
    413 	mctx->__gregs[_REG_RSI] = lsigctx->rsi;
    414 	mctx->__gregs[_REG_RBP] = lsigctx->rbp;
    415 	mctx->__gregs[_REG_RBX] = lsigctx->rbx;
    416 	mctx->__gregs[_REG_RAX] = lsigctx->rax;
    417 	mctx->__gregs[_REG_RDX] = lsigctx->rdx;
    418 	mctx->__gregs[_REG_RCX] = lsigctx->rcx;
    419 	mctx->__gregs[_REG_RIP] = lsigctx->rip;
    420 	mctx->__gregs[_REG_RFLAGS] = lsigctx->eflags;
    421 	mctx->__gregs[_REG_CS] = lsigctx->cs;
    422 	mctx->__gregs[_REG_GS] = lsigctx->gs;
    423 	mctx->__gregs[_REG_FS] = lsigctx->fs;
    424 	mctx->__gregs[_REG_ERR] = lsigctx->err;
    425 	mctx->__gregs[_REG_TRAPNO] = lsigctx->trapno;
    426 	mctx->__gregs[_REG_ES] = tf->tf_es;
    427 	mctx->__gregs[_REG_DS] = tf->tf_ds;
    428 	mctx->__gregs[_REG_RSP] = lsigctx->rsp; /* XXX */
    429 	mctx->__gregs[_REG_SS] = tf->tf_ss;
    430 
    431 	/*
    432 	 * FPU state
    433 	 */
    434 	if (lsigctx->fpstate != NULL) {
    435 		error = copyin(lsigctx->fpstate, &fpstate, sizeof(fpstate));
    436 		if (error != 0) {
    437 			mutex_enter(l->l_proc->p_lock);
    438 			sigexit(l, SIGILL);
    439 			return error;
    440 		}
    441 
    442 		fxarea->fx_fcw = fpstate.cwd;
    443 		fxarea->fx_fsw = fpstate.swd;
    444 		fxarea->fx_ftw = fpstate.twd;
    445 		fxarea->fx_fop = fpstate.fop;
    446 		fxarea->fx_rip = fpstate.rip;
    447 		fxarea->fx_rdp = fpstate.rdp;
    448 		fxarea->fx_mxcsr = fpstate.mxcsr;
    449 		fxarea->fx_mxcsr_mask = fpstate.mxcsr_mask;
    450 		memcpy(&fxarea->fx_st, &fpstate.st_space,
    451 		    sizeof(fxarea->fx_st));
    452 		memcpy(&fxarea->fx_xmm, &fpstate.xmm_space,
    453 		    sizeof(fxarea->fx_xmm));
    454 	}
    455 
    456 	/*
    457 	 * And the stack
    458 	 */
    459 	uctx.uc_stack.ss_flags = 0;
    460 	if (luctx->luc_stack.ss_flags & LINUX_SS_ONSTACK)
    461 		uctx.uc_stack.ss_flags |= SS_ONSTACK;
    462 
    463 	if (luctx->luc_stack.ss_flags & LINUX_SS_DISABLE)
    464 		uctx.uc_stack.ss_flags |= SS_DISABLE;
    465 
    466 	uctx.uc_stack.ss_sp = luctx->luc_stack.ss_sp;
    467 	uctx.uc_stack.ss_size = luctx->luc_stack.ss_size;
    468 
    469 	/*
    470 	 * And let setucontext deal with that.
    471 	 */
    472 	mutex_enter(l->l_proc->p_lock);
    473 	error = setucontext(l, &uctx);
    474 	mutex_exit(l->l_proc->p_lock);
    475 	if (error)
    476 		return error;
    477 
    478 	return EJUSTRETURN;
    479 }
    480 
    481 int
    482 linux_sys_arch_prctl(struct lwp *l,
    483     const struct linux_sys_arch_prctl_args *uap, register_t *retval)
    484 {
    485 	/* {
    486 		syscallarg(int) code;
    487 		syscallarg(unsigned long) addr;
    488 	} */
    489 	void *addr = (void *)SCARG(uap, addr);
    490 
    491 	switch(SCARG(uap, code)) {
    492 	case LINUX_ARCH_SET_GS:
    493 		return x86_set_sdbase(addr, 'g', l, true);
    494 
    495 	case LINUX_ARCH_GET_GS:
    496 		return x86_get_sdbase(addr, 'g');
    497 
    498 	case LINUX_ARCH_SET_FS:
    499 		return x86_set_sdbase(addr, 'f', l, true);
    500 
    501 	case LINUX_ARCH_GET_FS:
    502 		return x86_get_sdbase(addr, 'f');
    503 
    504 	default:
    505 #ifdef DEBUG_LINUX
    506 		printf("linux_sys_arch_prctl: unexpected code %d\n",
    507 		    SCARG(uap, code));
    508 #endif
    509 		return EINVAL;
    510 	}
    511 	/* NOTREACHED */
    512 }
    513 
    514 const int linux_vsyscall_to_syscall[] = {
    515 	LINUX_SYS_gettimeofday,
    516 	LINUX_SYS_time,
    517 	LINUX_SYS_nosys,	/* nosys */
    518 	LINUX_SYS_nosys,	/* nosys */
    519 };
    520 
    521 int
    522 linux_usertrap(struct lwp *l, vaddr_t trapaddr, void *arg)
    523 {
    524 	struct trapframe *tf = arg;
    525 	uint64_t retaddr;
    526 	int vsyscallnr;
    527 
    528 	/*
    529 	 * Check for a vsyscall. %rip must be the fault address,
    530 	 * and the address must be in the Linux vsyscall area.
    531 	 * Also, vsyscalls are only done at 1024-byte boundaries.
    532 	 */
    533 
    534 	if (__predict_true(trapaddr < LINUX_VSYSCALL_START))
    535 		return 0;
    536 
    537 	if (trapaddr != tf->tf_rip)
    538 		return 0;
    539 
    540 	if ((tf->tf_rip & (LINUX_VSYSCALL_SIZE - 1)) != 0)
    541 		return 0;
    542 
    543 	vsyscallnr = (tf->tf_rip - LINUX_VSYSCALL_START) / LINUX_VSYSCALL_SIZE;
    544 
    545 	if (vsyscallnr > LINUX_VSYSCALL_MAXNR)
    546 		return 0;
    547 
    548 	/*
    549 	 * Get the return address from the top of the stack,
    550 	 * and fix up the return address.
    551 	 * This assumes the faulting instruction was callq *reg,
    552 	 * which is the only way that vsyscalls are ever entered.
    553 	 */
    554 	if (copyin((void *)tf->tf_rsp, &retaddr, sizeof retaddr) != 0)
    555 		return 0;
    556 	tf->tf_rip = retaddr;
    557 	tf->tf_rax = linux_vsyscall_to_syscall[vsyscallnr];
    558 	tf->tf_rsp += 8;	/* "pop" the return address */
    559 
    560 #if 0
    561 	printf("usertrap: rip %p rsp %p retaddr %p vsys %d sys %d\n",
    562 	    (void *)tf->tf_rip, (void *)tf->tf_rsp, (void *)retaddr,
    563 	    vsyscallnr, (int)tf->tf_rax);
    564 #endif
    565 
    566 	(*l->l_proc->p_md.md_syscall)(tf);
    567 
    568 	return 1;
    569 }
    570 
    571 static void
    572 linux_buildcontext(struct lwp *l, void *catcher, void *f)
    573 {
    574 	struct trapframe *tf = l->l_md.md_regs;
    575 
    576 	tf->tf_ds = GSEL(GUDATA_SEL, SEL_UPL);
    577 	tf->tf_rip = (u_int64_t)catcher;
    578 	tf->tf_cs = GSEL(GUCODE_SEL, SEL_UPL);
    579 	tf->tf_rflags &= ~PSL_CLEARSIG;
    580 	tf->tf_rsp = (u_int64_t)f;
    581 	tf->tf_ss = GSEL(GUDATA_SEL, SEL_UPL);
    582 }
    583