uint_t get_syscall_args(klwp_t *lwp, long *argp, int *nargsp) { kthread_t *t = lwptot(lwp); ulong_t mask = 0xfffffffful; uint_t code; long *ap; int nargs; #if defined(_LP64) if (lwp_getdatamodel(lwp) == DATAMODEL_LP64) mask = 0xfffffffffffffffful; #endif /* * The thread lock must be held while looking at the arguments to ensure * they don't go away via post_syscall(). * get_syscall_args() is the only routine to read them which is callable * outside the LWP in question and hence the only one that must be * synchronized in this manner. */ thread_lock(t); code = t->t_sysnum; ap = lwp->lwp_ap; thread_unlock(t); if (code != 0 && code < NSYSCALL) { nargs = LWP_GETSYSENT(lwp)[code].sy_narg; ASSERT(nargs <= MAXSYSARGS); *nargsp = nargs; while (nargs-- > 0) *argp++ = *ap++ & mask; } else { *nargsp = 0; } return (code); }
/* * Perform pre-system-call processing, including stopping for tracing, * auditing, etc. * * This routine is called only if the t_pre_sys flag is set. Any condition * requiring pre-syscall handling must set the t_pre_sys flag. If the * condition is persistent, this routine will repost t_pre_sys. */ int pre_syscall() { kthread_t *t = curthread; unsigned code = t->t_sysnum; klwp_t *lwp = ttolwp(t); proc_t *p = ttoproc(t); int repost; t->t_pre_sys = repost = 0; /* clear pre-syscall processing flag */ ASSERT(t->t_schedflag & TS_DONT_SWAP); #if defined(DEBUG) /* * On the i386 kernel, lwp_ap points at the piece of the thread * stack that we copy the users arguments into. * * On the amd64 kernel, the syscall arguments in the rdi..r9 * registers should be pointed at by lwp_ap. If the args need to * be copied so that those registers can be changed without losing * the ability to get the args for /proc, they can be saved by * save_syscall_args(), and lwp_ap will be restored by post_syscall(). */ if (lwp_getdatamodel(lwp) == DATAMODEL_NATIVE) { #if defined(_LP64) ASSERT(lwp->lwp_ap == (long *)&lwptoregs(lwp)->r_rdi); } else { #endif ASSERT((caddr_t)lwp->lwp_ap > t->t_stkbase && (caddr_t)lwp->lwp_ap < t->t_stk); } #endif /* DEBUG */ /* * Make sure the thread is holding the latest credentials for the * process. The credentials in the process right now apply to this * thread for the entire system call. */ if (t->t_cred != p->p_cred) { cred_t *oldcred = t->t_cred; /* * DTrace accesses t_cred in probe context. t_cred must * always be either NULL, or point to a valid, allocated cred * structure. */ t->t_cred = crgetcred(); crfree(oldcred); } /* * From the proc(4) manual page: * When entry to a system call is being traced, the traced process * stops after having begun the call to the system but before the * system call arguments have been fetched from the process. */ if (PTOU(p)->u_systrap) { if (prismember(&PTOU(p)->u_entrymask, code)) { mutex_enter(&p->p_lock); /* * Recheck stop condition, now that lock is held. */ if (PTOU(p)->u_systrap && prismember(&PTOU(p)->u_entrymask, code)) { stop(PR_SYSENTRY, code); /* * /proc may have modified syscall args, * either in regs for amd64 or on ustack * for ia32. Either way, arrange to * copy them again, both for the syscall * handler and for other consumers in * post_syscall (like audit). Here, we * only do amd64, and just set lwp_ap * back to the kernel-entry stack copy; * the syscall ml code redoes * move-from-regs to set up for the * syscall handler after we return. For * ia32, save_syscall_args() below makes * an lwp_ap-accessible copy. */ #if defined(_LP64) if (lwp_getdatamodel(lwp) == DATAMODEL_NATIVE) { lwp->lwp_argsaved = 0; lwp->lwp_ap = (long *)&lwptoregs(lwp)->r_rdi; } #endif } mutex_exit(&p->p_lock); } repost = 1; } /* * ia32 kernel, or ia32 proc on amd64 kernel: keep args in * lwp_arg for post-syscall processing, regardless of whether * they might have been changed in /proc above. */ #if defined(_LP64) if (lwp_getdatamodel(lwp) != DATAMODEL_NATIVE) #endif (void) save_syscall_args(); if (lwp->lwp_sysabort) { /* * lwp_sysabort may have been set via /proc while the process * was stopped on PR_SYSENTRY. If so, abort the system call. * Override any error from the copyin() of the arguments. */ lwp->lwp_sysabort = 0; (void) set_errno(EINTR); /* forces post_sys */ t->t_pre_sys = 1; /* repost anyway */ return (1); /* don't do system call, return EINTR */ } #ifdef C2_AUDIT if (audit_active) { /* begin auditing for this syscall */ int error; if (error = audit_start(T_SYSCALL, code, 0, lwp)) { t->t_pre_sys = 1; /* repost anyway */ (void) set_errno(error); return (1); } repost = 1; } #endif /* C2_AUDIT */ #ifndef NPROBE /* Kernel probe */ if (tnf_tracing_active) { TNF_PROBE_1(syscall_start, "syscall thread", /* CSTYLED */, tnf_sysnum, sysnum, t->t_sysnum); t->t_post_sys = 1; /* make sure post_syscall runs */ repost = 1; } #endif /* NPROBE */ #ifdef SYSCALLTRACE if (syscalltrace) { int i; long *ap; char *cp; char *sysname; struct sysent *callp; if (code >= NSYSCALL) callp = &nosys_ent; /* nosys has no args */ else callp = LWP_GETSYSENT(lwp) + code; (void) save_syscall_args(); mutex_enter(&systrace_lock); printf("%d: ", p->p_pid); if (code >= NSYSCALL) printf("0x%x", code); else { sysname = mod_getsysname(code); printf("%s[0x%x/0x%p]", sysname == NULL ? "NULL" : sysname, code, callp->sy_callc); } cp = "("; for (i = 0, ap = lwp->lwp_ap; i < callp->sy_narg; i++, ap++) { printf("%s%lx", cp, *ap); cp = ", "; } if (i) printf(")"); printf(" %s id=0x%p\n", PTOU(p)->u_comm, curthread); mutex_exit(&systrace_lock); } #endif /* SYSCALLTRACE */ /* * If there was a continuing reason for pre-syscall processing, * set the t_pre_sys flag for the next system call. */ if (repost) t->t_pre_sys = 1; lwp->lwp_error = 0; /* for old drivers */ lwp->lwp_badpriv = PRIV_NONE; return (0); }
/* * Post-syscall processing. Perform abnormal system call completion * actions such as /proc tracing, profiling, signals, preemption, etc. * * This routine is called only if t_post_sys, t_sig_check, or t_astflag is set. * Any condition requiring pre-syscall handling must set one of these. * If the condition is persistent, this routine will repost t_post_sys. */ void post_syscall(long rval1, long rval2) { kthread_t *t = curthread; klwp_t *lwp = ttolwp(t); proc_t *p = ttoproc(t); struct regs *rp = lwptoregs(lwp); uint_t error; uint_t code = t->t_sysnum; int repost = 0; int proc_stop = 0; /* non-zero if stopping */ int sigprof = 0; /* non-zero if sending SIGPROF */ t->t_post_sys = 0; error = lwp->lwp_errno; /* * Code can be zero if this is a new LWP returning after a forkall(), * other than the one which matches the one in the parent which called * forkall(). In these LWPs, skip most of post-syscall activity. */ if (code == 0) goto sig_check; /* * If the trace flag is set, mark the lwp to take a single-step trap * on return to user level (below). The x86 lcall interface and * sysenter has already done this, and turned off the flag, but * amd64 syscall interface has not. */ if (rp->r_ps & PS_T) { lwp->lwp_pcb.pcb_flags |= DEBUG_PENDING; rp->r_ps &= ~PS_T; aston(curthread); } #ifdef C2_AUDIT if (audit_active) { /* put out audit record for this syscall */ rval_t rval; /* XX64 -- truncation of 64-bit return values? */ rval.r_val1 = (int)rval1; rval.r_val2 = (int)rval2; audit_finish(T_SYSCALL, code, error, &rval); repost = 1; } #endif /* C2_AUDIT */ if (curthread->t_pdmsg != NULL) { char *m = curthread->t_pdmsg; uprintf("%s", m); kmem_free(m, strlen(m) + 1); curthread->t_pdmsg = NULL; } /* * If we're going to stop for /proc tracing, set the flag and * save the arguments so that the return values don't smash them. */ if (PTOU(p)->u_systrap) { if (prismember(&PTOU(p)->u_exitmask, code)) { if (lwp_getdatamodel(lwp) == DATAMODEL_LP64) (void) save_syscall_args(); proc_stop = 1; } repost = 1; } /* * Similarly check to see if SIGPROF might be sent. */ if (curthread->t_rprof != NULL && curthread->t_rprof->rp_anystate != 0) { if (lwp_getdatamodel(lwp) == DATAMODEL_LP64) (void) save_syscall_args(); sigprof = 1; } if (lwp->lwp_eosys == NORMALRETURN) { if (error == 0) { #ifdef SYSCALLTRACE if (syscalltrace) { mutex_enter(&systrace_lock); printf( "%d: r_val1=0x%lx, r_val2=0x%lx, id 0x%p\n", p->p_pid, rval1, rval2, curthread); mutex_exit(&systrace_lock); } #endif /* SYSCALLTRACE */ rp->r_ps &= ~PS_C; rp->r_r0 = rval1; rp->r_r1 = rval2; } else { int sig; #ifdef SYSCALLTRACE if (syscalltrace) { mutex_enter(&systrace_lock); printf("%d: error=%d, id 0x%p\n", p->p_pid, error, curthread); mutex_exit(&systrace_lock); } #endif /* SYSCALLTRACE */ if (error == EINTR && t->t_activefd.a_stale) error = EBADF; if (error == EINTR && (sig = lwp->lwp_cursig) != 0 && sigismember(&PTOU(p)->u_sigrestart, sig) && PTOU(p)->u_signal[sig - 1] != SIG_DFL && PTOU(p)->u_signal[sig - 1] != SIG_IGN) error = ERESTART; rp->r_r0 = error; rp->r_ps |= PS_C; } } /* * From the proc(4) manual page: * When exit from a system call is being traced, the traced process * stops on completion of the system call just prior to checking for * signals and returning to user level. At this point all return * values have been stored into the traced process's saved registers. */ if (proc_stop) { mutex_enter(&p->p_lock); if (PTOU(p)->u_systrap && prismember(&PTOU(p)->u_exitmask, code)) stop(PR_SYSEXIT, code); mutex_exit(&p->p_lock); } /* * If we are the parent returning from a successful * vfork, wait for the child to exec or exit. * This code must be here and not in the bowels of the system * so that /proc can intercept exit from vfork in a timely way. */ if (code == SYS_vfork && rp->r_r1 == 0 && error == 0) vfwait((pid_t)rval1); /* * If profiling is active, bill the current PC in user-land * and keep reposting until profiling is disabled. */ if (p->p_prof.pr_scale) { if (lwp->lwp_oweupc) profil_tick(rp->r_pc); repost = 1; } sig_check: /* * Reset flag for next time. * We must do this after stopping on PR_SYSEXIT * because /proc uses the information in lwp_eosys. */ lwp->lwp_eosys = NORMALRETURN; clear_stale_fd(); t->t_flag &= ~T_FORKALL; if (t->t_astflag | t->t_sig_check) { /* * Turn off the AST flag before checking all the conditions that * may have caused an AST. This flag is on whenever a signal or * unusual condition should be handled after the next trap or * syscall. */ astoff(t); /* * If a single-step trap occurred on a syscall (see trap()) * recognize it now. Do this before checking for signals * because deferred_singlestep_trap() may generate a SIGTRAP to * the LWP or may otherwise mark the LWP to call issig(FORREAL). */ if (lwp->lwp_pcb.pcb_flags & DEBUG_PENDING) deferred_singlestep_trap((caddr_t)rp->r_pc); t->t_sig_check = 0; /* * The following check is legal for the following reasons: * 1) The thread we are checking, is ourselves, so there is * no way the proc can go away. * 2) The only time we need to be protected by the * lock is if the binding is changed. * * Note we will still take the lock and check the binding * if the condition was true without the lock held. This * prevents lock contention among threads owned by the * same proc. */ if (curthread->t_proc_flag & TP_CHANGEBIND) { mutex_enter(&p->p_lock); if (curthread->t_proc_flag & TP_CHANGEBIND) { timer_lwpbind(); curthread->t_proc_flag &= ~TP_CHANGEBIND; } mutex_exit(&p->p_lock); } /* * for kaio requests on the special kaio poll queue, * copyout their results to user memory. */ if (p->p_aio) aio_cleanup(0); /* * If this LWP was asked to hold, call holdlwp(), which will * stop. holdlwps() sets this up and calls pokelwps() which * sets the AST flag. * * Also check TP_EXITLWP, since this is used by fresh new LWPs * through lwp_rtt(). That flag is set if the lwp_create(2) * syscall failed after creating the LWP. */ if (ISHOLD(p) || (t->t_proc_flag & TP_EXITLWP)) holdlwp(); /* * All code that sets signals and makes ISSIG_PENDING * evaluate true must set t_sig_check afterwards. */ if (ISSIG_PENDING(t, lwp, p)) { if (issig(FORREAL)) psig(); t->t_sig_check = 1; /* recheck next time */ } if (sigprof) { realsigprof(code, error); t->t_sig_check = 1; /* recheck next time */ } /* * If a performance counter overflow interrupt was * delivered *during* the syscall, then re-enable the * AST so that we take a trip through trap() to cause * the SIGEMT to be delivered. */ if (lwp->lwp_pcb.pcb_flags & CPC_OVERFLOW) aston(t); /* * /proc can't enable/disable the trace bit itself * because that could race with the call gate used by * system calls via "lcall". If that happened, an * invalid EFLAGS would result. prstep()/prnostep() * therefore schedule an AST for the purpose. */ if (lwp->lwp_pcb.pcb_flags & REQUEST_STEP) { lwp->lwp_pcb.pcb_flags &= ~REQUEST_STEP; rp->r_ps |= PS_T; } if (lwp->lwp_pcb.pcb_flags & REQUEST_NOSTEP) { lwp->lwp_pcb.pcb_flags &= ~REQUEST_NOSTEP; rp->r_ps &= ~PS_T; } } lwp->lwp_errno = 0; /* clear error for next time */ #ifndef NPROBE /* Kernel probe */ if (tnf_tracing_active) { TNF_PROBE_3(syscall_end, "syscall thread", /* CSTYLED */, tnf_long, rval1, rval1, tnf_long, rval2, rval2, tnf_long, errno, (long)error); repost = 1; } #endif /* NPROBE */ /* * Set state to LWP_USER here so preempt won't give us a kernel * priority if it occurs after this point. Call CL_TRAPRET() to * restore the user-level priority. * * It is important that no locks (other than spinlocks) be entered * after this point before returning to user mode (unless lwp_state * is set back to LWP_SYS). * * XXX Sampled times past this point are charged to the user. */ lwp->lwp_state = LWP_USER; if (t->t_trapret) { t->t_trapret = 0; thread_lock(t); CL_TRAPRET(t); thread_unlock(t); } if (CPU->cpu_runrun) preempt(); lwp->lwp_errno = 0; /* clear error for next time */ /* * The thread lock must be held in order to clear sysnum and reset * lwp_ap atomically with respect to other threads in the system that * may be looking at the args via lwp_ap from get_syscall_args(). */ thread_lock(t); t->t_sysnum = 0; /* no longer in a system call */ if (lwp_getdatamodel(lwp) == DATAMODEL_NATIVE) { #if defined(_LP64) /* * In case the args were copied to the lwp, reset the * pointer so the next syscall will have the right * lwp_ap pointer. */ lwp->lwp_ap = (long *)&rp->r_rdi; } else { #endif lwp->lwp_ap = NULL; /* reset on every syscall entry */ } thread_unlock(t); lwp->lwp_argsaved = 0; /* * If there was a continuing reason for post-syscall processing, * set the t_post_sys flag for the next system call. */ if (repost) t->t_post_sys = 1; /* * If there is a ustack registered for this lwp, and the stack rlimit * has been altered, read in the ustack. If the saved stack rlimit * matches the bounds of the ustack, update the ustack to reflect * the new rlimit. If the new stack rlimit is RLIM_INFINITY, disable * stack checking by setting the size to 0. */ if (lwp->lwp_ustack != 0 && lwp->lwp_old_stk_ctl != 0) { rlim64_t new_size; caddr_t top; stack_t stk; struct rlimit64 rl; mutex_enter(&p->p_lock); new_size = p->p_stk_ctl; top = p->p_usrstack; (void) rctl_rlimit_get(rctlproc_legacy[RLIMIT_STACK], p, &rl); mutex_exit(&p->p_lock); if (rl.rlim_cur == RLIM64_INFINITY) new_size = 0; if (copyin((stack_t *)lwp->lwp_ustack, &stk, sizeof (stack_t)) == 0 && (stk.ss_size == lwp->lwp_old_stk_ctl || stk.ss_size == 0) && stk.ss_sp == top - stk.ss_size) { stk.ss_sp = (void *)((uintptr_t)stk.ss_sp + stk.ss_size - (uintptr_t)new_size); stk.ss_size = new_size; (void) copyout(&stk, (stack_t *)lwp->lwp_ustack, sizeof (stack_t)); } lwp->lwp_old_stk_ctl = 0; } }
/* * Save the system call arguments in a safe place. * * On the i386 kernel: * * Copy the users args prior to changing the stack or stack pointer. * This is so /proc will be able to get a valid copy of the * args from the user stack even after the user stack has been changed. * Note that the kernel stack copy of the args may also have been * changed by a system call handler which takes C-style arguments. * * Note that this may be called by stop() from trap(). In that case * t_sysnum will be zero (syscall_exit clears it), so no args will be * copied. * * On the amd64 kernel: * * For 64-bit applications, lwp->lwp_ap normally points to %rdi..%r9 * in the reg structure. If the user is going to change the argument * registers, rax, or the stack and might want to get the args (for * /proc tracing), it must copy the args elsewhere via save_syscall_args(). * * For 32-bit applications, lwp->lwp_ap normally points to a copy of * the system call arguments on the kernel stack made from the user * stack. Copy the args prior to change the stack or stack pointer. * This is so /proc will be able to get a valid copy of the args * from the user stack even after that stack has been changed. * * This may be called from stop() even when we're not in a system call. * Since there's no easy way to tell, this must be safe (not panic). * If the copyins get data faults, return non-zero. */ int save_syscall_args() { kthread_t *t = curthread; klwp_t *lwp = ttolwp(t); uint_t code = t->t_sysnum; uint_t nargs; if (lwp->lwp_argsaved || code == 0) return (0); /* args already saved or not needed */ if (code >= NSYSCALL) { nargs = 0; /* illegal syscall */ } else { struct sysent *se = LWP_GETSYSENT(lwp); struct sysent *callp = se + code; nargs = callp->sy_narg; if (LOADABLE_SYSCALL(callp) && nargs == 0) { krwlock_t *module_lock; /* * Find out how many arguments the system * call uses. * * We have the property that loaded syscalls * never change the number of arguments they * use after they've been loaded once. This * allows us to stop for /proc tracing without * holding the module lock. * /proc is assured that sy_narg is valid. */ module_lock = lock_syscall(se, code); nargs = callp->sy_narg; rw_exit(module_lock); } } /* * Fetch the system call arguments. */ if (nargs == 0) goto out; ASSERT(nargs <= MAXSYSARGS); if (lwp_getdatamodel(lwp) == DATAMODEL_NATIVE) { #if defined(_LP64) struct regs *rp = lwptoregs(lwp); lwp->lwp_arg[0] = rp->r_rdi; lwp->lwp_arg[1] = rp->r_rsi; lwp->lwp_arg[2] = rp->r_rdx; lwp->lwp_arg[3] = rp->r_rcx; lwp->lwp_arg[4] = rp->r_r8; lwp->lwp_arg[5] = rp->r_r9; if (nargs > 6 && copyin_args(rp, &lwp->lwp_arg[6], nargs - 6)) return (-1); } else { #endif if (COPYIN_ARGS32(lwptoregs(lwp), lwp->lwp_arg, nargs)) return (-1); } out: lwp->lwp_ap = lwp->lwp_arg; lwp->lwp_argsaved = 1; t->t_post_sys = 1; /* so lwp_ap will be reset */ return (0); }
/* * Save the system call arguments in a safe place. * lwp->lwp_ap normally points to the out regs in the reg structure. * If the user is going to change the out registers, g1, or the stack, * and might want to get the args (for /proc tracing), it must copy * the args elsewhere via save_syscall_args(). * * This may be called from stop() even when we're not in a system call. * Since there's no easy way to tell, this must be safe (not panic). * If the copyins get data faults, return non-zero. */ int save_syscall_args() { kthread_t *t = curthread; klwp_t *lwp = ttolwp(t); struct regs *rp = lwptoregs(lwp); uint_t code = t->t_sysnum; uint_t nargs; int i; caddr_t ua; model_t datamodel; if (lwp->lwp_argsaved || code == 0) return (0); /* args already saved or not needed */ if (code >= NSYSCALL) { nargs = 0; /* illegal syscall */ } else { struct sysent *se = LWP_GETSYSENT(lwp); struct sysent *callp = se + code; nargs = callp->sy_narg; if (LOADABLE_SYSCALL(callp) && nargs == 0) { krwlock_t *module_lock; /* * Find out how many arguments the system * call uses. * * We have the property that loaded syscalls * never change the number of arguments they * use after they've been loaded once. This * allows us to stop for /proc tracing without * holding the module lock. * /proc is assured that sy_narg is valid. */ module_lock = lock_syscall(se, code); nargs = callp->sy_narg; rw_exit(module_lock); } } /* * Fetch the system call arguments. */ if (nargs == 0) goto out; ASSERT(nargs <= MAXSYSARGS); if ((datamodel = lwp_getdatamodel(lwp)) == DATAMODEL_ILP32) { if (rp->r_g1 == 0) { /* indirect syscall */ lwp->lwp_arg[0] = (uint32_t)rp->r_o1; lwp->lwp_arg[1] = (uint32_t)rp->r_o2; lwp->lwp_arg[2] = (uint32_t)rp->r_o3; lwp->lwp_arg[3] = (uint32_t)rp->r_o4; lwp->lwp_arg[4] = (uint32_t)rp->r_o5; if (nargs > 5) { ua = (caddr_t)(uintptr_t)(caddr32_t)(uintptr_t) (rp->r_sp + MINFRAME32); for (i = 5; i < nargs; i++) { uint32_t a; if (fuword32(ua, &a) != 0) return (-1); lwp->lwp_arg[i] = a; ua += sizeof (a); } } } else { lwp->lwp_arg[0] = (uint32_t)rp->r_o0; lwp->lwp_arg[1] = (uint32_t)rp->r_o1; lwp->lwp_arg[2] = (uint32_t)rp->r_o2; lwp->lwp_arg[3] = (uint32_t)rp->r_o3; lwp->lwp_arg[4] = (uint32_t)rp->r_o4; lwp->lwp_arg[5] = (uint32_t)rp->r_o5; if (nargs > 6) { ua = (caddr_t)(uintptr_t)(caddr32_t)(uintptr_t) (rp->r_sp + MINFRAME32); for (i = 6; i < nargs; i++) { uint32_t a; if (fuword32(ua, &a) != 0) return (-1); lwp->lwp_arg[i] = a; ua += sizeof (a); } } } } else { ASSERT(datamodel == DATAMODEL_LP64); lwp->lwp_arg[0] = rp->r_o0; lwp->lwp_arg[1] = rp->r_o1; lwp->lwp_arg[2] = rp->r_o2; lwp->lwp_arg[3] = rp->r_o3; lwp->lwp_arg[4] = rp->r_o4; lwp->lwp_arg[5] = rp->r_o5; if (nargs > 6) { ua = (caddr_t)rp->r_sp + MINFRAME + STACK_BIAS; for (i = 6; i < nargs; i++) { unsigned long a; if (fulword(ua, &a) != 0) return (-1); lwp->lwp_arg[i] = a; ua += sizeof (a); } } } out: lwp->lwp_ap = lwp->lwp_arg; lwp->lwp_argsaved = 1; t->t_post_sys = 1; /* so lwp_ap will be reset */ return (0); }
int lwp_setprivate(klwp_t *lwp, int which, uintptr_t base) { pcb_t *pcb = &lwp->lwp_pcb; struct regs *rp = lwptoregs(lwp); kthread_t *t = lwptot(lwp); int thisthread = t == curthread; int rval; if (thisthread) kpreempt_disable(); #if defined(__amd64) /* * 32-bit compatibility processes point to the per-cpu GDT segment * descriptors that are virtualized to the lwp. That allows 32-bit * programs to mess with %fs and %gs; in particular it allows * things like this: * * movw %gs, %ax * ... * movw %ax, %gs * * to work, which is needed by emulators for legacy application * environments .. * * 64-bit processes may also point to a per-cpu GDT segment descriptor * virtualized to the lwp. However the descriptor base is forced * to zero (because we can't express the full 64-bit address range * in a long mode descriptor), so don't reload segment registers * in a 64-bit program! 64-bit processes must have selector values * of zero for %fs and %gs to use the 64-bit fs_base and gs_base * respectively. */ if (pcb->pcb_rupdate == 0) { pcb->pcb_ds = rp->r_ds; pcb->pcb_es = rp->r_es; pcb->pcb_fs = rp->r_fs; pcb->pcb_gs = rp->r_gs; pcb->pcb_rupdate = 1; t->t_post_sys = 1; } ASSERT(t->t_post_sys); switch (which) { case _LWP_FSBASE: if (lwp_getdatamodel(lwp) == DATAMODEL_NATIVE) { set_usegd(&pcb->pcb_fsdesc, SDP_LONG, 0, 0, SDT_MEMRWA, SEL_UPL, SDP_BYTES, SDP_OP32); rval = pcb->pcb_fs = 0; /* null gdt descriptor */ } else { set_usegd(&pcb->pcb_fsdesc, SDP_SHORT, (void *)base, -1, SDT_MEMRWA, SEL_UPL, SDP_PAGES, SDP_OP32); rval = pcb->pcb_fs = LWPFS_SEL; } if (thisthread) gdt_update_usegd(GDT_LWPFS, &pcb->pcb_fsdesc); pcb->pcb_fsbase = base; break; case _LWP_GSBASE: if (lwp_getdatamodel(lwp) == DATAMODEL_NATIVE) { set_usegd(&pcb->pcb_gsdesc, SDP_LONG, 0, 0, SDT_MEMRWA, SEL_UPL, SDP_BYTES, SDP_OP32); rval = pcb->pcb_gs = 0; /* null gdt descriptor */ } else { set_usegd(&pcb->pcb_gsdesc, SDP_SHORT, (void *)base, -1, SDT_MEMRWA, SEL_UPL, SDP_PAGES, SDP_OP32); rval = pcb->pcb_gs = LWPGS_SEL; } if (thisthread) gdt_update_usegd(GDT_LWPGS, &pcb->pcb_gsdesc); pcb->pcb_gsbase = base; break; default: rval = -1; break; } #elif defined(__i386) /* * 32-bit processes point to the per-cpu GDT segment * descriptors that are virtualized to the lwp. */ switch (which) { case _LWP_FSBASE: set_usegd(&pcb->pcb_fsdesc, (void *)base, -1, SDT_MEMRWA, SEL_UPL, SDP_PAGES, SDP_OP32); if (thisthread) gdt_update_usegd(GDT_LWPFS, &pcb->pcb_fsdesc); rval = rp->r_fs = LWPFS_SEL; break; case _LWP_GSBASE: set_usegd(&pcb->pcb_gsdesc, (void *)base, -1, SDT_MEMRWA, SEL_UPL, SDP_PAGES, SDP_OP32); if (thisthread) gdt_update_usegd(GDT_LWPGS, &pcb->pcb_gsdesc); rval = rp->r_gs = LWPGS_SEL; break; default: rval = -1; break; } #endif /* __i386 */ if (thisthread) kpreempt_enable(); return (rval); }
static int lwp_getprivate(klwp_t *lwp, int which, uintptr_t base) { pcb_t *pcb = &lwp->lwp_pcb; struct regs *rp = lwptoregs(lwp); uintptr_t sbase; int error = 0; ASSERT(lwptot(lwp) == curthread); kpreempt_disable(); switch (which) { #if defined(__amd64) case _LWP_FSBASE: if ((sbase = pcb->pcb_fsbase) != 0) { if (lwp_getdatamodel(lwp) == DATAMODEL_NATIVE) { if (pcb->pcb_rupdate == 1) { if (pcb->pcb_fs == 0) break; } else { if (rp->r_fs == 0) break; } } else { if (pcb->pcb_rupdate == 1) { if (pcb->pcb_fs == LWPFS_SEL) break; } else { if (rp->r_fs == LWPFS_SEL) break; } } } error = EINVAL; break; case _LWP_GSBASE: if ((sbase = pcb->pcb_gsbase) != 0) { if (lwp_getdatamodel(lwp) == DATAMODEL_NATIVE) { if (pcb->pcb_rupdate == 1) { if (pcb->pcb_gs == 0) break; } else { if (rp->r_gs == 0) break; } } else { if (pcb->pcb_rupdate == 1) { if (pcb->pcb_gs == LWPGS_SEL) break; } else { if (rp->r_gs == LWPGS_SEL) break; } } } error = EINVAL; break; #elif defined(__i386) case _LWP_FSBASE: if (rp->r_fs == LWPFS_SEL) { sbase = USEGD_GETBASE(&pcb->pcb_fsdesc); break; } error = EINVAL; break; case _LWP_GSBASE: if (rp->r_gs == LWPGS_SEL) { sbase = USEGD_GETBASE(&pcb->pcb_gsdesc); break; } error = EINVAL; break; #endif /* __i386 */ default: error = ENOTSUP; break; } kpreempt_enable(); if (error != 0) return (error); if (lwp_getdatamodel(lwp) == DATAMODEL_NATIVE) { if (sulword((void *)base, sbase) == -1) error = EFAULT; #if defined(_SYSCALL32_IMPL) } else { if (suword32((void *)base, (uint32_t)sbase) == -1) error = EFAULT; #endif } return (error); }
/* * Add any lwp-associated context handlers to the lwp at the beginning * of the lwp's useful life. * * All paths which create lwp's invoke lwp_create(); lwp_create() * invokes lwp_stk_init() which initializes the stack, sets up * lwp_regs, and invokes this routine. * * All paths which destroy lwp's invoke lwp_exit() to rip the lwp * apart and put it on 'lwp_deathrow'; if the lwp is destroyed it * ends up in thread_free() which invokes freectx(t, 0) before * invoking lwp_stk_fini(). When the lwp is recycled from death * row, lwp_stk_fini() is invoked, then thread_free(), and thus * freectx(t, 0) as before. * * In the case of exec, the surviving lwp is thoroughly scrubbed * clean; exec invokes freectx(t, 1) to destroy associated contexts. * On the way back to the new image, it invokes setregs() which * in turn invokes this routine. */ void lwp_installctx(klwp_t *lwp) { kthread_t *t = lwptot(lwp); int thisthread = t == curthread; #ifdef _SYSCALL32_IMPL void (*restop)(klwp_t *) = lwp_getdatamodel(lwp) == DATAMODEL_NATIVE ? lwp_segregs_restore : lwp_segregs_restore32; #else void (*restop)(klwp_t *) = lwp_segregs_restore; #endif /* * Install the basic lwp context handlers on each lwp. * * On the amd64 kernel, the context handlers are responsible for * virtualizing %ds, %es, %fs, and %gs to the lwp. The register * values are only ever changed via sys_rtt when the * pcb->pcb_rupdate == 1. Only sys_rtt gets to clear the bit. * * On the i386 kernel, the context handlers are responsible for * virtualizing %gs/%fs to the lwp by updating the per-cpu GDTs */ ASSERT(removectx(t, lwp, lwp_segregs_save, restop, NULL, NULL, NULL, NULL) == 0); if (thisthread) kpreempt_disable(); installctx(t, lwp, lwp_segregs_save, restop, NULL, NULL, NULL, NULL); if (thisthread) { /* * Since we're the right thread, set the values in the GDT */ restop(lwp); kpreempt_enable(); } /* * If we have sysenter/sysexit instructions enabled, we need * to ensure that the hardware mechanism is kept up-to-date with the * lwp's kernel stack pointer across context switches. * * sep_save zeros the sysenter stack pointer msr; sep_restore sets * it to the lwp's kernel stack pointer (kstktop). */ if (is_x86_feature(x86_featureset, X86FSET_SEP)) { #if defined(__amd64) caddr_t kstktop = (caddr_t)lwp->lwp_regs; #elif defined(__i386) caddr_t kstktop = ((caddr_t)lwp->lwp_regs - MINFRAME) + SA(sizeof (struct regs) + MINFRAME); #endif ASSERT(removectx(t, kstktop, sep_save, sep_restore, NULL, NULL, NULL, NULL) == 0); if (thisthread) kpreempt_disable(); installctx(t, kstktop, sep_save, sep_restore, NULL, NULL, NULL, NULL); if (thisthread) { /* * We're the right thread, so set the stack pointer * for the first sysenter instruction to use */ sep_restore(kstktop); kpreempt_enable(); } } if (PROC_IS_BRANDED(ttoproc(t))) lwp_attach_brand_hdlrs(lwp); }