Attachment #248297 for bug #247327




    struct linux_set_thread_area_args *args)
{
	struct l_user_desc info;
	struct linux_emuldata *em;
	struct pcb *pcb;
	int error;


	if (error)
		return (error);

	/* Linux keeps 3 GDT entries for TLS: glibc uses the first one,
	 * Wine uses the second and nobody seems to be using the third.
	 * We only maintain 2 such entries, so that suits us just fine.
	 * This syscall loads one of the selected TLS decriptors with a value
	 * and also loads GDT descriptors 6, 7 and 8 with the content of
	 * the per-thread descriptors.
	 *
	 * Semantics of FreeBSD version: I think we can ignore that Linux has
	 * three per-thread descriptors and use just the first one.
	 * The tls_array[] is used only in [gs]et_thread_area() syscalls and
	 * for loading the GDT descriptors. We use just one GDT descriptor
	 * for TLS, so we will load just one.
	 *
	 * XXX: This doesn't work when a user space process tries to use more
	 * than one TLS segment. Comment in the Linux source says wine might
	 * do this.
	 */
	if (info.entry_number == -1) {
		em = em_find(td);
		switch (em->tls_slots_used) {
		case 0:
			info.entry_number = GUGS32_SEL;
			em->tls_slots_used++;
			break;
		case 1:
			info.entry_number = GUFS32_SEL;
			em->tls_slots_used++;
			break;
		default:
			return (ESRCH);
		}

		/* We have to copy out entry_number. */
		error = copyout(&info, args->desc, sizeof(struct l_user_desc));
		if (error)
			return (error);
	}

	/*
	 * GLIBC reads current %gs and call set_thread_area() with it.
	 * We should let GUDATA_SEL and GUGS32_SEL proceed as well because
	 * we use these segments.
	 */
	switch (info.entry_number) {
	case GUGS32_SEL:
		pcb = td->td_pcb;
		update_pcb_bases(pcb);
		pcb->pcb_gsbase = (register_t)info.base_addr;
		update_gdt_gsbase(td, info.base_addr);
		break;
	case GUFS32_SEL:
		pcb = td->td_pcb;
		update_pcb_bases(pcb);
		pcb->pcb_fsbase = (register_t)info.base_addr;
		update_gdt_fsbase(td, info.base_addr);
		break;
	default:
		return (EINVAL);
	}

	/*
	 * We have to copy out the GDT entry we use.
	 *
	 * XXX: What if a user space program does not check the return value
	 * and tries to use 6, 7 or 8?
	 */
	error = copyout(&info, args->desc, sizeof(struct l_user_desc));
	if (error)
		return (error);

	pcb = td->td_pcb;
	update_pcb_bases(pcb);
	pcb->pcb_gsbase = (register_t)info.base_addr;
	update_gdt_gsbase(td, info.base_addr);

	return (0);
}





void
linux_proc_init(struct thread *td, struct thread *newtd, bool init_thread)
{
	struct linux_emuldata *em, *old_em;
	struct linux_pemuldata *pem;
	struct proc *p;

	if (newtd != NULL) {
		p = newtd->td_proc;
		old_em = em_find(td);

		/* non-exec call */
		em = malloc(sizeof(*em), M_TEMP, M_WAITOK | M_ZERO);

			    newtd->td_tid);

			em->em_tid = newtd->td_tid;
			em->tls_slots_used = old_em != NULL ? old_em->tls_slots_used : 0;
		} else {
			LINUX_CTR1(proc_init, "fork newtd(%d)", p->p_pid);

			em->em_tid = p->p_pid;
			em->tls_slots_used = old_em != NULL ? old_em->tls_slots_used : 0;

			pem = malloc(sizeof(*pem), M_LINUX, M_WAITOK | M_ZERO);
			sx_init(&pem->pem_sx, "lpemlk");

		em->robust_futexes = NULL;
		em->child_clear_tid = NULL;
		em->child_set_tid = NULL;
		em->tls_slots_used = 0;

		pem = pem_find(p);
		KASSERT(pem != NULL, ("proc_init: proc emuldata not found.\n"));

Lines 46-51 struct linux_emuldata { Link Here

(-)b/sys/compat/linux/linux_emul.h (-1 / +2 lines)
46	int em_tid; /* thread id */	46	int em_tid; /* thread id */
47		47
48	struct linux_robust_list_head *robust_futexes;	48	struct linux_robust_list_head *robust_futexes;
		49
		50	int tls_slots_used; /* GDT descriptor count for set_thread_area() on i386/amd64 */
49	};	51	};
50		52
51	struct linux_emuldata em_find(struct thread );	53	struct linux_emuldata em_find(struct thread );
52	-

Return to bug 247327

Lines 628-633 linux_set_thread_area(struct thread *td, Link Here

(-)b/sys/amd64/linux32/linux32_machdep.c (-40 / +34 lines)
628	struct linux_set_thread_area_args *args)	628	struct linux_set_thread_area_args *args)
629	{	629	{
630	struct l_user_desc info;	630	struct l_user_desc info;
		631	struct linux_emuldata *em;
631	struct pcb *pcb;	632	struct pcb *pcb;
632	int error;	633	int error;
633		634
Lines 635-689 linux_set_thread_area(struct thread *td, Link Here
635	if (error)	636	if (error)
636	return (error);	637	return (error);
637		638
638	/*	639	/* Linux keeps 3 GDT entries for TLS: glibc uses the first one,
639	* Semantics of Linux version: every thread in the system has array	640	* Wine uses the second and nobody seems to be using the third.
640	* of three TLS descriptors. 1st is GLIBC TLS, 2nd is WINE, 3rd unknown.	641	* We only maintain 2 such entries, so that suits us just fine.
641	* This syscall loads one of the selected TLS decriptors with a value
642	* and also loads GDT descriptors 6, 7 and 8 with the content of
643	* the per-thread descriptors.
644	*
645	* Semantics of FreeBSD version: I think we can ignore that Linux has
646	* three per-thread descriptors and use just the first one.
647	* The tls_array[] is used only in [gs]et_thread_area() syscalls and
648	* for loading the GDT descriptors. We use just one GDT descriptor
649	* for TLS, so we will load just one.
650	*
651	* XXX: This doesn't work when a user space process tries to use more
652	* than one TLS segment. Comment in the Linux source says wine might
653	* do this.
654	*/	642	*/
		643	if (info.entry_number == -1) {
		644	em = em_find(td);
		645	switch (em->tls_slots_used) {
		646	case 0:
		647	info.entry_number = GUGS32_SEL;
		648	em->tls_slots_used++;
		649	break;
		650	case 1:
		651	info.entry_number = GUFS32_SEL;
		652	em->tls_slots_used++;
		653	break;
		654	default:
		655	return (ESRCH);
		656	}
		657
		658	/* We have to copy out entry_number. */
		659	error = copyout(&info, args->desc, sizeof(struct l_user_desc));
		660	if (error)
		661	return (error);
		662	}
655		663
656	/*
657	* GLIBC reads current %gs and call set_thread_area() with it.
658	* We should let GUDATA_SEL and GUGS32_SEL proceed as well because
659	* we use these segments.
660	*/
661	switch (info.entry_number) {	664	switch (info.entry_number) {
662	case GUGS32_SEL:	665	case GUGS32_SEL:
663	case GUDATA_SEL:	666	pcb = td->td_pcb;
664	case 6:	667	update_pcb_bases(pcb);
665	case -1:	668	pcb->pcb_gsbase = (register_t)info.base_addr;
666	info.entry_number = GUGS32_SEL;	669	update_gdt_gsbase(td, info.base_addr);
		670	break;
		671	case GUFS32_SEL:
		672	pcb = td->td_pcb;
		673	update_pcb_bases(pcb);
		674	pcb->pcb_fsbase = (register_t)info.base_addr;
		675	update_gdt_fsbase(td, info.base_addr);
667	break;	676	break;
668	default:	677	default:
669	return (EINVAL);	678	return (EINVAL);
670	}	679	}
671		680
672	/*
673	* We have to copy out the GDT entry we use.
674	*
675	* XXX: What if a user space program does not check the return value
676	* and tries to use 6, 7 or 8?
677	*/
678	error = copyout(&info, args->desc, sizeof(struct l_user_desc));
679	if (error)
680	return (error);
681
682	pcb = td->td_pcb;
683	update_pcb_bases(pcb);
684	pcb->pcb_gsbase = (register_t)info.base_addr;
685	update_gdt_gsbase(td, info.base_addr);
686
687	return (0);	681	return (0);
688	}	682	}
689		683

Lines 141-152 linux_set_default_stacksize(struct thread td, struct proc p) Link Here

(-)b/sys/compat/linux/linux_emul.c (-1 / +5 lines)
141	void	141	void
142	linux_proc_init(struct thread td, struct thread newtd, bool init_thread)	142	linux_proc_init(struct thread td, struct thread newtd, bool init_thread)
143	{	143	{
144	struct linux_emuldata *em;	144	struct linux_emuldata em, old_em;
145	struct linux_pemuldata *pem;	145	struct linux_pemuldata *pem;
146	struct proc *p;	146	struct proc *p;
147		147
148	if (newtd != NULL) {	148	if (newtd != NULL) {
149	p = newtd->td_proc;	149	p = newtd->td_proc;
		150	old_em = em_find(td);
150		151
151	/* non-exec call */	152	/* non-exec call */
152	em = malloc(sizeof(*em), M_TEMP, M_WAITOK \| M_ZERO);	153	em = malloc(sizeof(*em), M_TEMP, M_WAITOK \| M_ZERO);
Lines 155-164 linux_proc_init(struct thread td, struct thread newtd, bool init_thread) Link Here
155	newtd->td_tid);	156	newtd->td_tid);
156		157
157	em->em_tid = newtd->td_tid;	158	em->em_tid = newtd->td_tid;
		159	em->tls_slots_used = old_em != NULL ? old_em->tls_slots_used : 0;
158	} else {	160	} else {
159	LINUX_CTR1(proc_init, "fork newtd(%d)", p->p_pid);	161	LINUX_CTR1(proc_init, "fork newtd(%d)", p->p_pid);
160		162
161	em->em_tid = p->p_pid;	163	em->em_tid = p->p_pid;
		164	em->tls_slots_used = old_em != NULL ? old_em->tls_slots_used : 0;
162		165
163	pem = malloc(sizeof(*pem), M_LINUX, M_WAITOK \| M_ZERO);	166	pem = malloc(sizeof(*pem), M_LINUX, M_WAITOK \| M_ZERO);
164	sx_init(&pem->pem_sx, "lpemlk");	167	sx_init(&pem->pem_sx, "lpemlk");
Lines 183-188 linux_proc_init(struct thread td, struct thread newtd, bool init_thread) Link Here
183	em->robust_futexes = NULL;	186	em->robust_futexes = NULL;
184	em->child_clear_tid = NULL;	187	em->child_clear_tid = NULL;
185	em->child_set_tid = NULL;	188	em->child_set_tid = NULL;
		189	em->tls_slots_used = 0;
186		190
187	pem = pem_find(p);	191	pem = pem_find(p);
188	KASSERT(pem != NULL, ("proc_init: proc emuldata not found.\n"));	192	KASSERT(pem != NULL, ("proc_init: proc emuldata not found.\n"));