On Sat, Apr 14, 2012 at 13:35 +0200, Mike Belopuhov wrote:
> some software needs fully functional per-thread %gs base address,
> hence the diff. limited testing shows no regressions.
> INTR_RESTORE_SELECTORS changes include:
> - %r11 is used to store curpcb instead of rdx that is used for
> wrmsr and gets trashed (it's safe to use %r11 because it's
> restored after INTR_RESTORE_SELECTORS gets called);
>
> - MSR_KERNELGSBASE needs to be updated instead of MSR_GSBASE
> so that we don't lose kernel gs.base stored in MSR_GSBASE
> and swapped by the swapgs.
>
> any objections? corrections?
>
updated and improved version of the above:
- don't use ci_cur_gsbase to avoid the problem described by guenther
in the fs.base diff;
- set %gs before gs.base in order to preserve both segment value
and the override;
- change the testcase to check the GS.base value (%gs:0) as well;
ok?
Index: sys/arch/amd64/amd64/genassym.cf
===================================================================
RCS file: /home/cvs/src/sys/arch/amd64/amd64/genassym.cf,v
retrieving revision 1.29
diff -u -p -r1.29 genassym.cf
--- sys/arch/amd64/amd64/genassym.cf 17 Apr 2012 16:02:33 -0000 1.29
+++ sys/arch/amd64/amd64/genassym.cf 18 Apr 2012 09:30:46 -0000
@@ -86,6 +86,7 @@ member pcb_rsp
member pcb_rbp
member pcb_kstack
member pcb_fsbase
+member pcb_gsbase
member pcb_onfault
member pcb_fpcpu
member pcb_pmap
Index: sys/arch/amd64/amd64/machdep.c
===================================================================
RCS file: /home/cvs/src/sys/arch/amd64/amd64/machdep.c,v
retrieving revision 1.152
diff -u -p -r1.152 machdep.c
--- sys/arch/amd64/amd64/machdep.c 13 Jan 2012 12:55:52 -0000 1.152
+++ sys/arch/amd64/amd64/machdep.c 12 Apr 2012 16:41:18 -0000
@@ -363,7 +363,7 @@ x86_64_proc0_tss_ldt_init(void)
cpu_info_primary.ci_curpcb = pcb = &proc0.p_addr->u_pcb;
pcb->pcb_cr0 = rcr0();
- pcb->pcb_fsbase = 0;
+ pcb->pcb_fsbase = pcb->pcb_gsbase = 0;
pcb->pcb_kstack = (u_int64_t)proc0.p_addr + USPACE - 16;
proc0.p_md.md_regs = (struct trapframe *)pcb->pcb_kstack - 1;
@@ -1022,6 +1022,7 @@ setregs(struct proc *p, struct exec_pack
fpusave_proc(p, 0);
p->p_md.md_flags &= ~MDP_USEDFPU;
p->p_addr->u_pcb.pcb_fsbase = 0;
+ p->p_addr->u_pcb.pcb_gsbase = 0;
tf = p->p_md.md_regs;
tf->tf_ds = GSEL(GUDATA_SEL, SEL_UPL);
Index: sys/arch/amd64/amd64/sys_machdep.c
===================================================================
RCS file: /home/cvs/src/sys/arch/amd64/amd64/sys_machdep.c,v
retrieving revision 1.12
diff -u -p -r1.12 sys_machdep.c
--- sys/arch/amd64/amd64/sys_machdep.c 13 Apr 2011 02:49:12 -0000 1.12
+++ sys/arch/amd64/amd64/sys_machdep.c 12 Apr 2012 16:37:30 -0000
@@ -159,6 +159,29 @@ amd64_set_fsbase(struct proc *p, void *a
}
int
+amd64_get_gsbase(struct proc *p, void *args)
+{
+ return copyout(&p->p_addr->u_pcb.pcb_gsbase, args,
+ sizeof(p->p_addr->u_pcb.pcb_gsbase));
+}
+
+int
+amd64_set_gsbase(struct proc *p, void *args)
+{
+ int error;
+ uint64_t base;
+
+ if ((error = copyin(args, &base, sizeof(base))) != 0)
+ return (error);
+
+ if (base >= VM_MAXUSER_ADDRESS)
+ return (EINVAL);
+
+ p->p_addr->u_pcb.pcb_gsbase = base;
+ return 0;
+}
+
+int
sys_sysarch(struct proc *p, void *v, register_t *retval)
{
struct sys_sysarch_args /* {
@@ -196,12 +219,20 @@ sys_sysarch(struct proc *p, void *v, reg
break;
#endif
- case AMD64_GET_FSBASE:
+ case AMD64_GET_FSBASE:
error = amd64_get_fsbase(p, SCARG(uap, parms));
break;
- case AMD64_SET_FSBASE:
+ case AMD64_SET_FSBASE:
error = amd64_set_fsbase(p, SCARG(uap, parms));
+ break;
+
+ case AMD64_GET_GSBASE:
+ error = amd64_get_gsbase(p, SCARG(uap, parms));
+ break;
+
+ case AMD64_SET_GSBASE:
+ error = amd64_set_gsbase(p, SCARG(uap, parms));
break;
default:
Index: sys/arch/amd64/include/frameasm.h
===================================================================
RCS file: /home/cvs/src/sys/arch/amd64/include/frameasm.h,v
retrieving revision 1.7
diff -u -p -r1.7 frameasm.h
--- sys/arch/amd64/include/frameasm.h 17 Apr 2012 16:02:33 -0000 1.7
+++ sys/arch/amd64/include/frameasm.h 19 Apr 2012 15:40:44 -0000
@@ -55,27 +55,37 @@
pushq %r13 ;
/*
- * Restore %ds, %es, %fs, and %gs, dealing with the FS.base MSR for
- * %fs and doing the cli/swapgs for %gs. Uses %rax, %rcx, and %rdx
+ * Restore %ds, %es, %fs, and %gs, dealing with the FS.base MSR for %fs,
+ * GS.base MSR and and doing the cli/swapgs for %gs. Uses %rax, %rcx,
+ * %rdx and %r11.
*/
#define INTR_RESTORE_SELECTORS \
- movq CPUVAR(CURPCB),%rdx /* for below */ ; \
+ movq CPUVAR(CURPCB),%r11 /* for below */ ; \
/* %es and %ds */ \
movw TF_ES(%rsp),%es ; \
movw $(GSEL(GUDATA_SEL, SEL_UPL)),%ax ; \
movw %ax,%ds ; \
/* Make sure both %fs and FS.base are the desired values */ \
movw TF_FS(%rsp),%fs ; \
- movq PCB_FSBASE(%rdx),%rax ; \
+ movq PCB_FSBASE(%r11),%rax ; \
cmpq $0,%rax ; \
- je 99f /* setting %fs has zeroed FS.base */ ; \
+ je 96f ; \
movq %rax,%rdx ; \
shrq $32,%rdx ; \
movl $MSR_FSBASE,%ecx ; \
wrmsr ; \
-99: cli /* %fs done, so swapgs and do %gs */ ; \
+96: cli ; \
swapgs ; \
- movw TF_GS(%rsp),%gs
+ /* Make sure both %gs and GS.base are the desired values */ \
+ movw TF_GS(%rsp),%gs ; \
+ movq PCB_GSBASE(%r11),%rax ; \
+ cmpq $0,%rax ; \
+ je 97f ; \
+ movq %rax,%rdx ; \
+ shrq $32,%rdx ; \
+ movl $MSR_GSBASE,%ecx ; \
+ wrmsr ; \
+97: /* out */
#define CHECK_ASTPENDING(reg) movq CPUVAR(CURPROC),reg ; \
Index: sys/arch/amd64/include/pcb.h
===================================================================
RCS file: /home/cvs/src/sys/arch/amd64/include/pcb.h,v
retrieving revision 1.12
diff -u -p -r1.12 pcb.h
--- sys/arch/amd64/include/pcb.h 10 Jul 2011 18:12:03 -0000 1.12
+++ sys/arch/amd64/include/pcb.h 12 Apr 2012 17:28:16 -0000
@@ -83,18 +83,19 @@ struct pcb {
u_int64_t pcb_rbp;
u_int64_t pcb_kstack; /* kernel stack address */
u_int64_t pcb_fsbase; /* per-thread offset: %fs */
+ u_int64_t pcb_gsbase; /* per-thread offset: %gs */
caddr_t pcb_onfault; /* copyin/out fault recovery */
struct cpu_info *pcb_fpcpu; /* cpu holding our fp state. */
struct pmap *pcb_pmap; /* back pointer to our pmap */
int pcb_cr0; /* saved image of CR0 */
};
-/*
- * The pcb is augmented with machine-dependent additional data for
+/*
+ * The pcb is augmented with machine-dependent additional data for
* core dumps. For the i386, there is nothing to add.
- */
+ */
struct md_coredump {
long md_pad[8];
-};
+};
#endif /* _MACHINE_PCB_H_ */
Index: sys/arch/amd64/include/sysarch.h
===================================================================
RCS file: /home/cvs/src/sys/arch/amd64/include/sysarch.h,v
retrieving revision 1.10
diff -u -p -r1.10 sysarch.h
--- sys/arch/amd64/include/sysarch.h 13 Apr 2011 02:49:12 -0000 1.10
+++ sys/arch/amd64/include/sysarch.h 12 Apr 2012 20:57:34 -0000
@@ -16,6 +16,8 @@
#define AMD64_PMC_READ 10
#define AMD64_GET_FSBASE 11
#define AMD64_SET_FSBASE 12
+#define AMD64_GET_GSBASE 13
+#define AMD64_SET_GSBASE 14
struct amd64_iopl_args {
int iopl;
@@ -67,6 +69,8 @@ struct amd64_pmc_read_args {
int amd64_iopl(struct proc *, void *, register_t *);
int amd64_set_fsbase(struct proc *, void *);
int amd64_get_fsbase(struct proc *, void *);
+int amd64_set_gsbase(struct proc *, void *);
+int amd64_get_gsbase(struct proc *, void *);
#else
int amd64_iopl(int);
int amd64_get_ioperm(u_long *);
@@ -76,6 +80,8 @@ int amd64_pmc_startstop(struct amd64_pmc
int amd64_pmc_read(struct amd64_pmc_read_args *);
int amd64_set_fsbase(void *);
int amd64_get_fsbase(void **);
+int amd64_set_gsbase(void *);
+int amd64_get_gsbase(void **);
int sysarch(int, void *);
#endif
Index: lib/libarch/amd64/Makefile
===================================================================
RCS file: /home/cvs/src/lib/libarch/amd64/Makefile,v
retrieving revision 1.10
diff -u -p -r1.10 Makefile
--- lib/libarch/amd64/Makefile 13 Apr 2011 02:49:12 -0000 1.10
+++ lib/libarch/amd64/Makefile 13 Apr 2012 19:20:17 -0000
@@ -3,15 +3,17 @@
MANSUBDIR=amd64
MAN+= amd64_iopl.2 amd64_get_ioperm.2 \
- amd64_get_fsbase.2
+ amd64_get_fsbase.2 amd64_get_gsbase.2
MLINKS+=amd64_get_ioperm.2 amd64_set_ioperm.2 \
- amd64_get_fsbase.2 amd64_set_fsbase.2
+ amd64_get_fsbase.2 amd64_set_fsbase.2 \
+ amd64_get_gsbase.2 amd64_set_gsbase.2
.if ${MACHINE_ARCH} == "amd64"
.PATH: ${LIBC}/amd64
NOPIC=
SRCS+= amd64_iopl.c amd64_get_ioperm.c amd64_set_ioperm.c \
- amd64_get_fsbase.c amd64_set_fsbase.c
+ amd64_get_fsbase.c amd64_set_fsbase.c \
+ amd64_get_gsbase.c amd64_set_gsbase.c
.include <bsd.lib.mk>
.else
NOPROG=
Index: lib/libarch/amd64/amd64_get_gsbase.2
===================================================================
RCS file: lib/libarch/amd64/amd64_get_gsbase.2
diff -N lib/libarch/amd64/amd64_get_gsbase.2
--- /dev/null 1 Jan 1970 00:00:00 -0000
+++ lib/libarch/amd64/amd64_get_gsbase.2 13 Apr 2012 19:24:18 -0000
@@ -0,0 +1,87 @@
+.\" $OpenBSD$
+.\" $NetBSD: i386_get_ioperm.2,v 1.3 1996/02/27 22:57:17 jtc Exp $
+.\"
+.\" Copyright (c) 1996 The NetBSD Foundation, Inc.
+.\" All rights reserved.
+.\"
+.\" This code is derived from software contributed to The NetBSD Foundation
+.\" by John T. Kohl and Charles M. Hannum.
+.\"
+.\" Redistribution and use in source and binary forms, with or without
+.\" modification, are permitted provided that the following conditions
+.\" are met:
+.\" 1. Redistributions of source code must retain the above copyright
+.\" notice, this list of conditions and the following disclaimer.
+.\" 2. Redistributions in binary form must reproduce the above copyright
+.\" notice, this list of conditions and the following disclaimer in the
+.\" documentation and/or other materials provided with the distribution.
+.\"
+.\" THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
+.\" ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
+.\" TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
+.\" PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE
+.\" LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+.\" CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+.\" SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+.\" INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+.\" CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+.\" ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+.\" POSSIBILITY OF SUCH DAMAGE.
+.\"
+.Dd $Mdocdate$
+.Dt AMD64_GET_GSBASE 2 amd64
+.Os
+.Sh NAME
+.Nm amd64_get_gsbase ,
+.Nm amd64_set_gsbase
+.Nd manage amd64 per-thread %gs base address
+.Sh SYNOPSIS
+.Fd #include <sys/types.h>
+.Fd #include <machine/sysarch.h>
+.Ft int
+.Fn amd64_get_gsbase "void **base"
+.Ft int
+.Fn amd64_set_gsbase "void *base"
+.Sh DESCRIPTION
+.Fn amd64_get_gsbase
+copies the current base address of the %gs segment into the memory
+referenced by
+.Fa base .
+.Pp
+.Fn amd64_set_gsbase
+sets the base address of the %gs segment to the address
+.Fa base .
+.Pp
+The segment base address is local to each thread.
+The initial thread of a new process inherits its segment base address
+from the parent thread.
+.Xr __tfork 2
+sets the initial segment base address for threads that it creates.
+.Pp
+.Sy Note:
+Code using the
+.Fn amd64_get_gsbase
+and
+.Fn amd64_set_gsbase
+functions must be compiled using
+.Cm -lamd64 .
+.Sh RETURN VALUES
+Upon successful completion,
+.Fn amd64_get_gsbase
+and
+.Fn amd64_set_gsbase
+return 0.
+Otherwise, a value of \-1 is returned and the global variable
+.Va errno
+is set to indicate the error.
+.Sh ERRORS
+.Fn amd64_get_gsbase
+will fail if:
+.Bl -tag -width [EINVAL]
+.It Bq Er EFAULT
+.Fa base
+points outside the process's allocated address space.
+.El
+.Sh SEE ALSO
+.Xr __tfork 2 ,
+.Xr fork 2
Index: lib/libarch/amd64/amd64_get_gsbase.c
===================================================================
RCS file: lib/libarch/amd64/amd64_get_gsbase.c
diff -N lib/libarch/amd64/amd64_get_gsbase.c
--- /dev/null 1 Jan 1970 00:00:00 -0000
+++ lib/libarch/amd64/amd64_get_gsbase.c 13 Apr 2012 19:28:32 -0000
@@ -0,0 +1,15 @@
+/* $OpenBSD$ */
+
+/* Public domain. Written by Mike Belopuhov <mi...@openbsd.org> */
+
+#include <sys/cdefs.h>
+#include <sys/types.h>
+
+#include <machine/segments.h>
+#include <machine/sysarch.h>
+
+int
+amd64_get_gsbase(void **base)
+{
+ return sysarch(AMD64_GET_GSBASE, base);
+}
Index: lib/libarch/amd64/amd64_set_gsbase.c
===================================================================
RCS file: lib/libarch/amd64/amd64_set_gsbase.c
diff -N lib/libarch/amd64/amd64_set_gsbase.c
--- /dev/null 1 Jan 1970 00:00:00 -0000
+++ lib/libarch/amd64/amd64_set_gsbase.c 13 Apr 2012 19:28:19 -0000
@@ -0,0 +1,15 @@
+/* $OpenBSD$ */
+
+/* Public domain. Written by Mike Belopuhov <mi...@openbsd.org> */
+
+#include <sys/cdefs.h>
+#include <sys/types.h>
+
+#include <machine/segments.h>
+#include <machine/sysarch.h>
+
+int
+amd64_set_gsbase(void *base)
+{
+ return sysarch(AMD64_SET_GSBASE, &base);
+}
Index: regress/lib/libpthread/Makefile
===================================================================
RCS file: /home/cvs/src/regress/lib/libpthread/Makefile,v
retrieving revision 1.38
diff -u -p -r1.38 Makefile
--- regress/lib/libpthread/Makefile 13 Apr 2012 19:04:09 -0000 1.38
+++ regress/lib/libpthread/Makefile 14 Apr 2012 10:27:30 -0000
@@ -12,6 +12,9 @@ SUBDIR= barrier blocked_close blocked_du
readdir restart select semaphore setjmp setsockopt sigdeliver siginfo \
siginterrupt signal signals signodefer sigsuspend sigwait sleep \
socket stack stdarg stdio switch system
+.if ${MACHINE_ARCH} == "amd64"
+SUBDIR+=amd64_set_gsbase
+.endif
# Not available or disabled: fcntl, getaddrinfo, pause, pw, sigmask, stdfiles
Index: regress/lib/libpthread/amd64_set_gsbase/Makefile
===================================================================
RCS file: regress/lib/libpthread/amd64_set_gsbase/Makefile
diff -N regress/lib/libpthread/amd64_set_gsbase/Makefile
--- /dev/null 1 Jan 1970 00:00:00 -0000
+++ regress/lib/libpthread/amd64_set_gsbase/Makefile 18 Apr 2012 10:27:18
-0000
@@ -0,0 +1,12 @@
+# $OpenBSD$
+
+PROG= amd64_set_gsbase
+
+LIBARCH=/usr/lib/libamd64.a
+
+LDADD+= ${LIBARCH}
+DPADD+= ${LIBARCH}
+
+CFLAGS+=-O0 -g
+
+.include <bsd.regress.mk>
Index: regress/lib/libpthread/amd64_set_gsbase/amd64_set_gsbase.c
===================================================================
RCS file: regress/lib/libpthread/amd64_set_gsbase/amd64_set_gsbase.c
diff -N regress/lib/libpthread/amd64_set_gsbase/amd64_set_gsbase.c
--- /dev/null 1 Jan 1970 00:00:00 -0000
+++ regress/lib/libpthread/amd64_set_gsbase/amd64_set_gsbase.c 19 Apr 2012
11:46:07 -0000
@@ -0,0 +1,55 @@
+/* $OpenBSD$ */
+
+/*
+ * Public domain. Written by Mike Belopuhov.
+ *
+ * Test amd64_set_gsbase and amd64_get_gsbase
+ */
+
+#include <sys/types.h>
+#include <machine/sysarch.h>
+#include <pthread.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include "test.h"
+
+#define NTHREADS 128
+
+void *
+new_thread(void *arg)
+{
+ long gsbase = 0;
+ int *val = NULL;
+
+ CHECKr(amd64_set_gsbase(arg));
+
+ pthread_yield();
+
+ CHECKr(amd64_get_gsbase((void **)&val));
+
+ __asm __volatile("movq %%gs:0,%0" : "=r" (gsbase));
+
+ ASSERT(val == arg);
+ ASSERT((long)val == gsbase);
+
+ return (NULL);
+}
+
+int
+main(int argc, char *argv[])
+{
+ pthread_t threads[NTHREADS];
+ int *vals[NTHREADS];
+ int i;
+
+ for (i = 0; i < NTHREADS; i++) {
+ vals[i] = (int *)&vals[i];
+ CHECKr(pthread_create(&threads[i], NULL, new_thread,
+ (void *)&vals[i]));
+ }
+ for (i = 0; i < NTHREADS; i++) {
+ CHECKr(pthread_join(threads[i], NULL));
+ }
+ SUCCEED;
+}
