Provide distinct segments for the %fs and %gs selectors to use by

default, with per-rthread base offsets and with sysarch() functions,
I386_{GET,SET}_{FS,GS}BASE, for fetching and setting those base
offsets.  This is necessary for both rthread and Linux compat support.

suggestions from kettenis@, prodding from pirofti@ and deraadt@

3 files changed, 22 insertions, 9 deletions

diff --git a/sys/arch/i386/include/pcb.h b/sys/arch/i386/include/pcb.h
index fa3623eafad..66c1b816a63 100644
--- a/sys/arch/i386/include/pcb.h
+++ b/sys/arch/i386/include/pcb.h
@@ -1,4 +1,4 @@
-/*	$OpenBSD: pcb.h,v 1.14 2007/10/03 07:51:26 kettenis Exp $	*/
+/*	$OpenBSD: pcb.h,v 1.15 2011/03/12 03:52:26 guenther Exp $	*/
 /*	$NetBSD: pcb.h,v 1.21 1996/01/08 13:51:42 mycroft Exp $	*/
 
 /*-
@@ -59,13 +59,13 @@ struct pcb {
 #define	pcb_ebp	pcb_tss.tss_ebp
 #define	pcb_cs	pcb_tss.tss_cs
 #define	pcb_ldt_sel	pcb_tss.tss_ldt
-	int	pcb_tss_sel;
 	union	descriptor *pcb_ldt;	/* per process (user) LDT */
 	int	pcb_ldt_len;		/*      number of LDT entries */
-	int	pcb_cr0;		/* saved image of CR0 */
-	int	pcb_pad[2];		/* savefpu on 16-byte boundary */
 	union	savefpu pcb_savefpu;	/* floating point state for FPU */
+	int	pcb_cr0;		/* saved image of CR0 */
 	struct	emcsts pcb_saveemc;	/* Cyrix EMC state */
+	struct	segment_descriptor pcb_threadsegs[2];
+					/* per-thread descriptors */
 /*
  * Software pcb (extension)
  */
@@ -81,6 +81,10 @@ struct pcb {
 #define PCB_SAVECTX	0x00000001
 };
 
+/* the indexes of the %fs/%gs segments in pcb_threadsegs */
+#define	TSEG_FS		0
+#define	TSEG_GS		1
+
 /*    
  * The pcb is augmented with machine-dependent additional data for 
  * core dumps. For the i386, there is nothing to add.
diff --git a/sys/arch/i386/include/segments.h b/sys/arch/i386/include/segments.h
index a6932a4e0fd..1a56a1887e2 100644
--- a/sys/arch/i386/include/segments.h
+++ b/sys/arch/i386/include/segments.h
@@ -1,4 +1,4 @@
-/*	$OpenBSD: segments.h,v 1.18 2010/12/24 20:26:30 tedu Exp $	*/
+/*	$OpenBSD: segments.h,v 1.19 2011/03/12 03:52:26 guenther Exp $	*/
 /*	$NetBSD: segments.h,v 1.23 1996/02/01 22:31:03 mycroft Exp $	*/
 
 /*-
@@ -215,15 +215,16 @@ void idt_vec_free(int);
 #define	GCODE_SEL	1	/* Kernel code descriptor */
 #define	GDATA_SEL	2	/* Kernel data descriptor */
 #define	GLDT_SEL	3	/* Default LDT descriptor */
-#define	GUCODE1_SEL	4	/* User code descriptor */
+#define	GCPU_SEL	4	/* per-CPU segment */
 #define	GUCODE_SEL	5	/* User code descriptor (a stack short) */
 #define	GUDATA_SEL	6	/* User data descriptor */
 #define	GAPM32CODE_SEL	7	/* 32 bit APM code descriptor */
 #define	GAPM16CODE_SEL	8	/* 16 bit APM code descriptor */
 #define	GAPMDATA_SEL	9	/* APM data descriptor */
 #define	GICODE_SEL	10	/* Interrupt code descriptor (same as Kernel code) */
-#define GCPU_SEL	11	/* per-CPU segment */
-#define	NGDT		12
+#define	GUFS_SEL	11	/* User per-thread (%fs) descriptor */
+#define	GUGS_SEL	12	/* User per-thread (%gs) descriptor */
+#define	NGDT		13
 
 /*
  * Entries in the Local Descriptor Table (LDT)
diff --git a/sys/arch/i386/include/sysarch.h b/sys/arch/i386/include/sysarch.h
index cae749a2b53..1115026c63d 100644
--- a/sys/arch/i386/include/sysarch.h
+++ b/sys/arch/i386/include/sysarch.h
@@ -1,4 +1,4 @@
-/*	$OpenBSD: sysarch.h,v 1.5 2004/09/15 18:46:50 deraadt Exp $	*/
+/*	$OpenBSD: sysarch.h,v 1.6 2011/03/12 03:52:26 guenther Exp $	*/
 /*	$NetBSD: sysarch.h,v 1.8 1996/01/08 13:51:44 mycroft Exp $	*/
 
 #ifndef _I386_SYSARCH_H_
@@ -13,6 +13,10 @@
 #define	I386_GET_IOPERM	3
 #define	I386_SET_IOPERM	4
 #define	I386_VM86	5
+#define	I386_GET_FSBASE	6
+#define	I386_SET_FSBASE	7
+#define	I386_GET_GSBASE	8
+#define	I386_SET_GSBASE	9
 
 struct i386_get_ldt_args {
 	int start;
@@ -44,6 +48,10 @@ int i386_set_ldt(int, union descriptor *, int);
 int i386_iopl(int);
 int i386_get_ioperm(u_long *);
 int i386_set_ioperm(u_long *);
+int i386_get_fsbase(void **);
+int i386_set_fsbase(void *);
+int i386_get_gsbase(void **);
+int i386_set_gsbase(void *);
 int sysarch(int, void *);
 #endif