Preserve %fs and %gs across context switches. This has a relatively low

cost since it is only done in cpu_switch(), not for every exception.
The extra state is kept in the pcb, and handled much like the npx state,
with similar deficiencies (the state is not preserved across signal
handlers, and error handling loses state).

8 files changed, 78 insertions, 9 deletions

diff --git a/sys/amd64/amd64/cpu_switch.S b/sys/amd64/amd64/cpu_switch.S
index 094e75b..923d694 100644
--- a/sys/amd64/amd64/cpu_switch.S
+++ b/sys/amd64/amd64/cpu_switch.S
@@ -33,7 +33,7 @@
  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  * SUCH DAMAGE.
  *
- *	$Id: swtch.s,v 1.50 1997/05/29 05:11:11 peter Exp $
+ *	$Id: swtch.s,v 1.51 1997/05/31 09:27:29 peter Exp $
  */
 
 #include "npx.h"
@@ -336,6 +336,8 @@ ENTRY(cpu_switch)
 	movl	%ebp,PCB_EBP(%ecx)
 	movl	%esi,PCB_ESI(%ecx)
 	movl	%edi,PCB_EDI(%ecx)
+	movl	%fs,PCB_FS(%ecx)
+	movl	%gs,PCB_GS(%ecx)
 
 #ifdef SMP
 	movl	_mp_lock, %eax
@@ -562,6 +564,14 @@ swtch_com:
 2:
 #endif
 
+	/* This must be done after loading the user LDT. */
+	.globl	cpu_switch_load_fs
+cpu_switch_load_fs:
+	movl	PCB_FS(%edx),%fs
+	.globl	cpu_switch_load_gs
+cpu_switch_load_gs:
+	movl	PCB_GS(%edx),%gs
+
 	sti
 	ret
 
@@ -592,6 +602,8 @@ ENTRY(savectx)
 	movl	%ebp,PCB_EBP(%ecx)
 	movl	%esi,PCB_ESI(%ecx)
 	movl	%edi,PCB_EDI(%ecx)
+	movl	%fs,PCB_FS(%ecx)
+	movl	%gs,PCB_GS(%ecx)
 
 #if NNPX > 0
 	/*
diff --git a/sys/amd64/amd64/genassym.c b/sys/amd64/amd64/genassym.c
index 18ecadc..d9473cf 100644
--- a/sys/amd64/amd64/genassym.c
+++ b/sys/amd64/amd64/genassym.c
@@ -34,7 +34,7 @@
  * SUCH DAMAGE.
  *
  *	from: @(#)genassym.c	5.11 (Berkeley) 5/10/91
- *	$Id: genassym.c,v 1.45 1997/04/26 11:45:06 peter Exp $
+ *	$Id: genassym.c,v 1.46 1997/05/10 08:01:13 bde Exp $
  */
 
 #include <stdio.h>
@@ -127,6 +127,8 @@ main()
 	printf("#define\tPCB_EIP %p\n", &pcb->pcb_eip);
 	printf("#define\tTSS_ESP0 %p\n", &tss->tss_esp0);
 	printf("#define\tPCB_USERLDT %p\n", &pcb->pcb_ldt);
+	printf("#define\tPCB_FS %p\n", &pcb->pcb_fs);
+	printf("#define\tPCB_GS %p\n", &pcb->pcb_gs);
 #ifdef SMP
 	printf("#define\tPCB_MPNEST %p\n", &pcb->pcb_mpnest);
 #endif
diff --git a/sys/amd64/amd64/machdep.c b/sys/amd64/amd64/machdep.c
index 186541c..b59d92e 100644
--- a/sys/amd64/amd64/machdep.c
+++ b/sys/amd64/amd64/machdep.c
@@ -35,7 +35,7 @@
  * SUCH DAMAGE.
  *
  *	from: @(#)machdep.c	7.4 (Berkeley) 6/3/91
- *	$Id: machdep.c,v 1.245 1997/05/26 18:40:45 fsmp Exp $
+ *	$Id: machdep.c,v 1.246 1997/06/02 08:19:03 dfr Exp $
  */
 
 #include "npx.h"
@@ -1516,6 +1516,7 @@ fill_regs(p, regs)
 	struct proc *p;
 	struct reg *regs;
 {
+	struct pcb *pcb;
 	struct trapframe *tp;
 
 	tp = p->p_md.md_regs;
@@ -1533,6 +1534,9 @@ fill_regs(p, regs)
 	regs->r_eflags = tp->tf_eflags;
 	regs->r_esp = tp->tf_esp;
 	regs->r_ss = tp->tf_ss;
+	pcb = &p->p_addr->u_pcb;
+	regs->r_fs = pcb->pcb_fs;
+	regs->r_gs = pcb->pcb_gs;
 	return (0);
 }
 
@@ -1541,6 +1545,7 @@ set_regs(p, regs)
 	struct proc *p;
 	struct reg *regs;
 {
+	struct pcb *pcb;
 	struct trapframe *tp;
 
 	tp = p->p_md.md_regs;
@@ -1561,6 +1566,9 @@ set_regs(p, regs)
 	tp->tf_eflags = regs->r_eflags;
 	tp->tf_esp = regs->r_esp;
 	tp->tf_ss = regs->r_ss;
+	pcb = &p->p_addr->u_pcb;
+	pcb->pcb_fs = regs->r_fs;
+	pcb->pcb_gs = regs->r_gs;
 	return (0);
 }
 
diff --git a/sys/amd64/amd64/swtch.s b/sys/amd64/amd64/swtch.s
index 094e75b..923d694 100644
--- a/sys/amd64/amd64/swtch.s
+++ b/sys/amd64/amd64/swtch.s
@@ -33,7 +33,7 @@
  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  * SUCH DAMAGE.
  *
- *	$Id: swtch.s,v 1.50 1997/05/29 05:11:11 peter Exp $
+ *	$Id: swtch.s,v 1.51 1997/05/31 09:27:29 peter Exp $
  */
 
 #include "npx.h"
@@ -336,6 +336,8 @@ ENTRY(cpu_switch)
 	movl	%ebp,PCB_EBP(%ecx)
 	movl	%esi,PCB_ESI(%ecx)
 	movl	%edi,PCB_EDI(%ecx)
+	movl	%fs,PCB_FS(%ecx)
+	movl	%gs,PCB_GS(%ecx)
 
 #ifdef SMP
 	movl	_mp_lock, %eax
@@ -562,6 +564,14 @@ swtch_com:
 2:
 #endif
 
+	/* This must be done after loading the user LDT. */
+	.globl	cpu_switch_load_fs
+cpu_switch_load_fs:
+	movl	PCB_FS(%edx),%fs
+	.globl	cpu_switch_load_gs
+cpu_switch_load_gs:
+	movl	PCB_GS(%edx),%gs
+
 	sti
 	ret
 
@@ -592,6 +602,8 @@ ENTRY(savectx)
 	movl	%ebp,PCB_EBP(%ecx)
 	movl	%esi,PCB_ESI(%ecx)
 	movl	%edi,PCB_EDI(%ecx)
+	movl	%fs,PCB_FS(%ecx)
+	movl	%gs,PCB_GS(%ecx)
 
 #if NNPX > 0
 	/*
diff --git a/sys/amd64/amd64/trap.c b/sys/amd64/amd64/trap.c
index f73c4f2..89dd34f 100644
--- a/sys/amd64/amd64/trap.c
+++ b/sys/amd64/amd64/trap.c
@@ -35,7 +35,7 @@
  * SUCH DAMAGE.
  *
  *	from: @(#)trap.c	7.4 (Berkeley) 5/13/91
- *	$Id: trap.c,v 1.97 1997/05/31 09:27:29 peter Exp $
+ *	$Id: trap.c,v 1.98 1997/06/02 08:19:03 dfr Exp $
  */
 
 /*
@@ -352,6 +352,25 @@ trap(frame)
 	} while (0)
 
 			if (intr_nesting_level == 0) {
+				/*
+				 * Invalid %fs's and %gs's can be created using
+				 * procfs or PT_SETREGS or by invalidating the
+				 * underlying LDT entry.  This causes a fault
+				 * in kernel mode when the kernel attempts to
+				 * switch contexts.  Lose the bad context
+				 * (XXX) so that we can continue, and generate
+				 * a signal.
+				 */
+				if (frame.tf_eip == (int)cpu_switch_load_fs) {
+					curpcb->pcb_fs = 0;
+					psignal(p, SIGBUS);
+					return;
+				}
+				if (frame.tf_eip == (int)cpu_switch_load_gs) {
+					curpcb->pcb_gs = 0;
+					psignal(p, SIGBUS);
+					return;
+				}
 				MAYBE_DORETI_FAULT(doreti_iret,
 						   doreti_iret_fault);
 				MAYBE_DORETI_FAULT(doreti_popl_ds,
diff --git a/sys/amd64/include/md_var.h b/sys/amd64/include/md_var.h
index 307257c..a7e7856 100644
--- a/sys/amd64/include/md_var.h
+++ b/sys/amd64/include/md_var.h
@@ -26,7 +26,7 @@
  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  * SUCH DAMAGE.
  *
- *	$Id: md_var.h,v 1.12 1997/02/22 09:34:49 peter Exp $
+ *	$Id: md_var.h,v 1.13 1997/03/22 18:53:08 kato Exp $
  */
 
 #ifndef _MACHINE_MD_VAR_H_
@@ -57,6 +57,8 @@ struct	reg;
 void	bcopyb __P((const void *from, void *to, size_t len));
 void	cpu_reset __P((void));
 void	cpu_halt __P((void));
+void	cpu_switch_load_fs __P((void)) __asm(__STRING(cpu_switch_load_fs));
+void	cpu_switch_load_gs __P((void)) __asm(__STRING(cpu_switch_load_gs));
 void	doreti_iret __P((void)) __asm(__STRING(doreti_iret));
 void	doreti_iret_fault __P((void)) __asm(__STRING(doreti_iret_fault));
 void	doreti_popl_ds __P((void)) __asm(__STRING(doreti_popl_ds));
diff --git a/sys/amd64/include/pcb.h b/sys/amd64/include/pcb.h
index 1cbca02..c93ed87 100644
--- a/sys/amd64/include/pcb.h
+++ b/sys/amd64/include/pcb.h
@@ -34,7 +34,7 @@
  * SUCH DAMAGE.
  *
  *	from: @(#)pcb.h	5.10 (Berkeley) 5/12/91
- *	$Id: pcb.h,v 1.20 1997/04/26 11:45:39 peter Exp $
+ *	$Id: pcb.h,v 1.21 1997/05/07 19:49:32 peter Exp $
  */
 
 #ifndef _I386_PCB_H_
@@ -64,7 +64,9 @@ struct pcb {
 #define	FP_SOFTFP	0x01	/* process using software fltng pnt emulator */
 	caddr_t	pcb_onfault;	/* copyin/out fault recovery */
 	u_long	pcb_mpnest;
-	u_long	__pcb_spare[7];	/* adjust to avoid core dump size changes */
+	int	pcb_fs;
+	int	pcb_gs;
+	u_long	__pcb_spare[5];	/* adjust to avoid core dump size changes */
 #if 0	/* some day we may switch between procs that have their own i386tss */
 	struct	i386tss pcb_tss;
 	u_char	pcb_iomap[NPORT/sizeof(u_char)]; /* i/o port bitmap */
diff --git a/sys/amd64/include/reg.h b/sys/amd64/include/reg.h
index c896fe5..5d36f27 100644
--- a/sys/amd64/include/reg.h
+++ b/sys/amd64/include/reg.h
@@ -34,7 +34,7 @@
  * SUCH DAMAGE.
  *
  *	from: @(#)reg.h	5.5 (Berkeley) 1/18/91
- *	$Id: reg.h,v 1.13 1997/02/22 09:35:07 peter Exp $
+ *	$Id: reg.h,v 1.14 1997/06/07 00:49:45 bde Exp $
  */
 
 #ifndef _MACHINE_REG_H_
@@ -69,6 +69,16 @@
 #define	tSS	(16)
 
 /*
+ * Indices for registers in `struct regs' only.
+ *
+ * Some registers live in the pcb and are only in an "array" with the
+ * other registers in application interfaces that copy all the registers
+ * to or from a `struct regs'.
+ */
+#define	tFS	(17)
+#define	tGS	(18)
+
+/*
  * Register set accessible via /proc/$pid/regs and PT_{SET,GET}REGS.
  */
 struct reg {
@@ -89,6 +99,8 @@ struct reg {
 	unsigned int	r_eflags;
 	unsigned int	r_esp;
 	unsigned int	r_ss;
+	unsigned int	r_fs;
+	unsigned int	r_gs;
 };
 
 /*