Preparation for i386 Meltdown fix:

- provide a cpu_softc for cpu_attach() etc.
- replace per PCB TSS with per CPU TSS

The first change prepares for cpu_info being embedded in a
cpu_full_info.  Therefore during autoconf/cpu_attach we hand down
a softc.

The second change removes the per PCB TSS.  We now have one TSS per
CPU, thus in cpu_switchto() we only have to patch the ring 0 stack
pointer instead of loading a new TSS.  This also allows for cleaning
up the GDT, so we only have a single slot for the TSS.

from hshoexer@;  OK deraadt@

6 files changed, 29 insertions, 39 deletions

diff --git a/sys/arch/i386/include/cpu.h b/sys/arch/i386/include/cpu.h
index e89d43951c0..f3294535bde 100644
--- a/sys/arch/i386/include/cpu.h
+++ b/sys/arch/i386/include/cpu.h
@@ -1,4 +1,4 @@
-/*	$OpenBSD: cpu.h,v 1.158 2017/10/17 14:25:35 visa Exp $	*/
+/*	$OpenBSD: cpu.h,v 1.159 2018/03/13 13:51:05 bluhm Exp $	*/
 /*	$NetBSD: cpu.h,v 1.35 1996/05/05 19:29:26 christos Exp $	*/
 
 /*-
@@ -46,6 +46,7 @@
 #include <machine/psl.h>
 #include <machine/segments.h>
 #include <machine/intrdefs.h>
+#include <machine/tss.h>
 
 #ifdef MULTIPROCESSOR
 #include <machine/i82489reg.h>
@@ -102,7 +103,7 @@ union vmm_cpu_cap {
 #ifdef _KERNEL
 /* XXX stuff to move to cpuvar.h later */
 struct cpu_info {
-	struct device ci_dev;		/* our device */
+	struct device	*ci_dev;	/* our device */
 	struct cpu_info *ci_self;	/* pointer to this structure */
 	struct schedstate_percpu ci_schedstate; /* scheduler state */
 	struct cpu_info *ci_next;	/* next cpu */
@@ -129,7 +130,6 @@ struct cpu_info {
 
 	struct pcb *ci_curpcb;		/* VA of current HW PCB */
 	struct pcb *ci_idle_pcb;	/* VA of current PCB */
-	int ci_idle_tss_sel;		/* TSS selector of idle PCB */
 	struct pmap *ci_curpmap;
 
 	struct intrsource *ci_isources[MAX_INTR_SOURCES];
@@ -175,6 +175,7 @@ struct cpu_info {
 	int		ci_want_resched;
 
 	union descriptor *ci_gdt;
+	struct i386tss	*ci_tss;
 
 	volatile int ci_ddb_paused;	/* paused due to other proc in ddb */
 #define CI_DDB_RUNNING		0
@@ -230,7 +231,7 @@ extern struct cpu_info *cpu_info_list;
 #define	CPU_INFO_FOREACH(cii, ci)	for (cii = 0, ci = cpu_info_list; \
 					    ci != NULL; ci = ci->ci_next)
 
-#define CPU_INFO_UNIT(ci)	((ci)->ci_dev.dv_unit)
+#define CPU_INFO_UNIT(ci)	((ci)->ci_dev ? (ci)->ci_dev->dv_unit : 0)
 
 #ifdef MULTIPROCESSOR
 
diff --git a/sys/arch/i386/include/gdt.h b/sys/arch/i386/include/gdt.h
index 2b5d0dcf3b3..fc7fe20f587 100644
--- a/sys/arch/i386/include/gdt.h
+++ b/sys/arch/i386/include/gdt.h
@@ -1,4 +1,4 @@
-/*	$OpenBSD: gdt.h,v 1.13 2016/03/03 12:41:30 naddy Exp $	*/
+/*	$OpenBSD: gdt.h,v 1.14 2018/03/13 13:51:05 bluhm Exp $	*/
 /*	$NetBSD: gdt.h,v 1.7.10.6 2002/08/19 01:22:36 sommerfeld Exp $	*/
 
 /*-
@@ -35,21 +35,11 @@
 struct cpu_info;
 struct pcb;
 struct pmap;
-union descriptor;
 
 void gdt_alloc_cpu(struct cpu_info *);
 int gdt_get_slot(void);
 void gdt_init(void);
 void gdt_init_cpu(struct cpu_info *);
 void gdt_reload_cpu(/* XXX struct cpu_info * */ void);
-int tss_alloc(struct pcb *);
-void tss_free(int);
 void setgdt(int, void *, size_t, int, int, int, int);
 #endif
-
-/*
- * Maximum GDT size.  It cannot exceed 65536 since the selector field of
- * a descriptor is just 16 bits, and used as free list link.
- */
-
-#define MAXGDTSIZ 65536
diff --git a/sys/arch/i386/include/pcb.h b/sys/arch/i386/include/pcb.h
index 6e6f5a578e7..a01afaed5ad 100644
--- a/sys/arch/i386/include/pcb.h
+++ b/sys/arch/i386/include/pcb.h
@@ -1,4 +1,4 @@
-/*	$OpenBSD: pcb.h,v 1.20 2016/03/24 04:56:08 guenther Exp $	*/
+/*	$OpenBSD: pcb.h,v 1.21 2018/03/13 13:51:05 bluhm Exp $	*/
 /*	$NetBSD: pcb.h,v 1.21 1996/01/08 13:51:42 mycroft Exp $	*/
 
 /*-
@@ -46,19 +46,20 @@
 #include <sys/signal.h>
 
 #include <machine/segments.h>
-#include <machine/tss.h>
 #include <machine/npx.h>
 #include <machine/sysarch.h>
 
+/*
+ * Please not that pcb_savefpu must be aligend to 16 bytes.
+ */
 struct pcb {
-	struct	i386tss pcb_tss;
-#define	pcb_cr3	pcb_tss.tss_cr3
-#define	pcb_esp	pcb_tss.tss_esp
-#define	pcb_ebp	pcb_tss.tss_ebp
-#define	pcb_cs	pcb_tss.tss_cs
+	union	savefpu pcb_savefpu;	/* floating point state for FPU */
+	int	pcb_cr3;
+	int	pcb_esp;
+	int	pcb_ebp;
+	int	pcb_kstack;		/* kernel stack address */
 	int	pcb_cr0;		/* saved image of CR0 */
 	caddr_t	pcb_onfault;		/* copyin/out fault recovery */
-	union	savefpu pcb_savefpu;	/* floating point state for FPU */
 	struct	segment_descriptor pcb_threadsegs[2];
 					/* per-thread descriptors */
 	int	vm86_eflags;		/* virtual eflags for vm86 mode */
diff --git a/sys/arch/i386/include/proc.h b/sys/arch/i386/include/proc.h
index 811577a20ea..9f3645a0f3b 100644
--- a/sys/arch/i386/include/proc.h
+++ b/sys/arch/i386/include/proc.h
@@ -1,4 +1,4 @@
-/*	$OpenBSD: proc.h,v 1.7 2017/04/13 03:52:25 guenther Exp $	*/
+/*	$OpenBSD: proc.h,v 1.8 2018/03/13 13:51:05 bluhm Exp $	*/
 /*	$NetBSD: proc.h,v 1.10 1995/08/06 05:33:23 mycroft Exp $	*/
 
 /*
@@ -38,7 +38,6 @@
 struct mdproc {
 	struct	trapframe *md_regs;	/* registers on current frame */
 	int	md_flags;		/* machine-dependent flags */
-	int	md_tss_sel;		/* TSS selector */
 	int	md_astpending;
 };
 
diff --git a/sys/arch/i386/include/segments.h b/sys/arch/i386/include/segments.h
index 8fe19ab2299..7c1a7bc4a47 100644
--- a/sys/arch/i386/include/segments.h
+++ b/sys/arch/i386/include/segments.h
@@ -1,4 +1,4 @@
-/*	$OpenBSD: segments.h,v 1.21 2016/03/15 03:17:51 guenther Exp $	*/
+/*	$OpenBSD: segments.h,v 1.22 2018/03/13 13:51:05 bluhm Exp $	*/
 /*	$NetBSD: segments.h,v 1.23 1996/02/01 22:31:03 mycroft Exp $	*/
 
 /*-
@@ -221,11 +221,10 @@ void idt_vec_free(int);
 #define	GICODE_SEL	10	/* Interrupt code descriptor (same as Kernel code) */
 #define	GUFS_SEL	11	/* User per-thread (%fs) descriptor */
 #define	GUGS_SEL	12	/* User per-thread (%gs) descriptor */
-#define	NGDT		13
+#define GTSS_SEL	13	/* common TSS */
+#define	GBIOS32_SEL	14	/* spare slot for 32 bit BIOS calls */
+#define	NGDT		15
 
-/*
- * Entries in the Local Descriptor Table (LDT)
- */
-#define	NLDT		17
+#define GDT_SIZE	(NGDT << 3)
 
 #endif /* _MACHINE_SEGMENTS_H_ */
diff --git a/sys/arch/i386/include/tss.h b/sys/arch/i386/include/tss.h
index 705d62b6b18..93efe7f7457 100644
--- a/sys/arch/i386/include/tss.h
+++ b/sys/arch/i386/include/tss.h
@@ -1,4 +1,4 @@
-/*	$OpenBSD: tss.h,v 1.8 2011/03/23 16:54:35 pirofti Exp $	*/
+/*	$OpenBSD: tss.h,v 1.9 2018/03/13 13:51:05 bluhm Exp $	*/
 /*	$NetBSD: tss.h,v 1.6 1995/10/11 04:20:28 mycroft Exp $	*/
 
 /*-
@@ -50,24 +50,24 @@ struct i386tss {
 	int	__tss_ss1;
 	int	__tss_esp2;
 	int	__tss_ss2;
-	int	tss_cr3;	/* page directory [pointer] paddr */
+	int	__tss_cr3;
 	int	__tss_eip;
 	int	__tss_eflags;
 	int	__tss_eax; 
 	int	__tss_ecx; 
 	int	__tss_edx; 
 	int	__tss_ebx; 
-	int	tss_esp;	/* saved stack pointer */
-	int	tss_ebp;	/* saved frame pointer */
+	int	__tss_esp;
+	int	__tss_ebp;
 	int	__tss_esi; 
 	int	__tss_edi; 
 	int	__tss_es;
-	int	tss_cs;
+	int	__tss_cs;
 	int	__tss_ss;
 	int	__tss_ds;
-	int	tss_fs;		/* saved segment register */
-	int	tss_gs;		/* saved segment register */
-	int	tss_ldt;	/* LDT selector */
+	int	__tss_fs;
+	int	__tss_gs;
+	int	__tss_ldt;
 	int	tss_ioopt;	/* options and I/O permission map offset */
 };