Add separate gdt descriptors for %fs and %gs on amd64.

Reorder amd64 gdt descriptors so that user-accessible selectors are the
same as on i386. At least Wine hard-codes this into the binary.

In collaboration with:	pho
Reviewed by:	jhb

2 files changed, 69 insertions, 24 deletions

diff --git a/sys/amd64/amd64/machdep.c b/sys/amd64/amd64/machdep.c
index f34e8159934d..cd86789fe292 100644
--- a/sys/amd64/amd64/machdep.c
+++ b/sys/amd64/amd64/machdep.c
@@ -826,7 +826,12 @@ CTASSERT(sizeof(struct nmi_pcpu) == 16);
 
 struct amd64tss common_tss[MAXCPU];
 
-/* software prototypes -- in more palatable form */
+/*
+ * Software prototypes -- in more palatable form.
+ *
+ * Keep GUFS32, GUGS32, GUCODE32 and GUDATA at the same
+ * slots as corresponding segments for i386 kernel.
+ */
 struct soft_segment_descriptor gdt_segs[] = {
 /* GNULL_SEL	0 Null Descriptor */
 {	.ssd_base = 0x0,
@@ -837,7 +842,34 @@ struct soft_segment_descriptor gdt_segs[] = {
 	.ssd_long = 0,
 	.ssd_def32 = 0,
 	.ssd_gran = 0		},
-/* GCODE_SEL	1 Code Descriptor for kernel */
+/* GNULL2_SEL	1 Null Descriptor */
+{	.ssd_base = 0x0,
+	.ssd_limit = 0x0,
+	.ssd_type = 0,
+	.ssd_dpl = 0,
+	.ssd_p = 0,
+	.ssd_long = 0,
+	.ssd_def32 = 0,
+	.ssd_gran = 0		},
+/* GUFS32_SEL	2 32 bit %gs Descriptor for user */
+{	.ssd_base = 0x0,
+	.ssd_limit = 0xfffff,
+	.ssd_type = SDT_MEMRWA,
+	.ssd_dpl = SEL_UPL,
+	.ssd_p = 1,
+	.ssd_long = 0,
+	.ssd_def32 = 1,
+	.ssd_gran = 1		},
+/* GUGS32_SEL	3 32 bit %fs Descriptor for user */
+{	.ssd_base = 0x0,
+	.ssd_limit = 0xfffff,
+	.ssd_type = SDT_MEMRWA,
+	.ssd_dpl = SEL_UPL,
+	.ssd_p = 1,
+	.ssd_long = 0,
+	.ssd_def32 = 1,
+	.ssd_gran = 1		},
+/* GCODE_SEL	4 Code Descriptor for kernel */
 {	.ssd_base = 0x0,
 	.ssd_limit = 0xfffff,
 	.ssd_type = SDT_MEMERA,
@@ -846,7 +878,7 @@ struct soft_segment_descriptor gdt_segs[] = {
 	.ssd_long = 1,
 	.ssd_def32 = 0,
 	.ssd_gran = 1		},
-/* GDATA_SEL	2 Data Descriptor for kernel */
+/* GDATA_SEL	5 Data Descriptor for kernel */
 {	.ssd_base = 0x0,
 	.ssd_limit = 0xfffff,
 	.ssd_type = SDT_MEMRWA,
@@ -855,7 +887,7 @@ struct soft_segment_descriptor gdt_segs[] = {
 	.ssd_long = 1,
 	.ssd_def32 = 0,
 	.ssd_gran = 1		},
-/* GUCODE32_SEL	3 32 bit Code Descriptor for user */
+/* GUCODE32_SEL	6 32 bit Code Descriptor for user */
 {	.ssd_base = 0x0,
 	.ssd_limit = 0xfffff,
 	.ssd_type = SDT_MEMERA,
@@ -864,7 +896,7 @@ struct soft_segment_descriptor gdt_segs[] = {
 	.ssd_long = 0,
 	.ssd_def32 = 1,
 	.ssd_gran = 1		},
-/* GUDATA_SEL	4 32/64 bit Data Descriptor for user */
+/* GUDATA_SEL	7 32/64 bit Data Descriptor for user */
 {	.ssd_base = 0x0,
 	.ssd_limit = 0xfffff,
 	.ssd_type = SDT_MEMRWA,
@@ -873,7 +905,7 @@ struct soft_segment_descriptor gdt_segs[] = {
 	.ssd_long = 0,
 	.ssd_def32 = 1,
 	.ssd_gran = 1		},
-/* GUCODE_SEL	5 64 bit Code Descriptor for user */
+/* GUCODE_SEL	8 64 bit Code Descriptor for user */
 {	.ssd_base = 0x0,
 	.ssd_limit = 0xfffff,
 	.ssd_type = SDT_MEMERA,
@@ -882,9 +914,9 @@ struct soft_segment_descriptor gdt_segs[] = {
 	.ssd_long = 1,
 	.ssd_def32 = 0,
 	.ssd_gran = 1		},
-/* GPROC0_SEL	6 Proc 0 Tss Descriptor */
+/* GPROC0_SEL	9 Proc 0 Tss Descriptor */
 {	.ssd_base = 0x0,
-	.ssd_limit = sizeof(struct amd64tss)-1,
+	.ssd_limit = sizeof(struct amd64tss) + IOPAGES * PAGE_SIZE - 1,
 	.ssd_type = SDT_SYSTSS,
 	.ssd_dpl = SEL_KPL,
 	.ssd_p = 1,
@@ -900,15 +932,24 @@ struct soft_segment_descriptor gdt_segs[] = {
 	.ssd_long = 0,
 	.ssd_def32 = 0,
 	.ssd_gran = 0		},
-/* GUGS32_SEL	8 32 bit GS Descriptor for user */
+/* GUSERLDT_SEL	11 LDT Descriptor */
 {	.ssd_base = 0x0,
-	.ssd_limit = 0xfffff,
-	.ssd_type = SDT_MEMRWA,
-	.ssd_dpl = SEL_UPL,
-	.ssd_p = 1,
+	.ssd_limit = 0x0,
+	.ssd_type = 0,
+	.ssd_dpl = 0,
+	.ssd_p = 0,
 	.ssd_long = 0,
-	.ssd_def32 = 1,
-	.ssd_gran = 1		},
+	.ssd_def32 = 0,
+	.ssd_gran = 0		},
+/* GUSERLDT_SEL	12 LDT Descriptor, double size */
+{	.ssd_base = 0x0,
+	.ssd_limit = 0x0,
+	.ssd_type = 0,
+	.ssd_dpl = 0,
+	.ssd_p = 0,
+	.ssd_long = 0,
+	.ssd_def32 = 0,
+	.ssd_gran = 0		},
 };
 
 void
diff --git a/sys/amd64/include/segments.h b/sys/amd64/include/segments.h
index 8ff3a0f9e27b..cab7554c82c1 100644
--- a/sys/amd64/include/segments.h
+++ b/sys/amd64/include/segments.h
@@ -212,15 +212,19 @@ struct region_descriptor {
  * Entries in the Global Descriptor Table (GDT)
  */
 #define	GNULL_SEL	0	/* Null Descriptor */
-#define	GCODE_SEL	1	/* Kernel Code Descriptor */
-#define	GDATA_SEL	2	/* Kernel Data Descriptor */
-#define	GUCODE32_SEL	3	/* User 32 bit code Descriptor */
-#define	GUDATA_SEL	4	/* User 32/64 bit Data Descriptor */
-#define	GUCODE_SEL	5	/* User 64 bit Code Descriptor */
-#define	GPROC0_SEL	6	/* TSS for entering kernel etc */
-/* slot 7 is second half of GPROC0_SEL */
-#define	GUGS32_SEL	8	/* User 32 bit GS Descriptor */
-#define	NGDT 		9
+#define	GNULL2_SEL	1	/* Null Descriptor */
+#define	GUFS32_SEL	2	/* User 32 bit %fs Descriptor */
+#define	GUGS32_SEL	3	/* User 32 bit %gs Descriptor */
+#define	GCODE_SEL	4	/* Kernel Code Descriptor */
+#define	GDATA_SEL	5	/* Kernel Data Descriptor */
+#define	GUCODE32_SEL	6	/* User 32 bit code Descriptor */
+#define	GUDATA_SEL	7	/* User 32/64 bit Data Descriptor */
+#define	GUCODE_SEL	8	/* User 64 bit Code Descriptor */
+#define	GPROC0_SEL	9	/* TSS for entering kernel etc */
+/* slot 10 is second half of GPROC0_SEL */
+#define	GUSERLDT_SEL	11	/* LDT */
+/* slot 11 is second half of GUSERLDT_SEL */
+#define	NGDT 		13
 
 #ifdef _KERNEL
 extern struct user_segment_descriptor gdt[];