x86_64: implement TSS initialisation and user/kernel stack pointer switching

arch/x86_64/include/arch/gdt.h

@@ -1,6 +1,7 @@
 #ifndef ARCH_GDT_H_
 #define ARCH_GDT_H_
 
+#include <arch/tss.h>
 #include <mango/compiler.h>
 #include <stdint.h>
 
@@ -33,6 +34,7 @@ struct gdt_entry {
 
 struct gdt {
 	struct gdt_entry g_entries[NR_GDT_ENTRIES];
+	struct tss_gdt_entry g_tss;
 } __packed;
 
 struct gdt_ptr {
@@ -41,6 +43,7 @@ struct gdt_ptr {
 } __packed;
 
 extern int gdt_init(struct gdt *gdt, struct gdt_ptr *gdtp);
+extern void gdt_write_tss(struct gdt *gdt, struct tss *tss);
 extern int gdt_load(struct gdt_ptr *gdtp);
 
 #ifdef __cplusplus

arch/x86_64/include/arch/tss.h

@@ -0,0 +1,55 @@
+#ifndef ARCH_TSS_H_
+#define ARCH_TSS_H_
+
+#include <mango/compiler.h>
+#include <mango/types.h>
+#include <stdint.h>
+
+#define TSS_GDT_INDEX 5
+
+struct tss {
+	uint32_t res0;
+	uint64_t rsp0;
+	uint64_t rsp1;
+	uint64_t rsp2;
+	uint64_t res1;
+	uint64_t ist1;
+	uint64_t ist2;
+	uint64_t ist3;
+	uint64_t ist4;
+	uint64_t ist5;
+	uint64_t ist6;
+	uint64_t ist7;
+	uint64_t res2;
+	uint16_t res3;
+	uint16_t iomap_offset;
+} __packed;
+
+struct tss_gdt_entry {
+	/* these fields are copied from struct gdt_entry */
+	uint16_t ge_limit_low;
+	uint16_t ge_base_low;
+	uint8_t ge_base_mid;
+	uint8_t ge_access;
+	uint8_t ge_gran;
+	uint8_t ge_base_hi;
+	/* these fields are specific to the TSS entry */
+	uint32_t ge_base_ext;
+	uint32_t ge_reserved;
+} __packed;
+
+struct tss_ptr {
+	uint16_t tss_limit;
+	uint64_t tss_base;
+} __packed;
+
+extern void tss_init(struct tss *tss, struct tss_ptr *ptr);
+extern void tss_load(struct tss *tss);
+
+extern virt_addr_t tss_get_kstack(struct tss *tss);
+extern virt_addr_t tss_get_ustack(struct tss *tss);
+
+extern void tss_set_kstack(struct tss *tss, virt_addr_t sp);
+extern void tss_set_ustack(struct tss *tss, virt_addr_t sp);
+
+#endif

arch/x86_64/include/mango/machine/cpu.h

@@ -21,6 +21,9 @@ typedef struct ml_cpu_block {
 	struct gdt c_gdt;
 	struct gdt_ptr c_gdt_ptr;
 
+	struct tss c_tss;
+	struct tss_ptr c_tss_ptr;
+
 	struct idt_ptr c_idt_ptr;
 	unsigned int c_cpu_id;
 
@@ -45,6 +48,12 @@ extern int ml_init_bootcpu(void);
 extern int ml_cpu_block_init(ml_cpu_block *p);
 extern int ml_cpu_block_use(ml_cpu_block *p);
 
+extern virt_addr_t ml_cpu_block_get_ustack(ml_cpu_block *p);
+extern virt_addr_t ml_cpu_block_get_kstack(ml_cpu_block *p);
+
+extern void ml_cpu_block_set_ustack(ml_cpu_block *p, virt_addr_t sp);
+extern void ml_cpu_block_set_kstack(ml_cpu_block *p, virt_addr_t sp);
+
 /* defined in cpu_ctrl.S */
 extern void ml_halt_cpu(void);
 extern ml_cpu_block *ml_this_cpu(void);

arch/x86_64/include/mango/machine/init.h

@@ -1,6 +1,7 @@
 #ifndef MANGO_X86_64_INIT_H_
 #define MANGO_X86_64_INIT_H_
 
+#include <stddef.h>
 #include <stdint.h>
 
 #ifdef __cplusplus