From 38375bab9e7814f4a676cefb610a31f2d85ee7a8 Mon Sep 17 00:00:00 2001
From: acevest <zhaoyanbai@126.com>
Date: Tue, 16 May 2023 21:09:04 +0800
Subject: [PATCH] =?utf8?q?=E6=8C=AA=E5=8A=A8tss=E7=9B=B8=E5=85=B3=E4=BB=A3?=
 =?utf8?q?=E7=A0=81?=
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---
 include/processor.h | 23 +++--------------------
 kernel/system.c     | 31 ++++++++++++++++++++++++++-----
 2 files changed, 29 insertions(+), 25 deletions(-)

diff --git a/include/processor.h b/include/processor.h
index eda56f2..56d6b9d 100644
--- a/include/processor.h
+++ b/include/processor.h
@@ -144,7 +144,7 @@ static inline void set_idt_gate(u32 vec, u32 handler, u8 type, u8 DPL) { idt[vec
         set_idt_gate(vect, (u32)handler, type, DPL); \
     } while (0)
 
-typedef struct {
+typedef struct tss {
     u16 backlink, _backlink;
     u32 esp0;
     u16 ss0, _ss0;
@@ -171,25 +171,8 @@ typedef struct {
     u16 gs, _gs;
     u16 ldt, _ldt;
     u16 T : 1, _T : 15, iomap_base;
-} TSS, *pTSS;
-static inline void set_tss_gate(u32 vec, u32 addr) {
-#if 1
-    pSeg p = (pSeg)(gdt + vec);
-    _init_desc((pDesc)p);
-    p->limitL = 0xFFFF & sizeof(TSS);
-    p->limitH = 0x0F & (sizeof(TSS) >> 16);
-    p->baseL = 0xFFFF & addr;
-    p->baseM = 0xFF & (addr >> 16);
-    p->baseH = 0xFF & (addr >> 24);
-
-    p->P = 1;
-    p->DPL = PRIVILEGE_USER;
-    p->S = 0;
-
-    p->type = TSS_DESC;
-#endif
-}
+} TSS_t;
 
-extern TSS tss;
+extern TSS_t tss;
 
 #endif  //_DESCRIPTOR_H
diff --git a/kernel/system.c b/kernel/system.c
index f5efd71..fa0d783 100644
--- a/kernel/system.c
+++ b/kernel/system.c
@@ -131,9 +131,26 @@ void setup_irqs() {
     open_irq(0x01);
     open_irq(0x0E);
 }
+
+void set_tss_gate(u32 vec, u32 addr, u32 limit) {
+    pSeg p = (pSeg)(gdt + vec);
+    _init_desc((pDesc)p);
+    p->limitL = 0xFFFF & limit;
+    p->limitH = 0x0F & (limit >> 16);
+    p->baseL = 0xFFFF & addr;
+    p->baseM = 0xFF & (addr >> 16);
+    p->baseH = 0xFF & (addr >> 24);
+
+    p->P = 1;
+    p->DPL = PRIVILEGE_USER;
+    p->S = 0;
+
+    p->type = TSS_DESC;
+}
+
 void set_tss() {
-    pTSS p = &tss;
-    memset((void *)p, sizeof(TSS), 0);
+    TSS_t *p = &tss;
+    memset((void *)p, sizeof(TSS_t), 0);
     p->esp0 = 0;  // delay to init root_task
     p->ss0 = SELECTOR_KRNL_DS;
     p->ss = SELECTOR_KRNL_DS;
@@ -143,8 +160,12 @@ void set_tss() {
     p->ds = SELECTOR_KRNL_DS;
     p->cs = SELECTOR_KRNL_CS;
     p->eflags = 0x1200;
-    p->iomap_base = sizeof(TSS);
-    set_tss_gate(INDEX_TSS, (u32)p);
+    p->iomap_base = sizeof(TSS_t);
+
+    // tss的iomap_base=sizeof(TSS_t) > TSS_GATE.LIMIT - 1
+    // 因此表示没有I/O位图
+    set_tss_gate(INDEX_TSS, (u32)p, sizeof(TSS_t));
+
     asm("ltr %%ax" ::"a"((INDEX_TSS << 3) + 3));
 }
 
@@ -165,7 +186,7 @@ int sysc_reboot(int mode) {
 }
 
 System system;
-TSS tss;
+TSS_t tss;
 Desc idt[NIDT] __attribute__((__aligned__(8)));
 Desc gdt[NGDT] __attribute__((__aligned__(8)));
 char gdtr[6] __attribute__((__aligned__(4)));
-- 
2.44.0