CH32V10X 适配

CPU/CH32V10x/cpu.h

@@ -28,7 +28,10 @@
 OS_STATIC_FORCE_INLINE
 os_uint_t cpu_save_disable_irq_in_isr(void){
     os_uint_t result;
-    __asm volatile ("csrrw %0, mstatus, %1":"=r"(result):"r"(0x1800):"memory");
+    __asm volatile ("csrrw %0, mstatus, %1"
+        :"=r"(result)
+        :"r"(0x1800)
+        :"memory");
     return result;
 }
 
@@ -44,4 +47,14 @@ void cpu_restore_irq_in_isr(os_uint_t value){
 #define os_port_save_disable_irq            cpu_save_disable_irq_in_isr
 #define os_port_restore_irq                 cpu_restore_irq_in_isr
 
+OS_STATIC_FORCE_INLINE
+void cpu_set_isr_sp(void){
+    __asm volatile("csrrw sp,mscratch,sp");
+}
+
+OS_STATIC_FORCE_INLINE
+void cpu_set_task_sp(void){
+    __asm volatile("csrrw sp,mscratch,sp");
+}
+
 #endif /*INCLUDED_CPU_H*/

CPU/CH32V10x/os_port.c

@@ -1,3 +1,4 @@
+#include <os_isr.h>
 #include "os_port.h"
 #include "os_stack.h"
 #include "os_macros.h"
@@ -5,7 +6,6 @@
 #include "os_compiler.h"
 #include "os_systick.h"
 #include "os_sched.h"
-#include "os_isr.h"
 #include "cpu.h"
 
 /* ------------------------------------------------------------------------------------------------------------------ */
@@ -20,7 +20,7 @@ uint32_t _SysTick_Config(os_tick_t ticks)
 {
 
 
-    NVIC->CFGR = (CPU_KEY1<<16) | (1<<1/*NESTCTRL*/) | (1<<0/*HWSTKCTRL*/); /* 关闭硬件压栈和嵌套 */
+    NVIC->CFGR = 0xFA050003; /* 关闭硬件压栈和嵌套 */
 
     NVIC_SetPriority(SysTick_IRQn,0xf0);
     NVIC_SetPriority(Software_IRQn,0xf0);
@@ -44,6 +44,38 @@ uint32_t _SysTick_Config(os_tick_t ticks)
 /*  */
 
 typedef struct {
+    os_uintptr_t mstatus;       /* zero, 用于 mstatus 保存 */
+    os_uintptr_t ra;            /* 返回地址 */
+    os_uintptr_t mepc;          /* 栈指针, mepc */
+    os_uintptr_t x3;            /* 全局指针 */
+    os_uintptr_t x4;            /* 线程指针 */
+    os_uintptr_t x5;            /* 临时寄存器0 */
+    os_uintptr_t x6;            /* 临时寄存器1 */
+    os_uintptr_t x7;            /* 临时寄存器2 */
+    os_uintptr_t x8;            /* s0/fp */
+    os_uintptr_t x9;            /* 保存寄存器1 */
+    os_uintptr_t a0;            /* 函数参数/返回值 */
+    os_uintptr_t x11;           /* 函数参数 */
+    os_uintptr_t x12;           /* 函数参数 */
+    os_uintptr_t x13;           /* 函数参数 */
+    os_uintptr_t x14;           /* 函数参数 */
+    os_uintptr_t x15;           /* 函数参数 */
+    os_uintptr_t x16;           /* 函数参数 */
+    os_uintptr_t x17;           /* 函数参数 */
+    os_uintptr_t x18;           /* 保存寄存器 */
+    os_uintptr_t x19;           /* 保存寄存器 */
+    os_uintptr_t x20;           /* 保存寄存器 */
+    os_uintptr_t x21;           /* 保存寄存器 */
+    os_uintptr_t x22;           /* 保存寄存器 */
+    os_uintptr_t x23;           /* 保存寄存器 */
+    os_uintptr_t x24;           /* 保存寄存器 */
+    os_uintptr_t x25;           /* 保存寄存器 */
+    os_uintptr_t x26;           /* 保存寄存器 */
+    os_uintptr_t x27;           /* 保存寄存器 */
+    os_uintptr_t x28;           /* 临时寄存器 */
+    os_uintptr_t x29;           /* 临时寄存器 */
+    os_uintptr_t x30;           /* 临时寄存器 */
+    os_uintptr_t x31;           /* 临时寄存器 */
 #if (OS_CFG_CPU_FPU_PRESENT)
     os_uintptr_t f0;
     os_uintptr_t f1;
@@ -78,55 +110,23 @@ typedef struct {
     os_uintptr_t f30;
     os_uintptr_t f31;
 #endif
-    os_uintptr_t mstatus;       /* zero, 用于 mstatus 保存 */
-    os_uintptr_t ra;            /* 返回地址 */
-    os_uintptr_t mepc;          /* 栈指针, mepc */
-    os_uintptr_t x3;            /* 全局指针 */
-    os_uintptr_t x4;            /* 线程指针 */
-    os_uintptr_t x5;            /* 临时寄存器0 */
-    os_uintptr_t x6;            /* 临时寄存器1 */
-    os_uintptr_t x7;            /* 临时寄存器2 */
-    os_uintptr_t x8;            /* s0/fp */
-    os_uintptr_t x9;            /* 保存寄存器1 */
-    os_uintptr_t a0;            /* 函数参数/返回值 */
-    os_uintptr_t x11;           /* 函数参数 */
-    os_uintptr_t x12;           /* 函数参数 */
-    os_uintptr_t x13;           /* 函数参数 */
-    os_uintptr_t x14;           /* 函数参数 */
-    os_uintptr_t x15;           /* 函数参数 */
-    os_uintptr_t x16;           /* 函数参数 */
-    os_uintptr_t x17;           /* 函数参数 */
-    os_uintptr_t x18;           /* 保存寄存器 */
-    os_uintptr_t x19;           /* 保存寄存器 */
-    os_uintptr_t x20;           /* 保存寄存器 */
-    os_uintptr_t x21;           /* 保存寄存器 */
-    os_uintptr_t x22;           /* 保存寄存器 */
-    os_uintptr_t x23;           /* 保存寄存器 */
-    os_uintptr_t x24;           /* 保存寄存器 */
-    os_uintptr_t x25;           /* 保存寄存器 */
-    os_uintptr_t x26;           /* 保存寄存器 */
-    os_uintptr_t x27;           /* 保存寄存器 */
-    os_uintptr_t x28;           /* 临时寄存器 */
-    os_uintptr_t x29;           /* 临时寄存器 */
-    os_uintptr_t x30;           /* 临时寄存器 */
-    os_uintptr_t x31;           /* 临时寄存器 */
 }os_stack_frame_t;
 
 #define STACK_FRAME_SIZE sizeof(os_stack_frame_t)
-#define MSTATUS_MPIE (1<<7)
 
 os_stack_t os_port_cpu_stack_init(os_task_entry_t entry, void* param
         , void* stack_base, os_size_t stack_size, void(*exit_entry)(void)){
     os_uintptr_t stack_max = (os_uintptr_t)((uint8_t *) stack_base + stack_size);
     os_uintptr_t real_max = OS_ALIGN_DOWN(stack_max, OS_ALIGN_SIZE); /* 实际栈顶的位置，对齐后的位置 */
     stack_size -= (stack_max - real_max); /* 实际栈大小 */
-
+    uint8_t value = 0x01;
     os_stack_frame_t* p_frame = (os_stack_frame_t*)(real_max - STACK_FRAME_SIZE);
     for(os_size_t i=0; i<STACK_FRAME_SIZE/sizeof(os_uintptr_t); i++){
-        ((os_uintptr_t*)(p_frame))[i] = 0x5ac0ffee;
+        ((os_uintptr_t*)(p_frame))[i] = (value<<24) | (value<<16) | (value << 8) | value;
+        value++;
     }
 
-    p_frame->mstatus = MSTATUS_MPIE;
+    p_frame->mstatus = 0x1880;
     p_frame->mepc = (os_uintptr_t)entry;
     p_frame->a0 = (os_uintptr_t)param;
     p_frame->ra = (os_uintptr_t)exit_entry;
@@ -139,29 +139,6 @@ os_stack_t os_port_cpu_stack_init(os_task_entry_t entry, void* param
     return stack;
 }
 
-//void os_port_disable_irq(void){
-//    RISCV_disable_irq();
-//}
-//
-//void os_port_enable_irq(void){
-//    RISCV_enable_irq();
-//}
-//
-//os_uint_t os_port_save_disable_irq(void){
-//    return os_port_save_disable_irq_in_isr();
-//}
-//
-//void os_port_restore_irq(os_uint_t level){
-//    os_port_restore_irq_in_isr(level);
-//}
-
-//os_uint_t os_port_save_disable_irq_in_isr(void){
-//    return RISCV_get_set_MSTATUS(0x1800);
-//}
-
-//void os_port_restore_irq_in_isr(os_uint_t level){
-//    RISCV_set_MSTATUS(level);
-//}
 
 void os_sched(void){
     os_sched_in_isr();
@@ -204,22 +181,21 @@ void os_port_context_switch(void* from_sp, void* to_sp){
     g_os_port_switch_from_sp = from_sp;
     g_os_port_switch_to_sp = to_sp;
     g_os_port_context_switch_flag = OS_TRUE;
-    os_critical_leave_in_isr();
     if(from_sp==0){
+        os_critical_leave_in_isr();
         os_port_context_switch_to((os_uintptr_t)to_sp);
     }else{
+        os_critical_leave_in_isr();
         os_port_send_context_switch_request();
     }
 }
 
 
-void SysTick_Handler(void) __attribute__((interrupt()));
+void SysTick_Handler_C(void){
-void SysTick_Handler(void){
     SysTick->CTLR=0;
     SysTick->CNTL0=0;SysTick->CNTL1=0;SysTick->CNTL2=0;SysTick->CNTL3=0;
     SysTick->CNTH0=0;SysTick->CNTH1=0;SysTick->CNTH2=0;SysTick->CNTH3=0;
     SysTick->CTLR=0x1;
-
     // 调用系统心跳处理
     os_systick_tick();
 }

CPU/CH32V10x/os_port_gnu.S

@@ -33,39 +33,73 @@ cpu_clz:
 #endif
 
 .section .text.os_port_context_switch_to,"ax",%progbits
-.align 8
+.align 2
 .func
 .global os_port_context_switch_to
 .extern os_port_on_switch_success
 os_port_context_switch_to:
-    /* machine mode, disable ISR */
     li   t0,        0x1800
-    csrw  mstatus, t0
+    csrw mstatus,   t0                      // 1. 关中断
 
-    /* first save interrupt stack */
+    /* 设置中断栈/系统栈空间 */
     la      t0, _eusrstack
     addi    t0, t0, -512
-    csrw mscratch,t0
+    csrw    mscratch, t0                    // 备用栈指针存入 mscratch
 
-    /* restore sp */
+    /* =====================================================================
-    LOAD sp, (a0)
+     * 第一步：切换到中断栈，安全调用通知 C 函数
+     * ===================================================================== */
+    jal     os_port_on_switch_success       // 调用 C 函数（此时随便它怎么污染寄存器）
 
-    csrrw sp, mscratch, sp
+    /* =====================================================================
-    jal   os_port_on_switch_success
+    * 第二步：获取新任务的栈指针 SP
-    csrrw sp, mscratch, sp
+    * ===================================================================== */
+    LOAD    sp, 0(a0)                       // a0 是传入的 &g_os_port_switch_to_sp，从中取出 sp
 
-    /* restore mstatus.MPIE */
+    /* =====================================================================
-    LOAD a0, 0*REG_BYTES(sp)
+     * 第三步：恢复 FPU 浮点寄存器（与保存栈帧严格镜像）
-    csrs mstatus, a0
+     * 修复宏定义：将 MPU 改回 FPU
+     * ===================================================================== */
+#if (OS_CFG_CPU_FPU_PRESENT)
+    FLOAD   f0,  (CONTEXT_SIZE + 0 * REG_BYTES)(sp)
+    FLOAD   f1,  (CONTEXT_SIZE + 1 * REG_BYTES)(sp)
+    FLOAD   f2,  (CONTEXT_SIZE + 2 * REG_BYTES)(sp)
+    FLOAD   f3,  (CONTEXT_SIZE + 3 * REG_BYTES)(sp)
+    FLOAD   f4,  (CONTEXT_SIZE + 4 * REG_BYTES)(sp)
+    FLOAD   f5,  (CONTEXT_SIZE + 5 * REG_BYTES)(sp)
+    FLOAD   f6,  (CONTEXT_SIZE + 6 * REG_BYTES)(sp)
+    FLOAD   f7,  (CONTEXT_SIZE + 7 * REG_BYTES)(sp)
+    FLOAD   f8,  (CONTEXT_SIZE + 8 * REG_BYTES)(sp)
+    FLOAD   f9,  (CONTEXT_SIZE + 9 * REG_BYTES)(sp)
+    FLOAD   f10, (CONTEXT_SIZE + 10 * REG_BYTES)(sp)
+    FLOAD   f11, (CONTEXT_SIZE + 11 * REG_BYTES)(sp)
+    FLOAD   f12, (CONTEXT_SIZE + 12 * REG_BYTES)(sp)
+    FLOAD   f13, (CONTEXT_SIZE + 13 * REG_BYTES)(sp)
+    FLOAD   f14, (CONTEXT_SIZE + 14 * REG_BYTES)(sp)
+    FLOAD   f15, (CONTEXT_SIZE + 15 * REG_BYTES)(sp)
+    FLOAD   f16, (CONTEXT_SIZE + 16 * REG_BYTES)(sp)
+    FLOAD   f17, (CONTEXT_SIZE + 17 * REG_BYTES)(sp)
+    FLOAD   f18, (CONTEXT_SIZE + 18 * REG_BYTES)(sp)
+    FLOAD   f19, (CONTEXT_SIZE + 19 * REG_BYTES)(sp)
+    FLOAD   f20, (CONTEXT_SIZE + 20 * REG_BYTES)(sp)
+    FLOAD   f21, (CONTEXT_SIZE + 21 * REG_BYTES)(sp)
+    FLOAD   f22, (CONTEXT_SIZE + 22 * REG_BYTES)(sp)
+    FLOAD   f23, (CONTEXT_SIZE + 23 * REG_BYTES)(sp)
+    FLOAD   f24, (CONTEXT_SIZE + 24 * REG_BYTES)(sp)
+    FLOAD   f25, (CONTEXT_SIZE + 25 * REG_BYTES)(sp)
+    FLOAD   f26, (CONTEXT_SIZE + 26 * REG_BYTES)(sp)
+    FLOAD   f27, (CONTEXT_SIZE + 27 * REG_BYTES)(sp)
+    FLOAD   f28, (CONTEXT_SIZE + 28 * REG_BYTES)(sp)
+    FLOAD   f29, (CONTEXT_SIZE + 29 * REG_BYTES)(sp)
+    FLOAD   f30, (CONTEXT_SIZE + 30 * REG_BYTES)(sp)
+    FLOAD   f31, (CONTEXT_SIZE + 31 * REG_BYTES)(sp)
+#endif
 
-    /* restore mepc */
+    /* =====================================================================
-    LOAD a0,   2 * REG_BYTES(sp)
+     * 第四步：恢复通用寄存器（最后恢复 t0）
-    csrw mepc, a0
+     * ===================================================================== */
-
-    /* return address */
     LOAD    x1,   1 * REG_BYTES(sp)
     LOAD    x4,   4 * REG_BYTES(sp)
-    LOAD x5,   5 * REG_BYTES(sp)
     LOAD    x6,   6 * REG_BYTES(sp)
     LOAD    x7,   7 * REG_BYTES(sp)
     LOAD    x8,   8 * REG_BYTES(sp)
@@ -92,161 +126,193 @@ os_port_context_switch_to:
     LOAD    x29, 29 * REG_BYTES(sp)
     LOAD    x30, 30 * REG_BYTES(sp)
     LOAD    x31, 31 * REG_BYTES(sp)
+
+    /* =====================================================================
+     * 第五步：恢复特权级控制 CSR 寄存器
+     * ===================================================================== */
+    LOAD    t0, 2 * REG_BYTES(sp)           // 恢复初始 PC 到 mepc
+    csrw    mepc, t0
+
+    LOAD    t0, 0 * REG_BYTES(sp)           // 从栈中读取准备好的初始 mstatus
+    csrw    mstatus, t0                     // 修复：改用 csrw 强行覆盖
+
+    LOAD    x5,   5 * REG_BYTES(sp)         // 此时最后安全恢复 t0(x5)
+
+    /* =====================================================================
+    * 第六步：统一释放栈空间并退出
+    * ===================================================================== */
+#if (OS_CFG_CPU_FPU_PRESENT)
+    addi    sp, sp, (CONTEXT_SIZE + 32 * REG_BYTES)
+#else
     addi    sp, sp, CONTEXT_SIZE
-
-    /* load float reg */
-#if (OS_CFG_CPU_MPU_PRESENT)
-    FLOAD   f0, 0 * REG_BYTES(sp)
-    FLOAD   f1, 1 * REG_BYTES(sp)
-    FLOAD   f2, 2 * REG_BYTES(sp)
-    FLOAD   f3, 3 * REG_BYTES(sp)
-    FLOAD   f4, 4 * REG_BYTES(sp)
-    FLOAD   f5, 5 * REG_BYTES(sp)
-    FLOAD   f6, 6 * REG_BYTES(sp)
-    FLOAD   f7, 7 * REG_BYTES(sp)
-    FLOAD   f8, 8 * REG_BYTES(sp)
-    FLOAD   f9, 9 * REG_BYTES(sp)
-    FLOAD   f10, 10 * REG_BYTES(sp)
-    FLOAD   f11, 11 * REG_BYTES(sp)
-    FLOAD   f12, 12 * REG_BYTES(sp)
-    FLOAD   f13, 13 * REG_BYTES(sp)
-    FLOAD   f14, 14 * REG_BYTES(sp)
-    FLOAD   f15, 15 * REG_BYTES(sp)
-    FLOAD   f16, 16 * REG_BYTES(sp)
-    FLOAD   f17, 17 * REG_BYTES(sp)
-    FLOAD   f18, 18 * REG_BYTES(sp)
-    FLOAD   f19, 19 * REG_BYTES(sp)
-    FLOAD   f20, 20 * REG_BYTES(sp)
-    FLOAD   f21, 21 * REG_BYTES(sp)
-    FLOAD   f22, 22 * REG_BYTES(sp)
-    FLOAD   f23, 23 * REG_BYTES(sp)
-    FLOAD   f24, 24 * REG_BYTES(sp)
-    FLOAD   f25, 25 * REG_BYTES(sp)
-    FLOAD   f26, 26 * REG_BYTES(sp)
-    FLOAD   f27, 27 * REG_BYTES(sp)
-    FLOAD   f28, 28 * REG_BYTES(sp)
-    FLOAD   f29, 29 * REG_BYTES(sp)
-    FLOAD   f30, 30 * REG_BYTES(sp)
-    FLOAD   f31, 31 * REG_BYTES(sp)
-    addi    sp, sp, 32 * REG_BYTES
 #endif
-
     mret
 
     .endfunc
 
 
 .section .text.SW_Handler,"ax",%progbits
-.align 8
+.align 2
 .func
 .global SW_Handler
 .extern g_os_port_switch_from_sp
 .extern g_os_port_switch_to_sp
-.extern os_isr_enter
-.extern os_isr_leave
 .extern os_port_on_switch_success
-.extern g_t0
 SW_Handler:
+    csrci mstatus, 0x08 // 立刻关闭全局中断 MIE = 0
+
+    /* =====================================================================
+    * 第一步：一揽子分配所有栈空间（防止碎片和二次偏移错误）
+    * ===================================================================== */
 #if (OS_CFG_CPU_FPU_PRESENT)
-    addi    sp, sp, -32 * REG_BYTES
+    addi sp, sp, -(CONTEXT_SIZE + 32 * REG_BYTES)
-    FSTORE  f0, 0 * REG_BYTES(sp)
+#else
-    FSTORE  f1, 1 * REG_BYTES(sp)
+    addi sp, sp, -CONTEXT_SIZE
-    FSTORE  f2, 2 * REG_BYTES(sp)
-    FSTORE  f3, 3 * REG_BYTES(sp)
-    FSTORE  f4, 4 * REG_BYTES(sp)
-    FSTORE  f5, 5 * REG_BYTES(sp)
-    FSTORE  f6, 6 * REG_BYTES(sp)
-    FSTORE  f7, 7 * REG_BYTES(sp)
-    FSTORE  f8, 8 * REG_BYTES(sp)
-    FSTORE  f9, 9 * REG_BYTES(sp)
-    FSTORE  f10, 10 * REG_BYTES(sp)
-    FSTORE  f11, 11 * REG_BYTES(sp)
-    FSTORE  f12, 12 * REG_BYTES(sp)
-    FSTORE  f13, 13 * REG_BYTES(sp)
-    FSTORE  f14, 14 * REG_BYTES(sp)
-    FSTORE  f15, 15 * REG_BYTES(sp)
-    FSTORE  f16, 16 * REG_BYTES(sp)
-    FSTORE  f17, 17 * REG_BYTES(sp)
-    FSTORE  f18, 18 * REG_BYTES(sp)
-    FSTORE  f19, 19 * REG_BYTES(sp)
-    FSTORE  f20, 20 * REG_BYTES(sp)
-    FSTORE  f21, 21 * REG_BYTES(sp)
-    FSTORE  f22, 22 * REG_BYTES(sp)
-    FSTORE  f23, 23 * REG_BYTES(sp)
-    FSTORE  f24, 24 * REG_BYTES(sp)
-    FSTORE  f25, 25 * REG_BYTES(sp)
-    FSTORE  f26, 26 * REG_BYTES(sp)
-    FSTORE  f27, 27 * REG_BYTES(sp)
-    FSTORE  f28, 28 * REG_BYTES(sp)
-    FSTORE  f29, 29 * REG_BYTES(sp)
-    FSTORE  f30, 30 * REG_BYTES(sp)
-    FSTORE  f31, 31 * REG_BYTES(sp)
 #endif
 
-    addi sp, sp, -CONTEXT_SIZE              // 留出栈空间
+    /* =====================================================================
-    STORE t0, 5*REG_BYTES(sp)               // 保存 t0
+     * 第二步：保存通用寄存器
+     * ===================================================================== */
+    STORE x5,   5 * REG_BYTES(sp)           // 优先保存 t0，腾出临时寄存器
 
-    li    t0,   0x80
+    li t0, 0x1800
+    csrw mstatus, t0                        // M 模式
+
+    li  t0,     0x1880
     STORE t0,   0 * REG_BYTES(sp)           // 设置 MPIE
 
     csrr  t0,   mepc
     STORE t0,   2*REG_BYTES(sp)             // 保存正在运行任务的 pc 指针
 
-    STORE x1,   1 * REG_BYTES(sp)           // return address
+    STORE x1,   1 * REG_BYTES(sp)           // ra
-    STORE x4,   4 * REG_BYTES(sp)
+    STORE x4,   4 * REG_BYTES(sp)           // tp
-    STORE x6,   6 * REG_BYTES(sp)
+    STORE x6,   6 * REG_BYTES(sp)           // t1
-    STORE x7,   7 * REG_BYTES(sp)
+    STORE x7,   7 * REG_BYTES(sp)           // t2
-    STORE x8,   8 * REG_BYTES(sp)
+    STORE x8,   8 * REG_BYTES(sp)           // s0/fp
-    STORE x9,   9 * REG_BYTES(sp)
+    STORE x9,   9 * REG_BYTES(sp)           // s1
-    STORE x10, 10 * REG_BYTES(sp)
+    STORE x10, 10 * REG_BYTES(sp)           // a0
-    STORE x11, 11 * REG_BYTES(sp)
+    STORE x11, 11 * REG_BYTES(sp)           // a1
-    STORE x12, 12 * REG_BYTES(sp)
+    STORE x12, 12 * REG_BYTES(sp)           // a2
-    STORE x13, 13 * REG_BYTES(sp)
+    STORE x13, 13 * REG_BYTES(sp)           // a3
-    STORE x14, 14 * REG_BYTES(sp)
+    STORE x14, 14 * REG_BYTES(sp)           // a4
-    STORE x15, 15 * REG_BYTES(sp)
+    STORE x15, 15 * REG_BYTES(sp)           // a5
-    STORE x16, 16 * REG_BYTES(sp)
+    STORE x16, 16 * REG_BYTES(sp)           // a6
-    STORE x17, 17 * REG_BYTES(sp)
+    STORE x17, 17 * REG_BYTES(sp)           // a7
-    STORE x18, 18 * REG_BYTES(sp)
+    STORE x18, 18 * REG_BYTES(sp)           // s2
-    STORE x19, 19 * REG_BYTES(sp)
+    STORE x19, 19 * REG_BYTES(sp)           // s3
-    STORE x20, 20 * REG_BYTES(sp)
+    STORE x20, 20 * REG_BYTES(sp)           // s4
-    STORE x21, 21 * REG_BYTES(sp)
+    STORE x21, 21 * REG_BYTES(sp)           // s5
-    STORE x22, 22 * REG_BYTES(sp)
+    STORE x22, 22 * REG_BYTES(sp)           // s6
-    STORE x23, 23 * REG_BYTES(sp)
+    STORE x23, 23 * REG_BYTES(sp)           // s7
-    STORE x24, 24 * REG_BYTES(sp)
+    STORE x24, 24 * REG_BYTES(sp)           // s8
-    STORE x25, 25 * REG_BYTES(sp)
+    STORE x25, 25 * REG_BYTES(sp)           // s9
-    STORE x26, 26 * REG_BYTES(sp)
+    STORE x26, 26 * REG_BYTES(sp)           // s10
-    STORE x27, 27 * REG_BYTES(sp)
+    STORE x27, 27 * REG_BYTES(sp)           // s11
-    STORE x28, 28 * REG_BYTES(sp)
+    STORE x28, 28 * REG_BYTES(sp)           // t3
-    STORE x29, 29 * REG_BYTES(sp)
+    STORE x29, 29 * REG_BYTES(sp)           // t4
-    STORE x30, 30 * REG_BYTES(sp)
+    STORE x30, 30 * REG_BYTES(sp)           // t5
-    STORE x31, 31 * REG_BYTES(sp)
+    STORE x31, 31 * REG_BYTES(sp)           // t6
 
-    la s0, g_os_port_switch_from_sp
+/* =====================================================================
-    LOAD s1, 0(s0)
+     * 第三步：保存 FPU 浮点寄存器（使用确定的、不受干扰的高位偏移）
-    STORE sp, 0(s1)     // 将 sp 存入 g_os_port_switch_from_sp
+     * ===================================================================== */
+#if (OS_CFG_CPU_FPU_PRESENT)
+    FSTORE  f0,  (CONTEXT_SIZE + 0 * REG_BYTES)(sp)
+    FSTORE  f1,  (CONTEXT_SIZE + 1 * REG_BYTES)(sp)
+    FSTORE  f2,  (CONTEXT_SIZE + 2 * REG_BYTES)(sp)
+    FSTORE  f3,  (CONTEXT_SIZE + 3 * REG_BYTES)(sp)
+    FSTORE  f4,  (CONTEXT_SIZE + 4 * REG_BYTES)(sp)
+    FSTORE  f5,  (CONTEXT_SIZE + 5 * REG_BYTES)(sp)
+    FSTORE  f6,  (CONTEXT_SIZE + 6 * REG_BYTES)(sp)
+    FSTORE  f7,  (CONTEXT_SIZE + 7 * REG_BYTES)(sp)
+    FSTORE  f8,  (CONTEXT_SIZE + 8 * REG_BYTES)(sp)
+    FSTORE  f9,  (CONTEXT_SIZE + 9 * REG_BYTES)(sp)
+    FSTORE  f10, (CONTEXT_SIZE + 10 * REG_BYTES)(sp)
+    FSTORE  f11, (CONTEXT_SIZE + 11 * REG_BYTES)(sp)
+    FSTORE  f12, (CONTEXT_SIZE + 12 * REG_BYTES)(sp)
+    FSTORE  f13, (CONTEXT_SIZE + 13 * REG_BYTES)(sp)
+    FSTORE  f14, (CONTEXT_SIZE + 14 * REG_BYTES)(sp)
+    FSTORE  f15, (CONTEXT_SIZE + 15 * REG_BYTES)(sp)
+    FSTORE  f16, (CONTEXT_SIZE + 16 * REG_BYTES)(sp)
+    FSTORE  f17, (CONTEXT_SIZE + 17 * REG_BYTES)(sp)
+    FSTORE  f18, (CONTEXT_SIZE + 18 * REG_BYTES)(sp)
+    FSTORE  f19, (CONTEXT_SIZE + 19 * REG_BYTES)(sp)
+    FSTORE  f20, (CONTEXT_SIZE + 20 * REG_BYTES)(sp)
+    FSTORE  f21, (CONTEXT_SIZE + 21 * REG_BYTES)(sp)
+    FSTORE  f22, (CONTEXT_SIZE + 22 * REG_BYTES)(sp)
+    FSTORE  f23, (CONTEXT_SIZE + 23 * REG_BYTES)(sp)
+    FSTORE  f24, (CONTEXT_SIZE + 24 * REG_BYTES)(sp)
+    FSTORE  f25, (CONTEXT_SIZE + 25 * REG_BYTES)(sp)
+    FSTORE  f26, (CONTEXT_SIZE + 26 * REG_BYTES)(sp)
+    FSTORE  f27, (CONTEXT_SIZE + 27 * REG_BYTES)(sp)
+    FSTORE  f28, (CONTEXT_SIZE + 28 * REG_BYTES)(sp)
+    FSTORE  f29, (CONTEXT_SIZE + 29 * REG_BYTES)(sp)
+    FSTORE  f30, (CONTEXT_SIZE + 30 * REG_BYTES)(sp)
+    FSTORE  f31, (CONTEXT_SIZE + 31 * REG_BYTES)(sp)
+#endif
 
-    // 切换到 isr stack
+    /* =====================================================================
-    csrrw sp,mscratch,sp
+     * 第四步：保存旧任务 sp，并安全调用通知函数
+     * ===================================================================== */
+    la t0, g_os_port_switch_from_sp
+    LOAD t0, 0(t0)
+    STORE sp, 0(t0)     // 将 sp 存入 g_os_port_switch_from_sp
+
+    // 此时调用 C 函数是完全安全的，因为所有寄存器都已在任务栈里备考
     jal   os_port_on_switch_success
-    csrrw sp,mscratch,sp
 
-    la s0, g_os_port_switch_to_sp
+    /* =====================================================================
-    LOAD s1, 0(s0)
+     * 第五步：载入新任务的栈指针（SP）
-    LOAD sp, 0(s1)      // 将 sp 指向 g_os_port_switch_to_sp 栈
+     * ===================================================================== */
+    la t0, g_os_port_switch_to_sp
+    LOAD t0, 0(t0)
+    LOAD sp, 0(t0)      // 将 sp 指向 g_os_port_switch_to_sp 栈
 
-    LOAD a0, 2 * REG_BYTES(sp) // 加载/恢复 mepc
+    /* =====================================================================
-    csrw mepc, a0
+     * 第六步：恢复新任务的 FPU 浮点寄存器
+     * ===================================================================== */
+#if (OS_CFG_CPU_FPU_PRESENT)
+    FLOAD   f0,  (CONTEXT_SIZE + 0 * REG_BYTES)(sp)
+    FLOAD   f1,  (CONTEXT_SIZE + 1 * REG_BYTES)(sp)
+    FLOAD   f2,  (CONTEXT_SIZE + 2 * REG_BYTES)(sp)
+    FLOAD   f3,  (CONTEXT_SIZE + 3 * REG_BYTES)(sp)
+    FLOAD   f4,  (CONTEXT_SIZE + 4 * REG_BYTES)(sp)
+    FLOAD   f5,  (CONTEXT_SIZE + 5 * REG_BYTES)(sp)
+    FLOAD   f6,  (CONTEXT_SIZE + 6 * REG_BYTES)(sp)
+    FLOAD   f7,  (CONTEXT_SIZE + 7 * REG_BYTES)(sp)
+    FLOAD   f8,  (CONTEXT_SIZE + 8 * REG_BYTES)(sp)
+    FLOAD   f9,  (CONTEXT_SIZE + 9 * REG_BYTES)(sp)
+    FLOAD   f10, (CONTEXT_SIZE + 10 * REG_BYTES)(sp)
+    FLOAD   f11, (CONTEXT_SIZE + 11 * REG_BYTES)(sp)
+    FLOAD   f12, (CONTEXT_SIZE + 12 * REG_BYTES)(sp)
+    FLOAD   f13, (CONTEXT_SIZE + 13 * REG_BYTES)(sp)
+    FLOAD   f14, (CONTEXT_SIZE + 14 * REG_BYTES)(sp)
+    FLOAD   f15, (CONTEXT_SIZE + 15 * REG_BYTES)(sp)
+    FLOAD   f16, (CONTEXT_SIZE + 16 * REG_BYTES)(sp)
+    FLOAD   f17, (CONTEXT_SIZE + 17 * REG_BYTES)(sp)
+    FLOAD   f18, (CONTEXT_SIZE + 18 * REG_BYTES)(sp)
+    FLOAD   f19, (CONTEXT_SIZE + 19 * REG_BYTES)(sp)
+    FLOAD   f20, (CONTEXT_SIZE + 20 * REG_BYTES)(sp)
+    FLOAD   f21, (CONTEXT_SIZE + 21 * REG_BYTES)(sp)
+    FLOAD   f22, (CONTEXT_SIZE + 22 * REG_BYTES)(sp)
+    FLOAD   f23, (CONTEXT_SIZE + 23 * REG_BYTES)(sp)
+    FLOAD   f24, (CONTEXT_SIZE + 24 * REG_BYTES)(sp)
+    FLOAD   f25, (CONTEXT_SIZE + 25 * REG_BYTES)(sp)
+    FLOAD   f26, (CONTEXT_SIZE + 26 * REG_BYTES)(sp)
+    FLOAD   f27, (CONTEXT_SIZE + 27 * REG_BYTES)(sp)
+    FLOAD   f28, (CONTEXT_SIZE + 28 * REG_BYTES)(sp)
+    FLOAD   f29, (CONTEXT_SIZE + 29 * REG_BYTES)(sp)
+    FLOAD   f30, (CONTEXT_SIZE + 30 * REG_BYTES)(sp)
+    FLOAD   f31, (CONTEXT_SIZE + 31 * REG_BYTES)(sp)
+#endif
 
+
+    /* =====================================================================
+     * 第七步：全面恢复通用寄存器（最后恢复 t0）
+     * ===================================================================== */
     LOAD  x1,   1 * REG_BYTES(sp)
-
-    li t0, 0x1800
-    csrs mstatus, t0                // 确保 M 模式
-
-    LOAD t0, 0*REG_BYTES(sp)        // 加载 mstatus
-    csrs mstatus, t0                // 恢复 mstatus
-
     LOAD  x4,   4 * REG_BYTES(sp)
-    LOAD  x5,   5 * REG_BYTES(sp)
+//    LOAD  x5,   5 * REG_BYTES(sp)   // 恢复 t0
     LOAD  x6,   6 * REG_BYTES(sp)
     LOAD  x7,   7 * REG_BYTES(sp)
     LOAD  x8,   8 * REG_BYTES(sp)
@@ -273,49 +339,88 @@ SW_Handler:
     LOAD  x29, 29 * REG_BYTES(sp)
     LOAD  x30, 30 * REG_BYTES(sp)
     LOAD  x31, 31 * REG_BYTES(sp)
-    addi sp, sp, CONTEXT_SIZE               // 恢复栈指针
 
-/* load float reg */
+
+    /* =====================================================================
+     * 第八步：恢复新任务的 CSR 寄存器
+     * ===================================================================== */
+    LOAD  t0, 2 * REG_BYTES(sp)             // 恢复 mepc
+    csrw  mepc, t0
+
+    LOAD  t0, 0 * REG_BYTES(sp)             // 恢复 mstatus
+    csrw  mstatus, t0
+
+    LOAD  x5,   5 * REG_BYTES(sp)   // 恢复 t0
+
+    /* =====================================================================
+     * 第九步：彻底释放栈空间并退出
+     * ===================================================================== */
 #if (OS_CFG_CPU_FPU_PRESENT)
-    FLOAD   f0, 0 * REG_BYTES(sp)
+    addi sp, sp, (CONTEXT_SIZE + 32 * REG_BYTES)
-    FLOAD   f1, 1 * REG_BYTES(sp)
+#else
-    FLOAD   f2, 2 * REG_BYTES(sp)
+    addi sp, sp, CONTEXT_SIZE
-    FLOAD   f3, 3 * REG_BYTES(sp)
-    FLOAD   f4, 4 * REG_BYTES(sp)
-    FLOAD   f5, 5 * REG_BYTES(sp)
-    FLOAD   f6, 6 * REG_BYTES(sp)
-    FLOAD   f7, 7 * REG_BYTES(sp)
-    FLOAD   f8, 8 * REG_BYTES(sp)
-    FLOAD   f9, 9 * REG_BYTES(sp)
-    FLOAD   f10, 10 * REG_BYTES(sp)
-    FLOAD   f11, 11 * REG_BYTES(sp)
-    FLOAD   f12, 12 * REG_BYTES(sp)
-    FLOAD   f13, 13 * REG_BYTES(sp)
-    FLOAD   f14, 14 * REG_BYTES(sp)
-    FLOAD   f15, 15 * REG_BYTES(sp)
-    FLOAD   f16, 16 * REG_BYTES(sp)
-    FLOAD   f17, 17 * REG_BYTES(sp)
-    FLOAD   f18, 18 * REG_BYTES(sp)
-    FLOAD   f19, 19 * REG_BYTES(sp)
-    FLOAD   f20, 20 * REG_BYTES(sp)
-    FLOAD   f21, 21 * REG_BYTES(sp)
-    FLOAD   f22, 22 * REG_BYTES(sp)
-    FLOAD   f23, 23 * REG_BYTES(sp)
-    FLOAD   f24, 24 * REG_BYTES(sp)
-    FLOAD   f25, 25 * REG_BYTES(sp)
-    FLOAD   f26, 26 * REG_BYTES(sp)
-    FLOAD   f27, 27 * REG_BYTES(sp)
-    FLOAD   f28, 28 * REG_BYTES(sp)
-    FLOAD   f29, 29 * REG_BYTES(sp)
-    FLOAD   f30, 30 * REG_BYTES(sp)
-    FLOAD   f31, 31 * REG_BYTES(sp)
-    addi    sp, sp, 32 * REG_BYTES
 #endif
 
+/* 执行 mret。此时：
+ * 1. 硬件会自动把当前 mstatus.MPIE (1) 复制到 mstatus.MIE，从而开启全局中断。
+ * 2. 程序跳转到 mepc 寄存器指向的地址（即新任务继续运行的代码处）。 */
     mret                                    // 从 M 模式退出
     .endfunc
 
 
 
+.section .text.SysTick_Handler,"ax",%progbits
+.align 2
+.global SysTick_Handler
+.extern SysTick_Handler_C
+.func
+SysTick_Handler:
+//    csrci mstatus, 8 // 关闭中断
+    /* 1. 因为是硬件中断，先在当前栈上保存必要的临时寄存器(Caller-saved) */
+    addi sp, sp, -16 * REG_BYTES
+    STORE x1,  0 * REG_BYTES(sp)    # ra
+    STORE x5,  1 * REG_BYTES(sp)    # t0
+    STORE x6,  2 * REG_BYTES(sp)    # t1
+    STORE x7,  3 * REG_BYTES(sp)    # t2
+    STORE x10, 4 * REG_BYTES(sp)   # a0
+    STORE x11, 5 * REG_BYTES(sp)   # a1
+    STORE x12, 6 * REG_BYTES(sp)   # a2
+    STORE x13, 7 * REG_BYTES(sp)   # a3
+    STORE x14, 8 * REG_BYTES(sp)   # a4
+    STORE x15, 9 * REG_BYTES(sp)   # a5
+    STORE x16, 10 * REG_BYTES(sp)   # a6
+    STORE x17, 11 * REG_BYTES(sp)   # a7
+    STORE x28, 12 * REG_BYTES(sp)   # t3
+    STORE x29, 13 * REG_BYTES(sp)   # t4
+    STORE x30, 14 * REG_BYTES(sp)   # t5
+    STORE x31, 15 * REG_BYTES(sp)   # t6
+
+    /* 2. 清除定时器硬件中断标志位（防止重复触发），并调用 C 语言的时钟处理函数 */
+    jal  SysTick_Handler_C
+
+    /* 3. 恢复临时寄存器 */
+    LOAD x1,  0 * REG_BYTES(sp)    # ra
+    LOAD x5,  1 * REG_BYTES(sp)    # t0
+    LOAD x6,  2 * REG_BYTES(sp)    # t1
+    LOAD x7,  3 * REG_BYTES(sp)    # t2
+    LOAD x10, 4 * REG_BYTES(sp)   # a0
+    LOAD x11, 5 * REG_BYTES(sp)   # a1
+    LOAD x12, 6 * REG_BYTES(sp)   # a2
+    LOAD x13, 7 * REG_BYTES(sp)   # a3
+    LOAD x14, 8 * REG_BYTES(sp)   # a4
+    LOAD x15, 9 * REG_BYTES(sp)   # a5
+    LOAD x16, 10 * REG_BYTES(sp)   # a6
+    LOAD x17, 11 * REG_BYTES(sp)   # a7
+    LOAD x28, 12 * REG_BYTES(sp)   # t3
+    LOAD x29, 13 * REG_BYTES(sp)   # t4
+    LOAD x30, 14 * REG_BYTES(sp)   # t5
+    LOAD x31, 15 * REG_BYTES(sp)   # t6
+
+    addi sp, sp, 16 * REG_BYTES
+
+    /* 4. 退出硬件中断 */
+    mret
+    .endfunc
+
     .align 4
     .end