426 lines
17 KiB
ArmAsm
426 lines
17 KiB
ArmAsm
#include "os_config.h"
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#if __riscv_xlen == 64
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#define REG_BYTES 8
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#define STORE sd
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#define LOAD ld
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#define FSTORE fsd
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#define FLOAD fld
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#elif __riscv_xlen == 32
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#define REG_BYTES 4
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#define STORE sw
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#define LOAD lw
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#define FSTORE fsw
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#define FLOAD flw
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#else
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#error Assembler did not define __riscv_xlen
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#endif
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#define CONTEXT_SIZE (32 * REG_BYTES)
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////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
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//// CODE
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#ifdef OS_CFG_CPU_CLZ_ASM_PRESENT
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.section .text.cpu_clz,"ax",%progbits
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.align 8
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.func
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.global cpu_clz
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cpu_clz:
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clz a0, a0
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ret
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.endfunc
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#endif
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.section .text.os_port_context_switch_to,"ax",%progbits
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.align 2
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.func
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.global os_port_context_switch_to
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.extern os_port_on_switch_success
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os_port_context_switch_to:
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li t0, 0x1800
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csrw mstatus, t0 // 1. 关中断
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/* 设置中断栈/系统栈空间 */
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la t0, _eusrstack
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addi t0, t0, -512
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csrw mscratch, t0 // 备用栈指针存入 mscratch
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/* =====================================================================
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* 第一步：切换到中断栈，安全调用通知 C 函数
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* ===================================================================== */
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jal os_port_on_switch_success // 调用 C 函数（此时随便它怎么污染寄存器）
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/* =====================================================================
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* 第二步：获取新任务的栈指针 SP
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* ===================================================================== */
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LOAD sp, 0(a0) // a0 是传入的 &g_os_port_switch_to_sp，从中取出 sp
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/* =====================================================================
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* 第三步：恢复 FPU 浮点寄存器（与保存栈帧严格镜像）
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* 修复宏定义：将 MPU 改回 FPU
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* ===================================================================== */
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#if (OS_CFG_CPU_FPU_PRESENT)
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FLOAD f0, (CONTEXT_SIZE + 0 * REG_BYTES)(sp)
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FLOAD f1, (CONTEXT_SIZE + 1 * REG_BYTES)(sp)
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FLOAD f2, (CONTEXT_SIZE + 2 * REG_BYTES)(sp)
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FLOAD f3, (CONTEXT_SIZE + 3 * REG_BYTES)(sp)
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FLOAD f4, (CONTEXT_SIZE + 4 * REG_BYTES)(sp)
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FLOAD f5, (CONTEXT_SIZE + 5 * REG_BYTES)(sp)
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FLOAD f6, (CONTEXT_SIZE + 6 * REG_BYTES)(sp)
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FLOAD f7, (CONTEXT_SIZE + 7 * REG_BYTES)(sp)
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FLOAD f8, (CONTEXT_SIZE + 8 * REG_BYTES)(sp)
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FLOAD f9, (CONTEXT_SIZE + 9 * REG_BYTES)(sp)
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FLOAD f10, (CONTEXT_SIZE + 10 * REG_BYTES)(sp)
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FLOAD f11, (CONTEXT_SIZE + 11 * REG_BYTES)(sp)
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FLOAD f12, (CONTEXT_SIZE + 12 * REG_BYTES)(sp)
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FLOAD f13, (CONTEXT_SIZE + 13 * REG_BYTES)(sp)
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FLOAD f14, (CONTEXT_SIZE + 14 * REG_BYTES)(sp)
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FLOAD f15, (CONTEXT_SIZE + 15 * REG_BYTES)(sp)
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FLOAD f16, (CONTEXT_SIZE + 16 * REG_BYTES)(sp)
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FLOAD f17, (CONTEXT_SIZE + 17 * REG_BYTES)(sp)
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FLOAD f18, (CONTEXT_SIZE + 18 * REG_BYTES)(sp)
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FLOAD f19, (CONTEXT_SIZE + 19 * REG_BYTES)(sp)
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FLOAD f20, (CONTEXT_SIZE + 20 * REG_BYTES)(sp)
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FLOAD f21, (CONTEXT_SIZE + 21 * REG_BYTES)(sp)
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FLOAD f22, (CONTEXT_SIZE + 22 * REG_BYTES)(sp)
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FLOAD f23, (CONTEXT_SIZE + 23 * REG_BYTES)(sp)
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FLOAD f24, (CONTEXT_SIZE + 24 * REG_BYTES)(sp)
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FLOAD f25, (CONTEXT_SIZE + 25 * REG_BYTES)(sp)
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FLOAD f26, (CONTEXT_SIZE + 26 * REG_BYTES)(sp)
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FLOAD f27, (CONTEXT_SIZE + 27 * REG_BYTES)(sp)
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FLOAD f28, (CONTEXT_SIZE + 28 * REG_BYTES)(sp)
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FLOAD f29, (CONTEXT_SIZE + 29 * REG_BYTES)(sp)
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FLOAD f30, (CONTEXT_SIZE + 30 * REG_BYTES)(sp)
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FLOAD f31, (CONTEXT_SIZE + 31 * REG_BYTES)(sp)
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#endif
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/* =====================================================================
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* 第四步：恢复通用寄存器（最后恢复 t0）
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* ===================================================================== */
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LOAD x1, 1 * REG_BYTES(sp)
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LOAD x4, 4 * REG_BYTES(sp)
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LOAD x6, 6 * REG_BYTES(sp)
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LOAD x7, 7 * REG_BYTES(sp)
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LOAD x8, 8 * REG_BYTES(sp)
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LOAD x9, 9 * REG_BYTES(sp)
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LOAD x10, 10 * REG_BYTES(sp)
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LOAD x11, 11 * REG_BYTES(sp)
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LOAD x12, 12 * REG_BYTES(sp)
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LOAD x13, 13 * REG_BYTES(sp)
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LOAD x14, 14 * REG_BYTES(sp)
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LOAD x15, 15 * REG_BYTES(sp)
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LOAD x16, 16 * REG_BYTES(sp)
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LOAD x17, 17 * REG_BYTES(sp)
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LOAD x18, 18 * REG_BYTES(sp)
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LOAD x19, 19 * REG_BYTES(sp)
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LOAD x20, 20 * REG_BYTES(sp)
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LOAD x21, 21 * REG_BYTES(sp)
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LOAD x22, 22 * REG_BYTES(sp)
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LOAD x23, 23 * REG_BYTES(sp)
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LOAD x24, 24 * REG_BYTES(sp)
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LOAD x25, 25 * REG_BYTES(sp)
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LOAD x26, 26 * REG_BYTES(sp)
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LOAD x27, 27 * REG_BYTES(sp)
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LOAD x28, 28 * REG_BYTES(sp)
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LOAD x29, 29 * REG_BYTES(sp)
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LOAD x30, 30 * REG_BYTES(sp)
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LOAD x31, 31 * REG_BYTES(sp)
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/* =====================================================================
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* 第五步：恢复特权级控制 CSR 寄存器
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* ===================================================================== */
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LOAD t0, 2 * REG_BYTES(sp) // 恢复初始 PC 到 mepc
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csrw mepc, t0
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LOAD t0, 0 * REG_BYTES(sp) // 从栈中读取准备好的初始 mstatus
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csrw mstatus, t0 // 修复：改用 csrw 强行覆盖
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LOAD x5, 5 * REG_BYTES(sp) // 此时最后安全恢复 t0(x5)
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/* =====================================================================
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* 第六步：统一释放栈空间并退出
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* ===================================================================== */
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#if (OS_CFG_CPU_FPU_PRESENT)
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addi sp, sp, (CONTEXT_SIZE + 32 * REG_BYTES)
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#else
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addi sp, sp, CONTEXT_SIZE
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#endif
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mret
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.endfunc
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.section .text.SW_Handler,"ax",%progbits
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.align 2
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.func
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.global SW_Handler
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.extern g_os_port_switch_from_sp
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.extern g_os_port_switch_to_sp
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.extern os_port_on_switch_success
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SW_Handler:
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csrci mstatus, 0x08 // 立刻关闭全局中断 MIE = 0
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/* =====================================================================
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* 第一步：一揽子分配所有栈空间（防止碎片和二次偏移错误）
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* ===================================================================== */
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#if (OS_CFG_CPU_FPU_PRESENT)
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addi sp, sp, -(CONTEXT_SIZE + 32 * REG_BYTES)
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#else
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addi sp, sp, -CONTEXT_SIZE
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#endif
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/* =====================================================================
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* 第二步：保存通用寄存器
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* ===================================================================== */
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STORE x5, 5 * REG_BYTES(sp) // 优先保存 t0，腾出临时寄存器
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li t0, 0x1800
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csrw mstatus, t0 // M 模式
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li t0, 0x1880
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STORE t0, 0 * REG_BYTES(sp) // 设置 MPIE
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csrr t0, mepc
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STORE t0, 2*REG_BYTES(sp) // 保存正在运行任务的 pc 指针
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STORE x1, 1 * REG_BYTES(sp) // ra
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STORE x4, 4 * REG_BYTES(sp) // tp
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STORE x6, 6 * REG_BYTES(sp) // t1
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STORE x7, 7 * REG_BYTES(sp) // t2
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STORE x8, 8 * REG_BYTES(sp) // s0/fp
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STORE x9, 9 * REG_BYTES(sp) // s1
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STORE x10, 10 * REG_BYTES(sp) // a0
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STORE x11, 11 * REG_BYTES(sp) // a1
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STORE x12, 12 * REG_BYTES(sp) // a2
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STORE x13, 13 * REG_BYTES(sp) // a3
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STORE x14, 14 * REG_BYTES(sp) // a4
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STORE x15, 15 * REG_BYTES(sp) // a5
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STORE x16, 16 * REG_BYTES(sp) // a6
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STORE x17, 17 * REG_BYTES(sp) // a7
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STORE x18, 18 * REG_BYTES(sp) // s2
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STORE x19, 19 * REG_BYTES(sp) // s3
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STORE x20, 20 * REG_BYTES(sp) // s4
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STORE x21, 21 * REG_BYTES(sp) // s5
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STORE x22, 22 * REG_BYTES(sp) // s6
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STORE x23, 23 * REG_BYTES(sp) // s7
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STORE x24, 24 * REG_BYTES(sp) // s8
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STORE x25, 25 * REG_BYTES(sp) // s9
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STORE x26, 26 * REG_BYTES(sp) // s10
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STORE x27, 27 * REG_BYTES(sp) // s11
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STORE x28, 28 * REG_BYTES(sp) // t3
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STORE x29, 29 * REG_BYTES(sp) // t4
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STORE x30, 30 * REG_BYTES(sp) // t5
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STORE x31, 31 * REG_BYTES(sp) // t6
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/* =====================================================================
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* 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）
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* ===================================================================== */
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#if (OS_CFG_CPU_FPU_PRESENT)
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FSTORE f0, (CONTEXT_SIZE + 0 * REG_BYTES)(sp)
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FSTORE f1, (CONTEXT_SIZE + 1 * REG_BYTES)(sp)
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FSTORE f2, (CONTEXT_SIZE + 2 * REG_BYTES)(sp)
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FSTORE f3, (CONTEXT_SIZE + 3 * REG_BYTES)(sp)
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FSTORE f4, (CONTEXT_SIZE + 4 * REG_BYTES)(sp)
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FSTORE f5, (CONTEXT_SIZE + 5 * REG_BYTES)(sp)
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FSTORE f6, (CONTEXT_SIZE + 6 * REG_BYTES)(sp)
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FSTORE f7, (CONTEXT_SIZE + 7 * REG_BYTES)(sp)
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FSTORE f8, (CONTEXT_SIZE + 8 * REG_BYTES)(sp)
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FSTORE f9, (CONTEXT_SIZE + 9 * REG_BYTES)(sp)
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FSTORE f10, (CONTEXT_SIZE + 10 * REG_BYTES)(sp)
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FSTORE f11, (CONTEXT_SIZE + 11 * REG_BYTES)(sp)
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FSTORE f12, (CONTEXT_SIZE + 12 * REG_BYTES)(sp)
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FSTORE f13, (CONTEXT_SIZE + 13 * REG_BYTES)(sp)
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FSTORE f14, (CONTEXT_SIZE + 14 * REG_BYTES)(sp)
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FSTORE f15, (CONTEXT_SIZE + 15 * REG_BYTES)(sp)
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FSTORE f16, (CONTEXT_SIZE + 16 * REG_BYTES)(sp)
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FSTORE f17, (CONTEXT_SIZE + 17 * REG_BYTES)(sp)
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FSTORE f18, (CONTEXT_SIZE + 18 * REG_BYTES)(sp)
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FSTORE f19, (CONTEXT_SIZE + 19 * REG_BYTES)(sp)
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FSTORE f20, (CONTEXT_SIZE + 20 * REG_BYTES)(sp)
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FSTORE f21, (CONTEXT_SIZE + 21 * REG_BYTES)(sp)
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FSTORE f22, (CONTEXT_SIZE + 22 * REG_BYTES)(sp)
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FSTORE f23, (CONTEXT_SIZE + 23 * REG_BYTES)(sp)
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FSTORE f24, (CONTEXT_SIZE + 24 * REG_BYTES)(sp)
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FSTORE f25, (CONTEXT_SIZE + 25 * REG_BYTES)(sp)
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FSTORE f26, (CONTEXT_SIZE + 26 * REG_BYTES)(sp)
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FSTORE f27, (CONTEXT_SIZE + 27 * REG_BYTES)(sp)
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FSTORE f28, (CONTEXT_SIZE + 28 * REG_BYTES)(sp)
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FSTORE f29, (CONTEXT_SIZE + 29 * REG_BYTES)(sp)
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FSTORE f30, (CONTEXT_SIZE + 30 * REG_BYTES)(sp)
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FSTORE f31, (CONTEXT_SIZE + 31 * REG_BYTES)(sp)
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#endif
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/* =====================================================================
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* 第四步：保存旧任务 sp，并安全调用通知函数
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* ===================================================================== */
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la t0, g_os_port_switch_from_sp
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LOAD t0, 0(t0)
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STORE sp, 0(t0) // 将 sp 存入 g_os_port_switch_from_sp
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// 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
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jal os_port_on_switch_success
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/* =====================================================================
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* 第五步：载入新任务的栈指针（SP）
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* ===================================================================== */
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la t0, g_os_port_switch_to_sp
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LOAD t0, 0(t0)
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LOAD sp, 0(t0) // 将 sp 指向 g_os_port_switch_to_sp 栈
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/* =====================================================================
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* 第六步：恢复新任务的 FPU 浮点寄存器
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* ===================================================================== */
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#if (OS_CFG_CPU_FPU_PRESENT)
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FLOAD f0, (CONTEXT_SIZE + 0 * REG_BYTES)(sp)
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FLOAD f1, (CONTEXT_SIZE + 1 * REG_BYTES)(sp)
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FLOAD f2, (CONTEXT_SIZE + 2 * REG_BYTES)(sp)
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FLOAD f3, (CONTEXT_SIZE + 3 * REG_BYTES)(sp)
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FLOAD f4, (CONTEXT_SIZE + 4 * REG_BYTES)(sp)
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FLOAD f5, (CONTEXT_SIZE + 5 * REG_BYTES)(sp)
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FLOAD f6, (CONTEXT_SIZE + 6 * REG_BYTES)(sp)
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FLOAD f7, (CONTEXT_SIZE + 7 * REG_BYTES)(sp)
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FLOAD f8, (CONTEXT_SIZE + 8 * REG_BYTES)(sp)
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FLOAD f9, (CONTEXT_SIZE + 9 * REG_BYTES)(sp)
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FLOAD f10, (CONTEXT_SIZE + 10 * REG_BYTES)(sp)
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FLOAD f11, (CONTEXT_SIZE + 11 * REG_BYTES)(sp)
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FLOAD f12, (CONTEXT_SIZE + 12 * REG_BYTES)(sp)
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FLOAD f13, (CONTEXT_SIZE + 13 * REG_BYTES)(sp)
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FLOAD f14, (CONTEXT_SIZE + 14 * REG_BYTES)(sp)
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FLOAD f15, (CONTEXT_SIZE + 15 * REG_BYTES)(sp)
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FLOAD f16, (CONTEXT_SIZE + 16 * REG_BYTES)(sp)
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FLOAD f17, (CONTEXT_SIZE + 17 * REG_BYTES)(sp)
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FLOAD f18, (CONTEXT_SIZE + 18 * REG_BYTES)(sp)
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FLOAD f19, (CONTEXT_SIZE + 19 * REG_BYTES)(sp)
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FLOAD f20, (CONTEXT_SIZE + 20 * REG_BYTES)(sp)
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FLOAD f21, (CONTEXT_SIZE + 21 * REG_BYTES)(sp)
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FLOAD f22, (CONTEXT_SIZE + 22 * REG_BYTES)(sp)
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FLOAD f23, (CONTEXT_SIZE + 23 * REG_BYTES)(sp)
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FLOAD f24, (CONTEXT_SIZE + 24 * REG_BYTES)(sp)
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FLOAD f25, (CONTEXT_SIZE + 25 * REG_BYTES)(sp)
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FLOAD f26, (CONTEXT_SIZE + 26 * REG_BYTES)(sp)
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FLOAD f27, (CONTEXT_SIZE + 27 * REG_BYTES)(sp)
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FLOAD f28, (CONTEXT_SIZE + 28 * REG_BYTES)(sp)
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FLOAD f29, (CONTEXT_SIZE + 29 * REG_BYTES)(sp)
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FLOAD f30, (CONTEXT_SIZE + 30 * REG_BYTES)(sp)
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FLOAD f31, (CONTEXT_SIZE + 31 * REG_BYTES)(sp)
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#endif
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/* =====================================================================
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* 第七步：全面恢复通用寄存器（最后恢复 t0）
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* ===================================================================== */
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LOAD x1, 1 * REG_BYTES(sp)
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LOAD x4, 4 * REG_BYTES(sp)
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// LOAD x5, 5 * REG_BYTES(sp) // 恢复 t0
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LOAD x6, 6 * REG_BYTES(sp)
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LOAD x7, 7 * REG_BYTES(sp)
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LOAD x8, 8 * REG_BYTES(sp)
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LOAD x9, 9 * REG_BYTES(sp)
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LOAD x10, 10 * REG_BYTES(sp)
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LOAD x11, 11 * REG_BYTES(sp)
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LOAD x12, 12 * REG_BYTES(sp)
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LOAD x13, 13 * REG_BYTES(sp)
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LOAD x14, 14 * REG_BYTES(sp)
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LOAD x15, 15 * REG_BYTES(sp)
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LOAD x16, 16 * REG_BYTES(sp)
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LOAD x17, 17 * REG_BYTES(sp)
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LOAD x18, 18 * REG_BYTES(sp)
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LOAD x19, 19 * REG_BYTES(sp)
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LOAD x20, 20 * REG_BYTES(sp)
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LOAD x21, 21 * REG_BYTES(sp)
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LOAD x22, 22 * REG_BYTES(sp)
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LOAD x23, 23 * REG_BYTES(sp)
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LOAD x24, 24 * REG_BYTES(sp)
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LOAD x25, 25 * REG_BYTES(sp)
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LOAD x26, 26 * REG_BYTES(sp)
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LOAD x27, 27 * REG_BYTES(sp)
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LOAD x28, 28 * REG_BYTES(sp)
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LOAD x29, 29 * REG_BYTES(sp)
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LOAD x30, 30 * REG_BYTES(sp)
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LOAD x31, 31 * REG_BYTES(sp)
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/* =====================================================================
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* 第八步：恢复新任务的 CSR 寄存器
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* ===================================================================== */
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LOAD t0, 2 * REG_BYTES(sp) // 恢复 mepc
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csrw mepc, t0
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LOAD t0, 0 * REG_BYTES(sp) // 恢复 mstatus
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csrw mstatus, t0
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LOAD x5, 5 * REG_BYTES(sp) // 恢复 t0
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/* =====================================================================
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* 第九步：彻底释放栈空间并退出
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* ===================================================================== */
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#if (OS_CFG_CPU_FPU_PRESENT)
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addi sp, sp, (CONTEXT_SIZE + 32 * REG_BYTES)
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#else
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addi sp, sp, CONTEXT_SIZE
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#endif
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/* 执行 mret。此时：
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* 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。
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* 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）。 */
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mret // 从 M 模式退出
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.endfunc
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.section .text.SysTick_Handler,"ax",%progbits
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.align 2
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.global SysTick_Handler
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.extern SysTick_Handler_C
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.func
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SysTick_Handler:
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// csrci mstatus, 8 // 关闭中断
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/* 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) */
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addi sp, sp, -16 * REG_BYTES
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STORE x1, 0 * REG_BYTES(sp) # ra
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STORE x5, 1 * REG_BYTES(sp) # t0
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STORE x6, 2 * REG_BYTES(sp) # t1
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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 |