269 lines
5.7 KiB
ArmAsm
Executable File
269 lines
5.7 KiB
ArmAsm
Executable File
#include <asm_config.h>
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#include <asm_offset.h>
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#define BAD_SYNC 0
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#define BAD_IRQ 1
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#define BAD_FIQ 2
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#define BAD_ERROR 3
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/*保存x0~x29，x30（lr），sp, elr, spsr保存到 栈中
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*/
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.macro kernel_entry el
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/*
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SP指向了栈底, S_FRAME_SIZE表示一个栈框的大小.
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定义一个struct pt_regs来描述一个栈框,
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用在异常发生时保存上下文.
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*/
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sub sp, sp, #S_FRAME_SIZE
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/*
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保存通用寄存器x0~x29到栈框里pt_regs->x0~x29
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*/
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stp x0, x1, [sp, #16 *0]
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stp x2, x3, [sp, #16 *1]
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stp x4, x5, [sp, #16 *2]
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stp x6, x7, [sp, #16 *3]
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stp x8, x9, [sp, #16 *4]
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stp x10, x11, [sp, #16 *5]
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stp x12, x13, [sp, #16 *6]
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stp x14, x15, [sp, #16 *7]
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stp x16, x17, [sp, #16 *8]
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stp x18, x19, [sp, #16 *9]
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stp x20, x21, [sp, #16 *10]
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stp x22, x23, [sp, #16 *11]
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stp x24, x25, [sp, #16 *12]
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stp x26, x27, [sp, #16 *13]
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stp x28, x29, [sp, #16 *14]
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/* x21: 栈顶 的位置*/
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add x21, sp, #S_FRAME_SIZE
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mov x0, sp
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mrs x22, elr_el2
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mrs x23, spsr_el2
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/* 把lr保存到pt_regs->lr, 把sp保存到pt_regs->sp位置*/
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stp lr, x21, [sp, #S_LR]
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/* 把elr_el1保存到pt_regs->pc中
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把spsr_elr保存到pt_regs->pstate中*/
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stp x22, x23, [sp, #S_PC]
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.endm
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/*
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恢复异常发生时保存下来的上下文
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*/
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.macro kernel_exit el
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/* 从pt_regs->pc中恢复elr_el1,
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从pt_regs->pstate中恢复spsr_el1
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*/
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ldp x21, x22, [sp, #S_PC] // load ELR, SPSR
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msr elr_el2, x21 // set up the return data
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msr spsr_el2, x22
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ldp x0, x1, [sp, #16 * 0]
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ldp x2, x3, [sp, #16 * 1]
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ldp x4, x5, [sp, #16 * 2]
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ldp x6, x7, [sp, #16 * 3]
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ldp x8, x9, [sp, #16 * 4]
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ldp x10, x11, [sp, #16 * 5]
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ldp x12, x13, [sp, #16 * 6]
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ldp x14, x15, [sp, #16 * 7]
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ldp x16, x17, [sp, #16 * 8]
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ldp x18, x19, [sp, #16 * 9]
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ldp x20, x21, [sp, #16 * 10]
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ldp x22, x23, [sp, #16 * 11]
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ldp x24, x25, [sp, #16 * 12]
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ldp x26, x27, [sp, #16 * 13]
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ldp x28, x29, [sp, #16 * 14]
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/* 从pt_regs->lr中恢复lr*/
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ldr lr, [sp, #S_LR]
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add sp, sp, #S_FRAME_SIZE // restore sp
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eret // return to kernel
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.endm
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/*
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处理无效的异常向量
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*/
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.macro inv_entry el, reason
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//kernel_entry el
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mov x0, sp
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mov x1, #\reason
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mrs x2, esr_el2
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b bad_mode
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.endm
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/*
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vector table entry
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每个表项是128字节， align 7表示128字节对齐
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*/
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.macro vtentry label
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.align 7
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b \label
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.endm
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/*
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* Vector Table
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*
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* ARM64的异常向量表一共占用2048个字节
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* 分成4组，每组4个表项，每个表项占128字节
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* 参见ARMv8 spec v8.6第D1.10节
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* align 11表示2048字节对齐
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*/
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.align 11
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.global vectors
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.section ".text.boot"
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vectors:
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/* Current EL with SP0
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当前系统运行在EL1时使用EL0的栈指针SP
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这是一种异常错误的类型
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*/
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vtentry el1_sync_invalid
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vtentry el1_irq_invalid
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vtentry el1_fiq_invalid
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vtentry el1_error_invalid
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/* Current EL with SPx
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当前系统运行在EL1时使用EL1的栈指针SP
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这说明系统在内核态发生了异常
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Note: 我们暂时只实现IRQ中断
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*/
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vtentry el1_sync_invalid
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vtentry el1_irq
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vtentry el1_fiq_invalid
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vtentry el1_error_invalid
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/* Lower EL using AArch64
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在用户态的aarch64的程序发生了异常
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*/
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vtentry el1_sync_invalid
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vtentry el1_irq
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vtentry el0_fiq_invalid
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vtentry el0_error_invalid
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/* Lower EL using AArch32
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在用户态的aarch32的程序发生了异常
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*/
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vtentry el0_sync_invalid
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vtentry el0_irq_invalid
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vtentry el0_fiq_invalid
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vtentry el0_error_invalid
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el1_sync_invalid:
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kernel_entry 2
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//mrs x25, ESR_EL2
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//lsr x24, x25, 26
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//cmp x24, 0x16
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//b.eq el2_svc
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//inv_entry 0, BAD_SYNC
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//el2_svc:
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// mov x0, sp
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// bl el2_svc_handler
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bl thread_sync_entry
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b ret_to_user
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el1_irq_invalid:
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inv_entry 1, BAD_IRQ
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el1_fiq_invalid:
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inv_entry 1, BAD_FIQ
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el1_error_invalid:
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inv_entry 1, BAD_ERROR
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el0_sync_invalid:
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inv_entry 0, BAD_SYNC
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el0_irq_invalid:
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inv_entry 0, BAD_IRQ
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el0_fiq_invalid:
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inv_entry 0, BAD_FIQ
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el0_error_invalid:
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inv_entry 0, BAD_ERROR
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tsk .req x28 // current thread_info
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.macro get_thread_info, rd
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mov \rd, sp
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and \rd, \rd, #(~(4096 - 1)) // top of stack
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.endm
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el1_irq:
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kernel_entry 2
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bl entry_handler
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get_thread_info tsk
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// bl 2f
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//1:
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// kernel_exit 2
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//2:
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// mov x24, lr
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//bl sched_printf
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bl SysTick_Handler
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kernel_exit 2
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// ret x24
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//
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//string_test:
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// .string "t"
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.global trigger_alignment
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trigger_alignment:
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ldr x0, =0x80002
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str wzr, [x0]
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/*
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对于用户进程，暂时还没实现
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*/
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.align 2
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.global ret_to_user
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ret_to_user:
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kernel_exit 2
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//inv_entry 0, BAD_ERROR
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/*
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对于内核线程：
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x19保存了进程回调函数的入口
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x20保存进程的回调函数的参数
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对于用户线程：
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x19为零时，跳转到ret_to_user执行
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*/
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.align 2
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.global ret_form_run
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ret_form_run:
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bl sched_tail
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cbz x19, 1f
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mov x0, x20
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blr x19
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1:
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//ldr x19, =test_user_stack
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//add x19, x19, #(4096 - 8)
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//msr sp_el1, x19
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b ret_to_user
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/* 进程切换： 保存prev进程的上下文，并且恢复next进程
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的上下文
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cpu_switch_to(struct cpu_context *prev,
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struct cpu_context *next);
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需要保存的上下文： x19 ~ x29， sp， lr
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保存到进程的task_struct->cpu_context
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*/
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.align
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.global cpu_switch_to
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cpu_switch_to:
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mov x8, x0
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mov x9, sp
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stp x19, x20, [x8], #16
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stp x21, x22, [x8], #16
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stp x23, x24, [x8], #16
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stp x25, x26, [x8], #16
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stp x27, x28, [x8], #16
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stp x29, x9, [x8], #16
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str lr, [x8]
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mov x8, x1
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ldp x19, x20, [x8], #16
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ldp x21, x22, [x8], #16
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ldp x23, x24, [x8], #16
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ldp x25, x26, [x8], #16
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ldp x27, x28, [x8], #16
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ldp x29, x9, [x8], #16
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ldr lr, [x8]
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mov sp, x9
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ret
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