企业网站服务器租用五年级上册优化设计答案
通用寄存器
示例：读取寄存器值
// 用户态程序或内核代码中均可使用
unsigned long reg_value;
asm volatile ("mov %0, x10" // 将X10的值保存到reg_value变量: "=r" (reg_value)
);
printk("X10 = 0x%lx\n", reg_value);
示例：写入寄存器值
unsigned long new_value = 0x1234;
asm volatile ("mov x9, %0" // 将new_value的值写入X9: : "r" (new_value)
);
内核模块中直接访问
// 内核模块示例
void read_registers(void) {unsigned long sp, pc;asm volatile ("mov %0, sp \n" // 读取SP（栈指针）"mov %1, pc \n" // 读取PC（程序计数器）: "=r" (sp), "=r" (pc));pr_info("SP=0x%lx, PC=0x%lx\n", sp, pc);
}
系统寄存器
需要通过msr写、mrs读取：
linux内核定义了read_sysreg/write_sysreg相关的函数：arch/arm64/include/asm/sysreg.h
以读取寄存器为例 ：read_sysreg和read_sysreg_s的区别是一个检测权限？（来自deepseek答案），实际操作read_sysreg接受字符串类型寄存器写法，如elr_el1,vbar_el1等(这些忽略大小写，本质上也是as汇编命令，属于binutils软件，中内置的)。./opcodes/aarch64-opc.c：
而read_sysreg_s只能接受SYS_ELR_EL1,SYS_VBAR_EL1这种内核定义的寄存器编码：
sys_reg：
/** ARMv8 ARM reserves the following encoding for system registers:* (Ref: ARMv8 ARM, Section: "System instruction class encoding overview",* C5.2, version:ARM DDI 0487A.f)* [20-19] : Op0* [18-16] : Op1* [15-12] : CRn* [11-8] : CRm* [7-5] : Op2*/
#define Op0_shift 19
#define Op0_mask 0x3
#define Op1_shift 16
#define Op1_mask 0x7
#define CRn_shift 12
#define CRn_mask 0xf
#define CRm_shift 8
#define CRm_mask 0xf
#define Op2_shift 5
#define Op2_mask 0x7#define sys_reg(op0, op1, crn, crm, op2) \(((op0) << Op0_shift) | ((op1) << Op1_shift) | \((crn) << CRn_shift) | ((crm) << CRm_shift) | \((op2) << Op2_shift))和寄存器的定义有说明：http://hehezhou.cn/register2025/AArch64-elr_el1.html
案例：
uint64_t read_ttbr0_el1(void) {uint64_t ttbr0;asm volatile("mrs %0, ttbr0_el1" : "=r" (ttbr0));return ttbr0;
}
static int __init test_init(void)
{printk("ttbr0_el1 %llx\n",read_ttbr0_el1());printk("ttbr0_el1 %llx\n",read_sysreg_s(SYS_TTBR0_EL1));printk("elr_el1 %llx\n",read_sysreg(elr_el1));printk("midr_el1 %llx\n",read_sysreg(midr_el1));printk("vbar_el1 %llx\n",read_sysreg(vbar_el1));printk("vbar_el1 %llx\n",read_sysreg_s(SYS_VBAR_EL1));return 0;
}