hw_breakpoint 是由处理器提供专门断点寄存器来保存一个地址,是需要处理器支持的。处理器在执行过程中会不断去匹配,当匹配上后则会产生中断。
内核自带了硬件断点的样例linux-3.16\samples\hw_breakpoint\data_breakpoint.c
cpp
static void sample_hbp_handler(struct perf_event *bp,
struct perf_sample_data *data,
struct pt_regs *regs)
{
printk(KERN_INFO "%s value is changed\n", ksym_name);
dump_stack();
printk(KERN_INFO "Dump stack from sample_hbp_handler\n");
}
static int __init hw_break_module_init(void* addr)
{
int ret;
struct perf_event_attr attr;
hw_breakpoint_init(&attr);
attr.bp_addr = addr;
attr.bp_len = HW_BREAKPOINT_LEN_4;//监控addr开始的4字节
attr.bp_type = HW_BREAKPOINT_W | HW_BREAKPOINT_R;//读写该地址都能触发
sample_hbp = register_wide_hw_breakpoint(&attr, sample_hbp_handler, NULL);
if (IS_ERR((void __force *)sample_hbp)) {
ret = PTR_ERR((void __force *)sample_hbp);
goto fail;
}
printk(KERN_INFO "HW Breakpoint for write installed\n");
return 0;
fail:
printk(KERN_INFO "Breakpoint registration failed\n");
return ret;
看网上说ARM Architecture Reference Manual Supplement ARMv8.1, for ARMv8-A architecture profile这些文档的degug register里面有。文档可以在这个网站下载
可以看到应该是每个cpu都注册了一个。感觉应该是在一个cpu上注册,所有cpu都会去检查(原理不清楚,上面的文档没有看明白,猜测的)
cpp
struct perf_event * __percpu *
register_wide_hw_breakpoint(struct perf_event_attr *attr,
perf_overflow_handler_t triggered,
void *context)
{
struct perf_event * __percpu *cpu_events, *bp;
........................................
for_each_online_cpu(cpu) {
bp = perf_event_create_kernel_counter(attr, cpu, NULL,
triggered, context);
...................................................
}
暂时不写了