Exception handling of arm

1. The kind of anomaly

1）IRQ, External interrupt request ： External hardware departure ;
2）Soft interrupt, Soft interrupt ： Main applications , system call , The application can access the address of the kernel through system call ;
 Add ： Software architecture of embedded products （ The diagram is as follows ） The three use different address spaces   Cannot access directly  

3）reset, Reset ： If the mobile phone crashes , Press power key ;
4）undefined instruction, Undefined instruction
5）data abort, Data exception
It is summarized in the table below ：

The general process of exception handling is mainly about interruption , Other similar

2. Interrupt exception

 When the mobile phone receives a call , The telephone module will receive this signal , Telephone and mobile phone internal CPU Connected through a pin , The telephone module sends the signal to CPU,CPU Other things are being handled at this time , When receiving this signal, it will interrupt the current cpu Things being handled .
1）ARM There are two levels of external interrupts ,FIQ and IRQ
2） be based on ARM Most systems have two interrupt sources 

Interrupt controller ： send cpu Multiple interrupt sources can be connected to the outside , Handle interrupt priority ;
3） Suppose the external interrupt source is a key , When the key is pressed ** High level or low level （ Rising edge or falling edge ）** As a trigger ;
Interrupt handling : Site protection -> Handling interrupts -> Restore the scene
If CPU Processing other interrupts , The current interruption cannot be handled in time ,0.5 Seconds later, press the key to lift , Interruption disappears , terms of settlement ：CPU Record all generated interrupts through the interrupt flag .
After the interrupt is generated randomly , How to jump to the interrupt handler （ Interrupt vector table ）

3. Interrupt vector table | Exception handling

After the interrupt is generated randomly , How to jump to the interrupt handler （ Interrupt vector table ）

SWI Soft interrupt instruction ： simulation CPU The pin of some external hardware generates an interrupt signal

4. Example of soft interrupt handler

Write from scratch Skip first , Need private chat .