Interrupt Handling 02

AArch64 Exception Vector Table §

ARMv7 Exception Vector Table §

• Reference: https://www.realdigital.org/doc/fb6974fbe87554b433bc0c6df2f14d69

Offset	Vector	Mode
0x00	Reset	Supervisor
0x04	Undefined Instruction	Undefined
0x08	Supervisor Call	Supervisor
0x0C	Prefetch Abort	Abort
0x10	Data Abort	Abort
0x14	Not Used	NA
0x18	IRQ Interrupt	IRQ
0x1C	FIQ Interrupt	FIQ

ARMv8 Exception Vector Table §

• Reference: https://developer.arm.com/documentation/den0024/a/CHDEEDDC

Address	Exception Type	Description
VBAR_ELn +0x000	Synchronous	Current EL with SP0
+0x080	IRQ/vIRQ	^
+0x100	FIQ/vFIQ	^
+0x180	SError/vSError	^
+0x200	Synchronous	Current EL with SPx
+0x280	IRQ/vIRQ	^
+0x300	FIQ/vFIQ	^
+0x380	SError/vSError	^
+0x400	Synchronous	Lower EL using AArch64
+0x480	IRQ/vIRQ	^
+0x500	FIQ/vFIQ	^
+0x580	SError/vSError	^
+0x600	Synchronous	Lower EL using AArch32
+0x680	IRQ/vIRQ	^
+0x700	FIQ/vFIQ	^
+0x780	SError/vSError	^

Stack Pointer Selection §

 MSR SPSel, #Imm1: Select whether to use the default SP_ELx Stack Pointer, or the SP_EL0 Stack Pointer

• t: Indicates use of the SP_EL0 Stack Pointer.
• h: Indicates use of the SP_ELx Stack Pointer.

SPSel

SPSel §

• Purpose: Allows the Stack Pointer to be selected between SP_EL0 and SP_ELx.
• Reference: https://developer.arm.com/documentation/ddi0601/2023-12/AArch64-Registers/SPSel—Stack-Pointer-Select

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Reference §

• Stack Pointer Selection: https://developer.arm.com/documentation/ddi0500/j/CHDDGJID

Registering Exception Vector Table §

Exception Level Transition from EL2 to EL1 §

arch/aarch64/start.rs

mov x1, 0x80000000 // HCR_EL2::RW::EL1IsAarch64
msr HCR_EL2, x1

HCR_EL2

HCR_EL2 §

• Purpose: Provides configuration controls for virtualization, including defining whether various operations are trapped to EL2.
• Reference: https://developer.arm.com/documentation/ddi0601/2024-03/AArch64-Registers/HCR-EL2—Hypervisor-Configuration-Register

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Registration §

arch/aarch64/exception/mod.rs

adrp x4 {vector_table}
add x4, x4, #:lo12:{vector_table}
msr VBAR_EL1, x4
isb sy
dsb sy

• VBAR_EL1에 Vector Table에 해당하는 주소를 등록하여 Exception이 발생하였을 때에 Exception Vector Table을 참조하여 해당 동작을 실행할 수 있도록 하였다.

VBAR_EL1

VBAR_EL1 §

• Purpose: Holds the vector base address for any exception that is taken to EL1.
• Reference: https://developer.arm.com/documentation/ddi0601/2024-03/AArch64-Registers/VBAR-EL1—Vector-Base-Address-Register—EL1-?lang=en

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