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# SP_EL3, Stack Pointer (EL3)

The SP_EL3 characteristics are:

## Purpose

Holds the stack pointer associated with EL3. When executing at EL3, the value of SPSel.SP determines the current stack pointer:

SPSel.SP | Current stack pointer
--- | ---
0b0 | SP_EL0
0b1 | SP_EL3

## Configuration

This register is present only when EL3 is implemented. Otherwise, direct accesses to SP_EL3 are UNDEFINED.

## Attributes

SP_EL3 is a 64-bit register.

## Field descriptions

63 | 62 | 61 | 60 | 59 | 58 | 57 | 56 | 55 | 54 | 53 | 52 | 51 | 50 | 49 | 48 | 47 | 46 | 45 | 44 | 43 | 42 | 41 | 40 | 39 | 38 | 37 | 36 | 35 | 34 | 33 | 32
31 | 30 | 29 | 28 | 27 | 26 | 25 | 24 | 23 | 22 | 21 | 20 | 19 | 18 | 17 | 16 | 15 | 14 | 13 | 12 | 11 | 10 | 9 | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | 0
Stack pointer
Stack pointer

#### Bits [63:0]

Stack pointer.

The reset behavior of this field is:

- On a Warm reset, this field resets to an architecturally UNKNOWN value.

## Accessing SP_EL3

This register is not accessible using MRS and MSR instructions.

When the value of SPSel.SP is 1, this register is accessible at EL3 as the current stack pointer.

Note

When the value of SPSel.SP is 0, SP_EL0 is used as the current stack pointer at all Exception levels.

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26/03/2024 09:49; 67c0ae5282a7629ba0ea0ba7267b43cd4f7939f6

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