limine/common/sys/smp_trampoline.asm_aarch64

#include <lib/macros.aarch64_asm.h>

.set tpl_booted_flag, -56
.set tpl_ttbr0, -48
.set tpl_ttbr1, -40
.set tpl_mair, -32
.set tpl_tcr, -24
.set tpl_sctlr, -16
.set tpl_info_struct, -8

.section .text

.global smp_trampoline_start
smp_trampoline_start:
    bl .L_entry
.L_entry:
    // Mask IRQs
    msr daifset, #0b1111

    // Address to next page (since our offsets into the boot data are negative)
    add x1, x30, #0xFFC

    ldr x0, [x1, tpl_info_struct]
    ldr x2, [x1, tpl_sctlr]
    ldr x3, [x1, tpl_mair]
    ldr x4, [x1, tpl_tcr]
    ldr x5, [x1, tpl_ttbr0]
    ldr x6, [x1, tpl_ttbr1]

    // Configure EL1 state
    msr mair_el1, x3
    msr tcr_el1, x4
    msr ttbr0_el1, x5
    msr ttbr1_el1, x6
    msr sctlr_el1, x2
    dsb sy
    isb

    PICK_EL x8, 1f, 0f
0:
    // Configure EL2-specific state for EL1

    // Don't trap counters to EL2
    mrs x8, cnthctl_el2
    orr x8, x8, #3
    msr cnthctl_el2, x8
    msr cntvoff_el2, xzr

    // Enable AArch64 in EL1
    mov x8, xzr
    orr x8, x8, #(1 << 31)
    orr x8, x8, #(1 << 1)
    msr hcr_el2, x8

    // Don't trap FP/SIMD to EL2
    mov x8, #0x33FF
    msr cptr_el2, x8
    msr hstr_el2, xzr

    // Run rest of trampoline in EL1
    mov x8, #0x3c4
    msr spsr_el2, x8
    adr x8, 1f
    msr elr_el2, x8

    eret

1:
    // Notify BSP we are alive
    mov x8, #1
    add x9, x1, tpl_booted_flag
    stlr x8, [x9]

    // Wait for BSP to tell us where to go
    add x9, x0, #24
2:
    ldar x8, [x9]
    cbnz x8, 3f
    yield
    b 2b

3:
    msr elr_el1, x8

    msr spsel, #0
    ldr x8, [x0, #16]
    mov sp, x8

    // Enter kernel
    mov x8, #0x3c4
    msr spsr_el1, x8

    ZERO_REGS_EXCEPT_X0

    eret

smp_trampoline_end:

.section .rodata

.global smp_trampoline_size
smp_trampoline_size:
    .quad smp_trampoline_end - smp_trampoline_start