Atmosphere/thermosphere/src/exception_vectors.s

/* Some macros taken from https://github.com/ARM-software/arm-trusted-firmware/blob/master/include/common/aarch64/asm_macros.S */
/*
 * Copyright (c) 2013-2017, ARM Limited and Contributors. All rights reserved.
 *
 * SPDX-License-Identifier: BSD-3-Clause
 */
 

/*
 * Declare the exception vector table, enforcing it is aligned on a
 * 2KB boundary, as required by the ARMv8 architecture.
 * Use zero bytes as the fill value to be stored in the padding bytes
 * so that it inserts illegal AArch64 instructions. This increases
 * security, robustness and potentially facilitates debugging.
 */
.macro vector_base  label, section_name=.vectors
.section \section_name, "ax"
.align 11, 0
\label:
.endm

/*
 * Create an entry in the exception vector table, enforcing it is
 * aligned on a 128-byte boundary, as required by the ARMv8 architecture.
 * Use zero bytes as the fill value to be stored in the padding bytes
 * so that it inserts illegal AArch64 instructions. This increases
 * security, robustness and potentially facilitates debugging.
 */
.macro vector_entry  label, section_name=.vectors
.cfi_sections .debug_frame
.section \section_name, "ax"
.align 7, 0
.type \label, %function
.func \label
.cfi_startproc
\label:
.endm

/*
 * This macro verifies that the given vector doesnt exceed the
 * architectural limit of 32 instructions. This is meant to be placed
 * immediately after the last instruction in the vector. It takes the
 * vector entry as the parameter
 */
.macro check_vector_size since
    .endfunc
    .cfi_endproc
    .if (. - \since) > (32 * 4)
        .error "Vector exceeds 32 instructions"
    .endif
.endm

.macro save_all_regs
    stp     x30, xzr, [sp, #-0x130]
    bl      _save_all_regs
.endm

.macro save_all_regs_reload_x18
    save_all_regs

    // Reload our x18 value (currentCoreCtx)
    ldp     x18, xzr, [sp, #0x120]
.endm

.macro pivot_stack_for_crash
    // Note: x18 assumed uncorrupted
    // Note: replace sp_el0 with crashing sp
    str     x16, [x18, #0x18]       // currentCoreCtx->scratch = x16
    mov     x16, sp
    msr     sp_el0, x16
    ldr     x16, [x18, #0x10]       // currentCoreCtx->crashStack
    mov     sp, x16
    ldr     x16, [x18, #0x18]
.endm

/* Actual Vectors for Thermosphere. */
.global thermosphere_vectors
vector_base thermosphere_vectors

/* Current EL, SP0 */
/* Those are unused by us, except on same-EL double-faults. */
.global unknown_exception
unknown_exception:
vector_entry synch_sp0
    pivot_stack_for_crash
    mov     x0, x30
    adr     x1, thermosphere_vectors + 4
    sub     x0, x0, x1
    bl      handleUnknownException
    b       .
    check_vector_size synch_sp0

vector_entry irq_sp0
    bl      unknown_exception
    .endfunc
    .cfi_endproc
    /* To save space, insert in an unused vector segment. */
    _save_all_regs:

    sub     sp, sp, #0x120
    stp     x0, x1, [sp, #0x00]
    stp     x2, x3, [sp, #0x10]
    stp     x4, x5, [sp, #0x20]
    stp     x6, x7, [sp, #0x30]
    stp     x8, x9, [sp, #0x40]
    stp     x10, x11, [sp, #0x50]
    stp     x12, x13, [sp, #0x60]
    stp     x14, x15, [sp, #0x70]
    stp     x16, x17, [sp, #0x80]
    stp     x18, x19, [sp, #0x90]
    stp     x20, x21, [sp, #0xA0]
    stp     x22, x23, [sp, #0xB0]
    stp     x24, x25, [sp, #0xC0]
    stp     x26, x27, [sp, #0xD0]
    stp     x28, x29, [sp, #0xE0]

    mov     x29, x30
    ldp     x30, xzr, [sp, #-0x10] // See save_all_regs macro

    mrs     x20, sp_el1
    mrs     x21, sp_el0
    mrs     x22, elr_el2
    mrs     x23, spsr_el2

    stp     x30, x20, [sp, #0xF0]
    stp     x21, x22, [sp, #0x100]
    stp     x23, xzr, [sp, #0x110]

    mov     x30, x29

    ret

vector_entry fiq_sp0
    bl      unknown_exception
    .endfunc
    .cfi_endproc
    /* To save space, insert in an unused vector segment. */
    .global _restore_all_regs
    _restore_all_regs:
    ldp     x30, x20, [sp, #0xF0]
    ldp     x21, x22, [sp, #0x100]
    ldp     x23, xzr, [sp, #0x110]

    msr     sp_el1, x20
    msr     sp_el0, x21
    msr     elr_el2, x22
    msr     spsr_el2, x23

    ldp     x0, x1, [sp, #0x00]
    ldp     x2, x3, [sp, #0x10]
    ldp     x4, x5, [sp, #0x20]
    ldp     x6, x7, [sp, #0x30]
    ldp     x8, x9, [sp, #0x40]
    ldp     x10, x11, [sp, #0x50]
    ldp     x12, x13, [sp, #0x60]
    ldp     x14, x15, [sp, #0x70]
    ldp     x16, x17, [sp, #0x80]
    ldp     x18, x19, [sp, #0x90]
    ldp     x20, x21, [sp, #0xA0]
    ldp     x22, x23, [sp, #0xB0]
    ldp     x24, x25, [sp, #0xC0]
    ldp     x26, x27, [sp, #0xD0]
    ldp     x28, x29, [sp, #0xE0]

    add     sp, sp, #0x120
    eret

vector_entry serror_sp0
    bl      unknown_exception
    .endfunc
    .cfi_endproc
    /* To save space, insert in an unused vector segment. */

.global semihosting_call
.type   semihosting_call, %function
semihosting_call:
    hlt     #0xF000
    ret

.global doSmcIndirectCallImpl
//.type   doSmcIndirectCallImpl, %function
doSmcIndirectCallImpl:
    stp     x19, x20, [sp, #-0x10]!
    mov     x19, x0

    ldp     x0, x1, [x19, #0x00]
    ldp     x2, x3, [x19, #0x10]
    ldp     x4, x5, [x19, #0x20]
    ldp     x6, x7, [x19, #0x30]

    _doSmcIndirectCallImplSmcInstruction:
    smc     #0

    stp     x0, x1, [x19, #0x00]
    stp     x2, x3, [x19, #0x10]
    stp     x4, x5, [x19, #0x20]
    stp     x6, x7, [x19, #0x30]

    ldp     x19, x20, [sp], #0x10
    ret

_doSmcIndirectCallImplEnd:
.global doSmcIndirectCallImplSmcInstructionOffset
doSmcIndirectCallImplSmcInstructionOffset:
    .word _doSmcIndirectCallImplSmcInstruction - doSmcIndirectCallImpl
.global doSmcIndirectCallImplSize
doSmcIndirectCallImplSize:
    .word _doSmcIndirectCallImplEnd - doSmcIndirectCallImpl

/* Current EL, SPx */
vector_entry synch_spx
    /* Only crashes go through there! */
    pivot_stack_for_crash

    save_all_regs

    mov     x0, sp
    mrs     x1, esr_el2

    bl      handleSameElSyncException
    b       .
    check_vector_size synch_spx

vector_entry irq_spx
    bl      unknown_exception
    check_vector_size irq_spx

vector_entry fiq_spx
    bl      unknown_exception
    check_vector_size fiq_spx

vector_entry serror_spx
    bl      unknown_exception
    check_vector_size serror_spx

/* Lower EL, A64 */
vector_entry synch_a64
    save_all_regs_reload_x18

    mov     x0, sp
    mrs     x1, esr_el2

    bl      handleLowerElSyncException

    b       _restore_all_regs
    check_vector_size synch_a64

vector_entry irq_a64
    bl      unknown_exception
    check_vector_size irq_a64

vector_entry fiq_a64
    bl      unknown_exception
    check_vector_size fiq_a64

vector_entry serror_a64
    bl      unknown_exception
    check_vector_size serror_a64


/* Lower EL, A32 */
vector_entry synch_a32
    bl      unknown_exception
    check_vector_size synch_a32

vector_entry irq_a32
    bl      unknown_exception
    check_vector_size irq_a32

vector_entry fiq_a32
    b       fiq_a64
    check_vector_size fiq_a32

vector_entry serror_a32
    bl      unknown_exception
    check_vector_size serror_a32