arch/arm64/kernel/relocate_kernel.S

root/arch/arm64/kernel/relocate_kernel.S
/* SPDX-License-Identifier: GPL-2.0-only */
/*
 * kexec for arm64
 *
 * Copyright (C) Linaro.
 * Copyright (C) Huawei Futurewei Technologies.
 * Copyright (C) 2021, Microsoft Corporation.
 * Pasha Tatashin <pasha.tatashin@soleen.com>
 */

#include <linux/kexec.h>
#include <linux/linkage.h>

#include <asm/assembler.h>
#include <asm/kexec.h>
#include <asm/page.h>
#include <asm/sysreg.h>
#include <asm/virt.h>

.macro turn_off_mmu tmp1, tmp2
        mov_q   \tmp1, INIT_SCTLR_EL1_MMU_OFF
        pre_disable_mmu_workaround
        msr     sctlr_el1, \tmp1
        isb
.endm

.section    ".kexec_relocate.text", "ax"
/*
 * arm64_relocate_new_kernel - Put a 2nd stage image in place and boot it.
 *
 * The memory that the old kernel occupies may be overwritten when copying the
 * new image to its final location.  To assure that the
 * arm64_relocate_new_kernel routine which does that copy is not overwritten,
 * all code and data needed by arm64_relocate_new_kernel must be between the
 * symbols arm64_relocate_new_kernel and arm64_relocate_new_kernel_end.  The
 * machine_kexec() routine will copy arm64_relocate_new_kernel to the kexec
 * safe memory that has been set up to be preserved during the copy operation.
 */
SYM_CODE_START(arm64_relocate_new_kernel)
        /*
         * The kimage structure isn't allocated specially and may be clobbered
         * during relocation. We must load any values we need from it prior to
         * any relocation occurring.
         */
        ldr     x28, [x0, #KIMAGE_START]
        ldr     x27, [x0, #KIMAGE_ARCH_EL2_VECTORS]
        ldr     x26, [x0, #KIMAGE_ARCH_DTB_MEM]

        /* Setup the list loop variables. */
        ldr     x18, [x0, #KIMAGE_ARCH_ZERO_PAGE] /* x18 = zero page for BBM */
        ldr     x17, [x0, #KIMAGE_ARCH_TTBR1]   /* x17 = linear map copy */
        ldr     x16, [x0, #KIMAGE_HEAD]         /* x16 = kimage_head */
        ldr     x22, [x0, #KIMAGE_ARCH_PHYS_OFFSET]     /* x22 phys_offset */
        raw_dcache_line_size x15, x1            /* x15 = dcache line size */
        break_before_make_ttbr_switch   x18, x17, x1, x2 /* set linear map */
.Lloop:
        and     x12, x16, PAGE_MASK             /* x12 = addr */
        sub     x12, x12, x22                   /* Convert x12 to virt */
        /* Test the entry flags. */
.Ltest_source:
        tbz     x16, IND_SOURCE_BIT, .Ltest_indirection

        /* Invalidate dest page to PoC. */
        mov     x19, x13
        copy_page x13, x12, x1, x2, x3, x4, x5, x6, x7, x8
        add     x1, x19, #PAGE_SIZE
        dcache_by_myline_op civac, sy, x19, x1, x15, x20
        b       .Lnext
.Ltest_indirection:
        tbz     x16, IND_INDIRECTION_BIT, .Ltest_destination
        mov     x14, x12                        /* ptr = addr */
        b       .Lnext
.Ltest_destination:
        tbz     x16, IND_DESTINATION_BIT, .Lnext
        mov     x13, x12                        /* dest = addr */
.Lnext:
        ldr     x16, [x14], #8                  /* entry = *ptr++ */
        tbz     x16, IND_DONE_BIT, .Lloop       /* while (!(entry & DONE)) */
        /* wait for writes from copy_page to finish */
        dsb     nsh
        ic      iallu
        dsb     nsh
        isb
        turn_off_mmu x12, x13

        /* Start new image. */
        cbz     x27, .Lel1
        mov     x1, x28                         /* kernel entry point */
        mov     x2, x26                         /* dtb address */
        mov     x3, xzr
        mov     x4, xzr
        mov     x0, #HVC_SOFT_RESTART
        hvc     #0                              /* Jumps from el2 */
.Lel1:
        mov     x0, x26                         /* dtb address */
        mov     x1, xzr
        mov     x2, xzr
        mov     x3, xzr
        br      x28                             /* Jumps from el1 */
SYM_CODE_END(arm64_relocate_new_kernel)
Linux
