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    Subject[PATCH v14 13/16] arm64: kexec_file: invoke the kernel without purgatory
    Date
    On arm64, purgatory would do almost nothing. So just invoke secondary
    kernel directly by jumping into its entry code.

    While, in this case, cpu_soft_restart() must be called with dtb address
    in the fifth argument, the behavior still stays compatible with kexec_load
    case as long as the argument is null.

    Signed-off-by: AKASHI Takahiro <takahiro.akashi@linaro.org>
    Reviewed-by: James Morse <james.morse@arm.com>
    Cc: Catalin Marinas <catalin.marinas@arm.com>
    Cc: Will Deacon <will.deacon@arm.com>
    ---
    arch/arm64/kernel/cpu-reset.S | 8 ++++----
    arch/arm64/kernel/machine_kexec.c | 12 ++++++++++--
    arch/arm64/kernel/relocate_kernel.S | 3 ++-
    3 files changed, 16 insertions(+), 7 deletions(-)

    diff --git a/arch/arm64/kernel/cpu-reset.S b/arch/arm64/kernel/cpu-reset.S
    index 8021b46c9743..a2be30275a73 100644
    --- a/arch/arm64/kernel/cpu-reset.S
    +++ b/arch/arm64/kernel/cpu-reset.S
    @@ -22,11 +22,11 @@
    * __cpu_soft_restart(el2_switch, entry, arg0, arg1, arg2) - Helper for
    * cpu_soft_restart.
    *
    - * @el2_switch: Flag to indicate a swich to EL2 is needed.
    + * @el2_switch: Flag to indicate a switch to EL2 is needed.
    * @entry: Location to jump to for soft reset.
    - * arg0: First argument passed to @entry.
    - * arg1: Second argument passed to @entry.
    - * arg2: Third argument passed to @entry.
    + * arg0: First argument passed to @entry. (relocation list)
    + * arg1: Second argument passed to @entry.(physical kernel entry)
    + * arg2: Third argument passed to @entry. (physical dtb address)
    *
    * Put the CPU into the same state as it would be if it had been reset, and
    * branch to what would be the reset vector. It must be executed with the
    diff --git a/arch/arm64/kernel/machine_kexec.c b/arch/arm64/kernel/machine_kexec.c
    index f6a5c6bc1434..c63c355e2f18 100644
    --- a/arch/arm64/kernel/machine_kexec.c
    +++ b/arch/arm64/kernel/machine_kexec.c
    @@ -212,9 +212,17 @@ void machine_kexec(struct kimage *kimage)
    * uses physical addressing to relocate the new image to its final
    * position and transfers control to the image entry point when the
    * relocation is complete.
    + * In kexec case, kimage->start points to purgatory assuming that
    + * kernel entry and dtb address are embedded in purgatory by
    + * userspace (kexec-tools).
    + * In kexec_file case, the kernel starts directly without purgatory.
    */
    -
    - cpu_soft_restart(reboot_code_buffer_phys, kimage->head, kimage->start, 0);
    + cpu_soft_restart(reboot_code_buffer_phys, kimage->head, kimage->start,
    +#ifdef CONFIG_KEXEC_FILE
    + kimage->arch.dtb_mem);
    +#else
    + 0);
    +#endif

    BUG(); /* Should never get here. */
    }
    diff --git a/arch/arm64/kernel/relocate_kernel.S b/arch/arm64/kernel/relocate_kernel.S
    index f407e422a720..95fd94209aae 100644
    --- a/arch/arm64/kernel/relocate_kernel.S
    +++ b/arch/arm64/kernel/relocate_kernel.S
    @@ -32,6 +32,7 @@
    ENTRY(arm64_relocate_new_kernel)

    /* Setup the list loop variables. */
    + mov x18, x2 /* x18 = dtb address */
    mov x17, x1 /* x17 = kimage_start */
    mov x16, x0 /* x16 = kimage_head */
    raw_dcache_line_size x15, x0 /* x15 = dcache line size */
    @@ -107,7 +108,7 @@ ENTRY(arm64_relocate_new_kernel)
    isb

    /* Start new image. */
    - mov x0, xzr
    + mov x0, x18
    mov x1, xzr
    mov x2, xzr
    mov x3, xzr
    --
    2.18.0
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