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    Subject[PATCH v9 03/11] arm64: kexec_file: invoke the kernel without purgatory
    Date
    On arm64, purugatory would do almosty nothing. So just invoke secondary
    kernel directy 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>
    Cc: Catalin Marinas <catalin.marinas@arm.com>
    Cc: Will Deacon <will.deacon@arm.com>
    ---
    arch/arm64/kernel/cpu-reset.S | 6 +++---
    arch/arm64/kernel/machine_kexec.c | 11 +++++++++--
    arch/arm64/kernel/relocate_kernel.S | 3 ++-
    3 files changed, 14 insertions(+), 6 deletions(-)

    diff --git a/arch/arm64/kernel/cpu-reset.S b/arch/arm64/kernel/cpu-reset.S
    index 8021b46c9743..391df91328ac 100644
    --- a/arch/arm64/kernel/cpu-reset.S
    +++ b/arch/arm64/kernel/cpu-reset.S
    @@ -24,9 +24,9 @@
    *
    * @el2_switch: Flag to indicate a swich 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.(physcal 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 f76ea92dff91..f7dbba00be10 100644
    --- a/arch/arm64/kernel/machine_kexec.c
    +++ b/arch/arm64/kernel/machine_kexec.c
    @@ -205,10 +205,17 @@ 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 case of kexec_file_load syscall, we directly start the kernel,
    + * skipping purgatory.
    */
    -
    cpu_soft_restart(kimage != kexec_crash_image,
    - reboot_code_buffer_phys, kimage->head, kimage->start, 0);
    + reboot_code_buffer_phys, kimage->head, kimage->start,
    +#ifdef CONFIG_KEXEC_FILE
    + kimage->purgatory_info.purgatory_buf ?
    + 0 : 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
    --
    2.17.0
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