Messages in this thread |  | | Subject | Re: [PATCH v9 03/11] arm64: kexec_file: invoke the kernel without purgatory | From | James Morse <> | Date | Tue, 1 May 2018 18:46:06 +0100 |
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Hi Akashi,
On 25/04/18 07:26, AKASHI Takahiro wrote: > On arm64, purugatory would do almosty nothing. So just invoke secondary > kernel directy by jumping into its entry code.
(Nits: purgatory, almost, directly)
> 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.
> 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.
(Nit: switch)
> * @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)
(Nit: physical)
> + * 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.
We're not really skipping purgatory, purgatory doesn't exist! For regular kexec the image/payload we run is up to kexec-tools. For kexec_file_load its a kernel-image. Purgatory is a kexec-tools-ism.
> 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
Where does kimage->arch.dtb_mem come from? This patch won't build until patch 8 adds the config option, which is going to make bisecting any kexec side-effects tricky.
purgatory_buf seems to only be set in kexec_purgatory_setup_kbuf(), called from kexec_load_purgatory(), which we don't use. How does this get a value?
Would it be better to always use kimage->arch.dtb_mem, and ensure that is 0 for regular kexec (as we can't know where the dtb is)? (image_arg may then be a better name).
Thanks,
James
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