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Message-ID: <e5f1ee17f8e4ac3a5f5077d85318e0ed@kernel.org>
Date: Wed, 29 Apr 2020 18:35:06 +0100
From: Marc Zyngier <maz@...nel.org>
To: Pavel Tatashin <pasha.tatashin@...een.com>
Cc: jmorris@...ei.org, sashal@...nel.org, ebiederm@...ssion.com,
kexec@...ts.infradead.org, linux-kernel@...r.kernel.org,
corbet@....net, catalin.marinas@....com, will@...nel.org,
linux-arm-kernel@...ts.infradead.org, james.morse@....com,
vladimir.murzin@....com, matthias.bgg@...il.com,
bhsharma@...hat.com, linux-mm@...ck.org, mark.rutland@....com,
steve.capper@....com, rfontana@...hat.com, tglx@...utronix.de,
selindag@...il.com
Subject: Re: [PATCH v9 15/18] arm64: kexec: kexec EL2 vectors
On 2020-03-26 03:24, Pavel Tatashin wrote:
> If we have a EL2 mode without VHE, the EL2 vectors are needed in order
> to switch to EL2 and jump to new world with hyperivsor privileges.
>
> Signed-off-by: Pavel Tatashin <pasha.tatashin@...een.com>
> ---
> arch/arm64/include/asm/kexec.h | 5 +++++
> arch/arm64/kernel/asm-offsets.c | 1 +
> arch/arm64/kernel/machine_kexec.c | 5 +++++
> arch/arm64/kernel/relocate_kernel.S | 35 +++++++++++++++++++++++++++++
> 4 files changed, 46 insertions(+)
>
> diff --git a/arch/arm64/include/asm/kexec.h
> b/arch/arm64/include/asm/kexec.h
> index d944c2e289b2..0f758fd51518 100644
> --- a/arch/arm64/include/asm/kexec.h
> +++ b/arch/arm64/include/asm/kexec.h
> @@ -95,6 +95,7 @@ static inline void crash_post_resume(void) {}
> extern const unsigned long kexec_relocate_code_size;
> extern const unsigned char kexec_relocate_code_start[];
> extern const unsigned long kexec_kern_reloc_offset;
> +extern const unsigned long kexec_el2_vectors_offset;
> #endif
>
> /*
> @@ -104,6 +105,9 @@ extern const unsigned long kexec_kern_reloc_offset;
> * kernel, or purgatory entry address).
> * kern_arg0 first argument to kernel is its dtb address. The other
> * arguments are currently unused, and must be set to 0
> + * el2_vector If present means that relocation routine will go to EL1
> + * from EL2 to do the copy, and then back to EL2 to do the jump
> + * to new world.
> */
> struct kern_reloc_arg {
> phys_addr_t head;
> @@ -112,6 +116,7 @@ struct kern_reloc_arg {
> phys_addr_t kern_arg1;
> phys_addr_t kern_arg2;
> phys_addr_t kern_arg3;
> + phys_addr_t el2_vector;
> };
>
> #define ARCH_HAS_KIMAGE_ARCH
> diff --git a/arch/arm64/kernel/asm-offsets.c
> b/arch/arm64/kernel/asm-offsets.c
> index 448230684749..ff974b648347 100644
> --- a/arch/arm64/kernel/asm-offsets.c
> +++ b/arch/arm64/kernel/asm-offsets.c
> @@ -136,6 +136,7 @@ int main(void)
> DEFINE(KEXEC_KRELOC_KERN_ARG1, offsetof(struct kern_reloc_arg,
> kern_arg1));
> DEFINE(KEXEC_KRELOC_KERN_ARG2, offsetof(struct kern_reloc_arg,
> kern_arg2));
> DEFINE(KEXEC_KRELOC_KERN_ARG3, offsetof(struct kern_reloc_arg,
> kern_arg3));
> + DEFINE(KEXEC_KRELOC_EL2_VECTOR, offsetof(struct kern_reloc_arg,
> el2_vector));
> #endif
> return 0;
> }
> diff --git a/arch/arm64/kernel/machine_kexec.c
> b/arch/arm64/kernel/machine_kexec.c
> index ab571fca9bd1..bd398def7627 100644
> --- a/arch/arm64/kernel/machine_kexec.c
> +++ b/arch/arm64/kernel/machine_kexec.c
> @@ -84,6 +84,11 @@ int machine_kexec_post_load(struct kimage *kimage)
> kern_reloc_arg->head = kimage->head;
> kern_reloc_arg->entry_addr = kimage->start;
> kern_reloc_arg->kern_arg0 = kimage->arch.dtb_mem;
> + /* Setup vector table only when EL2 is available, but no VHE */
> + if (is_hyp_mode_available() && !is_kernel_in_hyp_mode()) {
> + kern_reloc_arg->el2_vector = __pa(reloc_code)
> + + kexec_el2_vectors_offset;
> + }
> kexec_image_info(kimage);
>
> return 0;
> diff --git a/arch/arm64/kernel/relocate_kernel.S
> b/arch/arm64/kernel/relocate_kernel.S
> index aa9f2b2cd77c..6fd2fc0ef373 100644
> --- a/arch/arm64/kernel/relocate_kernel.S
> +++ b/arch/arm64/kernel/relocate_kernel.S
> @@ -89,6 +89,38 @@ ENTRY(arm64_relocate_new_kernel)
> .ltorg
> END(arm64_relocate_new_kernel)
>
> +.macro el1_sync_64
> + br x4 /* Jump to new world from el2 */
> + .fill 31, 4, 0 /* Set other 31 instr to zeroes */
> +.endm
The common idiom to write this is to align the beginning of the
macro, and not to bother about what follows:
.macro whatever
.align 7
br x4
.endm
Specially given that 0 is an undefined instruction, and I really hate to
see
those in the actual text. On the contrary, .align generates NOPs.
> +
> +.macro invalid_vector label
> +\label:
> + b \label
> + .fill 31, 4, 0 /* Set other 31 instr to zeroes */
> +.endm
> +
> +/* el2 vectors - switch el2 here while we restore the memory image. */
> + .align 11
> +ENTRY(kexec_el2_vectors)
Please see commit 617a2f392c92 ("arm64: kvm: Annotate assembly using
modern
annoations"), and follow the same pattern.
> + invalid_vector el2_sync_invalid_sp0 /* Synchronous EL2t */
> + invalid_vector el2_irq_invalid_sp0 /* IRQ EL2t */
> + invalid_vector el2_fiq_invalid_sp0 /* FIQ EL2t */
> + invalid_vector el2_error_invalid_sp0 /* Error EL2t */
> + invalid_vector el2_sync_invalid_spx /* Synchronous EL2h */
> + invalid_vector el2_irq_invalid_spx /* IRQ EL2h */
> + invalid_vector el2_fiq_invalid_spx /* FIQ EL2h */
> + invalid_vector el2_error_invalid_spx /* Error EL2h */
> + el1_sync_64 /* Synchronous 64-bit EL1 */
> + invalid_vector el1_irq_invalid_64 /* IRQ 64-bit EL1 */
> + invalid_vector el1_fiq_invalid_64 /* FIQ 64-bit EL1 */
> + invalid_vector el1_error_invalid_64 /* Error 64-bit EL1 */
> + invalid_vector el1_sync_invalid_32 /* Synchronous 32-bit EL1 */
> + invalid_vector el1_irq_invalid_32 /* IRQ 32-bit EL1 */
> + invalid_vector el1_fiq_invalid_32 /* FIQ 32-bit EL1 */
> + invalid_vector el1_error_invalid_32 /* Error 32-bit EL1 */
> +END(kexec_el2_vectors)
Please write the vectors in 4 groups of 4, as this makes it a lot easier
to follow what is what.
> +
> .Lkexec_relocate_code_end:
> .org KEXEC_CONTROL_PAGE_SIZE
> .align 3 /* To keep the 64-bit values below naturally aligned. */
> @@ -102,3 +134,6 @@ kexec_relocate_code_size:
> .globl kexec_kern_reloc_offset
> kexec_kern_reloc_offset:
> .quad arm64_relocate_new_kernel - kexec_relocate_code_start
> +.globl kexec_el2_vectors_offset
> +kexec_el2_vectors_offset:
> + .quad kexec_el2_vectors - kexec_relocate_code_start
Thanks,
M.
--
Jazz is not dead. It just smells funny...
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