On 2022-07-18 17:51, Kalesh Singh wrote:
On Mon, Jul 18, 2022 at 12:31 AM Marc Zyngier <maz@xxxxxxxxxx> wrote:
On Fri, 15 Jul 2022 07:10:20 +0100,
Kalesh Singh <kaleshsingh@xxxxxxxxxx> wrote:
>
> Add stub implementations of non-protected nVHE stack unwinder, for
> building. These are implemented later in this series.
>
> Signed-off-by: Kalesh Singh <kaleshsingh@xxxxxxxxxx>
> ---
> arch/arm64/include/asm/stacktrace/nvhe.h | 22 ++++++++++++++++++++++
> 1 file changed, 22 insertions(+)
>
> diff --git a/arch/arm64/include/asm/stacktrace/nvhe.h b/arch/arm64/include/asm/stacktrace/nvhe.h
> index 1eac4e57f2ae..36cf7858ddd8 100644
> --- a/arch/arm64/include/asm/stacktrace/nvhe.h
> +++ b/arch/arm64/include/asm/stacktrace/nvhe.h
> @@ -8,6 +8,12 @@
> * the HYP memory. The stack is unwinded in EL2 and dumped to a shared
> * buffer where the host can read and print the stacktrace.
> *
> + * 2) Non-protected nVHE mode - the host can directly access the
> + * HYP stack pages and unwind the HYP stack in EL1. This saves having
> + * to allocate shared buffers for the host to read the unwinded
> + * stacktrace.
> + *
> + *
> * Copyright (C) 2022 Google LLC
> */
> #ifndef __ASM_STACKTRACE_NVHE_H
> @@ -53,5 +59,21 @@ static int notrace unwind_next(struct unwind_state *state)
> NOKPROBE_SYMBOL(unwind_next);
> #endif /* CONFIG_PROTECTED_NVHE_STACKTRACE */
>
> +/*
> + * Non-protected nVHE HYP stack unwinder
> + */
> +#else /* !__KVM_NVHE_HYPERVISOR__ */
I don't get this path. This either represents the VHE hypervisor or
the kernel proper. Which one is it?
Hi Marc. This is run from kernel proper context. And it's the
unwinding for conventional nVHE (non-protected). The unwinding is done
from the host kernel in EL1.
This really deserves a comment here, as the one you currently
have is a bit misleading (and you probably want to move it
below the #else).
Thanks,
M.
--
Jazz is not dead. It just smells funny...
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