linux-kernel - Re: [PATCH v2 10/18] arm64: entry: Add exception trampoline page for exceptions from EL0

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Message-ID: <20171201133159.qphu3mc3uybm46js@lakrids.cambridge.arm.com>
Date:   Fri, 1 Dec 2017 13:31:59 +0000
From:   Mark Rutland <mark.rutland@....com>
To:     Will Deacon <will.deacon@....com>
Cc:     linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        catalin.marinas@....com, ard.biesheuvel@...aro.org,
        sboyd@...eaurora.org, dave.hansen@...ux.intel.com,
        keescook@...omium.org, msalter@...hat.com, labbott@...hat.com,
        tglx@...utronix.de
Subject: Re: [PATCH v2 10/18] arm64: entry: Add exception trampoline page for
 exceptions from EL0

On Thu, Nov 30, 2017 at 04:39:38PM +0000, Will Deacon wrote:
> +	.macro tramp_ventry, regsize = 64
> +	.align	7
> +1:
> +	.if	\regsize == 64
> +	msr	tpidrro_el0, x30
> +	.endif
> +	tramp_map_kernel	x30
> +	ldr	x30, =vectors
> +	prfm	plil1strm, [x30, #(1b - tramp_vectors)]
> +	msr	vbar_el1, x30
> +	add	x30, x30, #(1b - tramp_vectors)
> +	isb
> +	br	x30
> +	.endm

It might be worth a comment that the real vectors will restore x30 from
tpiddro_el0, since as-is, it looks like we're corrupting the value.

Otherwise, this looks good to me.

Thanks,
Mark.