From: Marc Zyngier <maz@kernel.org>
To: Mark Rutland <mark.rutland@arm.com>
Cc: Joakim Tjernlund <Joakim.Tjernlund@infinera.com>,
linux-arm-kernel@lists.infradead.org
Subject: Re: Buggy branch in __init_el2_gicv3?
Date: Mon, 14 Feb 2022 16:26:01 +0000 [thread overview]
Message-ID: <a5ee26b2e9fd44849fb598c0a2404cfb@kernel.org> (raw)
In-Reply-To: <YgptqviZbdXtaNH6@FVFF77S0Q05N>
On 2022-02-14 14:56, Mark Rutland wrote:
> On Mon, Feb 14, 2022 at 12:34:12PM +0000, Joakim Tjernlund wrote:
>> In init_el2_state calls __init_el2_gicv3 which looks:
>>
>> /* GICv3 system register access */
>> .macro __init_el2_gicv3
>> mrs x0, id_aa64pfr0_el1
>> ubfx x0, x0, #ID_AA64PFR0_GIC_SHIFT, #4
>> cbz x0, .Lskip_gicv3_\@
>>
>> mrs_s x0, SYS_ICC_SRE_EL2
>> orr x0, x0, #ICC_SRE_EL2_SRE // Set ICC_SRE_EL2.SRE==1
>> orr x0, x0, #ICC_SRE_EL2_ENABLE // Set ICC_SRE_EL2.Enable==1
>> msr_s SYS_ICC_SRE_EL2, x0
>> isb // Make sure SRE is now set
>> mrs_s x0, SYS_ICC_SRE_EL2 // Read SRE back,
>> tbz x0, #0, 1f
>> // tbz x0, #0, .Lskip_gicv3_\@ // and check that it sticks
>> msr_s SYS_ICH_HCR_EL2, xzr // Reset ICC_HCR_EL2 to defaults
>> .Lskip_gicv3_\@:
>> .endm
>>
>> Note the tbz x0, #0, 1f, this instruction causes my A53 CPU to
>> jump far out of the macro and make the
>> CPU go into EL0, failing with an exception a bit later. I believe the
>> 1f is a bug and if I replace it with
>> tbz x0, #0, .Lskip_gicv3_\@
>> the CPU continue too boot.
>
> You're right, that should be targetting `.Lskip_gicv3_\@`. It looks
> like that
> was left behind in commit:
>
> 114945d84a30a5fe ("arm64: Fix labels in el2_setup macros")
>
> Marc?
Yup, that's a glaring bug. My bad. Thanks for pointing that out.
Joakim, can you please write a patch and cc me?
Cheers,
M.
--
Jazz is not dead. It just smells funny...
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next prev parent reply other threads:[~2022-02-14 16:27 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-02-14 12:34 Buggy branch in __init_el2_gicv3? Joakim Tjernlund
2022-02-14 14:56 ` Mark Rutland
2022-02-14 15:14 ` Joakim Tjernlund
2022-02-14 17:16 ` Marc Zyngier
2022-02-14 16:26 ` Marc Zyngier [this message]
2022-02-14 17:12 ` Joakim Tjernlund
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