linux-kernel - Re: CONFIG_THUMB2_KERNEL=y boot failure after Spectre BHB fixes

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Date:   Wed, 30 Mar 2022 17:11:16 +0100
From:   "Russell King (Oracle)" <linux@...linux.org.uk>
To:     Christian Eggers <ceggers@...i.de>
Cc:     linux-arm-kernel@...ts.infradead.org,
        Catalin Marinas <catalin.marinas@....com>,
        linux-kernel@...r.kernel.org, llvm@...ts.linux.dev,
        Nathan Chancellor <nathan@...nel.org>
Subject: Re: CONFIG_THUMB2_KERNEL=y boot failure after Spectre BHB fixes

On Tue, Mar 22, 2022 at 06:49:17PM +0100, Christian Eggers wrote:
> Hi Nathan, hi Russel,
> 
> I stumbled today over the same problem (no output on serial console
> with v5.15.28-rt36). During `git bisect`, I had also some commits
> where a few lines of output were visible.
> 
> At commit 8d9d651ff227 ("ARM: use LOADADDR() to get load address of
> sections"), the system boots up to here:
> 
> start_kernel()
> +--setup_arch()
>    +--paging_init()
>       +--devicemaps_init()
>          +--eary_trap_init(vectors_base = 0xC7FFE000)
>             +--copy_from_lma(vectors_base = 0xC7FFE000, __vectors_start=0x0, __vectors_end=0x20)
>                +--__memcpy()
> 
>                copy_template.S:113
>                ldr8w   r1, r3, r4, r5, r6, r7, r8, ip, lr, abort=20f
>                r1 = 0
> 
> 
> With the final v5.15.28-rt36 I found out that the system boots fine
> after disabling CONFIG_HARDEN_BRANCH_HISTORY.
> 
> Is there anything else I could analyze? My SoC system is a NXP i.MX6LL
> with a ARMv7 core. I have access to a JTAG debugger.

I think this is already fixed in mainline. Commit:

6c7cb60bff7a ("ARM: fix Thumb2 regression")

-- 
RMK's Patch system: https://www.armlinux.org.uk/developer/patches/
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