Re: [PATCH] ARM: Fix userspace enter on LPAE with CC_OPTIMIZE_FOR_SIZE=y

[Florian Fainelli]

On 5/15/24 07:02, Geert Uytterhoeven wrote:
> Booting an LPAE-enabled kernel built with CONFIG_CC_OPTIMIZE_FOR_SIZE=y
> fails when starting userspace:
>
>      Kernel panic - not syncing: Attempted to kill init! exitcode=0x00000004
>      CPU: 1 PID: 1 Comm: init Tainted: G        W        N 6.9.0-rc1-koelsch-00004-g7af5b901e847 #1930
>      Hardware name: Generic R-Car Gen2 (Flattened Device Tree)
>      Call trace:
>       unwind_backtrace from show_stack+0x10/0x14
>       show_stack from dump_stack_lvl+0x78/0xa8
>       dump_stack_lvl from panic+0x118/0x398
>       panic from do_exit+0x1ec/0x938
>       do_exit from sys_exit_group+0x0/0x10
>      ---[ end Kernel panic - not syncing: Attempted to kill init!  exitcode=0x00000004 ]---
>
> Add the missing memory clobber to cpu_set_ttbcr(), as suggested by
> Russell King.
>
> Force inlining of uaccess_save_and_enable(), as suggested by Ard
> Biesheuvel.
>
> The latter fixes booting on Koelsch.
>
> Fixes: 7af5b901e84743c6 ("ARM: 9358/2: Implement PAN for LPAE by TTBR0 page table walks disablement")
> Closes: https://lore.kernel.org/r/CAMuHMdWTAJcZ9BReWNhpmsgkOzQxLNb5OhNYxzxv6D5TSh2fwQ@xxxxxxxxxxxxxx/
> Signed-off-by: Geert Uytterhoeven <geert+renesas@xxxxxxxxx>

Tested-by: Florian Fainelli <florian.fainelli@xxxxxxxxxxxx>
--
Florian

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