On Wed, May 15, 2024 at 4:02 PM Geert Uytterhoeven
<geert+renesas@xxxxxxxxx> 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>
Reviewed-by: Linus Walleij <linus.walleij@xxxxxxxxxx>
Thanks for digging into this, both you and Ard! And we found the root
cause it seems.
Yours,
Linus Walleij
