[PATCH v3 4/4] ARM: Implement PAN for LPAE by TTBR0 page table walks disablement

[Linus Walleij]

Hi Geert,

On Tue, May 7, 2024 at 3:10 PM Geert Uytterhoeven <geert at linux-m68k.org> wrote:

> Thanks for your patch, which is now commit 7af5b901e84743c6 ("ARM:
> 9358/2: Implement PAN for LPAE by TTBR0 page table walks disablement")
> in arm/for-next (next-20240502 and later).
>
> On Koelsch (R-Car M2-W with dual Cortex A15) with LPAE enabled:
>
>     Run /sbin/init as init process
>       with arguments:
>         /sbin/init
>       with environment:
>         HOME=/
>         TERM=linux
>     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 ]---
>
> Disabling LPAE fixes the issue.

How annoying. I guess it doesn't help you that it works like a charm on
Versatile Express in QEMU, and also actually tested on the real
hardware. (Dual Cortex-A9).

So init is not executing, which userspace is this? I was  just testing
with busybox so far, maybe I need to test on something
bigger?

Do you have your ARMv7 file system available in an image or so
I can test it on Versatile Express?

Yours,
Linus Walleij