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

[Geert Uytterhoeven]

Hi Russell,

On Tue, May 14, 2024 at 1:33 PM Russell King (Oracle)
<linux at armlinux.org.uk> wrote:
> On Tue, May 14, 2024 at 01:22:36PM +0200, Geert Uytterhoeven wrote:
> > On Tue, May 14, 2024 at 10:15 AM Russell King (Oracle)
> > <linux at armlinux.org.uk> wrote:
> > > On Mon, May 13, 2024 at 08:56:20PM -0700, Florian Fainelli wrote:
> > > > [   11.299106] Freeing unused kernel image (initmem) memory: 79872K
> > > > [   11.305720] Run /init as init process
> > > > [   11.314070] Kernel panic - not syncing: Attempted to kill init!
> > > > exitcode=0x00000004
> > > > [   11.321888] CPU: 0 PID: 1 Comm: init Not tainted 6.9.0-next-20240513 #32
> > > > [   11.328709] Hardware name: BCM2711
> > > > [   11.332169] Call trace:
> > > > [   11.332179]  unwind_backtrace from show_stack+0x10/0x14
> > > > [   11.340087]  show_stack from panic+0x20c/0x55c
> > > > [   11.344615]  panic from do_exit+0x6b0/0x1e74
> > > > [   11.348972]  do_exit from do_group_exit+0xcc/0x280
> > > > [   11.353857]  do_group_exit from get_signal+0xfb4/0x1340
> > > > [   11.359182]  get_signal from do_work_pending+0x2c0/0x7bc
> > > > [   11.364590]  do_work_pending from slow_work_pending+0xc/0x24
> > > > [   11.370351] Exception stack(0xf082bfb0 to 0xf082bff8)
> > > > [   11.375492] bfa0:                                     b6bca568 00000000
> > > > 003fa0d6 aedf3d20
> > > > [   11.383811] bfc0: aedf4a28 b6bca6f8 b6bca73c b6bca710 b6bca748 b6bca6f8
> > > > aedf4a28 b6bca6f8
> > > > [   11.392127] bfe0: b6bca590 b6bca548 aeddae15 aedeb660 200f0030 ffffffff
> > > > [   11.398954] ---[ end Kernel panic - not syncing: Attempted to kill init!
> > > > exitcode=0x00000004 ]---
> > >
> > > You could enable CONFiG_DEBUG_USER, and then pass "user_debug=24" to
> > > the kernel to get a report for the conditions that lead to SEGV/BUS
> > > signals being delivered to a userspace processd.
> >
> > That does not seem to make any difference for me, i.e. no report?
>
> Then it's not a SEGV/BUS (iow page fault.) Please try user_debug=31
> in that case. Thanks.

Thanks, much better:

    init (1): undefined instruction: pc=b6f4feda
    CPU: 1 PID: 1 Comm: init Not tainted
6.9.0-shmobile-09158-g1218ffc3659e #1820
    Hardware name: Generic R-Car Gen2 (Flattened Device Tree)
    PC is at 0xb6f4feda
    LR is at 0xb6f4ed31
    pc : [<b6f4feda>]    lr : [<b6f4ed31>]    psr: 60000030
    sp : be970630  ip : be970678  fp : b6f67978
    r10: 00000000  r9 : 004d48ff  r8 : be970844
    r7 : be9707f8  r6 : b6f67978  r5 : be970850  r4 : be970844
    r3 : b6f669b0  r2 : 003fb0d6  r1 : 00000000  r0 : be970650
    Flags: nZCv  IRQs on  FIQs on  Mode USER_32  ISA Thumb  Segment user
    Control: 30c5387d  Table: 41f6cac0  DAC: 55555555
    Code: bad PC value

Gr{oetje,eeting}s,

                        Geert

-- 
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert at linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds