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

From: "Russell King (Oracle)" <linux@armlinux.org.uk>
To: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Florian Fainelli <f.fainelli@gmail.com>,
	Linus Walleij <linus.walleij@linaro.org>,
	Ard Biesheuvel <ardb@kernel.org>, Arnd Bergmann <arnd@arndb.de>,
	Stefan Wahren <wahrenst@gmx.net>,
	Kees Cook <keescook@chromium.org>,
	linux-arm-kernel@lists.infradead.org,
	Catalin Marinas <catalin.marinas@arm.com>
Subject: Re: [PATCH v3 4/4] ARM: Implement PAN for LPAE by TTBR0 page table walks disablement
Date: Tue, 14 May 2024 12:33:42 +0100	[thread overview]
Message-ID: <ZkNMFpQDdKv6ZroY@shell.armlinux.org.uk> (raw)
In-Reply-To: <CAMuHMdU+2gbv1RMdw9mVBmibQWg8XOjam3VsjMEqfT+8kuCGVQ@mail.gmail.com>

On Tue, May 14, 2024 at 01:22:36PM +0200, Geert Uytterhoeven wrote:
> Hi Russell,
> 
> On Tue, May 14, 2024 at 10:15 AM Russell King (Oracle)
> <linux@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.

-- 
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