From: Linus Walleij <linus.walleij@linaro.org>
To: Florian Fainelli <f.fainelli@gmail.com>,
Abbott Liu <liuwenliang@huawei.com>,
Russell King <linux@armlinux.org.uk>,
Ard Biesheuvel <ardb@kernel.org>,
Andrey Ryabinin <aryabinin@virtuozzo.com>,
Mike Rapoport <rppt@linux.ibm.com>,
Will Deacon <will@kernel.org>
Cc: Dmitry Vyukov <dvyukov@google.com>,
kasan-dev <kasan-dev@googlegroups.com>,
Alexander Potapenko <glider@google.com>,
Arnd Bergmann <arnd@arndb.de>,
Linux ARM <linux-arm-kernel@lists.infradead.org>
Subject: Re: [PATCH 4/5 v10] ARM: Initialize the mapping of KASan shadow memory
Date: Mon, 29 Jun 2020 16:07:06 +0200 [thread overview]
Message-ID: <CACRpkdbuRCXvnaKvAcqQPCWBWmJYQ9orVhWNrOdhUVJUD2Zbbw@mail.gmail.com> (raw)
In-Reply-To: <20200615090247.5218-5-linus.walleij@linaro.org>
Asking for help here!
I have a problem with populating PTEs for the LPAE usecase using
Versatile Express Cortex A15 (TC1) in QEMU.
In this loop of the patch:
On Mon, Jun 15, 2020 at 11:05 AM Linus Walleij <linus.walleij@linaro.org> wrote:
> +static void __init kasan_pte_populate(pmd_t *pmdp, unsigned long addr,
> + unsigned long end, int node, bool early)
> +{
> + unsigned long next;
> + pte_t *ptep = pte_offset_kernel(pmdp, addr);
(...)
> + do {
> + next = pmd_addr_end(addr, end);
> + kasan_pte_populate(pmdp, addr, next, node, early);
> + } while (pmdp++, addr = next, addr != end && pmd_none(READ_ONCE(*pmdp)));
I first populate the PMD for 0x6ee00000 .. 0x6f000000
and this works fine, and the PTEs are all initialized.
pte_offset_kernel() returns something reasonable.
(0x815F5000).
Next the kernel processes the PMD for
0x6f000000 .. 0x6f200000 and now I run into trouble,
because pte_offset_kernel() suddenly returns a NULL
pointer 0x00000000.
Naturally dereferencing the pointer when checking
if (pte_none(*ptep)) hangs the machine since this
is in early init.
Does anyone have hints on why this happens, and why it
only happens on LPAE? non-LPAE on the Versatile Express
QEMU A15 works fine.
I'm debugging, but any hints are very welcome.
Yours,
Linus Walleij
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next prev parent reply other threads:[~2020-06-29 14:12 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-06-15 9:02 [PATCH 0/5 v10] KASan for Arm Linus Walleij
2020-06-15 9:02 ` [PATCH 1/5 v10] ARM: Disable KASan instrumentation for some code Linus Walleij
2020-06-15 9:02 ` [PATCH 2/5 v10] ARM: Replace string mem* functions for KASan Linus Walleij
2020-06-15 9:02 ` [PATCH 3/5 v10] ARM: Define the virtual space of KASan's shadow region Linus Walleij
2020-06-15 9:02 ` [PATCH 4/5 v10] ARM: Initialize the mapping of KASan shadow memory Linus Walleij
2020-06-15 14:33 ` Mike Rapoport
2020-06-30 13:22 ` Linus Walleij
2020-06-30 14:45 ` Mike Rapoport
2020-06-29 14:07 ` Linus Walleij [this message]
2020-06-29 14:37 ` Russell King - ARM Linux admin
2020-06-30 9:38 ` Linus Walleij
2020-06-15 9:02 ` [PATCH 5/5 v10] ARM: Enable KASan for ARM Linus Walleij
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