From: Ard Biesheuvel <ardb@kernel.org>
To: Will Deacon <will@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>,
Catalin Marinas <catalin.marinas@arm.com>,
Jonathan Marek <jonathan@marek.ca>,
Linux ARM <linux-arm-kernel@lists.infradead.org>,
Marc Zyngier <maz@kernel.org>
Subject: Re: [PATCH v2] arm64: warn on incorrect placement of the kernel by the bootloader
Date: Sat, 13 Jun 2020 10:45:10 +0200 [thread overview]
Message-ID: <CAMj1kXENVduZAWOqkSE3ZvW=u=vyVjXBCe-1+i3h1oi1RjW_JA@mail.gmail.com> (raw)
In-Reply-To: <159188119408.197277.6500663041357704124.b4-ty@kernel.org>
On Thu, 11 Jun 2020 at 15:23, Will Deacon <will@kernel.org> wrote:
>
> On Thu, 11 Jun 2020 14:43:30 +0200, Ard Biesheuvel wrote:
> > Commit cfa7ede20f133c ("arm64: set TEXT_OFFSET to 0x0 in preparation for
> > removing it entirely") results in boot failures when booting kernels that
> > are built without KASLR support on broken bootloaders that ignore the
> > TEXT_OFFSET value passed via the header, and use the default of 0x80000
> > instead.
> >
> > To work around this, turn CONFIG_RELOCATABLE on by default, even if KASLR
> > itself (CONFIG_RANDOMIZE_BASE) is turned off, and require CONFIG_EXPERT
> > to be enabled to deviate from this. Then, emit a warning into the kernel
> > log if we are not booting via the EFI stub (which is permitted to deviate
> > from the placement restrictions) and the kernel base address is not placed
> > according to the rules as laid out in Documentation/arm64/booting.rst.
>
> Applied to arm64 (for-next/core), thanks!
>
> [1/1] arm64: warn on incorrect placement of the kernel by the bootloader
> https://git.kernel.org/arm64/c/dd4bc6076587
>
This test
((u64)_text % MIN_KIMG_ALIGN) != 0
should have been written as
((u64)_text % MIN_KIMG_ALIGN) != TEXT_OFFSET
because now, we are throwing the warning when
CONFIG_ARM64_RANDOMIZE_TEXT_OFFSET is enabled :-(
I was reluctant to add another Makefile rule to add a
-DTEXT_OFFSET=... GCC option when compiling this source file, but it
appears we need it after all.
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next prev parent reply other threads:[~2020-06-13 8:45 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-06-11 12:43 [PATCH v2] arm64: warn on incorrect placement of the kernel by the bootloader Ard Biesheuvel
2020-06-11 13:23 ` Will Deacon
2020-06-13 8:45 ` Ard Biesheuvel [this message]
2020-06-15 9:51 ` Will Deacon
2020-06-15 9:53 ` Ard Biesheuvel
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