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From: Ard Biesheuvel <ardb@kernel.org>
To: Marc Zyngier <maz@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>,
	suzuki.poulose@arm.com, Catalin Marinas <catalin.marinas@arm.com>,
	James Morse <james.morse@arm.com>, Will Deacon <will@kernel.org>,
	Linux ARM <linux-arm-kernel@lists.infradead.org>
Subject: Re: [PATCH] arm64: set TEXT_OFFSET to 0x0 in preparation for removing it entirely
Date: Thu, 4 Jun 2020 17:41:45 +0200	[thread overview]
Message-ID: <CAMj1kXFS8Vvjfpb8HYzRvsaB0j7bs+2V4rXE8DzfNMJxsV3r0g@mail.gmail.com> (raw)
In-Reply-To: <fab4fb9e66fe48d82c9856a7d5839335@kernel.org>

On Thu, 4 Jun 2020 at 17:25, Marc Zyngier <maz@kernel.org> wrote:
>
> On 2020-06-04 16:01, Will Deacon wrote:
> > On Thu, Jun 04, 2020 at 03:41:41PM +0100, Marc Zyngier wrote:
> >> Hi all,
> >>
> >> On Tue, 28 Apr 2020 15:49:35 +0100
> >> Will Deacon <will@kernel.org> wrote:
> >>
> >> > On Wed, 15 Apr 2020 10:29:22 +0200, Ard Biesheuvel wrote:
> >> > > TEXT_OFFSET on arm64 is a historical artifact from the early days of
> >> > > the arm64 port where the boot protocol was basically 'copy this image
> >> > > to the base of memory + 512k', giving us 512 KB of guaranteed BSS space
> >> > > to put the swapper page tables. When the arm64 port was merged for
> >> > > v3.10, the Image header already carried the actual value of TEXT_OFFSET,
> >> > > to allow the bootloader to discover it dynamically rather than hardcode
> >> > > it to 512 KB.
> >> > >
> >> > > [...]
> >> >
> >> > Applied to arm64 (for-next/misc), thanks!
> >> >
> >> > [1/1] arm64: set TEXT_OFFSET to 0x0 in preparation for removing it entirely
> >> >       https://git.kernel.org/arm64/c/cfa7ede20f13
> >>
> >> This breaks a guest kernel booted with kvmtool (tested on my d05).
> >> Reverting it on top of 6929f71e46bd makes it work again. I haven't yet
> >> investigated what is happening here though.
> >
> > Weird, that's a combination I test, just not on d05. Are you using
> > defconfig? Can you share your full kvmtool invication please?
>
> Ah, good point. Not defconfig, but one that allows me to run the same
> kernel on my whole zoo[1]. As for the kvmtool invocation, it is pretty
> basic:
>
> lkvm run -m 512 -c 4 -p earlycon -k arch/arm64/boot/Image
>

OK, so my suspicions is that your config does not enable
CONFIG_RANDOMIZE_BASE, and that kvmtool ignores the text offset value
in the header altogether.

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  reply	other threads:[~2020-06-04 15:42 UTC|newest]

Thread overview: 17+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-04-15  8:29 [PATCH] arm64: set TEXT_OFFSET to 0x0 in preparation for removing it entirely Ard Biesheuvel
2020-04-15  8:39 ` Will Deacon
2020-04-15  8:48   ` Ard Biesheuvel
2020-04-15  9:15     ` Will Deacon
2020-04-28 13:41     ` Will Deacon
2020-04-28 14:49 ` Will Deacon
2020-06-04 14:41   ` Marc Zyngier
2020-06-04 15:01     ` Will Deacon
2020-06-04 15:25       ` Marc Zyngier
2020-06-04 15:41         ` Ard Biesheuvel [this message]
2020-06-04 15:48           ` Ard Biesheuvel
2020-06-04 16:07             ` Marc Zyngier
2020-06-09 12:35           ` Jonathan Marek
2020-06-09 12:37             ` Ard Biesheuvel
2020-06-09 12:52               ` Jonathan Marek
2020-06-10  8:57                 ` Mark Rutland
2020-06-10  9:25                   ` Ard Biesheuvel

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