From: Luis Machado <luis.machado@arm.com>
To: John Baldwin <jhb@FreeBSD.org>, gdb-patches@sourceware.org
Cc: thiago.bauermann@linaro.org
Subject: Re: [PATCH] [AArch64] Enable pointer authentication support for aarch64 bare metal/kernel mode addresses
Date: Thu, 19 Jan 2023 09:34:22 +0000 [thread overview]
Message-ID: <2fbe4596-17fa-1962-66ae-8b4b9f4edd22@arm.com> (raw)
In-Reply-To: <a83eaa2d-9494-9907-37f4-be7400af7a5b@FreeBSD.org>
Hi,
On 1/18/23 18:39, John Baldwin wrote:
> On 1/5/23 5:16 AM, Luis Machado wrote:
>> Hi John,
>>
>> Any thoughts on this patch from BSD's side?
>
> Sorry, I missed the cc earlier. FreeBSD does have support for the userland
> registers that I haven't yet added for userland PAC and this seems to make
> that easier as I will just need to add the registers to the tdesc when
> present/supported. However, one question I have is what does this do if the
> registers aren't available and kernel addresses are used? I have this use
> case for existing FreeBSD/aarch64 kernel debugging. The default version of
> the gdbarch hook seems to always assume TBI and strip the upper bits, but
> for kernel addresses what I kind of need is to sign-extend addresses based
> on bit 55. I do have a separate gdbarch for kernels vs userland programs
> so it might just be I need a custom version of this gdbarch hook for the kernel
> gdbarch?>
The default behavior in the absence of the PAC registers for the kernel addresses is to
assume TBI, remove the top bits and sign-extend based on bit 55.
This is done by aarch64_remove_top_bits.
I suppose that would work for you then.
next prev parent reply other threads:[~2023-01-19 9:34 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-12-16 10:57 Luis Machado
2022-12-20 3:20 ` Thiago Jung Bauermann
2022-12-20 9:17 ` Luis Machado
2023-01-05 13:16 ` Luis Machado
2023-01-18 18:39 ` John Baldwin
2023-01-19 9:34 ` Luis Machado [this message]
2023-01-19 18:35 ` John Baldwin
2023-02-21 9:11 ` Luis Machado
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