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Re: [PATCH] x86/pv: Rework TRY_LOAD_SEG() to use asm goto()
- To: Nicola Vetrini <nicola.vetrini@xxxxxxxxxxx>
- From: Jan Beulich <jbeulich@xxxxxxxx>
- Date: Mon, 21 Jul 2025 11:25:22 +0200
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- Cc: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>, Roger Pau Monné <roger.pau@xxxxxxxxxx>, Xen-devel <xen-devel@xxxxxxxxxxxxxxxxxxxx>
- Delivery-date: Mon, 21 Jul 2025 09:25:37 +0000
- List-id: Xen developer discussion <xen-devel.lists.xenproject.org>
On 21.07.2025 10:16, Nicola Vetrini wrote:
> On 2025-07-21 08:41, Jan Beulich wrote:
>> On 18.07.2025 22:25, Andrew Cooper wrote:
>>> This moves the exception path to being out-of-line within the
>>> function, rather
>>> than in the .fixup section, which improves backtraces.
>>>
>>> Because the macro is used multiple times, the fault label needs
>>> declaring as
>>> local.
>>>
>>> No functional change.
>>>
>>> Signed-off-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
>>> ---
>>> CC: Jan Beulich <JBeulich@xxxxxxxx>
>>> CC: Roger Pau Monné <roger.pau@xxxxxxxxxx>
>>>
>>> Slightly RFC. I haven't checked if Eclair will be happy with
>>> __label__ yet.
>>
>> Even if it is, I guess you'd need to update the list of extensions we
>> use (docs/misra/C-language-toolchain.rst)?
>
> Only for using the __label__ token in
> automation/eclair_analysis/ECLAIR/toolchain.ecl. The extension itself is
> already documented in 5590c7e6590d ("eclair: allow and document use of
> GCC extension for label addresses")
Except that it's not the address taking that is the point in question here.
We have meanwhile gained a number of asm-goto (and for the uses there I'm
not even sure they count as "address taking"). It's really the __label__
extended keyword (and the thus possible declaration of a scope-restricted
label) that my remark was about. But yes, toolchain.ecl looks to need a
change, too.
Jan
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