Re: [PATCH v2 23/24] x86/xen: Rework the xen_{cpu,irq,mmu}_ops[] arrays

Juergen Gross
2021-06-24T12:12:55Z

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On 24.06.21 11:41, Peter Zijlstra wrote:
> In order to allow objtool to make sense of all the various paravirt
> functions, it needs to either parse whole pv_ops[] tables, or observe
> individual assignments in the form:
>
> bf87: 48 c7 05 00 00 00 00 00 00 00 00 movq $0x0,0x0(%rip)
> bf92 <xen_init_spinlocks+0x5f>
> bf8a: R_X86_64_PC32 pv_ops+0x268
>
> As is, xen_cpu_ops[] is at offset +0 in pv_ops[] and could thus be
> parsed as a 'normal' pv_ops[] table, however xen_irq_ops[] and
> xen_mmu_ops[] are not.
>
> Worse, both the latter two are compiled into the individual assignment
> for by current GCC, but that's not something one can rely on.
>
> Therefore, convert all three into full pv_ops[] tables. This has the
> benefit of not needing to teach objtool about the offsets and
> resulting in more conservative code-gen.
>
> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>

First I was worried by the additional memory consumption, but as the
modified tables are all tagged to be __init I don't think this matters.

So:

Reviewed-by: Juergen Gross <jgross@suse.com>

Juergen

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