Re: [Xen-devel] [PATCH v4 10/11] livepatch/arm[32, 64]: Modify .livepatch.funcs section to be RW when patching

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 21.09.17 at 00:31, <konrad@xxxxxxxxxx> wrote:
> @@ -43,7 +46,29 @@ int arch_livepatch_quiesce(void)
>          return -ENOMEM;
>      }
>  
> -    return 0;
> +    if ( nfuncs )
> +    {
> +        unsigned long va = (unsigned long)func;
> +        unsigned int offs = va & (PAGE_SIZE - 1);
> +        unsigned int pages = PFN_UP(offs + nfuncs * sizeof(*func));
> +
> +        va &= PAGE_MASK;
> +
> +        rc = modify_xen_mappings(va, va + (pages * PAGE_SIZE), PTE_NX);
> +        if ( rc )
> +        {
> +            printk(XENLOG_ERR LIVEPATCH "Failed to modify 0x%lx to RW\n", 
> va);

%#lx ?

> +            vunmap(vmap_of_xen_text);
> +            vmap_of_xen_text = NULL;
> +        }
> +        else
> +        {
> +            livepatch_stash.va = va;
> +            livepatch_stash.pages = pages;
> +        }
> +    }

You're effectively doing all this behind the back of vmalloc() / vmap();
I'm not sure this is a good idea, but I'm also not a maintainer of this
code.

Jan


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