On 08/15/2016 04:10 PM, Jan Beulich wrote:
On 15.08.16 at 16:29, <konrad.w...@oracle.com> wrote:
On Mon, Aug 15, 2016 at 04:27:38AM -0600, Jan Beulich wrote:
On 14.08.16 at 23:52, <konrad.w...@oracle.com> wrote:
@@ -1034,6 +1047,9 @@ static int revert_payload(struct payload *data)
list_del_rcu(&data->applied_list);
unregister_virtual_region(&data->region);
+ /* And clear the BSS for subsequent operation. */
+ memset(data->bss, 0, data->bss_size);
Instead of doing it in two places, how about moving this into
apply_payload()?
I was thinking of it too, but then it occurred to me that between the
'check' -> 'apply' the BSS is left unitialized. And if we ever crash
(right as somebody scheduled the livepatch) one could form the opinion
that it is due to the .bss having garbage. Or more importantly - the
hooks may not have run, but all its values looked like they have been
initialized.
And spend considerable amount of time debugging something which in reality
is not a problem?
Perhaps put it in multiple places :-)
Well, you and Ross know. Afaic I'd always do things in just one
place if that's possible.
Yes, I'd also prefer it in just a single place.
However, assuming that there is only a single BSS section is wrong.
Especially when compiling with -fdata-sections (as livepatch-build-tools
does), a payload can have multiple BSS sections.
--
Ross Lagerwall
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