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Revert "livepatch: Remove reliable stacktrace check in klp_try_switch_task()"

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This reverts commit 1d98a69e5c. Commit
31adf2308f ("livepatch: Convert error about unsupported reliable
stacktrace into a warning") weakened the enforcement for architectures
to have reliable stack traces support. The system only warns now about
it.

It only makes sense to reintroduce the compile time checking in
klp_try_switch_task() again and bail out early.

Signed-off-by: Miroslav Benes <mbenes@suse.cz>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Reviewed-by: Kamalesh Babulal <kamalesh@linux.vnet.ibm.com>
Signed-off-by: Petr Mladek <pmladek@suse.com>
This commit is contained in:
Miroslav Benes 2019-06-11 16:13:19 +02:00 committed by Petr Mladek
parent 380178ef7f
commit 67059d65f7
1 changed files with 7 additions and 0 deletions
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7
kernel/livepatch/transition.c
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@ -305,6 +305,13 @@ static bool klp_try_switch_task(struct task_struct *task)
if (task->patch_state == klp_target_state)
return true;
/*
* For arches which don't have reliable stack traces, we have to rely
* on other methods (e.g., switching tasks at kernel exit).
*/
if (!klp_have_reliable_stack())
return false;
/*
* Now try to check the stack for any to-be-patched or to-be-unpatched
* functions. If all goes well, switch the task to the target patch