[aarch64-port-dev ] RFR(xs): Aarch64: ReservedStackAccess may leave stack guard in inconsistent state

[Andrew Haley]

On 12/19/18 2:08 PM, Andrey Petushkov wrote:
> Hi All,
> 
> Please review small fix for for the following problem: during execution of
> ReservedStackAccess annotated method it might happen that reserved pages
> are reguarded while yellow pages left unguarded. At the same time the state
> of stack guard is recorded as fully protected (stack_guard_enabled).
> Subsequent execution of ReservedStackAccess annotated method then may lead
> to VM crash instead of mere StackOverflowError.
> Reproduced with ReservedStackTestCompiler jtreg test on aarch32-jdk11 port
> codebase. The bug seem to be apparent and exists in aarch64-port as well,
> hence the review request.
> The actual fix is in aarch64-specific code but the shared code is changed
> as well to help to catch such bugs earlier in the future
> 
> the link http://cr.openjdk.java.net/~apetushkov/ReservedStackAccess/

Looks good. I note that this makes the AArch64 logic the same as x86. I've
diffed the relevant section and we're good now.

What seems to have happened is that the change to os_linux_x86 in the
commit for 8046936: JEP 270: Reserved Stack Areas for Critical Sections
was not completely ported to AArch64.

Thanks.

-- 
Andrew Haley
Java Platform Lead Engineer
Red Hat UK Ltd. <https://www.redhat.com>
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