[PATCH] Invalid value passed to critical JNI function (System V AMD64)

[David Holmes]

Thanks Ioannis.

I have filed:

https://bugs.openjdk.java.net/browse/JDK-8167409

David

On 10/10/2016 10:36 AM, Ioannis Tsakpinis wrote:
> This patch fixes invalid values passed to critical JNI functions on the
> System V AMD64 ABI (tested on Linux and MacOS).
>
> Specifically, this bug occurs when the arguments of a JNI method with 6 or
> more parameters are shuffled to match the critical native function order.
> The ABI provides 6 registers for passing arguments, so a temporary register
> must be used to break the shuffling cycle (handled in ComputeMoveOrder). If
> the temp register happens to be used for a 64bit argument, the target
> register will receive an invalid value.
>
> The fix is to call set2 when initializing the temp register to rbx. This
> marks the VMRegPair as a single physical register, which is important when
> copying 64bit values.
>
> diff -r fec31089c2ef src/cpu/x86/vm/sharedRuntime_x86_64.cpp
> --- a/src/cpu/x86/vm/sharedRuntime_x86_64.cpp   Thu Oct 06 18:05:53 2016 -0700
> +++ b/src/cpu/x86/vm/sharedRuntime_x86_64.cpp   Sun Oct 09 22:44:54 2016 +0300
> @@ -2178,7 +2178,7 @@
>    // critical natives they are offset down.
>    GrowableArray<int> arg_order(2 * total_in_args);
>    VMRegPair tmp_vmreg;
> -  tmp_vmreg.set1(rbx->as_VMReg());
> +  tmp_vmreg.set2(rbx->as_VMReg());
>
>    if (!is_critical_native) {
>      for (int i = total_in_args - 1, c_arg = total_c_args - 1; i >= 0;
> i--, c_arg--) {
>
> The shuffling implementation on AArch64 is similar and the same fix may be
> required there, but I have not tested it.
>
> Regards,
> Ioannis
>