[Tarantool-patches] [PATCH luajit] ARM64: Fix exit stub patching.

Kirill Yukhin kyukhin at tarantool.org
Thu Aug 19 10:33:32 MSK 2021


On 18 авг 22:51, Igor Munkin wrote:
> From: Mike Pall <mike>
> Contributed by Javier Guerra Giraldez.
> (cherry picked from commit 9da06535092d6d9dec442641a26c64bce5574322)
> When the side trace is assembled, it is linked to its parent trace. For
> this purpose, JIT runs through the parent trace mcode and updates jump
> instruction targeted to the corresponding exitno. Prior to this patch,
> these instructions were patched unconditionally, that leads to errors if
> the jump target address is out of the value ranges specified in ARM64
> references[1][2][3][4][5][6].
> As a result of the patch <lj_asm_patchexit> considers value ranges of
> the jump targets and updates directly only those instructions fitting
> the particular jump range. Moreover, the corresponding jump in the pad
> leading to <lj_vm_exit_handler> is also patched, so those instructions,
> that are not updated before, targets to the linked side trace too.
> Additionaly, there is some refactoring of jump targets assembling in
> scope of this patch.
> Igor Munkin:
> * added the description and the test for the problem
> [1]: https://developer.arm.com/documentation/dui0801/g/A64-General-Instructions/B
> [2]: https://developer.arm.com/documentation/dui0801/g/A64-General-Instructions/B-cond
> [3]: https://developer.arm.com/documentation/dui0801/g/A64-General-Instructions/CBZ
> [4]: https://developer.arm.com/documentation/dui0801/g/A64-General-Instructions/CBNZ
> [5]: https://developer.arm.com/documentation/dui0801/g/A64-General-Instructions/TBZ
> [6]: https://developer.arm.com/documentation/dui0801/g/A64-General-Instructions/TBNZ
> Resoves tarantool/tarantool#6098
> Part of tarantool/tarantool#5629


Regards, Kirill Yukhin

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