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

[Igor Munkin via Tarantool-patches <tarantool-patches@dev.tarantool.org>]

Kirill,

Thanks for your review!

On 19.08.21, Kirill Yukhin wrote:
> Hello,
> 
> 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
> 
> LGTM.

Added your tag:
| Reviewed-by: Kirill Yukhin <kyukhin@tarantool.org>

> 
> --
> Regards, Kirill Yukhin

-- 
Best regards,
IM