* bpf: jit: s390 64/32 bits for index in tail call
@ 2019-06-25 16:56 Yauheni Kaliuta
2019-07-03 9:22 ` Ilya Leoshkevich
0 siblings, 1 reply; 2+ messages in thread
From: Yauheni Kaliuta @ 2019-06-25 16:56 UTC (permalink / raw)
To: Michael Holzheu; +Cc: bpf, Jiri Olsa
Hi!
I have a question about 6651ee070b3124fe9b9db383e3a895a0e4aded65
```
With this patch a tail call generates the following code on s390x:
if (index >= array->map.max_entries)
goto out
000003ff8001c7e4: e31030100016 llgf %r1,16(%r3)
000003ff8001c7ea: ec41001fa065 clgrj %r4,%r1,10,3ff8001c828
```
Do I understand corretly, that it uses 64 bit index value?
"runtime/jit: pass > 32bit index to tail_call"
test_verifier's test fails for me and I see, for example,
/* mov edx, edx */ in the x86 implementation
--
WBR,
Yauheni Kaliuta
^ permalink raw reply [flat|nested] 2+ messages in thread
* Re: bpf: jit: s390 64/32 bits for index in tail call
2019-06-25 16:56 bpf: jit: s390 64/32 bits for index in tail call Yauheni Kaliuta
@ 2019-07-03 9:22 ` Ilya Leoshkevich
0 siblings, 0 replies; 2+ messages in thread
From: Ilya Leoshkevich @ 2019-07-03 9:22 UTC (permalink / raw)
To: Yauheni Kaliuta; +Cc: Michael Holzheu, bpf, Jiri Olsa
> ```
> With this patch a tail call generates the following code on s390x:
>
> if (index >= array->map.max_entries)
> goto out
> 000003ff8001c7e4: e31030100016 llgf %r1,16(%r3)
> 000003ff8001c7ea: ec41001fa065 clgrj %r4,%r1,10,3ff8001c828
> ```
>
> Do I understand corretly, that it uses 64 bit index value?
>
> "runtime/jit: pass > 32bit index to tail_call"
> test_verifier's test fails for me and I see, for example,
> /* mov edx, edx */ in the x86 implementation
Hi Yauheni,
llgf zero-extends a 32-bit value and puts it into a register, so I would
expect index to be a 32-bit value here. This test passes for me:
#752/u runtime/jit: pass > 32bit index to tail_call OK
#752/p runtime/jit: pass > 32bit index to tail_call OK
Which machine are you using for testing? I tried that on z14 (3906).
Best regards,
Ilya
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