From: Christophe Leroy <christophe.leroy@csgroup.eu>
To: Jordan Niethe <jniethe5@gmail.com>, linuxppc-dev@lists.ozlabs.org
Cc: naveen.n.rao@linux.vnet.ibm.com
Subject: Re: [PATCH 3/3] powerpc/bpf: Reallocate BPF registers to volatile registers when possible on PPC64
Date: Tue, 22 Feb 2022 15:23:19 +0100 [thread overview]
Message-ID: <468b04e9-4fa6-883d-fb9a-96a1371c6d8d@csgroup.eu> (raw)
In-Reply-To: <20210727065539.299598-3-jniethe5@gmail.com>
Le 27/07/2021 à 08:55, Jordan Niethe a écrit :
> Implement commit 40272035e1d0 ("powerpc/bpf: Reallocate BPF registers to
> volatile registers when possible on PPC32") for PPC64.
>
> When the BPF routine doesn't call any function, the non volatile
> registers can be reallocated to volatile registers in order to avoid
> having to save them/restore on the stack. To keep track of which
> registers can be reallocated to make sure registers are set seen when
> used.
>
> Before this patch, the test #359 ADD default X is:
> 0: nop
> 4: nop
> 8: std r27,-40(r1)
> c: std r28,-32(r1)
> 10: xor r8,r8,r8
> 14: rotlwi r8,r8,0
> 18: xor r28,r28,r28
> 1c: rotlwi r28,r28,0
> 20: mr r27,r3
> 24: li r8,66
> 28: add r8,r8,r28
> 2c: rotlwi r8,r8,0
> 30: ld r27,-40(r1)
> 34: ld r28,-32(r1)
> 38: mr r3,r8
> 3c: blr
>
> After this patch, the same test has become:
> 0: nop
> 4: nop
> 8: xor r8,r8,r8
> c: rotlwi r8,r8,0
> 10: xor r5,r5,r5
> 14: rotlwi r5,r5,0
> 18: mr r4,r3
> 1c: li r8,66
> 20: add r8,r8,r5
> 24: rotlwi r8,r8,0
> 28: mr r3,r8
> 2c: blr
>
> Signed-off-by: Jordan Niethe <jniethe5@gmail.com>
If this series is still applicable, it needs to be rebased of Naveen's
series https://patchwork.ozlabs.org/project/linuxppc-dev/list/?series=286000
Christophe
next prev parent reply other threads:[~2022-02-22 14:23 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-07-27 6:55 [PATCH 1/3] powerpc64/bpf: Store temp registers' bpf to ppc mapping Jordan Niethe
2021-07-27 6:55 ` [PATCH 2/3] powerpc/bpf: Use helper for mapping bpf to ppc registers on PPC64 Jordan Niethe
2022-01-07 17:25 ` Naveen N. Rao
2021-07-27 6:55 ` [PATCH 3/3] powerpc/bpf: Reallocate BPF registers to volatile registers when possible " Jordan Niethe
2021-08-05 8:21 ` Christophe Leroy
2022-01-07 17:58 ` Naveen N. Rao
2022-02-22 14:23 ` Christophe Leroy [this message]
2022-03-02 16:40 ` Naveen N. Rao
2022-01-07 17:13 ` [PATCH 1/3] powerpc64/bpf: Store temp registers' bpf to ppc mapping Naveen N. Rao
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