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From: dthaler1968@googlemail.com
To: "'Yonghong Song'" <yonghong.song@linux.dev>
Cc: <bpf@ietf.org>, <bpf@vger.kernel.org>
Subject: Jump instructions clarification
Date: Tue, 23 Jan 2024 18:07:59 -0800	[thread overview]
Message-ID: <1fc001da4e6a$2848cad0$78da6070$@gmail.com> (raw)
In-Reply-To: <4dfb0d6a-aa48-4d96-82f0-09a960b1012f@linux.dev>

Hi Yonghong,

The MOVSX clarification is now merged, but I just found another similar question for you
regarding jump instructions.

For BPF_CALL (same question for src=0, src=1, and src=2),
are both BPF_JMP and BPF_JMP32 legal?  If so, is there a semantic difference?
If not, then again I think the doc needs clarification.

BPF_JA's use of imm already has a note that it's BPF_JMP32 class only,
but what about BPF_CALL's use of imm?

Similarly about comparisons like BPF_JEQ etc when BPF_K is set. 
E.g., is BPF_JEQ | BPF_K | BPF_JMP permitted?  The document currently
has no restriction against it, but if it's permitted, the meaning is not explained.

Dave



WARNING: multiple messages have this Message-ID (diff)
From: dthaler1968=40googlemail.com@dmarc.ietf.org
To: "'Yonghong Song'" <yonghong.song@linux.dev>
Cc: <bpf@ietf.org>, <bpf@vger.kernel.org>
Subject: [Bpf] Jump instructions clarification
Date: Tue, 23 Jan 2024 18:07:59 -0800	[thread overview]
Message-ID: <1fc001da4e6a$2848cad0$78da6070$@gmail.com> (raw)
Message-ID: <20240124020759.2GHD93ugcoyV_-przLGRZ_RAsY2T61O4JhiJa2VgR3E@z> (raw)
In-Reply-To: <4dfb0d6a-aa48-4d96-82f0-09a960b1012f@linux.dev>

Hi Yonghong,

The MOVSX clarification is now merged, but I just found another similar question for you
regarding jump instructions.

For BPF_CALL (same question for src=0, src=1, and src=2),
are both BPF_JMP and BPF_JMP32 legal?  If so, is there a semantic difference?
If not, then again I think the doc needs clarification.

BPF_JA's use of imm already has a note that it's BPF_JMP32 class only,
but what about BPF_CALL's use of imm?

Similarly about comparisons like BPF_JEQ etc when BPF_K is set. 
E.g., is BPF_JEQ | BPF_K | BPF_JMP permitted?  The document currently
has no restriction against it, but if it's permitted, the meaning is not explained.

Dave


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Bpf@ietf.org
https://www.ietf.org/mailman/listinfo/bpf

  parent reply	other threads:[~2024-01-24  2:08 UTC|newest]

Thread overview: 23+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2024-01-16 20:38 [Bpf] Sign extension ISA question dthaler1968=40googlemail.com
2024-01-16 20:55 ` dthaler1968
2024-01-16 20:55   ` [Bpf] " dthaler1968=40googlemail.com
2024-01-16 22:34   ` Yonghong Song
2024-01-16 22:34     ` [Bpf] " Yonghong Song
2024-01-17  1:56     ` dthaler1968
2024-01-17  1:56       ` [Bpf] " dthaler1968=40googlemail.com
2024-01-17  3:48       ` Yonghong Song
2024-01-17  3:48         ` [Bpf] " Yonghong Song
2024-01-24  2:07         ` dthaler1968 [this message]
2024-01-24  2:07           ` [Bpf] Jump instructions clarification dthaler1968=40googlemail.com
2024-01-24 19:33           ` Yonghong Song
2024-01-24 19:33             ` [Bpf] " Yonghong Song
2024-01-26  1:12             ` 64-bit immediate " dthaler1968
2024-01-26  1:12               ` [Bpf] " dthaler1968=40googlemail.com
2024-01-26  5:34               ` Yonghong Song
2024-01-26  5:34                 ` [Bpf] " Yonghong Song
2024-01-26 22:27                 ` dthaler1968
2024-01-26 22:27                   ` [Bpf] " dthaler1968=40googlemail.com
2024-01-27  3:41                   ` Yonghong Song
2024-01-27  3:41                     ` [Bpf] " Yonghong Song
2024-01-27  6:56                     ` dthaler1968
2024-01-27  6:56                       ` [Bpf] " dthaler1968=40googlemail.com

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