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[67.170.74.237]) by smtp.gmail.com with ESMTPSA id z11-20020a62d10b000000b006e4432027d1sm7856656pfg.142.2024.02.21.11.17.27 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 21 Feb 2024 11:17:28 -0800 (PST) From: Dave Thaler X-Google-Original-From: Dave Thaler To: bpf@vger.kernel.org Cc: bpf@ietf.org, Dave Thaler Subject: [PATCH bpf-next v4] bpf, docs: Add callx instructions in new conformance group Date: Wed, 21 Feb 2024 11:17:25 -0800 Message-Id: <20240221191725.17586-1-dthaler1968@gmail.com> X-Mailer: git-send-email 2.40.1 Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit * Add a "callx" conformance group * Add callx row to table * Update helper function to section to be agnostic between BPF_K vs BPF_X * Rename "legacy" conformance group to "packet" Based on mailing list discussion at https://mailarchive.ietf.org/arch/msg/bpf/l5tNEgL-Wo7qSEuaGssOl5VChKk/ Only src=0 is currently listed for callx. Neither clang nor gcc use src=1 or src=2, and both use exactly the same semantics for src=0 which was agreed between them (Yonghong and Jose). Since src=0 semantics are agreed upon by both and is already implemented, src=0 is documented as implemented. v1->v2: Incorporated feedback from Will Hawkins v2->v3: Use "dst" not "imm" field v3->v4: Only use src=0 Signed-off-by: Dave Thaler --- .../bpf/standardization/instruction-set.rst | 29 ++++++++++++------- 1 file changed, 18 insertions(+), 11 deletions(-) diff --git a/Documentation/bpf/standardization/instruction-set.rst b/Documentation/bpf/standardization/instruction-set.rst index bdfe0cd0e..a68445899 100644 --- a/Documentation/bpf/standardization/instruction-set.rst +++ b/Documentation/bpf/standardization/instruction-set.rst @@ -127,7 +127,7 @@ This document defines the following conformance groups: * divmul32: includes 32-bit division, multiplication, and modulo instructions. * divmul64: includes divmul32, plus 64-bit division, multiplication, and modulo instructions. -* legacy: deprecated packet access instructions. +* packet: deprecated packet access instructions. Instruction encoding ==================== @@ -404,9 +404,10 @@ BPF_JSET 0x4 any PC += offset if dst & src BPF_JNE 0x5 any PC += offset if dst != src BPF_JSGT 0x6 any PC += offset if dst > src signed BPF_JSGE 0x7 any PC += offset if dst >= src signed -BPF_CALL 0x8 0x0 call helper function by address BPF_JMP | BPF_K only, see `Helper functions`_ +BPF_CALL 0x8 0x0 call_by_address(imm) BPF_JMP | BPF_K only +BPF_CALL 0x8 0x0 call_by_address(dst) BPF_JMP | BPF_X only BPF_CALL 0x8 0x1 call PC += imm BPF_JMP | BPF_K only, see `Program-local functions`_ -BPF_CALL 0x8 0x2 call helper function by BTF ID BPF_JMP | BPF_K only, see `Helper functions`_ +BPF_CALL 0x8 0x2 call_by_btfid(imm) BPF_JMP | BPF_K only BPF_EXIT 0x9 0x0 return BPF_JMP | BPF_K only BPF_JLT 0xa any PC += offset if dst < src unsigned BPF_JLE 0xb any PC += offset if dst <= src unsigned @@ -414,6 +415,11 @@ BPF_JSLT 0xc any PC += offset if dst < src signed BPF_JSLE 0xd any PC += offset if dst <= src signed ======== ===== === =============================== ============================================= +where + +* call_by_address(value) means to call a helper function by the address specified by 'value' (see `Helper functions`_ for details) +* call_by_btfid(value) means to call a helper function by the BTF ID specified by 'value' (see `Helper functions`_ for details) + The BPF program needs to store the return value into register R0 before doing a ``BPF_EXIT``. @@ -438,8 +444,9 @@ specified by the 'imm' field. A > 16-bit conditional jump may be converted to a < 16-bit conditional jump plus a 32-bit unconditional jump. -All ``BPF_CALL`` and ``BPF_JA`` instructions belong to the -base32 conformance group. +The ``BPF_CALL | BPF_X`` instruction belongs to the callx +conformance group. All other ``BPF_CALL`` instructions and all +``BPF_JA`` instructions belong to the base32 conformance group. Helper functions ~~~~~~~~~~~~~~~~ @@ -447,13 +454,13 @@ Helper functions Helper functions are a concept whereby BPF programs can call into a set of function calls exposed by the underlying platform. -Historically, each helper function was identified by an address -encoded in the imm field. The available helper functions may differ -for each program type, but address values are unique across all program types. +Historically, each helper function was identified by an address. +The available helper functions may differ for each program type, +but address values are unique across all program types. Platforms that support the BPF Type Format (BTF) support identifying -a helper function by a BTF ID encoded in the imm field, where the BTF ID -identifies the helper name and type. +a helper function by a BTF ID, where the BTF ID identifies the helper +name and type. Program-local functions ~~~~~~~~~~~~~~~~~~~~~~~ @@ -660,4 +667,4 @@ carried over from classic BPF. These instructions used an instruction class of BPF_LD, a size modifier of BPF_W, BPF_H, or BPF_B, and a mode modifier of BPF_ABS or BPF_IND. However, these instructions are deprecated and should no longer be used. All legacy packet access -instructions belong to the "legacy" conformance group. +instructions belong to the "packet" conformance group. -- 2.40.1 From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail.ietf.org (mail.ietf.org [50.223.129.194]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id F21068592D for ; Wed, 21 Feb 2024 19:17:35 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=50.223.129.194 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1708543057; cv=none; b=j23lXSDh6tzEl+Hd6FURh7MQratU9aavjFv2Gi3aLMb0MiYPynqOjelT03DyLuCookUMmR6q0YTW6BCdvsc1dW6CfOcwL7BlLhImGVmaKhwQzQ86b8mcS/w9kjaVp0nGi7uGeoEA6ZMK4eGutvr2ZPr4YjOpbm1BhksWFJKfTus= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1708543057; c=relaxed/simple; bh=K3rKCjiBOXotqm9J/WUhgsaV9DP2FxPu+sJSJ3/vu0Y=; h=To:Cc:Date:Message-Id:MIME-Version:Subject:Content-Type:From; 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[67.170.74.237]) by smtp.gmail.com with ESMTPSA id z11-20020a62d10b000000b006e4432027d1sm7856656pfg.142.2024.02.21.11.17.27 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 21 Feb 2024 11:17:28 -0800 (PST) X-Google-Original-From: Dave Thaler To: bpf@vger.kernel.org Cc: bpf@ietf.org, Dave Thaler Date: Wed, 21 Feb 2024 11:17:25 -0800 Message-ID: <20240221191725.17586-1-dthaler1968@gmail.com> X-Mailer: git-send-email 2.40.1 Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Archived-At: Subject: [Bpf] [PATCH bpf-next v4] bpf, docs: Add callx instructions in new conformance group X-BeenThere: bpf@ietf.org X-Mailman-Version: 2.1.39 Precedence: list List-Archive: List-Post: List-Help: Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: bpf-bounces@ietf.org Sender: "Bpf" X-Original-From: Dave Thaler From: Dave Thaler Message-ID: <20240221191725.Q1ASTMm8MYQzv_a4MTomP_CEy2DAZXg2eAtyGEDeTN4@z> * Add a "callx" conformance group * Add callx row to table * Update helper function to section to be agnostic between BPF_K vs BPF_X * Rename "legacy" conformance group to "packet" Based on mailing list discussion at https://mailarchive.ietf.org/arch/msg/bpf/l5tNEgL-Wo7qSEuaGssOl5VChKk/ Only src=0 is currently listed for callx. Neither clang nor gcc use src=1 or src=2, and both use exactly the same semantics for src=0 which was agreed between them (Yonghong and Jose). Since src=0 semantics are agreed upon by both and is already implemented, src=0 is documented as implemented. v1->v2: Incorporated feedback from Will Hawkins v2->v3: Use "dst" not "imm" field v3->v4: Only use src=0 Signed-off-by: Dave Thaler --- .../bpf/standardization/instruction-set.rst | 29 ++++++++++++------- 1 file changed, 18 insertions(+), 11 deletions(-) diff --git a/Documentation/bpf/standardization/instruction-set.rst b/Documentation/bpf/standardization/instruction-set.rst index bdfe0cd0e..a68445899 100644 --- a/Documentation/bpf/standardization/instruction-set.rst +++ b/Documentation/bpf/standardization/instruction-set.rst @@ -127,7 +127,7 @@ This document defines the following conformance groups: * divmul32: includes 32-bit division, multiplication, and modulo instructions. * divmul64: includes divmul32, plus 64-bit division, multiplication, and modulo instructions. -* legacy: deprecated packet access instructions. +* packet: deprecated packet access instructions. Instruction encoding ==================== @@ -404,9 +404,10 @@ BPF_JSET 0x4 any PC += offset if dst & src BPF_JNE 0x5 any PC += offset if dst != src BPF_JSGT 0x6 any PC += offset if dst > src signed BPF_JSGE 0x7 any PC += offset if dst >= src signed -BPF_CALL 0x8 0x0 call helper function by address BPF_JMP | BPF_K only, see `Helper functions`_ +BPF_CALL 0x8 0x0 call_by_address(imm) BPF_JMP | BPF_K only +BPF_CALL 0x8 0x0 call_by_address(dst) BPF_JMP | BPF_X only BPF_CALL 0x8 0x1 call PC += imm BPF_JMP | BPF_K only, see `Program-local functions`_ -BPF_CALL 0x8 0x2 call helper function by BTF ID BPF_JMP | BPF_K only, see `Helper functions`_ +BPF_CALL 0x8 0x2 call_by_btfid(imm) BPF_JMP | BPF_K only BPF_EXIT 0x9 0x0 return BPF_JMP | BPF_K only BPF_JLT 0xa any PC += offset if dst < src unsigned BPF_JLE 0xb any PC += offset if dst <= src unsigned @@ -414,6 +415,11 @@ BPF_JSLT 0xc any PC += offset if dst < src signed BPF_JSLE 0xd any PC += offset if dst <= src signed ======== ===== === =============================== ============================================= +where + +* call_by_address(value) means to call a helper function by the address specified by 'value' (see `Helper functions`_ for details) +* call_by_btfid(value) means to call a helper function by the BTF ID specified by 'value' (see `Helper functions`_ for details) + The BPF program needs to store the return value into register R0 before doing a ``BPF_EXIT``. @@ -438,8 +444,9 @@ specified by the 'imm' field. A > 16-bit conditional jump may be converted to a < 16-bit conditional jump plus a 32-bit unconditional jump. -All ``BPF_CALL`` and ``BPF_JA`` instructions belong to the -base32 conformance group. +The ``BPF_CALL | BPF_X`` instruction belongs to the callx +conformance group. All other ``BPF_CALL`` instructions and all +``BPF_JA`` instructions belong to the base32 conformance group. Helper functions ~~~~~~~~~~~~~~~~ @@ -447,13 +454,13 @@ Helper functions Helper functions are a concept whereby BPF programs can call into a set of function calls exposed by the underlying platform. -Historically, each helper function was identified by an address -encoded in the imm field. The available helper functions may differ -for each program type, but address values are unique across all program types. +Historically, each helper function was identified by an address. +The available helper functions may differ for each program type, +but address values are unique across all program types. Platforms that support the BPF Type Format (BTF) support identifying -a helper function by a BTF ID encoded in the imm field, where the BTF ID -identifies the helper name and type. +a helper function by a BTF ID, where the BTF ID identifies the helper +name and type. Program-local functions ~~~~~~~~~~~~~~~~~~~~~~~ @@ -660,4 +667,4 @@ carried over from classic BPF. These instructions used an instruction class of BPF_LD, a size modifier of BPF_W, BPF_H, or BPF_B, and a mode modifier of BPF_ABS or BPF_IND. However, these instructions are deprecated and should no longer be used. All legacy packet access -instructions belong to the "legacy" conformance group. +instructions belong to the "packet" conformance group. -- 2.40.1 -- Bpf mailing list Bpf@ietf.org https://www.ietf.org/mailman/listinfo/bpf