/* * Copyright 2024, The Android Open Source Project * * Licensed under the Apache License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. * You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */ #ifndef ANDROID_APF_APF_H #define ANDROID_APF_APF_H /* A brief overview of APF: * * APF machine is composed of: * 1. A read-only program consisting of bytecodes as described below. * 2. Two 32-bit registers, called R0 and R1. * 3. Sixteen 32-bit temporary memory slots (cleared between packets). * 4. A read-only packet. * 5. An optional read-write transmit buffer. * The program is executed by the interpreter below and parses the packet * to determine if the application processor (AP) should be woken up to * handle the packet or if it can be dropped. The program may also choose * to allocate/transmit/deallocate the transmit buffer. * * APF bytecode description: * * The APF interpreter uses big-endian byte order for loads from the packet * and for storing immediates in instructions. * * Each instruction starts with a byte composed of: * Top 5 bits form "opcode" field, see *_OPCODE defines below. * Next 2 bits form "size field", which indicates the length of an immediate * value which follows the first byte. Values in this field: * 0 => immediate value is 0 and no bytes follow. * 1 => immediate value is 1 byte big. * 2 => immediate value is 2 bytes big. * 3 => immediate value is 4 bytes big. * Bottom bit forms "register" field, which (usually) indicates which register * this instruction operates on. * * There are four main categories of instructions: * Load instructions * These instructions load byte(s) of the packet into a register. * They load either 1, 2 or 4 bytes, as determined by the "opcode" field. * They load into the register specified by the "register" field. * The immediate value that follows the first byte of the instruction is * the byte offset from the beginning of the packet to load from. * There are "indexing" loads which add the value in R1 to the byte offset * to load from. The "opcode" field determines which loads are "indexing". * Arithmetic instructions * These instructions perform simple operations, like addition, on register * values. The result of these instructions is always written into R0. One * argument of the arithmetic operation is R0's value. The other argument * of the arithmetic operation is determined by the "register" field: * If the "register" field is 0 then the immediate value following * the first byte of the instruction is used as the other argument * to the arithmetic operation. * If the "register" field is 1 then R1's value is used as the other * argument to the arithmetic operation. * Conditional jump instructions * These instructions compare register R0's value with another value, and if * the comparison succeeds, jump (i.e. adjust the program counter). The * immediate value that follows the first byte of the instruction * represents the jump target offset, i.e. the value added to the program * counter if the comparison succeeds. The other value compared is * determined by the "register" field: * If the "register" field is 0 then another immediate value * follows the jump target offset. This immediate value is of the * same size as the jump target offset, and represents the value * to compare against. * If the "register" field is 1 then register R1's value is * compared against. * The type of comparison (e.g. equal to, greater than etc) is determined * by the "opcode" field. The comparison interprets both values being * compared as unsigned values. * Miscellaneous instructions * Instructions for: * - allocating/transmitting/deallocating transmit buffer * - building the transmit packet (copying bytes into it) * - read/writing data section * * Miscellaneous details: * * Pre-filled temporary memory slot values * When the APF program begins execution, six of the sixteen memory slots * are pre-filled by the interpreter with values that may be useful for * programs: * #0 to #7 are zero initialized. * Slot #8 is initialized with apf version (on APF >4). * Slot #9 this is slot #15 with greater resolution (1/16384ths of a second) * Slot #10 starts at zero, implicitly used as tx buffer output pointer. * Slot #11 contains the size (in bytes) of the APF program. * Slot #12 contains the total size of the APF program + data. * Slot #13 is filled with the IPv4 header length. This value is calculated * by loading the first byte of the IPv4 header and taking the * bottom 4 bits and multiplying their value by 4. This value is * set to zero if the first 4 bits after the link layer header are * not 4, indicating not IPv4. * Slot #14 is filled with size of the packet in bytes, including the * ethernet link-layer header. * Slot #15 is filled with the filter age in seconds. This is the number of * seconds since the host installed the program. This may * be used by filters that should have a particular lifetime. For * example, it can be used to rate-limit particular packets to one * every N seconds. * Special jump targets: * When an APF program executes a jump to the byte immediately after the last * byte of the progam (i.e., one byte past the end of the program), this * signals the program has completed and determined the packet should be * passed to the AP. * When an APF program executes a jump two bytes past the end of the program, * this signals the program has completed and determined the packet should * be dropped. * Jump if byte sequence doesn't match: * This is a special instruction to facilitate matching long sequences of * bytes in the packet. Initially it is encoded like a conditional jump * instruction with two exceptions: * The first byte of the instruction is always followed by two immediate * fields: The first immediate field is the jump target offset like other * conditional jump instructions. The second immediate field specifies the * number of bytes to compare. * These two immediate fields are followed by a sequence of bytes. These * bytes are compared with the bytes in the packet starting from the * position specified by the value of the register specified by the * "register" field of the instruction. */ // Number of temporary memory slots, see ldm/stm instructions. #define MEMORY_ITEMS 16 // Upon program execution, some temporary memory slots are prefilled: typedef union { struct { u32 pad[8]; // 0..7 u32 apf_version; // 8: Initialized with apf_version() u32 filter_age_16384ths; // 9: Age since filter installed in 1/16384 seconds. u32 tx_buf_offset; // 10: Offset in tx_buf where next byte will be written u32 program_size; // 11: Size of program (in bytes) u32 ram_len; // 12: Total size of program + data, ie. ram_len u32 ipv4_header_size; // 13: 4*([APF_FRAME_HEADER_SIZE]&15) u32 packet_size; // 14: Size of packet in bytes. u32 filter_age; // 15: Age since filter installed in seconds. } named; u32 slot[MEMORY_ITEMS]; } memory_type; /* ---------------------------------------------------------------------------------------------- */ // Standard opcodes. /* Unconditionally pass (if R=0) or drop (if R=1) packet and optionally increment counter. * An optional non-zero unsigned immediate value can be provided to encode the counter number. * The counter is located (-4 * counter number) bytes from the end of the data region. * It is a U32 big-endian value and is always incremented by 1. * This is more or less equivalent to: lddw R0, -4*N; add R0, 1; stdw R0, -4*N; {pass,drop} * e.g. "pass", "pass 1", "drop", "drop 1" */ #define PASSDROP_OPCODE 0 #define LDB_OPCODE 1 // Load 1 byte from immediate offset, e.g. "ldb R0, [5]" #define LDH_OPCODE 2 // Load 2 bytes from immediate offset, e.g. "ldh R0, [5]" #define LDW_OPCODE 3 // Load 4 bytes from immediate offset, e.g. "ldw R0, [5]" #define LDBX_OPCODE 4 // Load 1 byte from immediate offset plus register, e.g. "ldbx R0, [5+R0]" #define LDHX_OPCODE 5 // Load 2 bytes from immediate offset plus register, e.g. "ldhx R0, [5+R0]" #define LDWX_OPCODE 6 // Load 4 bytes from immediate offset plus register, e.g. "ldwx R0, [5+R0]" #define ADD_OPCODE 7 // Add, e.g. "add R0,5" #define MUL_OPCODE 8 // Multiply, e.g. "mul R0,5" #define DIV_OPCODE 9 // Divide, e.g. "div R0,5" #define AND_OPCODE 10 // And, e.g. "and R0,5" #define OR_OPCODE 11 // Or, e.g. "or R0,5" #define SH_OPCODE 12 // Left shift, e.g. "sh R0, 5" or "sh R0, -5" (shifts right) #define LI_OPCODE 13 // Load signed immediate, e.g. "li R0,5" #define JMP_OPCODE 14 // Unconditional jump, e.g. "jmp label" #define JEQ_OPCODE 15 // Compare equal and branch, e.g. "jeq R0,5,label" #define JNE_OPCODE 16 // Compare not equal and branch, e.g. "jne R0,5,label" #define JGT_OPCODE 17 // Compare greater than and branch, e.g. "jgt R0,5,label" #define JLT_OPCODE 18 // Compare less than and branch, e.g. "jlt R0,5,label" #define JSET_OPCODE 19 // Compare any bits set and branch, e.g. "jset R0,5,label" #define JBSMATCH_OPCODE 20 // Compare byte sequence [R=0 not] equal, e.g. "jbsne R0,2,label,0x1122" // NOTE: Only APFv6+ implements R=1 'jbseq' version and multi match // imm1 is jmp target, imm2 is (cnt - 1) * 2048 + compare_len, // which is followed by cnt * compare_len bytes to compare against. // Warning: do not specify the same byte sequence multiple times. #define EXT_OPCODE 21 // Immediate value is one of *_EXT_OPCODE #define LDDW_OPCODE 22 // Load 4 bytes from data address (register + signed imm): "lddw R0, [5+R1]" // LDDW/STDW in APFv6+ *mode* load/store from counter specified in imm. #define STDW_OPCODE 23 // Store 4 bytes to data address (register + signed imm): "stdw R0, [5+R1]" /* Write 1, 2 or 4 byte immediate to the output buffer and auto-increment the output buffer pointer. * Immediate length field specifies size of write. R must be 0. imm_len != 0. * e.g. "write 5" */ #define WRITE_OPCODE 24 /* Copy bytes from input packet/APF program/data region to output buffer and * auto-increment the output buffer pointer. * Register bit is used to specify the source of data copy. * R=0 means copy from packet. * R=1 means copy from APF program/data region. * The source offset is stored in imm1, copy length is stored in u8 imm2. * e.g. "pktcopy 0, 16" or "datacopy 0, 16" */ #define PKTDATACOPY_OPCODE 25 #define JNSET_OPCODE 26 // JSET with reverse condition (jump if no bits set) /* ---------------------------------------------------------------------------------------------- */ // Extended opcodes. // These all have an opcode of EXT_OPCODE and specify the actual opcode in the immediate field. #define LDM_EXT_OPCODE 0 // Load from temporary memory, e.g. "ldm R0,5" // Values 0-15 represent loading the different temporary memory slots. #define STM_EXT_OPCODE 16 // Store to temporary memory, e.g. "stm R0,5" // Values 16-31 represent storing to the different temporary memory slots. #define NOT_EXT_OPCODE 32 // Not, e.g. "not R0" #define NEG_EXT_OPCODE 33 // Negate, e.g. "neg R0" #define SWAP_EXT_OPCODE 34 // Swap, e.g. "swap R0,R1" #define MOV_EXT_OPCODE 35 // Move, e.g. "move R0,R1" /* Allocate writable output buffer. * R=0: register R0 specifies the length * R=1: length provided in u16 imm2 * e.g. "allocate R0" or "allocate 123" * On failure automatically executes 'pass 3' */ #define ALLOCATE_EXT_OPCODE 36 /* Transmit and deallocate the buffer (transmission can be delayed until the program * terminates). Length of buffer is the output buffer pointer (0 means discard). * R=1 iff udp style L4 checksum * u8 imm2 - ip header offset from start of buffer (255 for non-ip packets) * u8 imm3 - offset from start of buffer to store L4 checksum (255 for no L4 checksum) * u8 imm4 - offset from start of buffer to begin L4 checksum calculation (present iff imm3 != 255) * u16 imm5 - partial checksum value to include in L4 checksum (present iff imm3 != 255) * "e.g. transmit" */ #define TRANSMIT_EXT_OPCODE 37 /* Write 1, 2 or 4 byte value from register to the output buffer and auto-increment the * output buffer pointer. * e.g. "ewrite1 r0" or "ewrite2 r1" */ #define EWRITE1_EXT_OPCODE 38 #define EWRITE2_EXT_OPCODE 39 #define EWRITE4_EXT_OPCODE 40 /* Copy bytes from input packet/APF program/data region to output buffer and * auto-increment the output buffer pointer. * Register bit is used to specify the source of data copy. * R=0 means copy from packet. * R=1 means copy from APF program/data region. * The source offset is stored in R0, copy length is stored in u8 imm2 or R1. * e.g. "epktcopy r0, 16", "edatacopy r0, 16", "epktcopy r0, r1", "edatacopy r0, r1" */ #define EPKTDATACOPYIMM_EXT_OPCODE 41 #define EPKTDATACOPYR1_EXT_OPCODE 42 /* Jumps if the UDP payload content (starting at R0) does [not] match one * of the specified QNAMEs in question records, applying case insensitivity. * SAFE version PASSES corrupt packets, while the other one DROPS. * R=0/1 meaning 'does not match'/'matches' * R0: Offset to UDP payload content * imm1: Extended opcode * imm2: Jump label offset * imm3(u8): Question type (PTR/SRV/TXT/A/AAAA) * imm4(bytes): null terminated list of null terminated LV-encoded QNAMEs * e.g.: "jdnsqeq R0,label,0xc,\002aa\005local\0\0", "jdnsqne R0,label,0xc,\002aa\005local\0\0" */ #define JDNSQMATCH_EXT_OPCODE 43 #define JDNSQMATCHSAFE_EXT_OPCODE 45 /* Jumps if the UDP payload content (starting at R0) does [not] match one * of the specified NAMEs in answers/authority/additional records, applying * case insensitivity. * SAFE version PASSES corrupt packets, while the other one DROPS. * R=0/1 meaning 'does not match'/'matches' * R0: Offset to UDP payload content * imm1: Extended opcode * imm2: Jump label offset * imm3(bytes): null terminated list of null terminated LV-encoded NAMEs * e.g.: "jdnsaeq R0,label,0xc,\002aa\005local\0\0", "jdnsane R0,label,0xc,\002aa\005local\0\0" */ #define JDNSAMATCH_EXT_OPCODE 44 #define JDNSAMATCHSAFE_EXT_OPCODE 46 /* Jump if register is [not] one of the list of values * R bit - specifies the register (R0/R1) to test * imm1: Extended opcode * imm2: Jump label offset * imm3(u8): top 5 bits - number 'n' of following u8/be16/be32 values - 2 * middle 2 bits - 1..4 length of immediates - 1 * bottom 1 bit - =0 jmp if in set, =1 if not in set * imm4(n * 1/2/3/4 bytes): the *UNIQUE* values to compare against */ #define JONEOF_EXT_OPCODE 47 /* Specify length of exception buffer, which is populated on abnormal program termination. * imm1: Extended opcode * imm2(u16): Length of exception buffer (located *immediately* after the program itself) */ #define EXCEPTIONBUFFER_EXT_OPCODE 48 // This extended opcode is used to implement PKTDATACOPY_OPCODE #define PKTDATACOPYIMM_EXT_OPCODE 65536 #define EXTRACT_OPCODE(i) (((i) >> 3) & 31) #define EXTRACT_REGISTER(i) ((i) & 1) #define EXTRACT_IMM_LENGTH(i) (((i) >> 1) & 3) #endif // ANDROID_APF_APF_H