diff options
Diffstat (limited to 'arch/arc/net/bpf_jit_core.c')
| -rw-r--r-- | arch/arc/net/bpf_jit_core.c | 1425 |
1 files changed, 1425 insertions, 0 deletions
diff --git a/arch/arc/net/bpf_jit_core.c b/arch/arc/net/bpf_jit_core.c new file mode 100644 index 000000000000..6f6b4ffccf2c --- /dev/null +++ b/arch/arc/net/bpf_jit_core.c @@ -0,0 +1,1425 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * The back-end-agnostic part of Just-In-Time compiler for eBPF bytecode. + * + * Copyright (c) 2024 Synopsys Inc. + * Author: Shahab Vahedi <shahab@synopsys.com> + */ +#include <linux/bug.h> +#include "bpf_jit.h" + +/* + * Check for the return value. A pattern used often in this file. + * There must be a "ret" variable of type "int" in the scope. + */ +#define CHECK_RET(cmd) \ + do { \ + ret = (cmd); \ + if (ret < 0) \ + return ret; \ + } while (0) + +#ifdef ARC_BPF_JIT_DEBUG +/* Dumps bytes in /var/log/messages at KERN_INFO level (4). */ +static void dump_bytes(const u8 *buf, u32 len, const char *header) +{ + u8 line[64]; + size_t i, j; + + pr_info("-----------------[ %s ]-----------------\n", header); + + for (i = 0, j = 0; i < len; i++) { + /* Last input byte? */ + if (i == len - 1) { + j += scnprintf(line + j, 64 - j, "0x%02x", buf[i]); + pr_info("%s\n", line); + break; + } + /* End of line? */ + else if (i % 8 == 7) { + j += scnprintf(line + j, 64 - j, "0x%02x", buf[i]); + pr_info("%s\n", line); + j = 0; + } else { + j += scnprintf(line + j, 64 - j, "0x%02x, ", buf[i]); + } + } +} +#endif /* ARC_BPF_JIT_DEBUG */ + +/********************* JIT context ***********************/ + +/* + * buf: Translated instructions end up here. + * len: The length of whole block in bytes. + * index: The offset at which the _next_ instruction may be put. + */ +struct jit_buffer { + u8 *buf; + u32 len; + u32 index; +}; + +/* + * This is a subset of "struct jit_context" that its information is deemed + * necessary for the next extra pass to come. + * + * bpf_header: Needed to finally lock the region. + * bpf2insn: Used to find the translation for instructions of interest. + * + * Things like "jit.buf" and "jit.len" can be retrieved respectively from + * "prog->bpf_func" and "prog->jited_len". + */ +struct arc_jit_data { + struct bpf_binary_header *bpf_header; + u32 *bpf2insn; +}; + +/* + * The JIT pertinent context that is used by different functions. + * + * prog: The current eBPF program being handled. + * orig_prog: The original eBPF program before any possible change. + * jit: The JIT buffer and its length. + * bpf_header: The JITed program header. "jit.buf" points inside it. + * emit: If set, opcodes are written to memory; else, a dry-run. + * do_zext: If true, 32-bit sub-regs must be zero extended. + * bpf2insn: Maps BPF insn indices to their counterparts in jit.buf. + * bpf2insn_valid: Indicates if "bpf2ins" is populated with the mappings. + * jit_data: A piece of memory to transfer data to the next pass. + * arc_regs_clobbered: Each bit status determines if that arc reg is clobbered. + * save_blink: Whether ARC's "blink" register needs to be saved. + * frame_size: Derived from "prog->aux->stack_depth". + * epilogue_offset: Used by early "return"s in the code to jump here. + * need_extra_pass: A forecast if an "extra_pass" will occur. + * is_extra_pass: Indicates if the current pass is an extra pass. + * user_bpf_prog: True, if VM opcodes come from a real program. + * blinded: True if "constant blinding" step returned a new "prog". + * success: Indicates if the whole JIT went OK. + */ +struct jit_context { + struct bpf_prog *prog; + struct bpf_prog *orig_prog; + struct jit_buffer jit; + struct bpf_binary_header *bpf_header; + bool emit; + bool do_zext; + u32 *bpf2insn; + bool bpf2insn_valid; + struct arc_jit_data *jit_data; + u32 arc_regs_clobbered; + bool save_blink; + u16 frame_size; + u32 epilogue_offset; + bool need_extra_pass; + bool is_extra_pass; + bool user_bpf_prog; + bool blinded; + bool success; +}; + +/* + * If we're in ARC_BPF_JIT_DEBUG mode and the debug level is right, dump the + * input BPF stream. "bpf_jit_dump()" is not fully suited for this purpose. + */ +static void vm_dump(const struct bpf_prog *prog) +{ +#ifdef ARC_BPF_JIT_DEBUG + if (bpf_jit_enable > 1) + dump_bytes((u8 *)prog->insns, 8 * prog->len, " VM "); +#endif +} + +/* + * If the right level of debug is set, dump the bytes. There are 2 variants + * of this function: + * + * 1. Use the standard bpf_jit_dump() which is meant only for JITed code. + * 2. Use the dump_bytes() to match its "vm_dump()" instance. + */ +static void jit_dump(const struct jit_context *ctx) +{ +#ifdef ARC_BPF_JIT_DEBUG + u8 header[8]; +#endif + const int pass = ctx->is_extra_pass ? 2 : 1; + + if (bpf_jit_enable <= 1 || !ctx->prog->jited) + return; + +#ifdef ARC_BPF_JIT_DEBUG + scnprintf(header, sizeof(header), "JIT:%d", pass); + dump_bytes(ctx->jit.buf, ctx->jit.len, header); + pr_info("\n"); +#else + bpf_jit_dump(ctx->prog->len, ctx->jit.len, pass, ctx->jit.buf); +#endif +} + +/* Initialise the context so there's no garbage. */ +static int jit_ctx_init(struct jit_context *ctx, struct bpf_prog *prog) +{ + memset(ctx, 0, sizeof(ctx)); + + ctx->orig_prog = prog; + + /* If constant blinding was requested but failed, scram. */ + ctx->prog = bpf_jit_blind_constants(prog); + if (IS_ERR(ctx->prog)) + return PTR_ERR(ctx->prog); + ctx->blinded = (ctx->prog == ctx->orig_prog ? false : true); + + /* If the verifier doesn't zero-extend, then we have to do it. */ + ctx->do_zext = !ctx->prog->aux->verifier_zext; + + ctx->is_extra_pass = ctx->prog->jited; + ctx->user_bpf_prog = ctx->prog->is_func; + + return 0; +} + +/* + * Only after the first iteration of normal pass (the dry-run), + * there are valid offsets in ctx->bpf2insn array. + */ +static inline bool offsets_available(const struct jit_context *ctx) +{ + return ctx->bpf2insn_valid; +} + +/* + * "*mem" should be freed when there is no "extra pass" to come, + * or the compilation terminated abruptly. A few of such memory + * allocations are: ctx->jit_data and ctx->bpf2insn. + */ +static inline void maybe_free(struct jit_context *ctx, void **mem) +{ + if (*mem) { + if (!ctx->success || !ctx->need_extra_pass) { + kfree(*mem); + *mem = NULL; + } + } +} + +/* + * Free memories based on the status of the context. + * + * A note about "bpf_header": On successful runs, "bpf_header" is + * not freed, because "jit.buf", a sub-array of it, is returned as + * the "bpf_func". However, "bpf_header" is lost and nothing points + * to it. This should not cause a leakage, because apparently + * "bpf_header" can be revived by "bpf_jit_binary_hdr()". This is + * how "bpf_jit_free()" in "kernel/bpf/core.c" releases the memory. + */ +static void jit_ctx_cleanup(struct jit_context *ctx) +{ + if (ctx->blinded) { + /* if all went well, release the orig_prog. */ + if (ctx->success) + bpf_jit_prog_release_other(ctx->prog, ctx->orig_prog); + else + bpf_jit_prog_release_other(ctx->orig_prog, ctx->prog); + } + + maybe_free(ctx, (void **)&ctx->bpf2insn); + maybe_free(ctx, (void **)&ctx->jit_data); + + if (!ctx->bpf2insn) + ctx->bpf2insn_valid = false; + + /* Freeing "bpf_header" is enough. "jit.buf" is a sub-array of it. */ + if (!ctx->success && ctx->bpf_header) { + bpf_jit_binary_free(ctx->bpf_header); + ctx->bpf_header = NULL; + ctx->jit.buf = NULL; + ctx->jit.index = 0; + ctx->jit.len = 0; + } + + ctx->emit = false; + ctx->do_zext = false; +} + +/* + * Analyse the register usage and record the frame size. + * The register usage is determined by consulting the back-end. + */ +static void analyze_reg_usage(struct jit_context *ctx) +{ + size_t i; + u32 usage = 0; + const struct bpf_insn *insn = ctx->prog->insnsi; + + for (i = 0; i < ctx->prog->len; i++) { + u8 bpf_reg; + bool call; + + bpf_reg = insn[i].dst_reg; + call = (insn[i].code == (BPF_JMP | BPF_CALL)) ? true : false; + usage |= mask_for_used_regs(bpf_reg, call); + } + + ctx->arc_regs_clobbered = usage; + ctx->frame_size = ctx->prog->aux->stack_depth; +} + +/* Verify that no instruction will be emitted when there is no buffer. */ +static inline int jit_buffer_check(const struct jit_context *ctx) +{ + if (ctx->emit) { + if (!ctx->jit.buf) { + pr_err("bpf-jit: inconsistence state; no " + "buffer to emit instructions.\n"); + return -EINVAL; + } else if (ctx->jit.index > ctx->jit.len) { + pr_err("bpf-jit: estimated JIT length is less " + "than the emitted instructions.\n"); + return -EFAULT; + } + } + return 0; +} + +/* On a dry-run (emit=false), "jit.len" is growing gradually. */ +static inline void jit_buffer_update(struct jit_context *ctx, u32 n) +{ + if (!ctx->emit) + ctx->jit.len += n; + else + ctx->jit.index += n; +} + +/* Based on "emit", determine the address where instructions are emitted. */ +static inline u8 *effective_jit_buf(const struct jit_context *ctx) +{ + return ctx->emit ? (ctx->jit.buf + ctx->jit.index) : NULL; +} + +/* Prologue based on context variables set by "analyze_reg_usage()". */ +static int handle_prologue(struct jit_context *ctx) +{ + int ret; + u8 *buf = effective_jit_buf(ctx); + u32 len = 0; + + CHECK_RET(jit_buffer_check(ctx)); + + len = arc_prologue(buf, ctx->arc_regs_clobbered, ctx->frame_size); + jit_buffer_update(ctx, len); + + return 0; +} + +/* The counter part for "handle_prologue()". */ +static int handle_epilogue(struct jit_context *ctx) +{ + int ret; + u8 *buf = effective_jit_buf(ctx); + u32 len = 0; + + CHECK_RET(jit_buffer_check(ctx)); + + len = arc_epilogue(buf, ctx->arc_regs_clobbered, ctx->frame_size); + jit_buffer_update(ctx, len); + + return 0; +} + +/* Tell which number of the BPF instruction we are dealing with. */ +static inline s32 get_index_for_insn(const struct jit_context *ctx, + const struct bpf_insn *insn) +{ + return (insn - ctx->prog->insnsi); +} + +/* + * In most of the cases, the "offset" is read from "insn->off". However, + * if it is an unconditional BPF_JMP32, then it comes from "insn->imm". + * + * (Courtesy of "cpu=v4" support) + */ +static inline s32 get_offset(const struct bpf_insn *insn) +{ + if ((BPF_CLASS(insn->code) == BPF_JMP32) && + (BPF_OP(insn->code) == BPF_JA)) + return insn->imm; + else + return insn->off; +} + +/* + * Determine to which number of the BPF instruction we're jumping to. + * + * The "offset" is interpreted as the "number" of BPF instructions + * from the _next_ BPF instruction. e.g.: + * + * 4 means 4 instructions after the next insn + * 0 means 0 instructions after the next insn -> fallthrough. + * -1 means 1 instruction before the next insn -> jmp to current insn. + * + * Another way to look at this, "offset" is the number of instructions + * that exist between the current instruction and the target instruction. + * + * It is worth noting that a "mov r,i64", which is 16-byte long, is + * treated as two instructions long, therefore "offset" needn't be + * treated specially for those. Everything is uniform. + */ +static inline s32 get_target_index_for_insn(const struct jit_context *ctx, + const struct bpf_insn *insn) +{ + return (get_index_for_insn(ctx, insn) + 1) + get_offset(insn); +} + +/* Is there an immediate operand encoded in the "insn"? */ +static inline bool has_imm(const struct bpf_insn *insn) +{ + return BPF_SRC(insn->code) == BPF_K; +} + +/* Is the last BPF instruction? */ +static inline bool is_last_insn(const struct bpf_prog *prog, u32 idx) +{ + return idx == (prog->len - 1); +} + +/* + * Invocation of this function, conditionally signals the need for + * an extra pass. The conditions that must be met are: + * + * 1. The current pass itself shouldn't be an extra pass. + * 2. The stream of bytes being JITed must come from a user program. + */ +static inline void set_need_for_extra_pass(struct jit_context *ctx) +{ + if (!ctx->is_extra_pass) + ctx->need_extra_pass = ctx->user_bpf_prog; +} + +/* + * Check if the "size" is valid and then transfer the control to + * the back-end for the swap. + */ +static int handle_swap(u8 *buf, u8 rd, u8 size, u8 endian, + bool force, bool do_zext, u8 *len) +{ + /* Sanity check on the size. */ + switch (size) { + case 16: + case 32: + case 64: + break; + default: + pr_err("bpf-jit: invalid size for swap.\n"); + return -EINVAL; + } + + *len = gen_swap(buf, rd, size, endian, force, do_zext); + + return 0; +} + +/* Checks if the (instruction) index is in valid range. */ +static inline bool check_insn_idx_valid(const struct jit_context *ctx, + const s32 idx) +{ + return (idx >= 0 && idx < ctx->prog->len); +} + +/* + * Decouple the back-end from BPF by converting BPF conditions + * to internal enum. ARC_CC_* start from 0 and are used as index + * to an array. BPF_J* usage must end after this conversion. + */ +static int bpf_cond_to_arc(const u8 op, u8 *arc_cc) +{ + switch (op) { + case BPF_JA: + *arc_cc = ARC_CC_AL; + break; + case BPF_JEQ: + *arc_cc = ARC_CC_EQ; + break; + case BPF_JGT: + *arc_cc = ARC_CC_UGT; + break; + case BPF_JGE: + *arc_cc = ARC_CC_UGE; + break; + case BPF_JSET: + *arc_cc = ARC_CC_SET; + break; + case BPF_JNE: + *arc_cc = ARC_CC_NE; + break; + case BPF_JSGT: + *arc_cc = ARC_CC_SGT; + break; + case BPF_JSGE: + *arc_cc = ARC_CC_SGE; + break; + case BPF_JLT: + *arc_cc = ARC_CC_ULT; + break; + case BPF_JLE: + *arc_cc = ARC_CC_ULE; + break; + case BPF_JSLT: + *arc_cc = ARC_CC_SLT; + break; + case BPF_JSLE: + *arc_cc = ARC_CC_SLE; + break; + default: + pr_err("bpf-jit: can't handle condition 0x%02X\n", op); + return -EINVAL; + } + return 0; +} + +/* + * Check a few things for a supposedly "jump" instruction: + * + * 0. "insn" is a "jump" instruction, but not the "call/exit" variant. + * 1. The current "insn" index is in valid range. + * 2. The index of target instruction is in valid range. + */ +static int check_bpf_jump(const struct jit_context *ctx, + const struct bpf_insn *insn) +{ + const u8 class = BPF_CLASS(insn->code); + const u8 op = BPF_OP(insn->code); + + /* Must be a jmp(32) instruction that is not a "call/exit". */ + if ((class != BPF_JMP && class != BPF_JMP32) || + (op == BPF_CALL || op == BPF_EXIT)) { + pr_err("bpf-jit: not a jump instruction.\n"); + return -EINVAL; + } + + if (!check_insn_idx_valid(ctx, get_index_for_insn(ctx, insn))) { + pr_err("bpf-jit: the bpf jump insn is not in prog.\n"); + return -EINVAL; + } + + if (!check_insn_idx_valid(ctx, get_target_index_for_insn(ctx, insn))) { + pr_err("bpf-jit: bpf jump label is out of range.\n"); + return -EINVAL; + } + + return 0; +} + +/* + * Based on input "insn", consult "ctx->bpf2insn" to get the + * related index (offset) of the translation in JIT stream. + */ +static u32 get_curr_jit_off(const struct jit_context *ctx, + const struct bpf_insn *insn) +{ + const s32 idx = get_index_for_insn(ctx, insn); +#ifdef ARC_BPF_JIT_DEBUG + BUG_ON(!offsets_available(ctx) || !check_insn_idx_valid(ctx, idx)); +#endif + return ctx->bpf2insn[idx]; +} + +/* + * The input "insn" must be a jump instruction. + * + * Based on input "insn", consult "ctx->bpf2insn" to get the + * related JIT index (offset) of "target instruction" that + * "insn" would jump to. + */ +static u32 get_targ_jit_off(const struct jit_context *ctx, + const struct bpf_insn *insn) +{ + const s32 tidx = get_target_index_for_insn(ctx, insn); +#ifdef ARC_BPF_JIT_DEBUG + BUG_ON(!offsets_available(ctx) || !check_insn_idx_valid(ctx, tidx)); +#endif + return ctx->bpf2insn[tidx]; +} + +/* + * This function will return 0 for a feasible jump. + * + * Consult the back-end to check if it finds it feasible to emit + * the necessary instructions based on "cond" and the displacement + * between the "from_off" and the "to_off". + */ +static int feasible_jit_jump(u32 from_off, u32 to_off, u8 cond, bool j32) +{ + int ret = 0; + + if (j32) { + if (!check_jmp_32(from_off, to_off, cond)) + ret = -EFAULT; + } else { + if (!check_jmp_64(from_off, to_off, cond)) + ret = -EFAULT; + } + + if (ret != 0) + pr_err("bpf-jit: the JIT displacement is not OK.\n"); + + return ret; +} + +/* + * This jump handler performs the following steps: + * + * 1. Compute ARC's internal condition code from BPF's + * 2. Determine the bitness of the operation (32 vs. 64) + * 3. Sanity check on BPF stream + * 4. Sanity check on what is supposed to be JIT's displacement + * 5. And finally, emit the necessary instructions + * + * The last two steps are performed through the back-end. + * The value of steps 1 and 2 are necessary inputs for the back-end. + */ +static int handle_jumps(const struct jit_context *ctx, + const struct bpf_insn *insn, + u8 *len) +{ + u8 cond; + int ret = 0; + u8 *buf = effective_jit_buf(ctx); + const bool j32 = (BPF_CLASS(insn->code) == BPF_JMP32) ? true : false; + const u8 rd = insn->dst_reg; + u8 rs = insn->src_reg; + u32 curr_off = 0, targ_off = 0; + + *len = 0; + + /* Map the BPF condition to internal enum. */ + CHECK_RET(bpf_cond_to_arc(BPF_OP(insn->code), &cond)); + + /* Sanity check on the BPF byte stream. */ + CHECK_RET(check_bpf_jump(ctx, insn)); + + /* + * Move the immediate into a temporary register _now_ for 2 reasons: + * + * 1. "gen_jmp_{32,64}()" deal with operands in registers. + * + * 2. The "len" parameter will grow so that the current jit offset + * (curr_off) will have increased to a point where the necessary + * instructions can be inserted by "gen_jmp_{32,64}()". + */ + if (has_imm(insn) && cond != ARC_CC_AL) { + if (j32) { + *len += mov_r32_i32(BUF(buf, *len), JIT_REG_TMP, + insn->imm); + } else { + *len += mov_r64_i32(BUF(buf, *len), JIT_REG_TMP, + insn->imm); + } + rs = JIT_REG_TMP; + } + + /* If the offsets are known, check if the branch can occur. */ + if (offsets_available(ctx)) { + curr_off = get_curr_jit_off(ctx, insn) + *len; + targ_off = get_targ_jit_off(ctx, insn); + + /* Sanity check on the back-end side. */ + CHECK_RET(feasible_jit_jump(curr_off, targ_off, cond, j32)); + } + + if (j32) { + *len += gen_jmp_32(BUF(buf, *len), rd, rs, cond, + curr_off, targ_off); + } else { + *len += gen_jmp_64(BUF(buf, *len), rd, rs, cond, + curr_off, targ_off); + } + + return ret; +} + +/* Jump to translated epilogue address. */ +static int handle_jmp_epilogue(struct jit_context *ctx, + const struct bpf_insn *insn, u8 *len) +{ + u8 *buf = effective_jit_buf(ctx); + u32 curr_off = 0, epi_off = 0; + + /* Check the offset only if the data is available. */ + if (offsets_available(ctx)) { + curr_off = get_curr_jit_off(ctx, insn); + epi_off = ctx->epilogue_offset; + + if (!check_jmp_64(curr_off, epi_off, ARC_CC_AL)) { + pr_err("bpf-jit: epilogue offset is not valid.\n"); + return -EINVAL; + } + } + + /* Jump to "epilogue offset" (rd and rs don't matter). */ + *len = gen_jmp_64(buf, 0, 0, ARC_CC_AL, curr_off, epi_off); + + return 0; +} + +/* Try to get the resolved address and generate the instructions. */ +static int handle_call(struct jit_context *ctx, + const struct bpf_insn *insn, + u8 *len) +{ + int ret; + bool in_kernel_func, fixed = false; + u64 addr = 0; + u8 *buf = effective_jit_buf(ctx); + + ret = bpf_jit_get_func_addr(ctx->prog, insn, ctx->is_extra_pass, + &addr, &fixed); + if (ret < 0) { + pr_err("bpf-jit: can't get the address for call.\n"); + return ret; + } + in_kernel_func = (fixed ? true : false); + + /* No valuable address retrieved (yet). */ + if (!fixed && !addr) + set_need_for_extra_pass(ctx); + + *len = gen_func_call(buf, (ARC_ADDR)addr, in_kernel_func); + + if (insn->src_reg != BPF_PSEUDO_CALL) { + /* Assigning ABI's return reg to JIT's return reg. */ + *len += arc_to_bpf_return(BUF(buf, *len)); + } + + return 0; +} + +/* + * Try to generate instructions for loading a 64-bit immediate. + * These sort of instructions are usually associated with the 64-bit + * relocations: R_BPF_64_64. Therefore, signal the need for an extra + * pass if the circumstances are right. + */ +static int handle_ld_imm64(struct jit_context *ctx, + const struct bpf_insn *insn, + u8 *len) +{ + const s32 idx = get_index_for_insn(ctx, insn); + u8 *buf = effective_jit_buf(ctx); + + /* We're about to consume 2 VM instructions. */ + if (is_last_insn(ctx->prog, idx)) { + pr_err("bpf-jit: need more data for 64-bit immediate.\n"); + return -EINVAL; + } + + *len = mov_r64_i64(buf, insn->dst_reg, insn->imm, (insn + 1)->imm); + + if (bpf_pseudo_func(insn)) + set_need_for_extra_pass(ctx); + + return 0; +} + +/* + * Handles one eBPF instruction at a time. To make this function faster, + * it does not call "jit_buffer_check()". Else, it would call it for every + * instruction. As a result, it should not be invoked directly. Only + * "handle_body()", that has already executed the "check", may call this + * function. + * + * If the "ret" value is negative, something has went wrong. Else, + * it mostly holds the value 0 and rarely 1. Number 1 signals + * the loop in "handle_body()" to skip the next instruction, because + * it has been consumed as part of a 64-bit immediate value. + */ +static int handle_insn(struct jit_context *ctx, u32 idx) +{ + const struct bpf_insn *insn = &ctx->prog->insnsi[idx]; + const u8 code = insn->code; + const u8 dst = insn->dst_reg; + const u8 src = insn->src_reg; + const s16 off = insn->off; + const s32 imm = insn->imm; + u8 *buf = effective_jit_buf(ctx); + u8 len = 0; + int ret = 0; + + switch (code) { + /* dst += src (32-bit) */ + case BPF_ALU | BPF_ADD | BPF_X: + len = add_r32(buf, dst, src); + break; + /* dst += imm (32-bit) */ + case BPF_ALU | BPF_ADD | BPF_K: + len = add_r32_i32(buf, dst, imm); + break; + /* dst -= src (32-bit) */ + case BPF_ALU | BPF_SUB | BPF_X: + len = sub_r32(buf, dst, src); + break; + /* dst -= imm (32-bit) */ + case BPF_ALU | BPF_SUB | BPF_K: + len = sub_r32_i32(buf, dst, imm); + break; + /* dst = -dst (32-bit) */ + case BPF_ALU | BPF_NEG: + len = neg_r32(buf, dst); + break; + /* dst *= src (32-bit) */ + case BPF_ALU | BPF_MUL | BPF_X: + len = mul_r32(buf, dst, src); + break; + /* dst *= imm (32-bit) */ + case BPF_ALU | BPF_MUL | BPF_K: + len = mul_r32_i32(buf, dst, imm); + break; + /* dst /= src (32-bit) */ + case BPF_ALU | BPF_DIV | BPF_X: + len = div_r32(buf, dst, src, off == 1); + break; + /* dst /= imm (32-bit) */ + case BPF_ALU | BPF_DIV | BPF_K: + len = div_r32_i32(buf, dst, imm, off == 1); + break; + /* dst %= src (32-bit) */ + case BPF_ALU | BPF_MOD | BPF_X: + len = mod_r32(buf, dst, src, off == 1); + break; + /* dst %= imm (32-bit) */ + case BPF_ALU | BPF_MOD | BPF_K: + len = mod_r32_i32(buf, dst, imm, off == 1); + break; + /* dst &= src (32-bit) */ + case BPF_ALU | BPF_AND | BPF_X: + len = and_r32(buf, dst, src); + break; + /* dst &= imm (32-bit) */ + case BPF_ALU | BPF_AND | BPF_K: + len = and_r32_i32(buf, dst, imm); + break; + /* dst |= src (32-bit) */ + case BPF_ALU | BPF_OR | BPF_X: + len = or_r32(buf, dst, src); + break; + /* dst |= imm (32-bit) */ + case BPF_ALU | BPF_OR | BPF_K: + len = or_r32_i32(buf, dst, imm); + break; + /* dst ^= src (32-bit) */ + case BPF_ALU | BPF_XOR | BPF_X: + len = xor_r32(buf, dst, src); + break; + /* dst ^= imm (32-bit) */ + case BPF_ALU | BPF_XOR | BPF_K: + len = xor_r32_i32(buf, dst, imm); + break; + /* dst <<= src (32-bit) */ + case BPF_ALU | BPF_LSH | BPF_X: + len = lsh_r32(buf, dst, src); + break; + /* dst <<= imm (32-bit) */ + case BPF_ALU | BPF_LSH | BPF_K: + len = lsh_r32_i32(buf, dst, imm); + break; + /* dst >>= src (32-bit) [unsigned] */ + case BPF_ALU | BPF_RSH | BPF_X: + len = rsh_r32(buf, dst, src); + break; + /* dst >>= imm (32-bit) [unsigned] */ + case BPF_ALU | BPF_RSH | BPF_K: + len = rsh_r32_i32(buf, dst, imm); + break; + /* dst >>= src (32-bit) [signed] */ + case BPF_ALU | BPF_ARSH | BPF_X: + len = arsh_r32(buf, dst, src); + break; + /* dst >>= imm (32-bit) [signed] */ + case BPF_ALU | BPF_ARSH | BPF_K: + len = arsh_r32_i32(buf, dst, imm); + break; + /* dst = src (32-bit) */ + case BPF_ALU | BPF_MOV | BPF_X: + len = mov_r32(buf, dst, src, (u8)off); + break; + /* dst = imm32 (32-bit) */ + case BPF_ALU | BPF_MOV | BPF_K: + len = mov_r32_i32(buf, dst, imm); + break; + /* dst = swap(dst) */ + case BPF_ALU | BPF_END | BPF_FROM_LE: + case BPF_ALU | BPF_END | BPF_FROM_BE: + case BPF_ALU64 | BPF_END | BPF_FROM_LE: { + CHECK_RET(handle_swap(buf, dst, imm, BPF_SRC(code), + BPF_CLASS(code) == BPF_ALU64, + ctx->do_zext, &len)); + break; + } + /* dst += src (64-bit) */ + case BPF_ALU64 | BPF_ADD | BPF_X: + len = add_r64(buf, dst, src); + break; + /* dst += imm32 (64-bit) */ + case BPF_ALU64 | BPF_ADD | BPF_K: + len = add_r64_i32(buf, dst, imm); + break; + /* dst -= src (64-bit) */ + case BPF_ALU64 | BPF_SUB | BPF_X: + len = sub_r64(buf, dst, src); + break; + /* dst -= imm32 (64-bit) */ + case BPF_ALU64 | BPF_SUB | BPF_K: + len = sub_r64_i32(buf, dst, imm); + break; + /* dst = -dst (64-bit) */ + case BPF_ALU64 | BPF_NEG: + len = neg_r64(buf, dst); + break; + /* dst *= src (64-bit) */ + case BPF_ALU64 | BPF_MUL | BPF_X: + len = mul_r64(buf, dst, src); + break; + /* dst *= imm32 (64-bit) */ + case BPF_ALU64 | BPF_MUL | BPF_K: + len = mul_r64_i32(buf, dst, imm); + break; + /* dst &= src (64-bit) */ + case BPF_ALU64 | BPF_AND | BPF_X: + len = and_r64(buf, dst, src); + break; + /* dst &= imm32 (64-bit) */ + case BPF_ALU64 | BPF_AND | BPF_K: + len = and_r64_i32(buf, dst, imm); + break; + /* dst |= src (64-bit) */ + case BPF_ALU64 | BPF_OR | BPF_X: + len = or_r64(buf, dst, src); + break; + /* dst |= imm32 (64-bit) */ + case BPF_ALU64 | BPF_OR | BPF_K: + len = or_r64_i32(buf, dst, imm); + break; + /* dst ^= src (64-bit) */ + case BPF_ALU64 | BPF_XOR | BPF_X: + len = xor_r64(buf, dst, src); + break; + /* dst ^= imm32 (64-bit) */ + case BPF_ALU64 | BPF_XOR | BPF_K: + len = xor_r64_i32(buf, dst, imm); + break; + /* dst <<= src (64-bit) */ + case BPF_ALU64 | BPF_LSH | BPF_X: + len = lsh_r64(buf, dst, src); + break; + /* dst <<= imm32 (64-bit) */ + case BPF_ALU64 | BPF_LSH | BPF_K: + len = lsh_r64_i32(buf, dst, imm); + break; + /* dst >>= src (64-bit) [unsigned] */ + case BPF_ALU64 | BPF_RSH | BPF_X: + len = rsh_r64(buf, dst, src); + break; + /* dst >>= imm32 (64-bit) [unsigned] */ + case BPF_ALU64 | BPF_RSH | BPF_K: + len = rsh_r64_i32(buf, dst, imm); + break; + /* dst >>= src (64-bit) [signed] */ + case BPF_ALU64 | BPF_ARSH | BPF_X: + len = arsh_r64(buf, dst, src); + break; + /* dst >>= imm32 (64-bit) [signed] */ + case BPF_ALU64 | BPF_ARSH | BPF_K: + len = arsh_r64_i32(buf, dst, imm); + break; + /* dst = src (64-bit) */ + case BPF_ALU64 | BPF_MOV | BPF_X: + len = mov_r64(buf, dst, src, (u8)off); + break; + /* dst = imm32 (sign extend to 64-bit) */ + case BPF_ALU64 | BPF_MOV | BPF_K: + len = mov_r64_i32(buf, dst, imm); + break; + /* dst = imm64 */ + case BPF_LD | BPF_DW | BPF_IMM: + CHECK_RET(handle_ld_imm64(ctx, insn, &len)); + /* Tell the loop to skip the next instruction. */ + ret = 1; + break; + /* dst = *(size *)(src + off) */ + case BPF_LDX | BPF_MEM | BPF_W: + case BPF_LDX | BPF_MEM | BPF_H: + case BPF_LDX | BPF_MEM | BPF_B: + case BPF_LDX | BPF_MEM | BPF_DW: + len = load_r(buf, dst, src, off, BPF_SIZE(code), false); + break; + case BPF_LDX | BPF_MEMSX | BPF_W: + case BPF_LDX | BPF_MEMSX | BPF_H: + case BPF_LDX | BPF_MEMSX | BPF_B: + len = load_r(buf, dst, src, off, BPF_SIZE(code), true); + break; + /* *(size *)(dst + off) = src */ + case BPF_STX | BPF_MEM | BPF_W: + case BPF_STX | BPF_MEM | BPF_H: + case BPF_STX | BPF_MEM | BPF_B: + case BPF_STX | BPF_MEM | BPF_DW: + len = store_r(buf, src, dst, off, BPF_SIZE(code)); + break; + case BPF_ST | BPF_MEM | BPF_W: + case BPF_ST | BPF_MEM | BPF_H: + case BPF_ST | BPF_MEM | BPF_B: + case BPF_ST | BPF_MEM | BPF_DW: + len = store_i(buf, imm, dst, off, BPF_SIZE(code)); + break; + case BPF_JMP | BPF_JA: + case BPF_JMP | BPF_JEQ | BPF_X: + case BPF_JMP | BPF_JEQ | BPF_K: + case BPF_JMP | BPF_JNE | BPF_X: + case BPF_JMP | BPF_JNE | BPF_K: + case BPF_JMP | BPF_JSET | BPF_X: + case BPF_JMP | BPF_JSET | BPF_K: + case BPF_JMP | BPF_JGT | BPF_X: + case BPF_JMP | BPF_JGT | BPF_K: + case BPF_JMP | BPF_JGE | BPF_X: + case BPF_JMP | BPF_JGE | BPF_K: + case BPF_JMP | BPF_JSGT | BPF_X: + case BPF_JMP | BPF_JSGT | BPF_K: + case BPF_JMP | BPF_JSGE | BPF_X: + case BPF_JMP | BPF_JSGE | BPF_K: + case BPF_JMP | BPF_JLT | BPF_X: + case BPF_JMP | BPF_JLT | BPF_K: + case BPF_JMP | BPF_JLE | BPF_X: + case BPF_JMP | BPF_JLE | BPF_K: + case BPF_JMP | BPF_JSLT | BPF_X: + case BPF_JMP | BPF_JSLT | BPF_K: + case BPF_JMP | BPF_JSLE | BPF_X: + case BPF_JMP | BPF_JSLE | BPF_K: + case BPF_JMP32 | BPF_JA: + case BPF_JMP32 | BPF_JEQ | BPF_X: + case BPF_JMP32 | BPF_JEQ | BPF_K: + case BPF_JMP32 | BPF_JNE | BPF_X: + case BPF_JMP32 | BPF_JNE | BPF_K: + case BPF_JMP32 | BPF_JSET | BPF_X: + case BPF_JMP32 | BPF_JSET | BPF_K: + case BPF_JMP32 | BPF_JGT | BPF_X: + case BPF_JMP32 | BPF_JGT | BPF_K: + case BPF_JMP32 | BPF_JGE | BPF_X: + case BPF_JMP32 | BPF_JGE | BPF_K: + case BPF_JMP32 | BPF_JSGT | BPF_X: + case BPF_JMP32 | BPF_JSGT | BPF_K: + case BPF_JMP32 | BPF_JSGE | BPF_X: + case BPF_JMP32 | BPF_JSGE | BPF_K: + case BPF_JMP32 | BPF_JLT | BPF_X: + case BPF_JMP32 | BPF_JLT | BPF_K: + case BPF_JMP32 | BPF_JLE | BPF_X: + case BPF_JMP32 | BPF_JLE | BPF_K: + case BPF_JMP32 | BPF_JSLT | BPF_X: + case BPF_JMP32 | BPF_JSLT | BPF_K: + case BPF_JMP32 | BPF_JSLE | BPF_X: + case BPF_JMP32 | BPF_JSLE | BPF_K: + CHECK_RET(handle_jumps(ctx, insn, &len)); + break; + case BPF_JMP | BPF_CALL: + CHECK_RET(handle_call(ctx, insn, &len)); + break; + + case BPF_JMP | BPF_EXIT: + /* If this is the last instruction, epilogue will follow. */ + if (is_last_insn(ctx->prog, idx)) + break; + CHECK_RET(handle_jmp_epilogue(ctx, insn, &len)); + break; + default: + pr_err("bpf-jit: can't handle instruction code 0x%02X\n", code); + return -EOPNOTSUPP; + } + + if (BPF_CLASS(code) == BPF_ALU) { + /* + * Skip the "swap" instructions. Even 64-bit swaps are of type + * BPF_ALU (and not BPF_ALU64). Therefore, for the swaps, one + * has to look at the "size" of the operations rather than the + * ALU type. "gen_swap()" specifically takes care of that. + */ + if (BPF_OP(code) != BPF_END && ctx->do_zext) + len += zext(BUF(buf, len), dst); + } + + jit_buffer_update(ctx, len); + + return ret; +} + +static int handle_body(struct jit_context *ctx) +{ + int ret; + bool populate_bpf2insn = false; + const struct bpf_prog *prog = ctx->prog; + + CHECK_RET(jit_buffer_check(ctx)); + + /* + * Record the mapping for the instructions during the dry-run. + * Doing it this way allows us to have the mapping ready for + * the jump instructions during the real compilation phase. + */ + if (!ctx->emit) + populate_bpf2insn = true; + + for (u32 i = 0; i < prog->len; i++) { + /* During the dry-run, jit.len grows gradually per BPF insn. */ + if (populate_bpf2insn) + ctx->bpf2insn[i] = ctx->jit.len; + + CHECK_RET(handle_insn(ctx, i)); + if (ret > 0) { + /* "ret" is 1 if two (64-bit) chunks were consumed. */ + ctx->bpf2insn[i + 1] = ctx->bpf2insn[i]; + i++; + } + } + + /* If bpf2insn had to be populated, then it is done at this point. */ + if (populate_bpf2insn) + ctx->bpf2insn_valid = true; + + return 0; +} + +/* + * Initialize the memory with "unimp_s" which is the mnemonic for + * "unimplemented" instruction and always raises an exception. + * + * The instruction is 2 bytes. If "size" is odd, there is not much + * that can be done about the last byte in "area". Because, the + * CPU always fetches instructions in two bytes. Therefore, the + * byte beyond the last one is going to accompany it during a + * possible fetch. In the most likely case of a little endian + * system, that beyond-byte will become the major opcode and + * we have no control over its initialisation. + */ +static void fill_ill_insn(void *area, unsigned int size) +{ + const u16 unimp_s = 0x79e0; + + if (size & 1) { + *((u8 *)area + (size - 1)) = 0xff; + size -= 1; + } + + memset16(area, unimp_s, size >> 1); +} + +/* Piece of memory that can be allocated at the beginning of jit_prepare(). */ +static int jit_prepare_early_mem_alloc(struct jit_context *ctx) +{ + ctx->bpf2insn = kcalloc(ctx->prog->len, sizeof(ctx->jit.len), + GFP_KERNEL); + + if (!ctx->bpf2insn) { + pr_err("bpf-jit: could not allocate memory for " + "mapping of the instructions.\n"); + return -ENOMEM; + } + + return 0; +} + +/* + * Memory allocations that rely on parameters known at the end of + * jit_prepare(). + */ +static int jit_prepare_final_mem_alloc(struct jit_context *ctx) +{ + const size_t alignment = sizeof(u32); + + ctx->bpf_header = bpf_jit_binary_alloc(ctx->jit.len, &ctx->jit.buf, + alignment, fill_ill_insn); + if (!ctx->bpf_header) { + pr_err("bpf-jit: could not allocate memory for translation.\n"); + return -ENOMEM; + } + + if (ctx->need_extra_pass) { + ctx->jit_data = kzalloc(sizeof(*ctx->jit_data), GFP_KERNEL); + if (!ctx->jit_data) + return -ENOMEM; + } + + return 0; +} + +/* + * The first phase of the translation without actually emitting any + * instruction. It helps in getting a forecast on some aspects, such + * as the length of the whole program or where the epilogue starts. + * + * Whenever the necessary parameters are known, memories are allocated. + */ +static int jit_prepare(struct jit_context *ctx) +{ + int ret; + + /* Dry run. */ + ctx->emit = false; + + CHECK_RET(jit_prepare_early_mem_alloc(ctx)); + + /* Get the length of prologue section after some register analysis. */ + analyze_reg_usage(ctx); + CHECK_RET(handle_prologue(ctx)); + + CHECK_RET(handle_body(ctx)); + + /* Record at which offset epilogue begins. */ + ctx->epilogue_offset = ctx->jit.len; + + /* Process the epilogue section now. */ + CHECK_RET(handle_epilogue(ctx)); + + CHECK_RET(jit_prepare_final_mem_alloc(ctx)); + + return 0; +} + +/* + * All the "handle_*()" functions have been called before by the + * "jit_prepare()". If there was an error, we would know by now. + * Therefore, no extra error checking at this point, other than + * a sanity check at the end that expects the calculated length + * (jit.len) to be equal to the length of generated instructions + * (jit.index). + */ +static int jit_compile(struct jit_context *ctx) +{ + int ret; + + /* Let there be code. */ + ctx->emit = true; + + CHECK_RET(handle_prologue(ctx)); + + CHECK_RET(handle_body(ctx)); + + CHECK_RET(handle_epilogue(ctx)); + + if (ctx->jit.index != ctx->jit.len) { + pr_err("bpf-jit: divergence between the phases; " + "%u vs. %u (bytes).\n", + ctx->jit.len, ctx->jit.index); + return -EFAULT; + } + + return 0; +} + +/* + * Calling this function implies a successful JIT. A successful + * translation is signaled by setting the right parameters: + * + * prog->jited=1, prog->jited_len=..., prog->bpf_func=... + */ +static int jit_finalize(struct jit_context *ctx) +{ + struct bpf_prog *prog = ctx->prog; + + /* We're going to need this information for the "do_extra_pass()". */ + if (ctx->need_extra_pass) { + ctx->jit_data->bpf_header = ctx->bpf_header; + ctx->jit_data->bpf2insn = ctx->bpf2insn; + prog->aux->jit_data = (void *)ctx->jit_data; + } else { + /* + * If things seem finalised, then mark the JITed memory + * as R-X and flush it. + */ + if (bpf_jit_binary_lock_ro(ctx->bpf_header)) { + pr_err("bpf-jit: Could not lock the JIT memory.\n"); + return -EFAULT; + } + flush_icache_range((unsigned long)ctx->bpf_header, + (unsigned long) + BUF(ctx->jit.buf, ctx->jit.len)); + prog->aux->jit_data = NULL; + bpf_prog_fill_jited_linfo(prog, ctx->bpf2insn); + } + + ctx->success = true; + prog->bpf_func = (void *)ctx->jit.buf; + prog->jited_len = ctx->jit.len; + prog->jited = 1; + + jit_ctx_cleanup(ctx); + jit_dump(ctx); + + return 0; +} + +/* + * A lenient verification for the existence of JIT context in "prog". + * Apparently the JIT internals, namely jit_subprogs() in bpf/verifier.c, + * may request for a second compilation although nothing needs to be done. + */ +static inline int check_jit_context(const struct bpf_prog *prog) +{ + if (!prog->aux->jit_data) { + pr_notice("bpf-jit: no jit data for the extra pass.\n"); + return 1; + } else { + return 0; + } +} + +/* Reuse the previous pass's data. */ +static int jit_resume_context(struct jit_context *ctx) +{ + struct arc_jit_data *jdata = + (struct arc_jit_data *)ctx->prog->aux->jit_data; + + if (!jdata) { + pr_err("bpf-jit: no jit data for the extra pass.\n"); + return -EINVAL; + } + + ctx->jit.buf = (u8 *)ctx->prog->bpf_func; + ctx->jit.len = ctx->prog->jited_len; + ctx->bpf_header = jdata->bpf_header; + ctx->bpf2insn = (u32 *)jdata->bpf2insn; + ctx->bpf2insn_valid = ctx->bpf2insn ? true : false; + ctx->jit_data = jdata; + + return 0; +} + +/* + * Patch in the new addresses. The instructions of interest are: + * + * - call + * - ld r64, imm64 + * + * For "call"s, it resolves the addresses one more time through the + * handle_call(). + * + * For 64-bit immediate loads, it just retranslates them, because the BPF + * core in kernel might have changed the value since the normal pass. + */ +static int jit_patch_relocations(struct jit_context *ctx) +{ + const u8 bpf_opc_call = BPF_JMP | BPF_CALL; + const u8 bpf_opc_ldi64 = BPF_LD | BPF_DW | BPF_IMM; + const struct bpf_prog *prog = ctx->prog; + int ret; + + ctx->emit = true; + for (u32 i = 0; i < prog->len; i++) { + const struct bpf_insn *insn = &prog->insnsi[i]; + u8 dummy; + /* + * Adjust "ctx.jit.index", so "gen_*()" functions below + * can use it for their output addresses. + */ + ctx->jit.index = ctx->bpf2insn[i]; + + if (insn->code == bpf_opc_call) { + CHECK_RET(handle_call(ctx, insn, &dummy)); + } else if (insn->code == bpf_opc_ldi64) { + CHECK_RET(handle_ld_imm64(ctx, insn, &dummy)); + /* Skip the next instruction. */ + ++i; + } + } + return 0; +} + +/* + * A normal pass that involves a "dry-run" phase, jit_prepare(), + * to get the necessary data for the real compilation phase, + * jit_compile(). + */ +static struct bpf_prog *do_normal_pass(struct bpf_prog *prog) +{ + struct jit_context ctx; + + /* Bail out if JIT is disabled. */ + if (!prog->jit_requested) + return prog; + + if (jit_ctx_init(&ctx, prog)) { + jit_ctx_cleanup(&ctx); + return prog; + } + + /* Get the lengths and allocate buffer. */ + if (jit_prepare(&ctx)) { + jit_ctx_cleanup(&ctx); + return prog; + } + + if (jit_compile(&ctx)) { + jit_ctx_cleanup(&ctx); + return prog; + } + + if (jit_finalize(&ctx)) { + jit_ctx_cleanup(&ctx); + return prog; + } + + return ctx.prog; +} + +/* + * If there are multi-function BPF programs that call each other, + * their translated addresses are not known all at once. Therefore, + * an extra pass is needed to consult the bpf_jit_get_func_addr() + * again to get the newly translated addresses in order to resolve + * the "call"s. + */ +static struct bpf_prog *do_extra_pass(struct bpf_prog *prog) +{ + struct jit_context ctx; + + /* Skip if there's no context to resume from. */ + if (check_jit_context(prog)) + return prog; + + if (jit_ctx_init(&ctx, prog)) { + jit_ctx_cleanup(&ctx); + return prog; + } + + if (jit_resume_context(&ctx)) { + jit_ctx_cleanup(&ctx); + return prog; + } + + if (jit_patch_relocations(&ctx)) { + jit_ctx_cleanup(&ctx); + return prog; + } + + if (jit_finalize(&ctx)) { + jit_ctx_cleanup(&ctx); + return prog; + } + + return ctx.prog; +} + +/* + * This function may be invoked twice for the same stream of BPF + * instructions. The "extra pass" happens, when there are "call"s + * involved that their addresses are not known during the first + * invocation. + */ +struct bpf_prog *bpf_int_jit_compile(struct bpf_prog *prog) +{ + vm_dump(prog); + + /* Was this program already translated? */ + if (!prog->jited) + return do_normal_pass(prog); + else + return do_extra_pass(prog); + + return prog; +} |