^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 1) // SPDX-License-Identifier: GPL-2.0
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 2) /*
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 3) * bpf-prologue.c
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 4) *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 5) * Copyright (C) 2015 He Kuang <hekuang@huawei.com>
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 6) * Copyright (C) 2015 Wang Nan <wangnan0@huawei.com>
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 7) * Copyright (C) 2015 Huawei Inc.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 8) */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 9)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 10) #include <bpf/libbpf.h>
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 11) #include "debug.h"
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 12) #include "bpf-loader.h"
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 13) #include "bpf-prologue.h"
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 14) #include "probe-finder.h"
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 15) #include <errno.h>
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 16) #include <stdlib.h>
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 17) #include <dwarf-regs.h>
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 18) #include <linux/filter.h>
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 19)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 20) #define BPF_REG_SIZE 8
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 21)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 22) #define JMP_TO_ERROR_CODE -1
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 23) #define JMP_TO_SUCCESS_CODE -2
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 24) #define JMP_TO_USER_CODE -3
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 25)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 26) struct bpf_insn_pos {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 27) struct bpf_insn *begin;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 28) struct bpf_insn *end;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 29) struct bpf_insn *pos;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 30) };
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 31)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 32) static inline int
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 33) pos_get_cnt(struct bpf_insn_pos *pos)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 34) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 35) return pos->pos - pos->begin;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 36) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 37)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 38) static int
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 39) append_insn(struct bpf_insn new_insn, struct bpf_insn_pos *pos)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 40) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 41) if (!pos->pos)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 42) return -BPF_LOADER_ERRNO__PROLOGUE2BIG;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 43)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 44) if (pos->pos + 1 >= pos->end) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 45) pr_err("bpf prologue: prologue too long\n");
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 46) pos->pos = NULL;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 47) return -BPF_LOADER_ERRNO__PROLOGUE2BIG;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 48) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 49)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 50) *(pos->pos)++ = new_insn;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 51) return 0;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 52) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 53)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 54) static int
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 55) check_pos(struct bpf_insn_pos *pos)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 56) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 57) if (!pos->pos || pos->pos >= pos->end)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 58) return -BPF_LOADER_ERRNO__PROLOGUE2BIG;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 59) return 0;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 60) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 61)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 62) /*
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 63) * Convert type string (u8/u16/u32/u64/s8/s16/s32/s64 ..., see
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 64) * Documentation/trace/kprobetrace.rst) to size field of BPF_LDX_MEM
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 65) * instruction (BPF_{B,H,W,DW}).
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 66) */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 67) static int
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 68) argtype_to_ldx_size(const char *type)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 69) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 70) int arg_size = type ? atoi(&type[1]) : 64;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 71)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 72) switch (arg_size) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 73) case 8:
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 74) return BPF_B;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 75) case 16:
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 76) return BPF_H;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 77) case 32:
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 78) return BPF_W;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 79) case 64:
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 80) default:
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 81) return BPF_DW;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 82) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 83) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 84)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 85) static const char *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 86) insn_sz_to_str(int insn_sz)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 87) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 88) switch (insn_sz) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 89) case BPF_B:
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 90) return "BPF_B";
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 91) case BPF_H:
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 92) return "BPF_H";
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 93) case BPF_W:
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 94) return "BPF_W";
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 95) case BPF_DW:
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 96) return "BPF_DW";
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 97) default:
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 98) return "UNKNOWN";
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 99) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 100) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 101)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 102) /* Give it a shorter name */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 103) #define ins(i, p) append_insn((i), (p))
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 104)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 105) /*
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 106) * Give a register name (in 'reg'), generate instruction to
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 107) * load register into an eBPF register rd:
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 108) * 'ldd target_reg, offset(ctx_reg)', where:
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 109) * ctx_reg is pre initialized to pointer of 'struct pt_regs'.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 110) */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 111) static int
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 112) gen_ldx_reg_from_ctx(struct bpf_insn_pos *pos, int ctx_reg,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 113) const char *reg, int target_reg)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 114) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 115) int offset = regs_query_register_offset(reg);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 116)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 117) if (offset < 0) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 118) pr_err("bpf: prologue: failed to get register %s\n",
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 119) reg);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 120) return offset;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 121) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 122) ins(BPF_LDX_MEM(BPF_DW, target_reg, ctx_reg, offset), pos);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 123)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 124) return check_pos(pos);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 125) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 126)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 127) /*
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 128) * Generate a BPF_FUNC_probe_read function call.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 129) *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 130) * src_base_addr_reg is a register holding base address,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 131) * dst_addr_reg is a register holding dest address (on stack),
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 132) * result is:
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 133) *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 134) * *[dst_addr_reg] = *([src_base_addr_reg] + offset)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 135) *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 136) * Arguments of BPF_FUNC_probe_read:
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 137) * ARG1: ptr to stack (dest)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 138) * ARG2: size (8)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 139) * ARG3: unsafe ptr (src)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 140) */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 141) static int
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 142) gen_read_mem(struct bpf_insn_pos *pos,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 143) int src_base_addr_reg,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 144) int dst_addr_reg,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 145) long offset,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 146) int probeid)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 147) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 148) /* mov arg3, src_base_addr_reg */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 149) if (src_base_addr_reg != BPF_REG_ARG3)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 150) ins(BPF_MOV64_REG(BPF_REG_ARG3, src_base_addr_reg), pos);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 151) /* add arg3, #offset */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 152) if (offset)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 153) ins(BPF_ALU64_IMM(BPF_ADD, BPF_REG_ARG3, offset), pos);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 154)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 155) /* mov arg2, #reg_size */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 156) ins(BPF_ALU64_IMM(BPF_MOV, BPF_REG_ARG2, BPF_REG_SIZE), pos);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 157)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 158) /* mov arg1, dst_addr_reg */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 159) if (dst_addr_reg != BPF_REG_ARG1)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 160) ins(BPF_MOV64_REG(BPF_REG_ARG1, dst_addr_reg), pos);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 161)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 162) /* Call probe_read */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 163) ins(BPF_EMIT_CALL(probeid), pos);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 164) /*
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 165) * Error processing: if read fail, goto error code,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 166) * will be relocated. Target should be the start of
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 167) * error processing code.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 168) */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 169) ins(BPF_JMP_IMM(BPF_JNE, BPF_REG_0, 0, JMP_TO_ERROR_CODE),
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 170) pos);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 171)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 172) return check_pos(pos);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 173) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 174)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 175) /*
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 176) * Each arg should be bare register. Fetch and save them into argument
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 177) * registers (r3 - r5).
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 178) *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 179) * BPF_REG_1 should have been initialized with pointer to
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 180) * 'struct pt_regs'.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 181) */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 182) static int
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 183) gen_prologue_fastpath(struct bpf_insn_pos *pos,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 184) struct probe_trace_arg *args, int nargs)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 185) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 186) int i, err = 0;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 187)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 188) for (i = 0; i < nargs; i++) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 189) err = gen_ldx_reg_from_ctx(pos, BPF_REG_1, args[i].value,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 190) BPF_PROLOGUE_START_ARG_REG + i);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 191) if (err)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 192) goto errout;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 193) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 194)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 195) return check_pos(pos);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 196) errout:
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 197) return err;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 198) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 199)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 200) /*
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 201) * Slow path:
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 202) * At least one argument has the form of 'offset($rx)'.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 203) *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 204) * Following code first stores them into stack, then loads all of then
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 205) * to r2 - r5.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 206) * Before final loading, the final result should be:
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 207) *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 208) * low address
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 209) * BPF_REG_FP - 24 ARG3
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 210) * BPF_REG_FP - 16 ARG2
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 211) * BPF_REG_FP - 8 ARG1
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 212) * BPF_REG_FP
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 213) * high address
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 214) *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 215) * For each argument (described as: offn(...off2(off1(reg)))),
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 216) * generates following code:
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 217) *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 218) * r7 <- fp
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 219) * r7 <- r7 - stack_offset // Ideal code should initialize r7 using
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 220) * // fp before generating args. However,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 221) * // eBPF won't regard r7 as stack pointer
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 222) * // if it is generated by minus 8 from
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 223) * // another stack pointer except fp.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 224) * // This is why we have to set r7
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 225) * // to fp for each variable.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 226) * r3 <- value of 'reg'-> generated using gen_ldx_reg_from_ctx()
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 227) * (r7) <- r3 // skip following instructions for bare reg
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 228) * r3 <- r3 + off1 . // skip if off1 == 0
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 229) * r2 <- 8 \
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 230) * r1 <- r7 |-> generated by gen_read_mem()
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 231) * call probe_read /
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 232) * jnei r0, 0, err ./
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 233) * r3 <- (r7)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 234) * r3 <- r3 + off2 . // skip if off2 == 0
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 235) * r2 <- 8 \ // r2 may be broken by probe_read, so set again
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 236) * r1 <- r7 |-> generated by gen_read_mem()
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 237) * call probe_read /
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 238) * jnei r0, 0, err ./
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 239) * ...
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 240) */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 241) static int
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 242) gen_prologue_slowpath(struct bpf_insn_pos *pos,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 243) struct probe_trace_arg *args, int nargs)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 244) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 245) int err, i, probeid;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 246)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 247) for (i = 0; i < nargs; i++) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 248) struct probe_trace_arg *arg = &args[i];
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 249) const char *reg = arg->value;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 250) struct probe_trace_arg_ref *ref = NULL;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 251) int stack_offset = (i + 1) * -8;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 252)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 253) pr_debug("prologue: fetch arg %d, base reg is %s\n",
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 254) i, reg);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 255)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 256) /* value of base register is stored into ARG3 */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 257) err = gen_ldx_reg_from_ctx(pos, BPF_REG_CTX, reg,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 258) BPF_REG_ARG3);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 259) if (err) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 260) pr_err("prologue: failed to get offset of register %s\n",
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 261) reg);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 262) goto errout;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 263) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 264)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 265) /* Make r7 the stack pointer. */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 266) ins(BPF_MOV64_REG(BPF_REG_7, BPF_REG_FP), pos);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 267) /* r7 += -8 */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 268) ins(BPF_ALU64_IMM(BPF_ADD, BPF_REG_7, stack_offset), pos);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 269) /*
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 270) * Store r3 (base register) onto stack
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 271) * Ensure fp[offset] is set.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 272) * fp is the only valid base register when storing
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 273) * into stack. We are not allowed to use r7 as base
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 274) * register here.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 275) */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 276) ins(BPF_STX_MEM(BPF_DW, BPF_REG_FP, BPF_REG_ARG3,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 277) stack_offset), pos);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 278)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 279) ref = arg->ref;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 280) probeid = BPF_FUNC_probe_read_kernel;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 281) while (ref) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 282) pr_debug("prologue: arg %d: offset %ld\n",
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 283) i, ref->offset);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 284)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 285) if (ref->user_access)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 286) probeid = BPF_FUNC_probe_read_user;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 287)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 288) err = gen_read_mem(pos, BPF_REG_3, BPF_REG_7,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 289) ref->offset, probeid);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 290) if (err) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 291) pr_err("prologue: failed to generate probe_read function call\n");
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 292) goto errout;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 293) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 294)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 295) ref = ref->next;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 296) /*
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 297) * Load previous result into ARG3. Use
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 298) * BPF_REG_FP instead of r7 because verifier
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 299) * allows FP based addressing only.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 300) */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 301) if (ref)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 302) ins(BPF_LDX_MEM(BPF_DW, BPF_REG_ARG3,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 303) BPF_REG_FP, stack_offset), pos);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 304) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 305) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 306)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 307) /* Final pass: read to registers */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 308) for (i = 0; i < nargs; i++) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 309) int insn_sz = (args[i].ref) ? argtype_to_ldx_size(args[i].type) : BPF_DW;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 310)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 311) pr_debug("prologue: load arg %d, insn_sz is %s\n",
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 312) i, insn_sz_to_str(insn_sz));
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 313) ins(BPF_LDX_MEM(insn_sz, BPF_PROLOGUE_START_ARG_REG + i,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 314) BPF_REG_FP, -BPF_REG_SIZE * (i + 1)), pos);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 315) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 316)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 317) ins(BPF_JMP_IMM(BPF_JA, BPF_REG_0, 0, JMP_TO_SUCCESS_CODE), pos);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 318)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 319) return check_pos(pos);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 320) errout:
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 321) return err;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 322) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 323)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 324) static int
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 325) prologue_relocate(struct bpf_insn_pos *pos, struct bpf_insn *error_code,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 326) struct bpf_insn *success_code, struct bpf_insn *user_code)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 327) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 328) struct bpf_insn *insn;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 329)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 330) if (check_pos(pos))
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 331) return -BPF_LOADER_ERRNO__PROLOGUE2BIG;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 332)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 333) for (insn = pos->begin; insn < pos->pos; insn++) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 334) struct bpf_insn *target;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 335) u8 class = BPF_CLASS(insn->code);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 336) u8 opcode;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 337)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 338) if (class != BPF_JMP)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 339) continue;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 340) opcode = BPF_OP(insn->code);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 341) if (opcode == BPF_CALL)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 342) continue;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 343)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 344) switch (insn->off) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 345) case JMP_TO_ERROR_CODE:
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 346) target = error_code;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 347) break;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 348) case JMP_TO_SUCCESS_CODE:
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 349) target = success_code;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 350) break;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 351) case JMP_TO_USER_CODE:
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 352) target = user_code;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 353) break;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 354) default:
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 355) pr_err("bpf prologue: internal error: relocation failed\n");
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 356) return -BPF_LOADER_ERRNO__PROLOGUE;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 357) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 358)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 359) insn->off = target - (insn + 1);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 360) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 361) return 0;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 362) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 363)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 364) int bpf__gen_prologue(struct probe_trace_arg *args, int nargs,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 365) struct bpf_insn *new_prog, size_t *new_cnt,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 366) size_t cnt_space)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 367) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 368) struct bpf_insn *success_code = NULL;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 369) struct bpf_insn *error_code = NULL;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 370) struct bpf_insn *user_code = NULL;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 371) struct bpf_insn_pos pos;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 372) bool fastpath = true;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 373) int err = 0, i;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 374)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 375) if (!new_prog || !new_cnt)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 376) return -EINVAL;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 377)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 378) if (cnt_space > BPF_MAXINSNS)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 379) cnt_space = BPF_MAXINSNS;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 380)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 381) pos.begin = new_prog;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 382) pos.end = new_prog + cnt_space;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 383) pos.pos = new_prog;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 384)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 385) if (!nargs) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 386) ins(BPF_ALU64_IMM(BPF_MOV, BPF_PROLOGUE_FETCH_RESULT_REG, 0),
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 387) &pos);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 388)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 389) if (check_pos(&pos))
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 390) goto errout;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 391)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 392) *new_cnt = pos_get_cnt(&pos);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 393) return 0;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 394) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 395)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 396) if (nargs > BPF_PROLOGUE_MAX_ARGS) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 397) pr_warning("bpf: prologue: %d arguments are dropped\n",
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 398) nargs - BPF_PROLOGUE_MAX_ARGS);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 399) nargs = BPF_PROLOGUE_MAX_ARGS;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 400) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 401)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 402) /* First pass: validation */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 403) for (i = 0; i < nargs; i++) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 404) struct probe_trace_arg_ref *ref = args[i].ref;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 405)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 406) if (args[i].value[0] == '@') {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 407) /* TODO: fetch global variable */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 408) pr_err("bpf: prologue: global %s%+ld not support\n",
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 409) args[i].value, ref ? ref->offset : 0);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 410) return -ENOTSUP;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 411) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 412)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 413) while (ref) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 414) /* fastpath is true if all args has ref == NULL */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 415) fastpath = false;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 416)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 417) /*
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 418) * Instruction encodes immediate value using
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 419) * s32, ref->offset is long. On systems which
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 420) * can't fill long in s32, refuse to process if
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 421) * ref->offset too large (or small).
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 422) */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 423) #ifdef __LP64__
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 424) #define OFFSET_MAX ((1LL << 31) - 1)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 425) #define OFFSET_MIN ((1LL << 31) * -1)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 426) if (ref->offset > OFFSET_MAX ||
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 427) ref->offset < OFFSET_MIN) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 428) pr_err("bpf: prologue: offset out of bound: %ld\n",
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 429) ref->offset);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 430) return -BPF_LOADER_ERRNO__PROLOGUEOOB;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 431) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 432) #endif
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 433) ref = ref->next;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 434) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 435) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 436) pr_debug("prologue: pass validation\n");
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 437)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 438) if (fastpath) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 439) /* If all variables are registers... */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 440) pr_debug("prologue: fast path\n");
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 441) err = gen_prologue_fastpath(&pos, args, nargs);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 442) if (err)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 443) goto errout;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 444) } else {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 445) pr_debug("prologue: slow path\n");
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 446)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 447) /* Initialization: move ctx to a callee saved register. */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 448) ins(BPF_MOV64_REG(BPF_REG_CTX, BPF_REG_ARG1), &pos);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 449)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 450) err = gen_prologue_slowpath(&pos, args, nargs);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 451) if (err)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 452) goto errout;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 453) /*
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 454) * start of ERROR_CODE (only slow pass needs error code)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 455) * mov r2 <- 1 // r2 is error number
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 456) * mov r3 <- 0 // r3, r4... should be touched or
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 457) * // verifier would complain
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 458) * mov r4 <- 0
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 459) * ...
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 460) * goto usercode
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 461) */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 462) error_code = pos.pos;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 463) ins(BPF_ALU64_IMM(BPF_MOV, BPF_PROLOGUE_FETCH_RESULT_REG, 1),
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 464) &pos);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 465)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 466) for (i = 0; i < nargs; i++)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 467) ins(BPF_ALU64_IMM(BPF_MOV,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 468) BPF_PROLOGUE_START_ARG_REG + i,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 469) 0),
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 470) &pos);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 471) ins(BPF_JMP_IMM(BPF_JA, BPF_REG_0, 0, JMP_TO_USER_CODE),
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 472) &pos);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 473) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 474)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 475) /*
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 476) * start of SUCCESS_CODE:
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 477) * mov r2 <- 0
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 478) * goto usercode // skip
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 479) */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 480) success_code = pos.pos;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 481) ins(BPF_ALU64_IMM(BPF_MOV, BPF_PROLOGUE_FETCH_RESULT_REG, 0), &pos);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 482)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 483) /*
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 484) * start of USER_CODE:
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 485) * Restore ctx to r1
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 486) */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 487) user_code = pos.pos;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 488) if (!fastpath) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 489) /*
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 490) * Only slow path needs restoring of ctx. In fast path,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 491) * register are loaded directly from r1.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 492) */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 493) ins(BPF_MOV64_REG(BPF_REG_ARG1, BPF_REG_CTX), &pos);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 494) err = prologue_relocate(&pos, error_code, success_code,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 495) user_code);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 496) if (err)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 497) goto errout;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 498) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 499)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 500) err = check_pos(&pos);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 501) if (err)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 502) goto errout;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 503)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 504) *new_cnt = pos_get_cnt(&pos);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 505) return 0;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 506) errout:
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 507) return err;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 508) }
Orange Pi5 kernel
Deprecated Linux kernel 5.10.110 for OrangePi 5/5B/5+ boards
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