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src/event/quic/bpf/bpfgen.sh - nginx source code

Functions defined

Source code

  1. #!/bin/bash

  3. export LANG=C

  5. set -e

  7. if [ $# -lt 1 ]; then
  8.     echo "Usage: PROGNAME=foo LICENSE=bar $0 <bpf object file>"
  9.     exit 1
  10. fi


  13. self=$0
  14. filename=$1
  15. funcname=$PROGNAME

  17. ‌generate_head()
  18. {
  19.     cat << END
  20. /* AUTO-GENERATED, DO NOT EDIT. */

  22. #include <stddef.h>
  23. #include <stdint.h>

  25. #include "ngx_bpf.h"


  28. END
  29. }

  31. ‌generate_tail()
  32. {
  33.     cat << END

  35. ngx_bpf_program_t $PROGNAME = {
  36.     .relocs = bpf_reloc_prog_$funcname,
  37.     .nrelocs = sizeof(bpf_reloc_prog_$funcname)
  38.                / sizeof(bpf_reloc_prog_$funcname[0]),
  39.     .ins = bpf_insn_prog_$funcname,
  40.     .nins = sizeof(bpf_insn_prog_$funcname)
  41.             / sizeof(bpf_insn_prog_$funcname[0]),
  42.     .license = "$LICENSE",
  43.     .type = BPF_PROG_TYPE_SK_REUSEPORT,
  44. };

  46. END
  47. }

  49. ‌process_relocations()
  50. {
  51.     echo "static ngx_bpf_reloc_t bpf_reloc_prog_$funcname[] = {"

  53.     objdump -r $filename | awk '{

  55.     if (enabled && $NF > 0) {
  56.         off = strtonum(sprintf("0x%s", $1));
  57.         name = $3;

  59.         printf("    { \"%s\", %d },\n", name, off/8);
  60.     }

  62.     if ($1 == "OFFSET") {
  63.         enabled=1;
  64.     }
  65. }'
  66.     echo "};"
  67.     echo
  68. }

  70. ‌process_section()
  71. {
  72.     echo "static struct bpf_insn bpf_insn_prog_$funcname[] = {"
  73.     echo "    /* opcode dst          src         offset imm */"

  75.     section_info=$(objdump -h $filename --section=$funcname | grep "1 $funcname")

  77.     # dd doesn't know hex
  78.     length=$(printf "%d" 0x$(echo $section_info | cut -d ' ' -f3))
  79.     offset=$(printf "%d" 0x$(echo $section_info | cut -d ' ' -f6))

  81.     for ins in $(dd if="$filename" bs=1 count=$length skip=$offset status=none | xxd -p -c 8)
  82.     do
  83.         opcode=0x${ins:0:2}
  84.         srcdst=0x${ins:2:2}

  86.         # bytes are dumped in LE order
  87.         offset=0x${ins:6:2}${ins:4:2}                        # short
  88.         immedi=0x${ins:14:2}${ins:12:2}${ins:10:2}${ins:8:2} # int

  90.         dst="$(($srcdst & 0xF))"
  91.         src="$(($srcdst & 0xF0))"
  92.         src="$(($src >> 4))"

  94.         opcode=$(printf "0x%x" $opcode)
  95.         dst=$(printf "BPF_REG_%d" $dst)
  96.         src=$(printf "BPF_REG_%d" $src)
  97.         offset=$(printf "%d" $offset)
  98.         immedi=$(printf "0x%x" $immedi)

  100.         printf "    { %4s, %11s, %11s, (int16_t) %6s, %10s },\n" $opcode $dst $src $offset $immedi
  101.     done

  103. cat << END
  104. };

  106. END
  107. }

  109. generate_head
  110. process_relocations
  111. process_section
  112. generate_tail

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