filter: add minimal BPF JIT image disassembler
This is a minimal stand-alone user space helper, that allows for debugging or
verification of emitted BPF JIT images. This is in particular useful for
emitted opcode debugging, since minor bugs in the JIT compiler can be fatal.
The disassembler is architecture generic and uses libopcodes and libbfd.
How to get to the disassembly, example:
1) `echo 2 > /proc/sys/net/core/bpf_jit_enable`
2) Load a BPF filter (e.g. `tcpdump -p -n -s 0 -i eth1 host 192.168.20.0/24`)
3) Run e.g. `bpf_jit_disasm -o` to disassemble the most recent JIT code output
`bpf_jit_disasm -o` will display the related opcodes to a particular instruction
as well. Example for x86_64:
$ ./bpf_jit_disasm
94 bytes emitted from JIT compiler (pass:3, flen:9)
ffffffffa0356000 + <x>:
0: push %rbp
1: mov %rsp,%rbp
4: sub $0x60,%rsp
8: mov %rbx,-0x8(%rbp)
c: mov 0x68(%rdi),%r9d
10: sub 0x6c(%rdi),%r9d
14: mov 0xe0(%rdi),%r8
1b: mov $0xc,%esi
20: callq 0xffffffffe0d01b71
25: cmp $0x86dd,%eax
2a: jne 0x000000000000003d
2c: mov $0x14,%esi
31: callq 0xffffffffe0d01b8d
36: cmp $0x6,%eax
[...]
5c: leaveq
5d: retq
$ ./bpf_jit_disasm -o
94 bytes emitted from JIT compiler (pass:3, flen:9)
ffffffffa0356000 + <x>:
0: push %rbp
55
1: mov %rsp,%rbp
48 89 e5
4: sub $0x60,%rsp
48 83 ec 60
8: mov %rbx,-0x8(%rbp)
48 89 5d f8
c: mov 0x68(%rdi),%r9d
44 8b 4f 68
10: sub 0x6c(%rdi),%r9d
44 2b 4f 6c
[...]
5c: leaveq
c9
5d: retq
c3
Signed-off-by: Daniel Borkmann <dborkman@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2013-03-20 12:11:47 +00:00
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/*
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* Minimal BPF JIT image disassembler
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*
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* Disassembles BPF JIT compiler emitted opcodes back to asm insn's for
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* debugging or verification purposes.
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*
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* To get the disassembly of the JIT code, do the following:
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*
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* 1) `echo 2 > /proc/sys/net/core/bpf_jit_enable`
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* 2) Load a BPF filter (e.g. `tcpdump -p -n -s 0 -i eth1 host 192.168.20.0/24`)
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* 3) Run e.g. `bpf_jit_disasm -o` to read out the last JIT code
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*
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* Copyright 2013 Daniel Borkmann <borkmann@redhat.com>
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* Licensed under the GNU General Public License, version 2.0 (GPLv2)
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*/
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#include <stdint.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <assert.h>
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#include <unistd.h>
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#include <string.h>
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#include <bfd.h>
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#include <dis-asm.h>
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2015-07-30 14:04:22 +00:00
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#include <regex.h>
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#include <fcntl.h>
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filter: add minimal BPF JIT image disassembler
This is a minimal stand-alone user space helper, that allows for debugging or
verification of emitted BPF JIT images. This is in particular useful for
emitted opcode debugging, since minor bugs in the JIT compiler can be fatal.
The disassembler is architecture generic and uses libopcodes and libbfd.
How to get to the disassembly, example:
1) `echo 2 > /proc/sys/net/core/bpf_jit_enable`
2) Load a BPF filter (e.g. `tcpdump -p -n -s 0 -i eth1 host 192.168.20.0/24`)
3) Run e.g. `bpf_jit_disasm -o` to disassemble the most recent JIT code output
`bpf_jit_disasm -o` will display the related opcodes to a particular instruction
as well. Example for x86_64:
$ ./bpf_jit_disasm
94 bytes emitted from JIT compiler (pass:3, flen:9)
ffffffffa0356000 + <x>:
0: push %rbp
1: mov %rsp,%rbp
4: sub $0x60,%rsp
8: mov %rbx,-0x8(%rbp)
c: mov 0x68(%rdi),%r9d
10: sub 0x6c(%rdi),%r9d
14: mov 0xe0(%rdi),%r8
1b: mov $0xc,%esi
20: callq 0xffffffffe0d01b71
25: cmp $0x86dd,%eax
2a: jne 0x000000000000003d
2c: mov $0x14,%esi
31: callq 0xffffffffe0d01b8d
36: cmp $0x6,%eax
[...]
5c: leaveq
5d: retq
$ ./bpf_jit_disasm -o
94 bytes emitted from JIT compiler (pass:3, flen:9)
ffffffffa0356000 + <x>:
0: push %rbp
55
1: mov %rsp,%rbp
48 89 e5
4: sub $0x60,%rsp
48 83 ec 60
8: mov %rbx,-0x8(%rbp)
48 89 5d f8
c: mov 0x68(%rdi),%r9d
44 8b 4f 68
10: sub 0x6c(%rdi),%r9d
44 2b 4f 6c
[...]
5c: leaveq
c9
5d: retq
c3
Signed-off-by: Daniel Borkmann <dborkman@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2013-03-20 12:11:47 +00:00
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#include <sys/klog.h>
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#include <sys/types.h>
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2015-07-30 14:04:22 +00:00
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#include <sys/stat.h>
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2017-11-02 08:09:45 +00:00
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#include <limits.h>
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2015-07-30 14:04:22 +00:00
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#define CMD_ACTION_SIZE_BUFFER 10
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#define CMD_ACTION_READ_ALL 3
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filter: add minimal BPF JIT image disassembler
This is a minimal stand-alone user space helper, that allows for debugging or
verification of emitted BPF JIT images. This is in particular useful for
emitted opcode debugging, since minor bugs in the JIT compiler can be fatal.
The disassembler is architecture generic and uses libopcodes and libbfd.
How to get to the disassembly, example:
1) `echo 2 > /proc/sys/net/core/bpf_jit_enable`
2) Load a BPF filter (e.g. `tcpdump -p -n -s 0 -i eth1 host 192.168.20.0/24`)
3) Run e.g. `bpf_jit_disasm -o` to disassemble the most recent JIT code output
`bpf_jit_disasm -o` will display the related opcodes to a particular instruction
as well. Example for x86_64:
$ ./bpf_jit_disasm
94 bytes emitted from JIT compiler (pass:3, flen:9)
ffffffffa0356000 + <x>:
0: push %rbp
1: mov %rsp,%rbp
4: sub $0x60,%rsp
8: mov %rbx,-0x8(%rbp)
c: mov 0x68(%rdi),%r9d
10: sub 0x6c(%rdi),%r9d
14: mov 0xe0(%rdi),%r8
1b: mov $0xc,%esi
20: callq 0xffffffffe0d01b71
25: cmp $0x86dd,%eax
2a: jne 0x000000000000003d
2c: mov $0x14,%esi
31: callq 0xffffffffe0d01b8d
36: cmp $0x6,%eax
[...]
5c: leaveq
5d: retq
$ ./bpf_jit_disasm -o
94 bytes emitted from JIT compiler (pass:3, flen:9)
ffffffffa0356000 + <x>:
0: push %rbp
55
1: mov %rsp,%rbp
48 89 e5
4: sub $0x60,%rsp
48 83 ec 60
8: mov %rbx,-0x8(%rbp)
48 89 5d f8
c: mov 0x68(%rdi),%r9d
44 8b 4f 68
10: sub 0x6c(%rdi),%r9d
44 2b 4f 6c
[...]
5c: leaveq
c9
5d: retq
c3
Signed-off-by: Daniel Borkmann <dborkman@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2013-03-20 12:11:47 +00:00
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static void get_exec_path(char *tpath, size_t size)
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{
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char *path;
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ssize_t len;
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snprintf(tpath, size, "/proc/%d/exe", (int) getpid());
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tpath[size - 1] = 0;
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path = strdup(tpath);
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assert(path);
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len = readlink(path, tpath, size);
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tpath[len] = 0;
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free(path);
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}
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2014-05-15 22:56:38 +00:00
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static void get_asm_insns(uint8_t *image, size_t len, int opcodes)
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filter: add minimal BPF JIT image disassembler
This is a minimal stand-alone user space helper, that allows for debugging or
verification of emitted BPF JIT images. This is in particular useful for
emitted opcode debugging, since minor bugs in the JIT compiler can be fatal.
The disassembler is architecture generic and uses libopcodes and libbfd.
How to get to the disassembly, example:
1) `echo 2 > /proc/sys/net/core/bpf_jit_enable`
2) Load a BPF filter (e.g. `tcpdump -p -n -s 0 -i eth1 host 192.168.20.0/24`)
3) Run e.g. `bpf_jit_disasm -o` to disassemble the most recent JIT code output
`bpf_jit_disasm -o` will display the related opcodes to a particular instruction
as well. Example for x86_64:
$ ./bpf_jit_disasm
94 bytes emitted from JIT compiler (pass:3, flen:9)
ffffffffa0356000 + <x>:
0: push %rbp
1: mov %rsp,%rbp
4: sub $0x60,%rsp
8: mov %rbx,-0x8(%rbp)
c: mov 0x68(%rdi),%r9d
10: sub 0x6c(%rdi),%r9d
14: mov 0xe0(%rdi),%r8
1b: mov $0xc,%esi
20: callq 0xffffffffe0d01b71
25: cmp $0x86dd,%eax
2a: jne 0x000000000000003d
2c: mov $0x14,%esi
31: callq 0xffffffffe0d01b8d
36: cmp $0x6,%eax
[...]
5c: leaveq
5d: retq
$ ./bpf_jit_disasm -o
94 bytes emitted from JIT compiler (pass:3, flen:9)
ffffffffa0356000 + <x>:
0: push %rbp
55
1: mov %rsp,%rbp
48 89 e5
4: sub $0x60,%rsp
48 83 ec 60
8: mov %rbx,-0x8(%rbp)
48 89 5d f8
c: mov 0x68(%rdi),%r9d
44 8b 4f 68
10: sub 0x6c(%rdi),%r9d
44 2b 4f 6c
[...]
5c: leaveq
c9
5d: retq
c3
Signed-off-by: Daniel Borkmann <dborkman@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2013-03-20 12:11:47 +00:00
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{
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int count, i, pc = 0;
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2017-11-02 08:09:45 +00:00
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char tpath[PATH_MAX];
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filter: add minimal BPF JIT image disassembler
This is a minimal stand-alone user space helper, that allows for debugging or
verification of emitted BPF JIT images. This is in particular useful for
emitted opcode debugging, since minor bugs in the JIT compiler can be fatal.
The disassembler is architecture generic and uses libopcodes and libbfd.
How to get to the disassembly, example:
1) `echo 2 > /proc/sys/net/core/bpf_jit_enable`
2) Load a BPF filter (e.g. `tcpdump -p -n -s 0 -i eth1 host 192.168.20.0/24`)
3) Run e.g. `bpf_jit_disasm -o` to disassemble the most recent JIT code output
`bpf_jit_disasm -o` will display the related opcodes to a particular instruction
as well. Example for x86_64:
$ ./bpf_jit_disasm
94 bytes emitted from JIT compiler (pass:3, flen:9)
ffffffffa0356000 + <x>:
0: push %rbp
1: mov %rsp,%rbp
4: sub $0x60,%rsp
8: mov %rbx,-0x8(%rbp)
c: mov 0x68(%rdi),%r9d
10: sub 0x6c(%rdi),%r9d
14: mov 0xe0(%rdi),%r8
1b: mov $0xc,%esi
20: callq 0xffffffffe0d01b71
25: cmp $0x86dd,%eax
2a: jne 0x000000000000003d
2c: mov $0x14,%esi
31: callq 0xffffffffe0d01b8d
36: cmp $0x6,%eax
[...]
5c: leaveq
5d: retq
$ ./bpf_jit_disasm -o
94 bytes emitted from JIT compiler (pass:3, flen:9)
ffffffffa0356000 + <x>:
0: push %rbp
55
1: mov %rsp,%rbp
48 89 e5
4: sub $0x60,%rsp
48 83 ec 60
8: mov %rbx,-0x8(%rbp)
48 89 5d f8
c: mov 0x68(%rdi),%r9d
44 8b 4f 68
10: sub 0x6c(%rdi),%r9d
44 2b 4f 6c
[...]
5c: leaveq
c9
5d: retq
c3
Signed-off-by: Daniel Borkmann <dborkman@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2013-03-20 12:11:47 +00:00
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struct disassemble_info info;
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disassembler_ftype disassemble;
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bfd *bfdf;
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memset(tpath, 0, sizeof(tpath));
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get_exec_path(tpath, sizeof(tpath));
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bfdf = bfd_openr(tpath, NULL);
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assert(bfdf);
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assert(bfd_check_format(bfdf, bfd_object));
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init_disassemble_info(&info, stdout, (fprintf_ftype) fprintf);
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info.arch = bfd_get_arch(bfdf);
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info.mach = bfd_get_mach(bfdf);
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info.buffer = image;
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info.buffer_length = len;
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disassemble_init_for_target(&info);
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disassemble = disassembler(bfdf);
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assert(disassemble);
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do {
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printf("%4x:\t", pc);
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count = disassemble(pc, &info);
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if (opcodes) {
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printf("\n\t");
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for (i = 0; i < count; ++i)
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printf("%02x ", (uint8_t) image[pc + i]);
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}
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printf("\n");
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pc += count;
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} while(count > 0 && pc < len);
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bfd_close(bfdf);
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}
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2015-07-30 14:04:22 +00:00
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static char *get_klog_buff(unsigned int *klen)
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filter: add minimal BPF JIT image disassembler
This is a minimal stand-alone user space helper, that allows for debugging or
verification of emitted BPF JIT images. This is in particular useful for
emitted opcode debugging, since minor bugs in the JIT compiler can be fatal.
The disassembler is architecture generic and uses libopcodes and libbfd.
How to get to the disassembly, example:
1) `echo 2 > /proc/sys/net/core/bpf_jit_enable`
2) Load a BPF filter (e.g. `tcpdump -p -n -s 0 -i eth1 host 192.168.20.0/24`)
3) Run e.g. `bpf_jit_disasm -o` to disassemble the most recent JIT code output
`bpf_jit_disasm -o` will display the related opcodes to a particular instruction
as well. Example for x86_64:
$ ./bpf_jit_disasm
94 bytes emitted from JIT compiler (pass:3, flen:9)
ffffffffa0356000 + <x>:
0: push %rbp
1: mov %rsp,%rbp
4: sub $0x60,%rsp
8: mov %rbx,-0x8(%rbp)
c: mov 0x68(%rdi),%r9d
10: sub 0x6c(%rdi),%r9d
14: mov 0xe0(%rdi),%r8
1b: mov $0xc,%esi
20: callq 0xffffffffe0d01b71
25: cmp $0x86dd,%eax
2a: jne 0x000000000000003d
2c: mov $0x14,%esi
31: callq 0xffffffffe0d01b8d
36: cmp $0x6,%eax
[...]
5c: leaveq
5d: retq
$ ./bpf_jit_disasm -o
94 bytes emitted from JIT compiler (pass:3, flen:9)
ffffffffa0356000 + <x>:
0: push %rbp
55
1: mov %rsp,%rbp
48 89 e5
4: sub $0x60,%rsp
48 83 ec 60
8: mov %rbx,-0x8(%rbp)
48 89 5d f8
c: mov 0x68(%rdi),%r9d
44 8b 4f 68
10: sub 0x6c(%rdi),%r9d
44 2b 4f 6c
[...]
5c: leaveq
c9
5d: retq
c3
Signed-off-by: Daniel Borkmann <dborkman@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2013-03-20 12:11:47 +00:00
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{
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2015-07-30 14:04:22 +00:00
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int ret, len;
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char *buff;
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len = klogctl(CMD_ACTION_SIZE_BUFFER, NULL, 0);
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2016-05-05 22:39:33 +00:00
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if (len < 0)
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return NULL;
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2015-07-30 14:04:22 +00:00
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buff = malloc(len);
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if (!buff)
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return NULL;
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ret = klogctl(CMD_ACTION_READ_ALL, buff, len);
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if (ret < 0) {
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free(buff);
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return NULL;
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}
|
filter: add minimal BPF JIT image disassembler
This is a minimal stand-alone user space helper, that allows for debugging or
verification of emitted BPF JIT images. This is in particular useful for
emitted opcode debugging, since minor bugs in the JIT compiler can be fatal.
The disassembler is architecture generic and uses libopcodes and libbfd.
How to get to the disassembly, example:
1) `echo 2 > /proc/sys/net/core/bpf_jit_enable`
2) Load a BPF filter (e.g. `tcpdump -p -n -s 0 -i eth1 host 192.168.20.0/24`)
3) Run e.g. `bpf_jit_disasm -o` to disassemble the most recent JIT code output
`bpf_jit_disasm -o` will display the related opcodes to a particular instruction
as well. Example for x86_64:
$ ./bpf_jit_disasm
94 bytes emitted from JIT compiler (pass:3, flen:9)
ffffffffa0356000 + <x>:
0: push %rbp
1: mov %rsp,%rbp
4: sub $0x60,%rsp
8: mov %rbx,-0x8(%rbp)
c: mov 0x68(%rdi),%r9d
10: sub 0x6c(%rdi),%r9d
14: mov 0xe0(%rdi),%r8
1b: mov $0xc,%esi
20: callq 0xffffffffe0d01b71
25: cmp $0x86dd,%eax
2a: jne 0x000000000000003d
2c: mov $0x14,%esi
31: callq 0xffffffffe0d01b8d
36: cmp $0x6,%eax
[...]
5c: leaveq
5d: retq
$ ./bpf_jit_disasm -o
94 bytes emitted from JIT compiler (pass:3, flen:9)
ffffffffa0356000 + <x>:
0: push %rbp
55
1: mov %rsp,%rbp
48 89 e5
4: sub $0x60,%rsp
48 83 ec 60
8: mov %rbx,-0x8(%rbp)
48 89 5d f8
c: mov 0x68(%rdi),%r9d
44 8b 4f 68
10: sub 0x6c(%rdi),%r9d
44 2b 4f 6c
[...]
5c: leaveq
c9
5d: retq
c3
Signed-off-by: Daniel Borkmann <dborkman@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2013-03-20 12:11:47 +00:00
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|
*klen = ret;
|
2015-07-30 14:04:22 +00:00
|
|
|
return buff;
|
|
|
|
}
|
filter: add minimal BPF JIT image disassembler
This is a minimal stand-alone user space helper, that allows for debugging or
verification of emitted BPF JIT images. This is in particular useful for
emitted opcode debugging, since minor bugs in the JIT compiler can be fatal.
The disassembler is architecture generic and uses libopcodes and libbfd.
How to get to the disassembly, example:
1) `echo 2 > /proc/sys/net/core/bpf_jit_enable`
2) Load a BPF filter (e.g. `tcpdump -p -n -s 0 -i eth1 host 192.168.20.0/24`)
3) Run e.g. `bpf_jit_disasm -o` to disassemble the most recent JIT code output
`bpf_jit_disasm -o` will display the related opcodes to a particular instruction
as well. Example for x86_64:
$ ./bpf_jit_disasm
94 bytes emitted from JIT compiler (pass:3, flen:9)
ffffffffa0356000 + <x>:
0: push %rbp
1: mov %rsp,%rbp
4: sub $0x60,%rsp
8: mov %rbx,-0x8(%rbp)
c: mov 0x68(%rdi),%r9d
10: sub 0x6c(%rdi),%r9d
14: mov 0xe0(%rdi),%r8
1b: mov $0xc,%esi
20: callq 0xffffffffe0d01b71
25: cmp $0x86dd,%eax
2a: jne 0x000000000000003d
2c: mov $0x14,%esi
31: callq 0xffffffffe0d01b8d
36: cmp $0x6,%eax
[...]
5c: leaveq
5d: retq
$ ./bpf_jit_disasm -o
94 bytes emitted from JIT compiler (pass:3, flen:9)
ffffffffa0356000 + <x>:
0: push %rbp
55
1: mov %rsp,%rbp
48 89 e5
4: sub $0x60,%rsp
48 83 ec 60
8: mov %rbx,-0x8(%rbp)
48 89 5d f8
c: mov 0x68(%rdi),%r9d
44 8b 4f 68
10: sub 0x6c(%rdi),%r9d
44 2b 4f 6c
[...]
5c: leaveq
c9
5d: retq
c3
Signed-off-by: Daniel Borkmann <dborkman@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2013-03-20 12:11:47 +00:00
|
|
|
|
2015-07-30 14:04:22 +00:00
|
|
|
static char *get_flog_buff(const char *file, unsigned int *klen)
|
|
|
|
{
|
|
|
|
int fd, ret, len;
|
|
|
|
struct stat fi;
|
|
|
|
char *buff;
|
|
|
|
|
|
|
|
fd = open(file, O_RDONLY);
|
|
|
|
if (fd < 0)
|
|
|
|
return NULL;
|
|
|
|
|
|
|
|
ret = fstat(fd, &fi);
|
|
|
|
if (ret < 0 || !S_ISREG(fi.st_mode))
|
|
|
|
goto out;
|
|
|
|
|
|
|
|
len = fi.st_size + 1;
|
|
|
|
buff = malloc(len);
|
|
|
|
if (!buff)
|
|
|
|
goto out;
|
|
|
|
|
|
|
|
memset(buff, 0, len);
|
|
|
|
ret = read(fd, buff, len - 1);
|
|
|
|
if (ret <= 0)
|
|
|
|
goto out_free;
|
|
|
|
|
|
|
|
close(fd);
|
|
|
|
*klen = ret;
|
filter: add minimal BPF JIT image disassembler
This is a minimal stand-alone user space helper, that allows for debugging or
verification of emitted BPF JIT images. This is in particular useful for
emitted opcode debugging, since minor bugs in the JIT compiler can be fatal.
The disassembler is architecture generic and uses libopcodes and libbfd.
How to get to the disassembly, example:
1) `echo 2 > /proc/sys/net/core/bpf_jit_enable`
2) Load a BPF filter (e.g. `tcpdump -p -n -s 0 -i eth1 host 192.168.20.0/24`)
3) Run e.g. `bpf_jit_disasm -o` to disassemble the most recent JIT code output
`bpf_jit_disasm -o` will display the related opcodes to a particular instruction
as well. Example for x86_64:
$ ./bpf_jit_disasm
94 bytes emitted from JIT compiler (pass:3, flen:9)
ffffffffa0356000 + <x>:
0: push %rbp
1: mov %rsp,%rbp
4: sub $0x60,%rsp
8: mov %rbx,-0x8(%rbp)
c: mov 0x68(%rdi),%r9d
10: sub 0x6c(%rdi),%r9d
14: mov 0xe0(%rdi),%r8
1b: mov $0xc,%esi
20: callq 0xffffffffe0d01b71
25: cmp $0x86dd,%eax
2a: jne 0x000000000000003d
2c: mov $0x14,%esi
31: callq 0xffffffffe0d01b8d
36: cmp $0x6,%eax
[...]
5c: leaveq
5d: retq
$ ./bpf_jit_disasm -o
94 bytes emitted from JIT compiler (pass:3, flen:9)
ffffffffa0356000 + <x>:
0: push %rbp
55
1: mov %rsp,%rbp
48 89 e5
4: sub $0x60,%rsp
48 83 ec 60
8: mov %rbx,-0x8(%rbp)
48 89 5d f8
c: mov 0x68(%rdi),%r9d
44 8b 4f 68
10: sub 0x6c(%rdi),%r9d
44 2b 4f 6c
[...]
5c: leaveq
c9
5d: retq
c3
Signed-off-by: Daniel Borkmann <dborkman@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2013-03-20 12:11:47 +00:00
|
|
|
return buff;
|
2015-07-30 14:04:22 +00:00
|
|
|
out_free:
|
|
|
|
free(buff);
|
|
|
|
out:
|
|
|
|
close(fd);
|
|
|
|
return NULL;
|
|
|
|
}
|
|
|
|
|
|
|
|
static char *get_log_buff(const char *file, unsigned int *klen)
|
|
|
|
{
|
|
|
|
return file ? get_flog_buff(file, klen) : get_klog_buff(klen);
|
filter: add minimal BPF JIT image disassembler
This is a minimal stand-alone user space helper, that allows for debugging or
verification of emitted BPF JIT images. This is in particular useful for
emitted opcode debugging, since minor bugs in the JIT compiler can be fatal.
The disassembler is architecture generic and uses libopcodes and libbfd.
How to get to the disassembly, example:
1) `echo 2 > /proc/sys/net/core/bpf_jit_enable`
2) Load a BPF filter (e.g. `tcpdump -p -n -s 0 -i eth1 host 192.168.20.0/24`)
3) Run e.g. `bpf_jit_disasm -o` to disassemble the most recent JIT code output
`bpf_jit_disasm -o` will display the related opcodes to a particular instruction
as well. Example for x86_64:
$ ./bpf_jit_disasm
94 bytes emitted from JIT compiler (pass:3, flen:9)
ffffffffa0356000 + <x>:
0: push %rbp
1: mov %rsp,%rbp
4: sub $0x60,%rsp
8: mov %rbx,-0x8(%rbp)
c: mov 0x68(%rdi),%r9d
10: sub 0x6c(%rdi),%r9d
14: mov 0xe0(%rdi),%r8
1b: mov $0xc,%esi
20: callq 0xffffffffe0d01b71
25: cmp $0x86dd,%eax
2a: jne 0x000000000000003d
2c: mov $0x14,%esi
31: callq 0xffffffffe0d01b8d
36: cmp $0x6,%eax
[...]
5c: leaveq
5d: retq
$ ./bpf_jit_disasm -o
94 bytes emitted from JIT compiler (pass:3, flen:9)
ffffffffa0356000 + <x>:
0: push %rbp
55
1: mov %rsp,%rbp
48 89 e5
4: sub $0x60,%rsp
48 83 ec 60
8: mov %rbx,-0x8(%rbp)
48 89 5d f8
c: mov 0x68(%rdi),%r9d
44 8b 4f 68
10: sub 0x6c(%rdi),%r9d
44 2b 4f 6c
[...]
5c: leaveq
c9
5d: retq
c3
Signed-off-by: Daniel Borkmann <dborkman@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2013-03-20 12:11:47 +00:00
|
|
|
}
|
|
|
|
|
2015-07-30 14:04:22 +00:00
|
|
|
static void put_log_buff(char *buff)
|
filter: add minimal BPF JIT image disassembler
This is a minimal stand-alone user space helper, that allows for debugging or
verification of emitted BPF JIT images. This is in particular useful for
emitted opcode debugging, since minor bugs in the JIT compiler can be fatal.
The disassembler is architecture generic and uses libopcodes and libbfd.
How to get to the disassembly, example:
1) `echo 2 > /proc/sys/net/core/bpf_jit_enable`
2) Load a BPF filter (e.g. `tcpdump -p -n -s 0 -i eth1 host 192.168.20.0/24`)
3) Run e.g. `bpf_jit_disasm -o` to disassemble the most recent JIT code output
`bpf_jit_disasm -o` will display the related opcodes to a particular instruction
as well. Example for x86_64:
$ ./bpf_jit_disasm
94 bytes emitted from JIT compiler (pass:3, flen:9)
ffffffffa0356000 + <x>:
0: push %rbp
1: mov %rsp,%rbp
4: sub $0x60,%rsp
8: mov %rbx,-0x8(%rbp)
c: mov 0x68(%rdi),%r9d
10: sub 0x6c(%rdi),%r9d
14: mov 0xe0(%rdi),%r8
1b: mov $0xc,%esi
20: callq 0xffffffffe0d01b71
25: cmp $0x86dd,%eax
2a: jne 0x000000000000003d
2c: mov $0x14,%esi
31: callq 0xffffffffe0d01b8d
36: cmp $0x6,%eax
[...]
5c: leaveq
5d: retq
$ ./bpf_jit_disasm -o
94 bytes emitted from JIT compiler (pass:3, flen:9)
ffffffffa0356000 + <x>:
0: push %rbp
55
1: mov %rsp,%rbp
48 89 e5
4: sub $0x60,%rsp
48 83 ec 60
8: mov %rbx,-0x8(%rbp)
48 89 5d f8
c: mov 0x68(%rdi),%r9d
44 8b 4f 68
10: sub 0x6c(%rdi),%r9d
44 2b 4f 6c
[...]
5c: leaveq
c9
5d: retq
c3
Signed-off-by: Daniel Borkmann <dborkman@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2013-03-20 12:11:47 +00:00
|
|
|
{
|
|
|
|
free(buff);
|
|
|
|
}
|
|
|
|
|
2017-06-13 23:49:35 +00:00
|
|
|
static uint8_t *get_last_jit_image(char *haystack, size_t hlen,
|
|
|
|
unsigned int *ilen)
|
filter: add minimal BPF JIT image disassembler
This is a minimal stand-alone user space helper, that allows for debugging or
verification of emitted BPF JIT images. This is in particular useful for
emitted opcode debugging, since minor bugs in the JIT compiler can be fatal.
The disassembler is architecture generic and uses libopcodes and libbfd.
How to get to the disassembly, example:
1) `echo 2 > /proc/sys/net/core/bpf_jit_enable`
2) Load a BPF filter (e.g. `tcpdump -p -n -s 0 -i eth1 host 192.168.20.0/24`)
3) Run e.g. `bpf_jit_disasm -o` to disassemble the most recent JIT code output
`bpf_jit_disasm -o` will display the related opcodes to a particular instruction
as well. Example for x86_64:
$ ./bpf_jit_disasm
94 bytes emitted from JIT compiler (pass:3, flen:9)
ffffffffa0356000 + <x>:
0: push %rbp
1: mov %rsp,%rbp
4: sub $0x60,%rsp
8: mov %rbx,-0x8(%rbp)
c: mov 0x68(%rdi),%r9d
10: sub 0x6c(%rdi),%r9d
14: mov 0xe0(%rdi),%r8
1b: mov $0xc,%esi
20: callq 0xffffffffe0d01b71
25: cmp $0x86dd,%eax
2a: jne 0x000000000000003d
2c: mov $0x14,%esi
31: callq 0xffffffffe0d01b8d
36: cmp $0x6,%eax
[...]
5c: leaveq
5d: retq
$ ./bpf_jit_disasm -o
94 bytes emitted from JIT compiler (pass:3, flen:9)
ffffffffa0356000 + <x>:
0: push %rbp
55
1: mov %rsp,%rbp
48 89 e5
4: sub $0x60,%rsp
48 83 ec 60
8: mov %rbx,-0x8(%rbp)
48 89 5d f8
c: mov 0x68(%rdi),%r9d
44 8b 4f 68
10: sub 0x6c(%rdi),%r9d
44 2b 4f 6c
[...]
5c: leaveq
c9
5d: retq
c3
Signed-off-by: Daniel Borkmann <dborkman@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2013-03-20 12:11:47 +00:00
|
|
|
{
|
|
|
|
char *ptr, *pptr, *tmp;
|
|
|
|
off_t off = 0;
|
|
|
|
int ret, flen, proglen, pass, ulen = 0;
|
|
|
|
regmatch_t pmatch[1];
|
2014-05-15 22:56:38 +00:00
|
|
|
unsigned long base;
|
filter: add minimal BPF JIT image disassembler
This is a minimal stand-alone user space helper, that allows for debugging or
verification of emitted BPF JIT images. This is in particular useful for
emitted opcode debugging, since minor bugs in the JIT compiler can be fatal.
The disassembler is architecture generic and uses libopcodes and libbfd.
How to get to the disassembly, example:
1) `echo 2 > /proc/sys/net/core/bpf_jit_enable`
2) Load a BPF filter (e.g. `tcpdump -p -n -s 0 -i eth1 host 192.168.20.0/24`)
3) Run e.g. `bpf_jit_disasm -o` to disassemble the most recent JIT code output
`bpf_jit_disasm -o` will display the related opcodes to a particular instruction
as well. Example for x86_64:
$ ./bpf_jit_disasm
94 bytes emitted from JIT compiler (pass:3, flen:9)
ffffffffa0356000 + <x>:
0: push %rbp
1: mov %rsp,%rbp
4: sub $0x60,%rsp
8: mov %rbx,-0x8(%rbp)
c: mov 0x68(%rdi),%r9d
10: sub 0x6c(%rdi),%r9d
14: mov 0xe0(%rdi),%r8
1b: mov $0xc,%esi
20: callq 0xffffffffe0d01b71
25: cmp $0x86dd,%eax
2a: jne 0x000000000000003d
2c: mov $0x14,%esi
31: callq 0xffffffffe0d01b8d
36: cmp $0x6,%eax
[...]
5c: leaveq
5d: retq
$ ./bpf_jit_disasm -o
94 bytes emitted from JIT compiler (pass:3, flen:9)
ffffffffa0356000 + <x>:
0: push %rbp
55
1: mov %rsp,%rbp
48 89 e5
4: sub $0x60,%rsp
48 83 ec 60
8: mov %rbx,-0x8(%rbp)
48 89 5d f8
c: mov 0x68(%rdi),%r9d
44 8b 4f 68
10: sub 0x6c(%rdi),%r9d
44 2b 4f 6c
[...]
5c: leaveq
c9
5d: retq
c3
Signed-off-by: Daniel Borkmann <dborkman@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2013-03-20 12:11:47 +00:00
|
|
|
regex_t regex;
|
2017-06-13 23:49:35 +00:00
|
|
|
uint8_t *image;
|
filter: add minimal BPF JIT image disassembler
This is a minimal stand-alone user space helper, that allows for debugging or
verification of emitted BPF JIT images. This is in particular useful for
emitted opcode debugging, since minor bugs in the JIT compiler can be fatal.
The disassembler is architecture generic and uses libopcodes and libbfd.
How to get to the disassembly, example:
1) `echo 2 > /proc/sys/net/core/bpf_jit_enable`
2) Load a BPF filter (e.g. `tcpdump -p -n -s 0 -i eth1 host 192.168.20.0/24`)
3) Run e.g. `bpf_jit_disasm -o` to disassemble the most recent JIT code output
`bpf_jit_disasm -o` will display the related opcodes to a particular instruction
as well. Example for x86_64:
$ ./bpf_jit_disasm
94 bytes emitted from JIT compiler (pass:3, flen:9)
ffffffffa0356000 + <x>:
0: push %rbp
1: mov %rsp,%rbp
4: sub $0x60,%rsp
8: mov %rbx,-0x8(%rbp)
c: mov 0x68(%rdi),%r9d
10: sub 0x6c(%rdi),%r9d
14: mov 0xe0(%rdi),%r8
1b: mov $0xc,%esi
20: callq 0xffffffffe0d01b71
25: cmp $0x86dd,%eax
2a: jne 0x000000000000003d
2c: mov $0x14,%esi
31: callq 0xffffffffe0d01b8d
36: cmp $0x6,%eax
[...]
5c: leaveq
5d: retq
$ ./bpf_jit_disasm -o
94 bytes emitted from JIT compiler (pass:3, flen:9)
ffffffffa0356000 + <x>:
0: push %rbp
55
1: mov %rsp,%rbp
48 89 e5
4: sub $0x60,%rsp
48 83 ec 60
8: mov %rbx,-0x8(%rbp)
48 89 5d f8
c: mov 0x68(%rdi),%r9d
44 8b 4f 68
10: sub 0x6c(%rdi),%r9d
44 2b 4f 6c
[...]
5c: leaveq
c9
5d: retq
c3
Signed-off-by: Daniel Borkmann <dborkman@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2013-03-20 12:11:47 +00:00
|
|
|
|
|
|
|
if (hlen == 0)
|
2017-06-13 23:49:35 +00:00
|
|
|
return NULL;
|
filter: add minimal BPF JIT image disassembler
This is a minimal stand-alone user space helper, that allows for debugging or
verification of emitted BPF JIT images. This is in particular useful for
emitted opcode debugging, since minor bugs in the JIT compiler can be fatal.
The disassembler is architecture generic and uses libopcodes and libbfd.
How to get to the disassembly, example:
1) `echo 2 > /proc/sys/net/core/bpf_jit_enable`
2) Load a BPF filter (e.g. `tcpdump -p -n -s 0 -i eth1 host 192.168.20.0/24`)
3) Run e.g. `bpf_jit_disasm -o` to disassemble the most recent JIT code output
`bpf_jit_disasm -o` will display the related opcodes to a particular instruction
as well. Example for x86_64:
$ ./bpf_jit_disasm
94 bytes emitted from JIT compiler (pass:3, flen:9)
ffffffffa0356000 + <x>:
0: push %rbp
1: mov %rsp,%rbp
4: sub $0x60,%rsp
8: mov %rbx,-0x8(%rbp)
c: mov 0x68(%rdi),%r9d
10: sub 0x6c(%rdi),%r9d
14: mov 0xe0(%rdi),%r8
1b: mov $0xc,%esi
20: callq 0xffffffffe0d01b71
25: cmp $0x86dd,%eax
2a: jne 0x000000000000003d
2c: mov $0x14,%esi
31: callq 0xffffffffe0d01b8d
36: cmp $0x6,%eax
[...]
5c: leaveq
5d: retq
$ ./bpf_jit_disasm -o
94 bytes emitted from JIT compiler (pass:3, flen:9)
ffffffffa0356000 + <x>:
0: push %rbp
55
1: mov %rsp,%rbp
48 89 e5
4: sub $0x60,%rsp
48 83 ec 60
8: mov %rbx,-0x8(%rbp)
48 89 5d f8
c: mov 0x68(%rdi),%r9d
44 8b 4f 68
10: sub 0x6c(%rdi),%r9d
44 2b 4f 6c
[...]
5c: leaveq
c9
5d: retq
c3
Signed-off-by: Daniel Borkmann <dborkman@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2013-03-20 12:11:47 +00:00
|
|
|
|
|
|
|
ret = regcomp(®ex, "flen=[[:alnum:]]+ proglen=[[:digit:]]+ "
|
|
|
|
"pass=[[:digit:]]+ image=[[:xdigit:]]+", REG_EXTENDED);
|
|
|
|
assert(ret == 0);
|
|
|
|
|
|
|
|
ptr = haystack;
|
2015-05-25 12:08:03 +00:00
|
|
|
memset(pmatch, 0, sizeof(pmatch));
|
|
|
|
|
filter: add minimal BPF JIT image disassembler
This is a minimal stand-alone user space helper, that allows for debugging or
verification of emitted BPF JIT images. This is in particular useful for
emitted opcode debugging, since minor bugs in the JIT compiler can be fatal.
The disassembler is architecture generic and uses libopcodes and libbfd.
How to get to the disassembly, example:
1) `echo 2 > /proc/sys/net/core/bpf_jit_enable`
2) Load a BPF filter (e.g. `tcpdump -p -n -s 0 -i eth1 host 192.168.20.0/24`)
3) Run e.g. `bpf_jit_disasm -o` to disassemble the most recent JIT code output
`bpf_jit_disasm -o` will display the related opcodes to a particular instruction
as well. Example for x86_64:
$ ./bpf_jit_disasm
94 bytes emitted from JIT compiler (pass:3, flen:9)
ffffffffa0356000 + <x>:
0: push %rbp
1: mov %rsp,%rbp
4: sub $0x60,%rsp
8: mov %rbx,-0x8(%rbp)
c: mov 0x68(%rdi),%r9d
10: sub 0x6c(%rdi),%r9d
14: mov 0xe0(%rdi),%r8
1b: mov $0xc,%esi
20: callq 0xffffffffe0d01b71
25: cmp $0x86dd,%eax
2a: jne 0x000000000000003d
2c: mov $0x14,%esi
31: callq 0xffffffffe0d01b8d
36: cmp $0x6,%eax
[...]
5c: leaveq
5d: retq
$ ./bpf_jit_disasm -o
94 bytes emitted from JIT compiler (pass:3, flen:9)
ffffffffa0356000 + <x>:
0: push %rbp
55
1: mov %rsp,%rbp
48 89 e5
4: sub $0x60,%rsp
48 83 ec 60
8: mov %rbx,-0x8(%rbp)
48 89 5d f8
c: mov 0x68(%rdi),%r9d
44 8b 4f 68
10: sub 0x6c(%rdi),%r9d
44 2b 4f 6c
[...]
5c: leaveq
c9
5d: retq
c3
Signed-off-by: Daniel Borkmann <dborkman@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2013-03-20 12:11:47 +00:00
|
|
|
while (1) {
|
|
|
|
ret = regexec(®ex, ptr, 1, pmatch, 0);
|
|
|
|
if (ret == 0) {
|
|
|
|
ptr += pmatch[0].rm_eo;
|
|
|
|
off += pmatch[0].rm_eo;
|
|
|
|
assert(off < hlen);
|
|
|
|
} else
|
|
|
|
break;
|
|
|
|
}
|
|
|
|
|
|
|
|
ptr = haystack + off - (pmatch[0].rm_eo - pmatch[0].rm_so);
|
|
|
|
ret = sscanf(ptr, "flen=%d proglen=%d pass=%d image=%lx",
|
2014-05-15 22:56:38 +00:00
|
|
|
&flen, &proglen, &pass, &base);
|
2015-07-30 14:04:22 +00:00
|
|
|
if (ret != 4) {
|
|
|
|
regfree(®ex);
|
2017-06-13 23:49:35 +00:00
|
|
|
return NULL;
|
|
|
|
}
|
|
|
|
if (proglen > 1000000) {
|
|
|
|
printf("proglen of %d too big, stopping\n", proglen);
|
|
|
|
return NULL;
|
2015-07-30 14:04:22 +00:00
|
|
|
}
|
filter: add minimal BPF JIT image disassembler
This is a minimal stand-alone user space helper, that allows for debugging or
verification of emitted BPF JIT images. This is in particular useful for
emitted opcode debugging, since minor bugs in the JIT compiler can be fatal.
The disassembler is architecture generic and uses libopcodes and libbfd.
How to get to the disassembly, example:
1) `echo 2 > /proc/sys/net/core/bpf_jit_enable`
2) Load a BPF filter (e.g. `tcpdump -p -n -s 0 -i eth1 host 192.168.20.0/24`)
3) Run e.g. `bpf_jit_disasm -o` to disassemble the most recent JIT code output
`bpf_jit_disasm -o` will display the related opcodes to a particular instruction
as well. Example for x86_64:
$ ./bpf_jit_disasm
94 bytes emitted from JIT compiler (pass:3, flen:9)
ffffffffa0356000 + <x>:
0: push %rbp
1: mov %rsp,%rbp
4: sub $0x60,%rsp
8: mov %rbx,-0x8(%rbp)
c: mov 0x68(%rdi),%r9d
10: sub 0x6c(%rdi),%r9d
14: mov 0xe0(%rdi),%r8
1b: mov $0xc,%esi
20: callq 0xffffffffe0d01b71
25: cmp $0x86dd,%eax
2a: jne 0x000000000000003d
2c: mov $0x14,%esi
31: callq 0xffffffffe0d01b8d
36: cmp $0x6,%eax
[...]
5c: leaveq
5d: retq
$ ./bpf_jit_disasm -o
94 bytes emitted from JIT compiler (pass:3, flen:9)
ffffffffa0356000 + <x>:
0: push %rbp
55
1: mov %rsp,%rbp
48 89 e5
4: sub $0x60,%rsp
48 83 ec 60
8: mov %rbx,-0x8(%rbp)
48 89 5d f8
c: mov 0x68(%rdi),%r9d
44 8b 4f 68
10: sub 0x6c(%rdi),%r9d
44 2b 4f 6c
[...]
5c: leaveq
c9
5d: retq
c3
Signed-off-by: Daniel Borkmann <dborkman@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2013-03-20 12:11:47 +00:00
|
|
|
|
2017-06-13 23:49:35 +00:00
|
|
|
image = malloc(proglen);
|
|
|
|
if (!image) {
|
|
|
|
printf("Out of memory\n");
|
|
|
|
return NULL;
|
|
|
|
}
|
|
|
|
memset(image, 0, proglen);
|
|
|
|
|
filter: add minimal BPF JIT image disassembler
This is a minimal stand-alone user space helper, that allows for debugging or
verification of emitted BPF JIT images. This is in particular useful for
emitted opcode debugging, since minor bugs in the JIT compiler can be fatal.
The disassembler is architecture generic and uses libopcodes and libbfd.
How to get to the disassembly, example:
1) `echo 2 > /proc/sys/net/core/bpf_jit_enable`
2) Load a BPF filter (e.g. `tcpdump -p -n -s 0 -i eth1 host 192.168.20.0/24`)
3) Run e.g. `bpf_jit_disasm -o` to disassemble the most recent JIT code output
`bpf_jit_disasm -o` will display the related opcodes to a particular instruction
as well. Example for x86_64:
$ ./bpf_jit_disasm
94 bytes emitted from JIT compiler (pass:3, flen:9)
ffffffffa0356000 + <x>:
0: push %rbp
1: mov %rsp,%rbp
4: sub $0x60,%rsp
8: mov %rbx,-0x8(%rbp)
c: mov 0x68(%rdi),%r9d
10: sub 0x6c(%rdi),%r9d
14: mov 0xe0(%rdi),%r8
1b: mov $0xc,%esi
20: callq 0xffffffffe0d01b71
25: cmp $0x86dd,%eax
2a: jne 0x000000000000003d
2c: mov $0x14,%esi
31: callq 0xffffffffe0d01b8d
36: cmp $0x6,%eax
[...]
5c: leaveq
5d: retq
$ ./bpf_jit_disasm -o
94 bytes emitted from JIT compiler (pass:3, flen:9)
ffffffffa0356000 + <x>:
0: push %rbp
55
1: mov %rsp,%rbp
48 89 e5
4: sub $0x60,%rsp
48 83 ec 60
8: mov %rbx,-0x8(%rbp)
48 89 5d f8
c: mov 0x68(%rdi),%r9d
44 8b 4f 68
10: sub 0x6c(%rdi),%r9d
44 2b 4f 6c
[...]
5c: leaveq
c9
5d: retq
c3
Signed-off-by: Daniel Borkmann <dborkman@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2013-03-20 12:11:47 +00:00
|
|
|
tmp = ptr = haystack + off;
|
2017-06-13 23:49:35 +00:00
|
|
|
while ((ptr = strtok(tmp, "\n")) != NULL && ulen < proglen) {
|
filter: add minimal BPF JIT image disassembler
This is a minimal stand-alone user space helper, that allows for debugging or
verification of emitted BPF JIT images. This is in particular useful for
emitted opcode debugging, since minor bugs in the JIT compiler can be fatal.
The disassembler is architecture generic and uses libopcodes and libbfd.
How to get to the disassembly, example:
1) `echo 2 > /proc/sys/net/core/bpf_jit_enable`
2) Load a BPF filter (e.g. `tcpdump -p -n -s 0 -i eth1 host 192.168.20.0/24`)
3) Run e.g. `bpf_jit_disasm -o` to disassemble the most recent JIT code output
`bpf_jit_disasm -o` will display the related opcodes to a particular instruction
as well. Example for x86_64:
$ ./bpf_jit_disasm
94 bytes emitted from JIT compiler (pass:3, flen:9)
ffffffffa0356000 + <x>:
0: push %rbp
1: mov %rsp,%rbp
4: sub $0x60,%rsp
8: mov %rbx,-0x8(%rbp)
c: mov 0x68(%rdi),%r9d
10: sub 0x6c(%rdi),%r9d
14: mov 0xe0(%rdi),%r8
1b: mov $0xc,%esi
20: callq 0xffffffffe0d01b71
25: cmp $0x86dd,%eax
2a: jne 0x000000000000003d
2c: mov $0x14,%esi
31: callq 0xffffffffe0d01b8d
36: cmp $0x6,%eax
[...]
5c: leaveq
5d: retq
$ ./bpf_jit_disasm -o
94 bytes emitted from JIT compiler (pass:3, flen:9)
ffffffffa0356000 + <x>:
0: push %rbp
55
1: mov %rsp,%rbp
48 89 e5
4: sub $0x60,%rsp
48 83 ec 60
8: mov %rbx,-0x8(%rbp)
48 89 5d f8
c: mov 0x68(%rdi),%r9d
44 8b 4f 68
10: sub 0x6c(%rdi),%r9d
44 2b 4f 6c
[...]
5c: leaveq
c9
5d: retq
c3
Signed-off-by: Daniel Borkmann <dborkman@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2013-03-20 12:11:47 +00:00
|
|
|
tmp = NULL;
|
|
|
|
if (!strstr(ptr, "JIT code"))
|
|
|
|
continue;
|
|
|
|
pptr = ptr;
|
|
|
|
while ((ptr = strstr(pptr, ":")))
|
|
|
|
pptr = ptr + 1;
|
|
|
|
ptr = pptr;
|
|
|
|
do {
|
|
|
|
image[ulen++] = (uint8_t) strtoul(pptr, &pptr, 16);
|
2017-06-13 23:49:35 +00:00
|
|
|
if (ptr == pptr) {
|
filter: add minimal BPF JIT image disassembler
This is a minimal stand-alone user space helper, that allows for debugging or
verification of emitted BPF JIT images. This is in particular useful for
emitted opcode debugging, since minor bugs in the JIT compiler can be fatal.
The disassembler is architecture generic and uses libopcodes and libbfd.
How to get to the disassembly, example:
1) `echo 2 > /proc/sys/net/core/bpf_jit_enable`
2) Load a BPF filter (e.g. `tcpdump -p -n -s 0 -i eth1 host 192.168.20.0/24`)
3) Run e.g. `bpf_jit_disasm -o` to disassemble the most recent JIT code output
`bpf_jit_disasm -o` will display the related opcodes to a particular instruction
as well. Example for x86_64:
$ ./bpf_jit_disasm
94 bytes emitted from JIT compiler (pass:3, flen:9)
ffffffffa0356000 + <x>:
0: push %rbp
1: mov %rsp,%rbp
4: sub $0x60,%rsp
8: mov %rbx,-0x8(%rbp)
c: mov 0x68(%rdi),%r9d
10: sub 0x6c(%rdi),%r9d
14: mov 0xe0(%rdi),%r8
1b: mov $0xc,%esi
20: callq 0xffffffffe0d01b71
25: cmp $0x86dd,%eax
2a: jne 0x000000000000003d
2c: mov $0x14,%esi
31: callq 0xffffffffe0d01b8d
36: cmp $0x6,%eax
[...]
5c: leaveq
5d: retq
$ ./bpf_jit_disasm -o
94 bytes emitted from JIT compiler (pass:3, flen:9)
ffffffffa0356000 + <x>:
0: push %rbp
55
1: mov %rsp,%rbp
48 89 e5
4: sub $0x60,%rsp
48 83 ec 60
8: mov %rbx,-0x8(%rbp)
48 89 5d f8
c: mov 0x68(%rdi),%r9d
44 8b 4f 68
10: sub 0x6c(%rdi),%r9d
44 2b 4f 6c
[...]
5c: leaveq
c9
5d: retq
c3
Signed-off-by: Daniel Borkmann <dborkman@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2013-03-20 12:11:47 +00:00
|
|
|
ulen--;
|
|
|
|
break;
|
|
|
|
}
|
2017-06-13 23:49:35 +00:00
|
|
|
if (ulen >= proglen)
|
|
|
|
break;
|
filter: add minimal BPF JIT image disassembler
This is a minimal stand-alone user space helper, that allows for debugging or
verification of emitted BPF JIT images. This is in particular useful for
emitted opcode debugging, since minor bugs in the JIT compiler can be fatal.
The disassembler is architecture generic and uses libopcodes and libbfd.
How to get to the disassembly, example:
1) `echo 2 > /proc/sys/net/core/bpf_jit_enable`
2) Load a BPF filter (e.g. `tcpdump -p -n -s 0 -i eth1 host 192.168.20.0/24`)
3) Run e.g. `bpf_jit_disasm -o` to disassemble the most recent JIT code output
`bpf_jit_disasm -o` will display the related opcodes to a particular instruction
as well. Example for x86_64:
$ ./bpf_jit_disasm
94 bytes emitted from JIT compiler (pass:3, flen:9)
ffffffffa0356000 + <x>:
0: push %rbp
1: mov %rsp,%rbp
4: sub $0x60,%rsp
8: mov %rbx,-0x8(%rbp)
c: mov 0x68(%rdi),%r9d
10: sub 0x6c(%rdi),%r9d
14: mov 0xe0(%rdi),%r8
1b: mov $0xc,%esi
20: callq 0xffffffffe0d01b71
25: cmp $0x86dd,%eax
2a: jne 0x000000000000003d
2c: mov $0x14,%esi
31: callq 0xffffffffe0d01b8d
36: cmp $0x6,%eax
[...]
5c: leaveq
5d: retq
$ ./bpf_jit_disasm -o
94 bytes emitted from JIT compiler (pass:3, flen:9)
ffffffffa0356000 + <x>:
0: push %rbp
55
1: mov %rsp,%rbp
48 89 e5
4: sub $0x60,%rsp
48 83 ec 60
8: mov %rbx,-0x8(%rbp)
48 89 5d f8
c: mov 0x68(%rdi),%r9d
44 8b 4f 68
10: sub 0x6c(%rdi),%r9d
44 2b 4f 6c
[...]
5c: leaveq
c9
5d: retq
c3
Signed-off-by: Daniel Borkmann <dborkman@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2013-03-20 12:11:47 +00:00
|
|
|
ptr = pptr;
|
|
|
|
} while (1);
|
|
|
|
}
|
|
|
|
|
|
|
|
assert(ulen == proglen);
|
|
|
|
printf("%d bytes emitted from JIT compiler (pass:%d, flen:%d)\n",
|
|
|
|
proglen, pass, flen);
|
2014-05-15 22:56:38 +00:00
|
|
|
printf("%lx + <x>:\n", base);
|
filter: add minimal BPF JIT image disassembler
This is a minimal stand-alone user space helper, that allows for debugging or
verification of emitted BPF JIT images. This is in particular useful for
emitted opcode debugging, since minor bugs in the JIT compiler can be fatal.
The disassembler is architecture generic and uses libopcodes and libbfd.
How to get to the disassembly, example:
1) `echo 2 > /proc/sys/net/core/bpf_jit_enable`
2) Load a BPF filter (e.g. `tcpdump -p -n -s 0 -i eth1 host 192.168.20.0/24`)
3) Run e.g. `bpf_jit_disasm -o` to disassemble the most recent JIT code output
`bpf_jit_disasm -o` will display the related opcodes to a particular instruction
as well. Example for x86_64:
$ ./bpf_jit_disasm
94 bytes emitted from JIT compiler (pass:3, flen:9)
ffffffffa0356000 + <x>:
0: push %rbp
1: mov %rsp,%rbp
4: sub $0x60,%rsp
8: mov %rbx,-0x8(%rbp)
c: mov 0x68(%rdi),%r9d
10: sub 0x6c(%rdi),%r9d
14: mov 0xe0(%rdi),%r8
1b: mov $0xc,%esi
20: callq 0xffffffffe0d01b71
25: cmp $0x86dd,%eax
2a: jne 0x000000000000003d
2c: mov $0x14,%esi
31: callq 0xffffffffe0d01b8d
36: cmp $0x6,%eax
[...]
5c: leaveq
5d: retq
$ ./bpf_jit_disasm -o
94 bytes emitted from JIT compiler (pass:3, flen:9)
ffffffffa0356000 + <x>:
0: push %rbp
55
1: mov %rsp,%rbp
48 89 e5
4: sub $0x60,%rsp
48 83 ec 60
8: mov %rbx,-0x8(%rbp)
48 89 5d f8
c: mov 0x68(%rdi),%r9d
44 8b 4f 68
10: sub 0x6c(%rdi),%r9d
44 2b 4f 6c
[...]
5c: leaveq
c9
5d: retq
c3
Signed-off-by: Daniel Borkmann <dborkman@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2013-03-20 12:11:47 +00:00
|
|
|
|
|
|
|
regfree(®ex);
|
2017-06-13 23:49:35 +00:00
|
|
|
*ilen = ulen;
|
|
|
|
return image;
|
filter: add minimal BPF JIT image disassembler
This is a minimal stand-alone user space helper, that allows for debugging or
verification of emitted BPF JIT images. This is in particular useful for
emitted opcode debugging, since minor bugs in the JIT compiler can be fatal.
The disassembler is architecture generic and uses libopcodes and libbfd.
How to get to the disassembly, example:
1) `echo 2 > /proc/sys/net/core/bpf_jit_enable`
2) Load a BPF filter (e.g. `tcpdump -p -n -s 0 -i eth1 host 192.168.20.0/24`)
3) Run e.g. `bpf_jit_disasm -o` to disassemble the most recent JIT code output
`bpf_jit_disasm -o` will display the related opcodes to a particular instruction
as well. Example for x86_64:
$ ./bpf_jit_disasm
94 bytes emitted from JIT compiler (pass:3, flen:9)
ffffffffa0356000 + <x>:
0: push %rbp
1: mov %rsp,%rbp
4: sub $0x60,%rsp
8: mov %rbx,-0x8(%rbp)
c: mov 0x68(%rdi),%r9d
10: sub 0x6c(%rdi),%r9d
14: mov 0xe0(%rdi),%r8
1b: mov $0xc,%esi
20: callq 0xffffffffe0d01b71
25: cmp $0x86dd,%eax
2a: jne 0x000000000000003d
2c: mov $0x14,%esi
31: callq 0xffffffffe0d01b8d
36: cmp $0x6,%eax
[...]
5c: leaveq
5d: retq
$ ./bpf_jit_disasm -o
94 bytes emitted from JIT compiler (pass:3, flen:9)
ffffffffa0356000 + <x>:
0: push %rbp
55
1: mov %rsp,%rbp
48 89 e5
4: sub $0x60,%rsp
48 83 ec 60
8: mov %rbx,-0x8(%rbp)
48 89 5d f8
c: mov 0x68(%rdi),%r9d
44 8b 4f 68
10: sub 0x6c(%rdi),%r9d
44 2b 4f 6c
[...]
5c: leaveq
c9
5d: retq
c3
Signed-off-by: Daniel Borkmann <dborkman@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2013-03-20 12:11:47 +00:00
|
|
|
}
|
|
|
|
|
2015-07-30 14:04:22 +00:00
|
|
|
static void usage(void)
|
|
|
|
{
|
|
|
|
printf("Usage: bpf_jit_disasm [...]\n");
|
|
|
|
printf(" -o Also display related opcodes (default: off).\n");
|
2017-04-11 21:30:52 +00:00
|
|
|
printf(" -O <file> Write binary image of code to file, don't disassemble to stdout.\n");
|
2015-07-30 14:04:22 +00:00
|
|
|
printf(" -f <file> Read last image dump from file or stdin (default: klog).\n");
|
|
|
|
printf(" -h Display this help.\n");
|
|
|
|
}
|
|
|
|
|
filter: add minimal BPF JIT image disassembler
This is a minimal stand-alone user space helper, that allows for debugging or
verification of emitted BPF JIT images. This is in particular useful for
emitted opcode debugging, since minor bugs in the JIT compiler can be fatal.
The disassembler is architecture generic and uses libopcodes and libbfd.
How to get to the disassembly, example:
1) `echo 2 > /proc/sys/net/core/bpf_jit_enable`
2) Load a BPF filter (e.g. `tcpdump -p -n -s 0 -i eth1 host 192.168.20.0/24`)
3) Run e.g. `bpf_jit_disasm -o` to disassemble the most recent JIT code output
`bpf_jit_disasm -o` will display the related opcodes to a particular instruction
as well. Example for x86_64:
$ ./bpf_jit_disasm
94 bytes emitted from JIT compiler (pass:3, flen:9)
ffffffffa0356000 + <x>:
0: push %rbp
1: mov %rsp,%rbp
4: sub $0x60,%rsp
8: mov %rbx,-0x8(%rbp)
c: mov 0x68(%rdi),%r9d
10: sub 0x6c(%rdi),%r9d
14: mov 0xe0(%rdi),%r8
1b: mov $0xc,%esi
20: callq 0xffffffffe0d01b71
25: cmp $0x86dd,%eax
2a: jne 0x000000000000003d
2c: mov $0x14,%esi
31: callq 0xffffffffe0d01b8d
36: cmp $0x6,%eax
[...]
5c: leaveq
5d: retq
$ ./bpf_jit_disasm -o
94 bytes emitted from JIT compiler (pass:3, flen:9)
ffffffffa0356000 + <x>:
0: push %rbp
55
1: mov %rsp,%rbp
48 89 e5
4: sub $0x60,%rsp
48 83 ec 60
8: mov %rbx,-0x8(%rbp)
48 89 5d f8
c: mov 0x68(%rdi),%r9d
44 8b 4f 68
10: sub 0x6c(%rdi),%r9d
44 2b 4f 6c
[...]
5c: leaveq
c9
5d: retq
c3
Signed-off-by: Daniel Borkmann <dborkman@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2013-03-20 12:11:47 +00:00
|
|
|
int main(int argc, char **argv)
|
|
|
|
{
|
2015-07-30 14:04:22 +00:00
|
|
|
unsigned int len, klen, opt, opcodes = 0;
|
|
|
|
char *kbuff, *file = NULL;
|
2017-04-11 21:30:52 +00:00
|
|
|
char *ofile = NULL;
|
|
|
|
int ofd;
|
|
|
|
ssize_t nr;
|
|
|
|
uint8_t *pos;
|
2017-06-13 23:49:35 +00:00
|
|
|
uint8_t *image = NULL;
|
filter: add minimal BPF JIT image disassembler
This is a minimal stand-alone user space helper, that allows for debugging or
verification of emitted BPF JIT images. This is in particular useful for
emitted opcode debugging, since minor bugs in the JIT compiler can be fatal.
The disassembler is architecture generic and uses libopcodes and libbfd.
How to get to the disassembly, example:
1) `echo 2 > /proc/sys/net/core/bpf_jit_enable`
2) Load a BPF filter (e.g. `tcpdump -p -n -s 0 -i eth1 host 192.168.20.0/24`)
3) Run e.g. `bpf_jit_disasm -o` to disassemble the most recent JIT code output
`bpf_jit_disasm -o` will display the related opcodes to a particular instruction
as well. Example for x86_64:
$ ./bpf_jit_disasm
94 bytes emitted from JIT compiler (pass:3, flen:9)
ffffffffa0356000 + <x>:
0: push %rbp
1: mov %rsp,%rbp
4: sub $0x60,%rsp
8: mov %rbx,-0x8(%rbp)
c: mov 0x68(%rdi),%r9d
10: sub 0x6c(%rdi),%r9d
14: mov 0xe0(%rdi),%r8
1b: mov $0xc,%esi
20: callq 0xffffffffe0d01b71
25: cmp $0x86dd,%eax
2a: jne 0x000000000000003d
2c: mov $0x14,%esi
31: callq 0xffffffffe0d01b8d
36: cmp $0x6,%eax
[...]
5c: leaveq
5d: retq
$ ./bpf_jit_disasm -o
94 bytes emitted from JIT compiler (pass:3, flen:9)
ffffffffa0356000 + <x>:
0: push %rbp
55
1: mov %rsp,%rbp
48 89 e5
4: sub $0x60,%rsp
48 83 ec 60
8: mov %rbx,-0x8(%rbp)
48 89 5d f8
c: mov 0x68(%rdi),%r9d
44 8b 4f 68
10: sub 0x6c(%rdi),%r9d
44 2b 4f 6c
[...]
5c: leaveq
c9
5d: retq
c3
Signed-off-by: Daniel Borkmann <dborkman@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2013-03-20 12:11:47 +00:00
|
|
|
|
2017-04-11 21:30:52 +00:00
|
|
|
while ((opt = getopt(argc, argv, "of:O:")) != -1) {
|
2015-07-30 14:04:22 +00:00
|
|
|
switch (opt) {
|
|
|
|
case 'o':
|
filter: add minimal BPF JIT image disassembler
This is a minimal stand-alone user space helper, that allows for debugging or
verification of emitted BPF JIT images. This is in particular useful for
emitted opcode debugging, since minor bugs in the JIT compiler can be fatal.
The disassembler is architecture generic and uses libopcodes and libbfd.
How to get to the disassembly, example:
1) `echo 2 > /proc/sys/net/core/bpf_jit_enable`
2) Load a BPF filter (e.g. `tcpdump -p -n -s 0 -i eth1 host 192.168.20.0/24`)
3) Run e.g. `bpf_jit_disasm -o` to disassemble the most recent JIT code output
`bpf_jit_disasm -o` will display the related opcodes to a particular instruction
as well. Example for x86_64:
$ ./bpf_jit_disasm
94 bytes emitted from JIT compiler (pass:3, flen:9)
ffffffffa0356000 + <x>:
0: push %rbp
1: mov %rsp,%rbp
4: sub $0x60,%rsp
8: mov %rbx,-0x8(%rbp)
c: mov 0x68(%rdi),%r9d
10: sub 0x6c(%rdi),%r9d
14: mov 0xe0(%rdi),%r8
1b: mov $0xc,%esi
20: callq 0xffffffffe0d01b71
25: cmp $0x86dd,%eax
2a: jne 0x000000000000003d
2c: mov $0x14,%esi
31: callq 0xffffffffe0d01b8d
36: cmp $0x6,%eax
[...]
5c: leaveq
5d: retq
$ ./bpf_jit_disasm -o
94 bytes emitted from JIT compiler (pass:3, flen:9)
ffffffffa0356000 + <x>:
0: push %rbp
55
1: mov %rsp,%rbp
48 89 e5
4: sub $0x60,%rsp
48 83 ec 60
8: mov %rbx,-0x8(%rbp)
48 89 5d f8
c: mov 0x68(%rdi),%r9d
44 8b 4f 68
10: sub 0x6c(%rdi),%r9d
44 2b 4f 6c
[...]
5c: leaveq
c9
5d: retq
c3
Signed-off-by: Daniel Borkmann <dborkman@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2013-03-20 12:11:47 +00:00
|
|
|
opcodes = 1;
|
2015-07-30 14:04:22 +00:00
|
|
|
break;
|
2017-04-11 21:30:52 +00:00
|
|
|
case 'O':
|
|
|
|
ofile = optarg;
|
|
|
|
break;
|
2015-07-30 14:04:22 +00:00
|
|
|
case 'f':
|
|
|
|
file = optarg;
|
|
|
|
break;
|
|
|
|
default:
|
|
|
|
usage();
|
|
|
|
return -1;
|
filter: add minimal BPF JIT image disassembler
This is a minimal stand-alone user space helper, that allows for debugging or
verification of emitted BPF JIT images. This is in particular useful for
emitted opcode debugging, since minor bugs in the JIT compiler can be fatal.
The disassembler is architecture generic and uses libopcodes and libbfd.
How to get to the disassembly, example:
1) `echo 2 > /proc/sys/net/core/bpf_jit_enable`
2) Load a BPF filter (e.g. `tcpdump -p -n -s 0 -i eth1 host 192.168.20.0/24`)
3) Run e.g. `bpf_jit_disasm -o` to disassemble the most recent JIT code output
`bpf_jit_disasm -o` will display the related opcodes to a particular instruction
as well. Example for x86_64:
$ ./bpf_jit_disasm
94 bytes emitted from JIT compiler (pass:3, flen:9)
ffffffffa0356000 + <x>:
0: push %rbp
1: mov %rsp,%rbp
4: sub $0x60,%rsp
8: mov %rbx,-0x8(%rbp)
c: mov 0x68(%rdi),%r9d
10: sub 0x6c(%rdi),%r9d
14: mov 0xe0(%rdi),%r8
1b: mov $0xc,%esi
20: callq 0xffffffffe0d01b71
25: cmp $0x86dd,%eax
2a: jne 0x000000000000003d
2c: mov $0x14,%esi
31: callq 0xffffffffe0d01b8d
36: cmp $0x6,%eax
[...]
5c: leaveq
5d: retq
$ ./bpf_jit_disasm -o
94 bytes emitted from JIT compiler (pass:3, flen:9)
ffffffffa0356000 + <x>:
0: push %rbp
55
1: mov %rsp,%rbp
48 89 e5
4: sub $0x60,%rsp
48 83 ec 60
8: mov %rbx,-0x8(%rbp)
48 89 5d f8
c: mov 0x68(%rdi),%r9d
44 8b 4f 68
10: sub 0x6c(%rdi),%r9d
44 2b 4f 6c
[...]
5c: leaveq
c9
5d: retq
c3
Signed-off-by: Daniel Borkmann <dborkman@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2013-03-20 12:11:47 +00:00
|
|
|
}
|
|
|
|
}
|
|
|
|
|
|
|
|
bfd_init();
|
|
|
|
|
2015-07-30 14:04:22 +00:00
|
|
|
kbuff = get_log_buff(file, &klen);
|
|
|
|
if (!kbuff) {
|
|
|
|
fprintf(stderr, "Could not retrieve log buffer!\n");
|
|
|
|
return -1;
|
|
|
|
}
|
filter: add minimal BPF JIT image disassembler
This is a minimal stand-alone user space helper, that allows for debugging or
verification of emitted BPF JIT images. This is in particular useful for
emitted opcode debugging, since minor bugs in the JIT compiler can be fatal.
The disassembler is architecture generic and uses libopcodes and libbfd.
How to get to the disassembly, example:
1) `echo 2 > /proc/sys/net/core/bpf_jit_enable`
2) Load a BPF filter (e.g. `tcpdump -p -n -s 0 -i eth1 host 192.168.20.0/24`)
3) Run e.g. `bpf_jit_disasm -o` to disassemble the most recent JIT code output
`bpf_jit_disasm -o` will display the related opcodes to a particular instruction
as well. Example for x86_64:
$ ./bpf_jit_disasm
94 bytes emitted from JIT compiler (pass:3, flen:9)
ffffffffa0356000 + <x>:
0: push %rbp
1: mov %rsp,%rbp
4: sub $0x60,%rsp
8: mov %rbx,-0x8(%rbp)
c: mov 0x68(%rdi),%r9d
10: sub 0x6c(%rdi),%r9d
14: mov 0xe0(%rdi),%r8
1b: mov $0xc,%esi
20: callq 0xffffffffe0d01b71
25: cmp $0x86dd,%eax
2a: jne 0x000000000000003d
2c: mov $0x14,%esi
31: callq 0xffffffffe0d01b8d
36: cmp $0x6,%eax
[...]
5c: leaveq
5d: retq
$ ./bpf_jit_disasm -o
94 bytes emitted from JIT compiler (pass:3, flen:9)
ffffffffa0356000 + <x>:
0: push %rbp
55
1: mov %rsp,%rbp
48 89 e5
4: sub $0x60,%rsp
48 83 ec 60
8: mov %rbx,-0x8(%rbp)
48 89 5d f8
c: mov 0x68(%rdi),%r9d
44 8b 4f 68
10: sub 0x6c(%rdi),%r9d
44 2b 4f 6c
[...]
5c: leaveq
c9
5d: retq
c3
Signed-off-by: Daniel Borkmann <dborkman@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2013-03-20 12:11:47 +00:00
|
|
|
|
2017-06-13 23:49:35 +00:00
|
|
|
image = get_last_jit_image(kbuff, klen, &len);
|
|
|
|
if (!image) {
|
2015-07-30 14:04:22 +00:00
|
|
|
fprintf(stderr, "No JIT image found!\n");
|
2017-04-11 21:30:52 +00:00
|
|
|
goto done;
|
|
|
|
}
|
|
|
|
if (!ofile) {
|
|
|
|
get_asm_insns(image, len, opcodes);
|
|
|
|
goto done;
|
|
|
|
}
|
|
|
|
|
|
|
|
ofd = open(ofile, O_WRONLY | O_CREAT | O_TRUNC, DEFFILEMODE);
|
|
|
|
if (ofd < 0) {
|
|
|
|
fprintf(stderr, "Could not open file %s for writing: ", ofile);
|
|
|
|
perror(NULL);
|
|
|
|
goto done;
|
|
|
|
}
|
|
|
|
pos = image;
|
|
|
|
do {
|
|
|
|
nr = write(ofd, pos, len);
|
|
|
|
if (nr < 0) {
|
|
|
|
fprintf(stderr, "Could not write data to %s: ", ofile);
|
|
|
|
perror(NULL);
|
|
|
|
goto done;
|
|
|
|
}
|
|
|
|
len -= nr;
|
|
|
|
pos += nr;
|
|
|
|
} while (len);
|
|
|
|
close(ofd);
|
filter: add minimal BPF JIT image disassembler
This is a minimal stand-alone user space helper, that allows for debugging or
verification of emitted BPF JIT images. This is in particular useful for
emitted opcode debugging, since minor bugs in the JIT compiler can be fatal.
The disassembler is architecture generic and uses libopcodes and libbfd.
How to get to the disassembly, example:
1) `echo 2 > /proc/sys/net/core/bpf_jit_enable`
2) Load a BPF filter (e.g. `tcpdump -p -n -s 0 -i eth1 host 192.168.20.0/24`)
3) Run e.g. `bpf_jit_disasm -o` to disassemble the most recent JIT code output
`bpf_jit_disasm -o` will display the related opcodes to a particular instruction
as well. Example for x86_64:
$ ./bpf_jit_disasm
94 bytes emitted from JIT compiler (pass:3, flen:9)
ffffffffa0356000 + <x>:
0: push %rbp
1: mov %rsp,%rbp
4: sub $0x60,%rsp
8: mov %rbx,-0x8(%rbp)
c: mov 0x68(%rdi),%r9d
10: sub 0x6c(%rdi),%r9d
14: mov 0xe0(%rdi),%r8
1b: mov $0xc,%esi
20: callq 0xffffffffe0d01b71
25: cmp $0x86dd,%eax
2a: jne 0x000000000000003d
2c: mov $0x14,%esi
31: callq 0xffffffffe0d01b8d
36: cmp $0x6,%eax
[...]
5c: leaveq
5d: retq
$ ./bpf_jit_disasm -o
94 bytes emitted from JIT compiler (pass:3, flen:9)
ffffffffa0356000 + <x>:
0: push %rbp
55
1: mov %rsp,%rbp
48 89 e5
4: sub $0x60,%rsp
48 83 ec 60
8: mov %rbx,-0x8(%rbp)
48 89 5d f8
c: mov 0x68(%rdi),%r9d
44 8b 4f 68
10: sub 0x6c(%rdi),%r9d
44 2b 4f 6c
[...]
5c: leaveq
c9
5d: retq
c3
Signed-off-by: Daniel Borkmann <dborkman@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2013-03-20 12:11:47 +00:00
|
|
|
|
2017-04-11 21:30:52 +00:00
|
|
|
done:
|
2015-07-30 14:04:22 +00:00
|
|
|
put_log_buff(kbuff);
|
2017-06-13 23:49:35 +00:00
|
|
|
free(image);
|
filter: add minimal BPF JIT image disassembler
This is a minimal stand-alone user space helper, that allows for debugging or
verification of emitted BPF JIT images. This is in particular useful for
emitted opcode debugging, since minor bugs in the JIT compiler can be fatal.
The disassembler is architecture generic and uses libopcodes and libbfd.
How to get to the disassembly, example:
1) `echo 2 > /proc/sys/net/core/bpf_jit_enable`
2) Load a BPF filter (e.g. `tcpdump -p -n -s 0 -i eth1 host 192.168.20.0/24`)
3) Run e.g. `bpf_jit_disasm -o` to disassemble the most recent JIT code output
`bpf_jit_disasm -o` will display the related opcodes to a particular instruction
as well. Example for x86_64:
$ ./bpf_jit_disasm
94 bytes emitted from JIT compiler (pass:3, flen:9)
ffffffffa0356000 + <x>:
0: push %rbp
1: mov %rsp,%rbp
4: sub $0x60,%rsp
8: mov %rbx,-0x8(%rbp)
c: mov 0x68(%rdi),%r9d
10: sub 0x6c(%rdi),%r9d
14: mov 0xe0(%rdi),%r8
1b: mov $0xc,%esi
20: callq 0xffffffffe0d01b71
25: cmp $0x86dd,%eax
2a: jne 0x000000000000003d
2c: mov $0x14,%esi
31: callq 0xffffffffe0d01b8d
36: cmp $0x6,%eax
[...]
5c: leaveq
5d: retq
$ ./bpf_jit_disasm -o
94 bytes emitted from JIT compiler (pass:3, flen:9)
ffffffffa0356000 + <x>:
0: push %rbp
55
1: mov %rsp,%rbp
48 89 e5
4: sub $0x60,%rsp
48 83 ec 60
8: mov %rbx,-0x8(%rbp)
48 89 5d f8
c: mov 0x68(%rdi),%r9d
44 8b 4f 68
10: sub 0x6c(%rdi),%r9d
44 2b 4f 6c
[...]
5c: leaveq
c9
5d: retq
c3
Signed-off-by: Daniel Borkmann <dborkman@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2013-03-20 12:11:47 +00:00
|
|
|
return 0;
|
|
|
|
}
|