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tools: bpftool: add delimiters to multi-function JITed dumps

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This splits up the contiguous JITed dump obtained via the bpf
system call into more relatable chunks for each function in
the program. If the kernel symbols corresponding to these are
known, they are printed in the header for each JIT image dump
otherwise the masked start address is printed.

Before applying this patch:

  # bpftool prog dump jited id 1

     0:	push   %rbp
     1:	mov    %rsp,%rbp
  ...
    70:	leaveq
    71:	retq
    72:	push   %rbp
    73:	mov    %rsp,%rbp
  ...
    dd:	leaveq
    de:	retq

  # bpftool -p prog dump jited id 1

  [{
          "pc": "0x0",
          "operation": "push",
          "operands": ["%rbp"
          ]
      },{
  ...
      },{
          "pc": "0x71",
          "operation": "retq",
          "operands": [null
          ]
      },{
          "pc": "0x72",
          "operation": "push",
          "operands": ["%rbp"
          ]
      },{
  ...
      },{
          "pc": "0xde",
          "operation": "retq",
          "operands": [null
          ]
      }
  ]

After applying this patch:

  # echo 0 > /proc/sys/net/core/bpf_jit_kallsyms
  # bpftool prog dump jited id 1

  0xffffffffc02c7000:
     0:	push   %rbp
     1:	mov    %rsp,%rbp
  ...
    70:	leaveq
    71:	retq

  0xffffffffc02cf000:
     0:	push   %rbp
     1:	mov    %rsp,%rbp
  ...
    6b:	leaveq
    6c:	retq

  # bpftool -p prog dump jited id 1

  [{
          "name": "0xffffffffc02c7000",
          "insns": [{
                  "pc": "0x0",
                  "operation": "push",
                  "operands": ["%rbp"
                  ]
              },{
  ...
              },{
                  "pc": "0x71",
                  "operation": "retq",
                  "operands": [null
                  ]
              }
          ]
      },{
          "name": "0xffffffffc02cf000",
          "insns": [{
                  "pc": "0x0",
                  "operation": "push",
                  "operands": ["%rbp"
                  ]
              },{
  ...
              },{
                  "pc": "0x6c",
                  "operation": "retq",
                  "operands": [null
                  ]
              }
          ]
      }
  ]

  # echo 1 > /proc/sys/net/core/bpf_jit_kallsyms
  # bpftool prog dump jited id 1

  bpf_prog_b811aab41a39ad3d_foo:
     0:	push   %rbp
     1:	mov    %rsp,%rbp
  ...
    70:	leaveq
    71:	retq

  bpf_prog_cf418ac8b67bebd9_F:
     0:	push   %rbp
     1:	mov    %rsp,%rbp
  ...
    6b:	leaveq
    6c:	retq

  # bpftool -p prog dump jited id 1

  [{
          "name": "bpf_prog_b811aab41a39ad3d_foo",
          "insns": [{
                  "pc": "0x0",
                  "operation": "push",
                  "operands": ["%rbp"
                  ]
              },{
  ...
              },{
                  "pc": "0x71",
                  "operation": "retq",
                  "operands": [null
                  ]
              }
          ]
      },{
          "name": "bpf_prog_cf418ac8b67bebd9_F",
          "insns": [{
                  "pc": "0x0",
                  "operation": "push",
                  "operands": ["%rbp"
                  ]
              },{
  ...
              },{
                  "pc": "0x6c",
                  "operation": "retq",
                  "operands": [null
                  ]
              }
          ]
      }
  ]

Signed-off-by: Sandipan Das <sandipan@linux.vnet.ibm.com>
Reviewed-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
This commit is contained in:
Sandipan Das
2018-05-24 12:26:54 +05:30
committed by Daniel Borkmann
parent bd980d43b9
commit f7f62c7134
3 changed files with 75 additions and 3 deletions
Download Patch File Download Diff File Expand all files Collapse all files

4
tools/bpf/bpftool/xlated_dumper.c
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@@ -102,8 +102,8 @@ void kernel_syms_destroy(struct dump_data *dd)
free(dd->sym_mapping);
}
static struct kernel_sym *kernel_syms_search(struct dump_data *dd,
unsigned long key)
struct kernel_sym *kernel_syms_search(struct dump_data *dd,
unsigned long key)
{
struct kernel_sym sym = {
.address = key,