libbpf-tools/offcputime: Add dso info and symbol offset to backtrace for -v option

[ekyooo]

Add additional information and change format of backtrace

• add symbol base offset, dso name, dso base offset
• symbol and dso info is included if it's available in target binary
• changed format: INDEX ADDR [SYMBOL+OFFSET] (MODULE+OFFSET)

Print backtrace of ip if it failed to get syms.

Before:

  # offcputime -v
      psiginfo
      vscanf
      __snprintf_chk
      [unknown]
      [unknown]
      [unknown]
      [unknown]
      [unknown]
      sd_event_exit
      sd_event_dispatch
      sd_event_run
      [unknown]
      __libc_start_main
      [unknown]
      -                systemd-journal (204)
          1

      xas_load
      xas_find
      filemap_map_pages
      __handle_mm_fault
      handle_mm_fault
      do_page_fault
      do_translation_fault
      do_mem_abort
      do_el0_ia_bp_hardening
      el0_ia
      xas_load
      --
  failed to get syms
      -                PmLogCtl (138757)
        1

After:

  # offcputime -v
      #0  0xffffffc01018b7e8 __arm64_sys_clock_nanosleep+0x0
      #1  0xffffffc01009a93c el0_svc_handler+0x34
      #2  0xffffffc010084a08 el0_svc+0x8
      #3  0xffffffc01018b7e8 __arm64_sys_clock_nanosleep+0x0
      --
      #4  0x0000007fa0bffd14 clock_nanosleep+0x94 (/usr/lib/libc-2.31.so+0x9ed14)
      #5  0x0000007fa0c0530c nanosleep+0x1c (/usr/lib/libc-2.31.so+0xa430c)
      #6  0x0000007fa0c051e4 sleep+0x34 (/usr/lib/libc-2.31.so+0xa41e4)
      #7  0x000000558a5a9608 flb_loop+0x28 (/usr/bin/fluent-bit+0x52608)
      #8  0x000000558a59f1c4 flb_main+0xa84 (/usr/bin/fluent-bit+0x481c4)
      #9  0x0000007fa0b85124 __libc_start_main+0xe4 (/usr/lib/libc-2.31.so+0x24124)
      #10 0x000000558a59d828 _start+0x34 (/usr/bin/fluent-bit+0x46828)
      -                fluent-bit (1238)
          1

      #0  0xffffffc01027daa4 generic_copy_file_checks+0x334
      #1  0xffffffc0102ba634 __handle_mm_fault+0x8dc
      #2  0xffffffc0102baa20 handle_mm_fault+0x168
      #3  0xffffffc010ad23c0 do_page_fault+0x148
      #4  0xffffffc010ad27c0 do_translation_fault+0xb0
      #5  0xffffffc0100816b0 do_mem_abort+0x50
      #6  0xffffffc0100843b0 el0_da+0x1c
      #7  0xffffffc01027daa4 generic_copy_file_checks+0x334
      --
      #8  0x0000007f8dc12648 [unknown]
      #9  0x0000007f8dc0aef8 [unknown]
      #10 0x0000007f8dc1c990 [unknown]
      #11 0x0000007f8dc08b0c [unknown]
      #12 0x0000007f8dc08e48 [unknown]
      #13 0x0000007f8dc081c8 [unknown]
    -                PmLogCtl (2412)
        1

Fixed: #3884
Signed-off-by: Eunseon Lee [email protected]

[brendangregg]

Why include the offset in MODULE+OFFSET? I don't really mind, but I want to know if there's a precedent.

Note that stackcount added -s for symbol offsets, but since this adds more fields I'm ok with it being -v.

[ekyooo]

Why include the offset in MODULE+OFFSET? I don't really mind, but I want to know if there's a precedent.

Note that stackcount added -s for symbol offsets, but since this adds more fields I'm ok with it being -v.

I think Leaksanitizer can be a precedent for this format. (https://github.com/google/sanitizers/wiki/AddressSanitizerLeakSanitizer)

Direct leak of 5 byte(s) in 1 object(s) allocated from:
    #0 0x44f2de in malloc /usr/home/hacker/llvm/projects/compiler-rt/lib/asan/asan_malloc_linux.cc:74
    #1 0x464e86 in Baz() (/usr/home/hacker/a.out+0x464e86)  //  MODULE+OFFSET
    #2 0x464fb4 in main (/usr/home/hacker/a.out+0x464fb4)  //  MODULE+OFFSET
    #3 0x7f7e760b476c in __libc_start_main /build/buildd/eglibc-2.15/csu/libc-start.c:226

We can also use the module name and module offset instead of symbol information if symbol resolution fails as in the example below.

                 #2 0x7f97fea90c (/usr/lib/libcbe.so+0x1baf90c)                                                                                                                    
                 #3 0x7f99250430  (/usr/lib/libcbe.so+0x2e15430)                                                                                                                    
                 #4 0x7f99250ae8 (/usr/lib/libcbe.so+0x2e15ae8)                                                                                                                    
                 #5 0x7f9925ac40 (/usr/lib/libcbe.so+0x2e1fc40)                                                                                                                    
                 #6 0x7f9925afc0 (/usr/lib/libcbe.so+0x2e1ffc0)                                                                                                                    
                 #7 0x7f9921c8d4 (/usr/lib/libcbe.so+0x2de18d4)   

Also, if a module has multiple static functions with the same name, we can use MODULE OFFSET to differentiate them as I think.

Thank you.