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1.18: type "filenamehere" not found #14

Open
jengelh opened this issue Oct 2, 2020 · 0 comments
Open

1.18: type "filenamehere" not found #14

jengelh opened this issue Oct 2, 2020 · 0 comments

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@jengelh
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jengelh commented Oct 2, 2020

Input:

» cat x.c
#include <stdio.h>
int main()
{
        fprintf(stderr, "hi world\n");
        return 0;
}
» gcc x.c -Wall -ggdb3
» strip -s a.out

Observed behavior (pahole 1.18):

» pahole ./a.out 
pahole: type './a.out' not found
»

Expected behavior (like pahole 1.17):

» pahole a.out 
»
acmel added a commit that referenced this issue Nov 10, 2020
@acmel
pahole: Check if the sole arg is a file, not considering it a type if so
fc06ee1 
Before we would have:

  $ gcc x.c -Wall -ggdb3
  $ strip -s a.out
  $ pahole ./a.out
  $

I.e. no types, no output.

Then when we started trying out the sole arg as a type to lookup either
on a vmlinux found via its build id in /sys/kernel/notes or
/sys/kernel/btf/vmlinux we instead showed this for a binary without type
info:

  $ pahole ./a.out
  pahole: type './a.out' not found
  $

Now we show:

  $ pahole a.out
  pahole: file 'a.out' has no supported type information.
  $

Reported-by: Jan Engelhardt <[email protected]>
Bugtracker: #14
Signed-off-by: Arnaldo Carvalho de Melo <[email protected]>
@captain5050 captain5050 mentioned this issue Feb 5, 2021
Open
acmel added a commit that referenced this issue Jul 8, 2021
@acmel
dwarf_loader: Add a lock around dwarf_decl_file() and dwarf_decl_line…
7098c7a 
…() calls

As this ends up racing on a tsearch() call, probably for some libdw
cache that gets updated/lookedup in concurrent pahole threads (-j N).

This cures the following, a patch for libdw will be cooked up and sent.

  (gdb) run -j -I -F dwarf vmlinux > /dev/null
  Starting program: /var/home/acme/git/pahole/build/pahole -j -I -F dwarf vmlinux > /dev/null
  warning: Expected absolute pathname for libpthread in the inferior, but got .gnu_debugdata for /lib64/libpthread.so.0.
  warning: File "/usr/lib64/libthread_db-1.0.so" auto-loading has been declined by your `auto-load safe-path' set to "$debugdir:$datadir/auto-load".
  warning: Unable to find libthread_db matching inferior's thread library, thread debugging will not be available.
  [New LWP 844789]
  [New LWP 844790]
  [New LWP 844791]
  [New LWP 844792]
  [New LWP 844793]
  [New LWP 844794]
  [New LWP 844795]
  [New LWP 844796]
  [New LWP 844797]
  [New LWP 844798]
  [New LWP 844799]
  [New LWP 844800]
  [New LWP 844801]
  [New LWP 844802]
  [New LWP 844803]
  [New LWP 844804]
  [New LWP 844805]
  [New LWP 844806]
  [New LWP 844807]
  [New LWP 844808]
  [New LWP 844809]
  [New LWP 844810]
  [New LWP 844811]
  [New LWP 844812]
  [New LWP 844813]
  [New LWP 844814]

  Thread 2 "pahole" received signal SIGSEGV, Segmentation fault.
  [Switching to LWP 844789]
  0x00007ffff7dfa321 in ?? () from /lib64/libc.so.6
  (gdb) bt
  #0  0x00007ffff7dfa321 in ?? () from /lib64/libc.so.6
  #1  0x00007ffff7dfa4bb in ?? () from /lib64/libc.so.6
  #2  0x00007ffff7f5eaa6 in __libdw_getsrclines (dbg=0x4a7f90, debug_line_offset=10383710, comp_dir=0x7ffff3c29f01 "/var/home/acme/git/build/v5.13.0-rc6+", address_size=address_size@entry=8, linesp=linesp@entry=0x7fffcfe04ba0, filesp=filesp@entry=0x7fffcfe04ba8)
      at dwarf_getsrclines.c:1129
  #3  0x00007ffff7f5ed14 in dwarf_getsrclines (cudie=cudie@entry=0x7fffd210caf0, lines=lines@entry=0x7fffd210cac0, nlines=nlines@entry=0x7fffd210cac8) at dwarf_getsrclines.c:1213
  #4  0x00007ffff7f64883 in dwarf_decl_file (die=<optimized out>) at dwarf_decl_file.c:66
  #5  0x0000000000425f24 in tag__init (tag=0x7fff0421b710, cu=0x7fffcc001e40, die=0x7fffd210cd30) at /var/home/acme/git/pahole/dwarf_loader.c:476
  #6  0x00000000004262ec in namespace__init (namespace=0x7fff0421b710, die=0x7fffd210cd30, cu=0x7fffcc001e40, conf=0x475600 <conf_load>) at /var/home/acme/git/pahole/dwarf_loader.c:576
  #7  0x00000000004263ac in type__init (type=0x7fff0421b710, die=0x7fffd210cd30, cu=0x7fffcc001e40, conf=0x475600 <conf_load>) at /var/home/acme/git/pahole/dwarf_loader.c:595
  #8  0x00000000004264d1 in type__new (die=0x7fffd210cd30, cu=0x7fffcc001e40, conf=0x475600 <conf_load>) at /var/home/acme/git/pahole/dwarf_loader.c:614
  #9  0x0000000000427ba6 in die__create_new_typedef (die=0x7fffd210cd30, cu=0x7fffcc001e40, conf=0x475600 <conf_load>) at /var/home/acme/git/pahole/dwarf_loader.c:1212
  #10 0x0000000000428df5 in __die__process_tag (die=0x7fffd210cd30, cu=0x7fffcc001e40, top_level=1, fn=0x45cee0 <__FUNCTION__.10> "die__process_unit", conf=0x475600 <conf_load>) at /var/home/acme/git/pahole/dwarf_loader.c:1823
  #11 0x0000000000428ea1 in die__process_unit (die=0x7fffd210cd30, cu=0x7fffcc001e40, conf=0x475600 <conf_load>) at /var/home/acme/git/pahole/dwarf_loader.c:1848
  #12 0x0000000000429e45 in die__process (die=0x7fffd210ce20, cu=0x7fffcc001e40, conf=0x475600 <conf_load>) at /var/home/acme/git/pahole/dwarf_loader.c:2311
  #13 0x0000000000429ecb in die__process_and_recode (die=0x7fffd210ce20, cu=0x7fffcc001e40, conf=0x475600 <conf_load>) at /var/home/acme/git/pahole/dwarf_loader.c:2326
  #14 0x000000000042a9d6 in dwarf_cus__create_and_process_cu (dcus=0x7fffffffddc0, cu_die=0x7fffd210ce20, pointer_size=8 '\b') at /var/home/acme/git/pahole/dwarf_loader.c:2644
  #15 0x000000000042ab28 in dwarf_cus__process_cu_thread (arg=0x7fffffffddc0) at /var/home/acme/git/pahole/dwarf_loader.c:2687
  #16 0x00007ffff7ed6299 in start_thread () from /lib64/libpthread.so.0
  #17 0x00007ffff7dfe353 in ?? () from /lib64/libc.so.6
  (gdb)
  (gdb) fr 2
  1085
  (gdb) list files_lines_compare
  1086    static int
  1087    files_lines_compare (const void *p1, const void *p2)
  1088    {
  1089	  const struct files_lines_s *t1 = p1;
  1090	  const struct files_lines_s *t2 = p2;
  1091
  1092	  if (t1->debug_line_offset < t2->debug_line_offset)
  (gdb)
  1093        return -1;
  1094	  if (t1->debug_line_offset > t2->debug_line_offset)
  1095        return 1;
  1096
  1097	  return 0;
  1098    }
  1099
  1100    int
  1101    internal_function
  1102    __libdw_getsrclines (Dwarf *dbg, Dwarf_Off debug_line_offset,
  (gdb) list __libdw_getsrclines
  1100    int
  1101    internal_function
  1102    __libdw_getsrclines (Dwarf *dbg, Dwarf_Off debug_line_offset,
  1103                         const char *comp_dir, unsigned address_size,
  1104                         Dwarf_Lines **linesp, Dwarf_Files **filesp)
  1105    {
  1106	  struct files_lines_s fake = { .debug_line_offset = debug_line_offset };
  1107	  struct files_lines_s **found = tfind (&fake, &dbg->files_lines,
  1108                                            files_lines_compare);
  1109	  if (found == NULL)
  (gdb)
  1110        {
  1111          Elf_Data *data = __libdw_checked_get_data (dbg, IDX_debug_line);
  1112          if (data == NULL
  1113              || __libdw_offset_in_section (dbg, IDX_debug_line,
  1114                                            debug_line_offset, 1) != 0)
  1115            return -1;
  1116
  1117          const unsigned char *linep = data->d_buf + debug_line_offset;
  1118          const unsigned char *lineendp = data->d_buf + data->d_size;
  1119
  (gdb)
  1120          struct files_lines_s *node = libdw_alloc (dbg, struct files_lines_s,
  1121                                                    sizeof *node, 1);
  1122
  1123          if (read_srclines (dbg, linep, lineendp, comp_dir, address_size,
  1124                             &node->lines, &node->files) != 0)
  1125            return -1;
  1126
  1127          node->debug_line_offset = debug_line_offset;
  1128
  1129          found = tsearch (node, &dbg->files_lines, files_lines_compare);
  (gdb)

Signed-off-by: Arnaldo Carvalho de Melo <[email protected]>
acmel added a commit that referenced this issue Jul 27, 2021
@acmel
dwarf_loader: Add a lock around dwarf_decl_file() and dwarf_decl_line…
604ae9b 
…() calls

As this ends up racing on a tsearch() call, probably for some libdw
cache that gets updated/lookedup in concurrent pahole threads (-j N).

This cures the following, a patch for libdw will be cooked up and sent.

  (gdb) run -j -I -F dwarf vmlinux > /dev/null
  Starting program: /var/home/acme/git/pahole/build/pahole -j -I -F dwarf vmlinux > /dev/null
  warning: Expected absolute pathname for libpthread in the inferior, but got .gnu_debugdata for /lib64/libpthread.so.0.
  warning: File "/usr/lib64/libthread_db-1.0.so" auto-loading has been declined by your `auto-load safe-path' set to "$debugdir:$datadir/auto-load".
  warning: Unable to find libthread_db matching inferior's thread library, thread debugging will not be available.
  [New LWP 844789]
  [New LWP 844790]
  [New LWP 844791]
  [New LWP 844792]
  [New LWP 844793]
  [New LWP 844794]
  [New LWP 844795]
  [New LWP 844796]
  [New LWP 844797]
  [New LWP 844798]
  [New LWP 844799]
  [New LWP 844800]
  [New LWP 844801]
  [New LWP 844802]
  [New LWP 844803]
  [New LWP 844804]
  [New LWP 844805]
  [New LWP 844806]
  [New LWP 844807]
  [New LWP 844808]
  [New LWP 844809]
  [New LWP 844810]
  [New LWP 844811]
  [New LWP 844812]
  [New LWP 844813]
  [New LWP 844814]

  Thread 2 "pahole" received signal SIGSEGV, Segmentation fault.
  [Switching to LWP 844789]
  0x00007ffff7dfa321 in ?? () from /lib64/libc.so.6
  (gdb) bt
  #0  0x00007ffff7dfa321 in ?? () from /lib64/libc.so.6
  #1  0x00007ffff7dfa4bb in ?? () from /lib64/libc.so.6
  #2  0x00007ffff7f5eaa6 in __libdw_getsrclines (dbg=0x4a7f90, debug_line_offset=10383710, comp_dir=0x7ffff3c29f01 "/var/home/acme/git/build/v5.13.0-rc6+", address_size=address_size@entry=8, linesp=linesp@entry=0x7fffcfe04ba0, filesp=filesp@entry=0x7fffcfe04ba8)
      at dwarf_getsrclines.c:1129
  #3  0x00007ffff7f5ed14 in dwarf_getsrclines (cudie=cudie@entry=0x7fffd210caf0, lines=lines@entry=0x7fffd210cac0, nlines=nlines@entry=0x7fffd210cac8) at dwarf_getsrclines.c:1213
  #4  0x00007ffff7f64883 in dwarf_decl_file (die=<optimized out>) at dwarf_decl_file.c:66
  #5  0x0000000000425f24 in tag__init (tag=0x7fff0421b710, cu=0x7fffcc001e40, die=0x7fffd210cd30) at /var/home/acme/git/pahole/dwarf_loader.c:476
  #6  0x00000000004262ec in namespace__init (namespace=0x7fff0421b710, die=0x7fffd210cd30, cu=0x7fffcc001e40, conf=0x475600 <conf_load>) at /var/home/acme/git/pahole/dwarf_loader.c:576
  #7  0x00000000004263ac in type__init (type=0x7fff0421b710, die=0x7fffd210cd30, cu=0x7fffcc001e40, conf=0x475600 <conf_load>) at /var/home/acme/git/pahole/dwarf_loader.c:595
  #8  0x00000000004264d1 in type__new (die=0x7fffd210cd30, cu=0x7fffcc001e40, conf=0x475600 <conf_load>) at /var/home/acme/git/pahole/dwarf_loader.c:614
  #9  0x0000000000427ba6 in die__create_new_typedef (die=0x7fffd210cd30, cu=0x7fffcc001e40, conf=0x475600 <conf_load>) at /var/home/acme/git/pahole/dwarf_loader.c:1212
  #10 0x0000000000428df5 in __die__process_tag (die=0x7fffd210cd30, cu=0x7fffcc001e40, top_level=1, fn=0x45cee0 <__FUNCTION__.10> "die__process_unit", conf=0x475600 <conf_load>) at /var/home/acme/git/pahole/dwarf_loader.c:1823
  #11 0x0000000000428ea1 in die__process_unit (die=0x7fffd210cd30, cu=0x7fffcc001e40, conf=0x475600 <conf_load>) at /var/home/acme/git/pahole/dwarf_loader.c:1848
  #12 0x0000000000429e45 in die__process (die=0x7fffd210ce20, cu=0x7fffcc001e40, conf=0x475600 <conf_load>) at /var/home/acme/git/pahole/dwarf_loader.c:2311
  #13 0x0000000000429ecb in die__process_and_recode (die=0x7fffd210ce20, cu=0x7fffcc001e40, conf=0x475600 <conf_load>) at /var/home/acme/git/pahole/dwarf_loader.c:2326
  #14 0x000000000042a9d6 in dwarf_cus__create_and_process_cu (dcus=0x7fffffffddc0, cu_die=0x7fffd210ce20, pointer_size=8 '\b') at /var/home/acme/git/pahole/dwarf_loader.c:2644
  #15 0x000000000042ab28 in dwarf_cus__process_cu_thread (arg=0x7fffffffddc0) at /var/home/acme/git/pahole/dwarf_loader.c:2687
  #16 0x00007ffff7ed6299 in start_thread () from /lib64/libpthread.so.0
  #17 0x00007ffff7dfe353 in ?? () from /lib64/libc.so.6
  (gdb)
  (gdb) fr 2
  1085
  (gdb) list files_lines_compare
  1086    static int
  1087    files_lines_compare (const void *p1, const void *p2)
  1088    {
  1089	  const struct files_lines_s *t1 = p1;
  1090	  const struct files_lines_s *t2 = p2;
  1091
  1092	  if (t1->debug_line_offset < t2->debug_line_offset)
  (gdb)
  1093        return -1;
  1094	  if (t1->debug_line_offset > t2->debug_line_offset)
  1095        return 1;
  1096
  1097	  return 0;
  1098    }
  1099
  1100    int
  1101    internal_function
  1102    __libdw_getsrclines (Dwarf *dbg, Dwarf_Off debug_line_offset,
  (gdb) list __libdw_getsrclines
  1100    int
  1101    internal_function
  1102    __libdw_getsrclines (Dwarf *dbg, Dwarf_Off debug_line_offset,
  1103                         const char *comp_dir, unsigned address_size,
  1104                         Dwarf_Lines **linesp, Dwarf_Files **filesp)
  1105    {
  1106	  struct files_lines_s fake = { .debug_line_offset = debug_line_offset };
  1107	  struct files_lines_s **found = tfind (&fake, &dbg->files_lines,
  1108                                            files_lines_compare);
  1109	  if (found == NULL)
  (gdb)
  1110        {
  1111          Elf_Data *data = __libdw_checked_get_data (dbg, IDX_debug_line);
  1112          if (data == NULL
  1113              || __libdw_offset_in_section (dbg, IDX_debug_line,
  1114                                            debug_line_offset, 1) != 0)
  1115            return -1;
  1116
  1117          const unsigned char *linep = data->d_buf + debug_line_offset;
  1118          const unsigned char *lineendp = data->d_buf + data->d_size;
  1119
  (gdb)
  1120          struct files_lines_s *node = libdw_alloc (dbg, struct files_lines_s,
  1121                                                    sizeof *node, 1);
  1122
  1123          if (read_srclines (dbg, linep, lineendp, comp_dir, address_size,
  1124                             &node->lines, &node->files) != 0)
  1125            return -1;
  1126
  1127          node->debug_line_offset = debug_line_offset;
  1128
  1129          found = tsearch (node, &dbg->files_lines, files_lines_compare);
  (gdb)

Signed-off-by: Arnaldo Carvalho de Melo <[email protected]>
acmel added a commit that referenced this issue Jul 28, 2021
@acmel
dwarf_loader: Add a lock around dwarf_decl_file() and dwarf_decl_line…
d7b5a94 
…() calls

As this ends up racing on a tsearch() call, probably for some libdw
cache that gets updated/lookedup in concurrent pahole threads (-j N).

This cures the following, a patch for libdw will be cooked up and sent.

  (gdb) run -j -I -F dwarf vmlinux > /dev/null
  Starting program: /var/home/acme/git/pahole/build/pahole -j -I -F dwarf vmlinux > /dev/null
  warning: Expected absolute pathname for libpthread in the inferior, but got .gnu_debugdata for /lib64/libpthread.so.0.
  warning: File "/usr/lib64/libthread_db-1.0.so" auto-loading has been declined by your `auto-load safe-path' set to "$debugdir:$datadir/auto-load".
  warning: Unable to find libthread_db matching inferior's thread library, thread debugging will not be available.
  [New LWP 844789]
  [New LWP 844790]
  [New LWP 844791]
  [New LWP 844792]
  [New LWP 844793]
  [New LWP 844794]
  [New LWP 844795]
  [New LWP 844796]
  [New LWP 844797]
  [New LWP 844798]
  [New LWP 844799]
  [New LWP 844800]
  [New LWP 844801]
  [New LWP 844802]
  [New LWP 844803]
  [New LWP 844804]
  [New LWP 844805]
  [New LWP 844806]
  [New LWP 844807]
  [New LWP 844808]
  [New LWP 844809]
  [New LWP 844810]
  [New LWP 844811]
  [New LWP 844812]
  [New LWP 844813]
  [New LWP 844814]

  Thread 2 "pahole" received signal SIGSEGV, Segmentation fault.
  [Switching to LWP 844789]
  0x00007ffff7dfa321 in ?? () from /lib64/libc.so.6
  (gdb) bt
  #0  0x00007ffff7dfa321 in ?? () from /lib64/libc.so.6
  #1  0x00007ffff7dfa4bb in ?? () from /lib64/libc.so.6
  #2  0x00007ffff7f5eaa6 in __libdw_getsrclines (dbg=0x4a7f90, debug_line_offset=10383710, comp_dir=0x7ffff3c29f01 "/var/home/acme/git/build/v5.13.0-rc6+", address_size=address_size@entry=8, linesp=linesp@entry=0x7fffcfe04ba0, filesp=filesp@entry=0x7fffcfe04ba8)
      at dwarf_getsrclines.c:1129
  #3  0x00007ffff7f5ed14 in dwarf_getsrclines (cudie=cudie@entry=0x7fffd210caf0, lines=lines@entry=0x7fffd210cac0, nlines=nlines@entry=0x7fffd210cac8) at dwarf_getsrclines.c:1213
  #4  0x00007ffff7f64883 in dwarf_decl_file (die=<optimized out>) at dwarf_decl_file.c:66
  #5  0x0000000000425f24 in tag__init (tag=0x7fff0421b710, cu=0x7fffcc001e40, die=0x7fffd210cd30) at /var/home/acme/git/pahole/dwarf_loader.c:476
  #6  0x00000000004262ec in namespace__init (namespace=0x7fff0421b710, die=0x7fffd210cd30, cu=0x7fffcc001e40, conf=0x475600 <conf_load>) at /var/home/acme/git/pahole/dwarf_loader.c:576
  #7  0x00000000004263ac in type__init (type=0x7fff0421b710, die=0x7fffd210cd30, cu=0x7fffcc001e40, conf=0x475600 <conf_load>) at /var/home/acme/git/pahole/dwarf_loader.c:595
  #8  0x00000000004264d1 in type__new (die=0x7fffd210cd30, cu=0x7fffcc001e40, conf=0x475600 <conf_load>) at /var/home/acme/git/pahole/dwarf_loader.c:614
  #9  0x0000000000427ba6 in die__create_new_typedef (die=0x7fffd210cd30, cu=0x7fffcc001e40, conf=0x475600 <conf_load>) at /var/home/acme/git/pahole/dwarf_loader.c:1212
  #10 0x0000000000428df5 in __die__process_tag (die=0x7fffd210cd30, cu=0x7fffcc001e40, top_level=1, fn=0x45cee0 <__FUNCTION__.10> "die__process_unit", conf=0x475600 <conf_load>) at /var/home/acme/git/pahole/dwarf_loader.c:1823
  #11 0x0000000000428ea1 in die__process_unit (die=0x7fffd210cd30, cu=0x7fffcc001e40, conf=0x475600 <conf_load>) at /var/home/acme/git/pahole/dwarf_loader.c:1848
  #12 0x0000000000429e45 in die__process (die=0x7fffd210ce20, cu=0x7fffcc001e40, conf=0x475600 <conf_load>) at /var/home/acme/git/pahole/dwarf_loader.c:2311
  #13 0x0000000000429ecb in die__process_and_recode (die=0x7fffd210ce20, cu=0x7fffcc001e40, conf=0x475600 <conf_load>) at /var/home/acme/git/pahole/dwarf_loader.c:2326
  #14 0x000000000042a9d6 in dwarf_cus__create_and_process_cu (dcus=0x7fffffffddc0, cu_die=0x7fffd210ce20, pointer_size=8 '\b') at /var/home/acme/git/pahole/dwarf_loader.c:2644
  #15 0x000000000042ab28 in dwarf_cus__process_cu_thread (arg=0x7fffffffddc0) at /var/home/acme/git/pahole/dwarf_loader.c:2687
  #16 0x00007ffff7ed6299 in start_thread () from /lib64/libpthread.so.0
  #17 0x00007ffff7dfe353 in ?? () from /lib64/libc.so.6
  (gdb)
  (gdb) fr 2
  1085
  (gdb) list files_lines_compare
  1086    static int
  1087    files_lines_compare (const void *p1, const void *p2)
  1088    {
  1089	  const struct files_lines_s *t1 = p1;
  1090	  const struct files_lines_s *t2 = p2;
  1091
  1092	  if (t1->debug_line_offset < t2->debug_line_offset)
  (gdb)
  1093        return -1;
  1094	  if (t1->debug_line_offset > t2->debug_line_offset)
  1095        return 1;
  1096
  1097	  return 0;
  1098    }
  1099
  1100    int
  1101    internal_function
  1102    __libdw_getsrclines (Dwarf *dbg, Dwarf_Off debug_line_offset,
  (gdb) list __libdw_getsrclines
  1100    int
  1101    internal_function
  1102    __libdw_getsrclines (Dwarf *dbg, Dwarf_Off debug_line_offset,
  1103                         const char *comp_dir, unsigned address_size,
  1104                         Dwarf_Lines **linesp, Dwarf_Files **filesp)
  1105    {
  1106	  struct files_lines_s fake = { .debug_line_offset = debug_line_offset };
  1107	  struct files_lines_s **found = tfind (&fake, &dbg->files_lines,
  1108                                            files_lines_compare);
  1109	  if (found == NULL)
  (gdb)
  1110        {
  1111          Elf_Data *data = __libdw_checked_get_data (dbg, IDX_debug_line);
  1112          if (data == NULL
  1113              || __libdw_offset_in_section (dbg, IDX_debug_line,
  1114                                            debug_line_offset, 1) != 0)
  1115            return -1;
  1116
  1117          const unsigned char *linep = data->d_buf + debug_line_offset;
  1118          const unsigned char *lineendp = data->d_buf + data->d_size;
  1119
  (gdb)
  1120          struct files_lines_s *node = libdw_alloc (dbg, struct files_lines_s,
  1121                                                    sizeof *node, 1);
  1122
  1123          if (read_srclines (dbg, linep, lineendp, comp_dir, address_size,
  1124                             &node->lines, &node->files) != 0)
  1125            return -1;
  1126
  1127          node->debug_line_offset = debug_line_offset;
  1128
  1129          found = tsearch (node, &dbg->files_lines, files_lines_compare);
  (gdb)

Signed-off-by: Arnaldo Carvalho de Melo <[email protected]>
acmel added a commit that referenced this issue Aug 6, 2021
@acmel
dwarf_loader: Add a lock around dwarf_decl_file() and dwarf_decl_line…
5992fd7 
…() calls

As this ends up racing on a tsearch() call, probably for some libdw
cache that gets updated/lookedup in concurrent pahole threads (-j N).

This cures the following, a patch for libdw will be cooked up and sent.

  (gdb) run -j -I -F dwarf vmlinux > /dev/null
  Starting program: /var/home/acme/git/pahole/build/pahole -j -I -F dwarf vmlinux > /dev/null
  warning: Expected absolute pathname for libpthread in the inferior, but got .gnu_debugdata for /lib64/libpthread.so.0.
  warning: File "/usr/lib64/libthread_db-1.0.so" auto-loading has been declined by your `auto-load safe-path' set to "$debugdir:$datadir/auto-load".
  warning: Unable to find libthread_db matching inferior's thread library, thread debugging will not be available.
  [New LWP 844789]
  [New LWP 844790]
  [New LWP 844791]
  [New LWP 844792]
  [New LWP 844793]
  [New LWP 844794]
  [New LWP 844795]
  [New LWP 844796]
  [New LWP 844797]
  [New LWP 844798]
  [New LWP 844799]
  [New LWP 844800]
  [New LWP 844801]
  [New LWP 844802]
  [New LWP 844803]
  [New LWP 844804]
  [New LWP 844805]
  [New LWP 844806]
  [New LWP 844807]
  [New LWP 844808]
  [New LWP 844809]
  [New LWP 844810]
  [New LWP 844811]
  [New LWP 844812]
  [New LWP 844813]
  [New LWP 844814]

  Thread 2 "pahole" received signal SIGSEGV, Segmentation fault.
  [Switching to LWP 844789]
  0x00007ffff7dfa321 in ?? () from /lib64/libc.so.6
  (gdb) bt
  #0  0x00007ffff7dfa321 in ?? () from /lib64/libc.so.6
  #1  0x00007ffff7dfa4bb in ?? () from /lib64/libc.so.6
  #2  0x00007ffff7f5eaa6 in __libdw_getsrclines (dbg=0x4a7f90, debug_line_offset=10383710, comp_dir=0x7ffff3c29f01 "/var/home/acme/git/build/v5.13.0-rc6+", address_size=address_size@entry=8, linesp=linesp@entry=0x7fffcfe04ba0, filesp=filesp@entry=0x7fffcfe04ba8)
      at dwarf_getsrclines.c:1129
  #3  0x00007ffff7f5ed14 in dwarf_getsrclines (cudie=cudie@entry=0x7fffd210caf0, lines=lines@entry=0x7fffd210cac0, nlines=nlines@entry=0x7fffd210cac8) at dwarf_getsrclines.c:1213
  #4  0x00007ffff7f64883 in dwarf_decl_file (die=<optimized out>) at dwarf_decl_file.c:66
  #5  0x0000000000425f24 in tag__init (tag=0x7fff0421b710, cu=0x7fffcc001e40, die=0x7fffd210cd30) at /var/home/acme/git/pahole/dwarf_loader.c:476
  #6  0x00000000004262ec in namespace__init (namespace=0x7fff0421b710, die=0x7fffd210cd30, cu=0x7fffcc001e40, conf=0x475600 <conf_load>) at /var/home/acme/git/pahole/dwarf_loader.c:576
  #7  0x00000000004263ac in type__init (type=0x7fff0421b710, die=0x7fffd210cd30, cu=0x7fffcc001e40, conf=0x475600 <conf_load>) at /var/home/acme/git/pahole/dwarf_loader.c:595
  #8  0x00000000004264d1 in type__new (die=0x7fffd210cd30, cu=0x7fffcc001e40, conf=0x475600 <conf_load>) at /var/home/acme/git/pahole/dwarf_loader.c:614
  #9  0x0000000000427ba6 in die__create_new_typedef (die=0x7fffd210cd30, cu=0x7fffcc001e40, conf=0x475600 <conf_load>) at /var/home/acme/git/pahole/dwarf_loader.c:1212
  #10 0x0000000000428df5 in __die__process_tag (die=0x7fffd210cd30, cu=0x7fffcc001e40, top_level=1, fn=0x45cee0 <__FUNCTION__.10> "die__process_unit", conf=0x475600 <conf_load>) at /var/home/acme/git/pahole/dwarf_loader.c:1823
  #11 0x0000000000428ea1 in die__process_unit (die=0x7fffd210cd30, cu=0x7fffcc001e40, conf=0x475600 <conf_load>) at /var/home/acme/git/pahole/dwarf_loader.c:1848
  #12 0x0000000000429e45 in die__process (die=0x7fffd210ce20, cu=0x7fffcc001e40, conf=0x475600 <conf_load>) at /var/home/acme/git/pahole/dwarf_loader.c:2311
  #13 0x0000000000429ecb in die__process_and_recode (die=0x7fffd210ce20, cu=0x7fffcc001e40, conf=0x475600 <conf_load>) at /var/home/acme/git/pahole/dwarf_loader.c:2326
  #14 0x000000000042a9d6 in dwarf_cus__create_and_process_cu (dcus=0x7fffffffddc0, cu_die=0x7fffd210ce20, pointer_size=8 '\b') at /var/home/acme/git/pahole/dwarf_loader.c:2644
  #15 0x000000000042ab28 in dwarf_cus__process_cu_thread (arg=0x7fffffffddc0) at /var/home/acme/git/pahole/dwarf_loader.c:2687
  #16 0x00007ffff7ed6299 in start_thread () from /lib64/libpthread.so.0
  #17 0x00007ffff7dfe353 in ?? () from /lib64/libc.so.6
  (gdb)
  (gdb) fr 2
  1085
  (gdb) list files_lines_compare
  1086    static int
  1087    files_lines_compare (const void *p1, const void *p2)
  1088    {
  1089	  const struct files_lines_s *t1 = p1;
  1090	  const struct files_lines_s *t2 = p2;
  1091
  1092	  if (t1->debug_line_offset < t2->debug_line_offset)
  (gdb)
  1093        return -1;
  1094	  if (t1->debug_line_offset > t2->debug_line_offset)
  1095        return 1;
  1096
  1097	  return 0;
  1098    }
  1099
  1100    int
  1101    internal_function
  1102    __libdw_getsrclines (Dwarf *dbg, Dwarf_Off debug_line_offset,
  (gdb) list __libdw_getsrclines
  1100    int
  1101    internal_function
  1102    __libdw_getsrclines (Dwarf *dbg, Dwarf_Off debug_line_offset,
  1103                         const char *comp_dir, unsigned address_size,
  1104                         Dwarf_Lines **linesp, Dwarf_Files **filesp)
  1105    {
  1106	  struct files_lines_s fake = { .debug_line_offset = debug_line_offset };
  1107	  struct files_lines_s **found = tfind (&fake, &dbg->files_lines,
  1108                                            files_lines_compare);
  1109	  if (found == NULL)
  (gdb)
  1110        {
  1111          Elf_Data *data = __libdw_checked_get_data (dbg, IDX_debug_line);
  1112          if (data == NULL
  1113              || __libdw_offset_in_section (dbg, IDX_debug_line,
  1114                                            debug_line_offset, 1) != 0)
  1115            return -1;
  1116
  1117          const unsigned char *linep = data->d_buf + debug_line_offset;
  1118          const unsigned char *lineendp = data->d_buf + data->d_size;
  1119
  (gdb)
  1120          struct files_lines_s *node = libdw_alloc (dbg, struct files_lines_s,
  1121                                                    sizeof *node, 1);
  1122
  1123          if (read_srclines (dbg, linep, lineendp, comp_dir, address_size,
  1124                             &node->lines, &node->files) != 0)
  1125            return -1;
  1126
  1127          node->debug_line_offset = debug_line_offset;
  1128
  1129          found = tsearch (node, &dbg->files_lines, files_lines_compare);
  (gdb)

Signed-off-by: Arnaldo Carvalho de Melo <[email protected]>
acmel added a commit that referenced this issue Aug 12, 2021
@acmel
dwarf_loader: Add a lock around dwarf_decl_file() and dwarf_decl_line…
1caed1c 
…() calls

As this ends up racing on a tsearch() call, probably for some libdw
cache that gets updated/lookedup in concurrent pahole threads (-j N).

This cures the following, a patch for libdw will be cooked up and sent.

  (gdb) run -j -I -F dwarf vmlinux > /dev/null
  Starting program: /var/home/acme/git/pahole/build/pahole -j -I -F dwarf vmlinux > /dev/null
  warning: Expected absolute pathname for libpthread in the inferior, but got .gnu_debugdata for /lib64/libpthread.so.0.
  warning: File "/usr/lib64/libthread_db-1.0.so" auto-loading has been declined by your `auto-load safe-path' set to "$debugdir:$datadir/auto-load".
  warning: Unable to find libthread_db matching inferior's thread library, thread debugging will not be available.
  [New LWP 844789]
  [New LWP 844790]
  [New LWP 844791]
  [New LWP 844792]
  [New LWP 844793]
  [New LWP 844794]
  [New LWP 844795]
  [New LWP 844796]
  [New LWP 844797]
  [New LWP 844798]
  [New LWP 844799]
  [New LWP 844800]
  [New LWP 844801]
  [New LWP 844802]
  [New LWP 844803]
  [New LWP 844804]
  [New LWP 844805]
  [New LWP 844806]
  [New LWP 844807]
  [New LWP 844808]
  [New LWP 844809]
  [New LWP 844810]
  [New LWP 844811]
  [New LWP 844812]
  [New LWP 844813]
  [New LWP 844814]

  Thread 2 "pahole" received signal SIGSEGV, Segmentation fault.
  [Switching to LWP 844789]
  0x00007ffff7dfa321 in ?? () from /lib64/libc.so.6
  (gdb) bt
  #0  0x00007ffff7dfa321 in ?? () from /lib64/libc.so.6
  #1  0x00007ffff7dfa4bb in ?? () from /lib64/libc.so.6
  #2  0x00007ffff7f5eaa6 in __libdw_getsrclines (dbg=0x4a7f90, debug_line_offset=10383710, comp_dir=0x7ffff3c29f01 "/var/home/acme/git/build/v5.13.0-rc6+", address_size=address_size@entry=8, linesp=linesp@entry=0x7fffcfe04ba0, filesp=filesp@entry=0x7fffcfe04ba8)
      at dwarf_getsrclines.c:1129
  #3  0x00007ffff7f5ed14 in dwarf_getsrclines (cudie=cudie@entry=0x7fffd210caf0, lines=lines@entry=0x7fffd210cac0, nlines=nlines@entry=0x7fffd210cac8) at dwarf_getsrclines.c:1213
  #4  0x00007ffff7f64883 in dwarf_decl_file (die=<optimized out>) at dwarf_decl_file.c:66
  #5  0x0000000000425f24 in tag__init (tag=0x7fff0421b710, cu=0x7fffcc001e40, die=0x7fffd210cd30) at /var/home/acme/git/pahole/dwarf_loader.c:476
  #6  0x00000000004262ec in namespace__init (namespace=0x7fff0421b710, die=0x7fffd210cd30, cu=0x7fffcc001e40, conf=0x475600 <conf_load>) at /var/home/acme/git/pahole/dwarf_loader.c:576
  #7  0x00000000004263ac in type__init (type=0x7fff0421b710, die=0x7fffd210cd30, cu=0x7fffcc001e40, conf=0x475600 <conf_load>) at /var/home/acme/git/pahole/dwarf_loader.c:595
  #8  0x00000000004264d1 in type__new (die=0x7fffd210cd30, cu=0x7fffcc001e40, conf=0x475600 <conf_load>) at /var/home/acme/git/pahole/dwarf_loader.c:614
  #9  0x0000000000427ba6 in die__create_new_typedef (die=0x7fffd210cd30, cu=0x7fffcc001e40, conf=0x475600 <conf_load>) at /var/home/acme/git/pahole/dwarf_loader.c:1212
  #10 0x0000000000428df5 in __die__process_tag (die=0x7fffd210cd30, cu=0x7fffcc001e40, top_level=1, fn=0x45cee0 <__FUNCTION__.10> "die__process_unit", conf=0x475600 <conf_load>) at /var/home/acme/git/pahole/dwarf_loader.c:1823
  #11 0x0000000000428ea1 in die__process_unit (die=0x7fffd210cd30, cu=0x7fffcc001e40, conf=0x475600 <conf_load>) at /var/home/acme/git/pahole/dwarf_loader.c:1848
  #12 0x0000000000429e45 in die__process (die=0x7fffd210ce20, cu=0x7fffcc001e40, conf=0x475600 <conf_load>) at /var/home/acme/git/pahole/dwarf_loader.c:2311
  #13 0x0000000000429ecb in die__process_and_recode (die=0x7fffd210ce20, cu=0x7fffcc001e40, conf=0x475600 <conf_load>) at /var/home/acme/git/pahole/dwarf_loader.c:2326
  #14 0x000000000042a9d6 in dwarf_cus__create_and_process_cu (dcus=0x7fffffffddc0, cu_die=0x7fffd210ce20, pointer_size=8 '\b') at /var/home/acme/git/pahole/dwarf_loader.c:2644
  #15 0x000000000042ab28 in dwarf_cus__process_cu_thread (arg=0x7fffffffddc0) at /var/home/acme/git/pahole/dwarf_loader.c:2687
  #16 0x00007ffff7ed6299 in start_thread () from /lib64/libpthread.so.0
  #17 0x00007ffff7dfe353 in ?? () from /lib64/libc.so.6
  (gdb)
  (gdb) fr 2
  1085
  (gdb) list files_lines_compare
  1086    static int
  1087    files_lines_compare (const void *p1, const void *p2)
  1088    {
  1089	  const struct files_lines_s *t1 = p1;
  1090	  const struct files_lines_s *t2 = p2;
  1091
  1092	  if (t1->debug_line_offset < t2->debug_line_offset)
  (gdb)
  1093        return -1;
  1094	  if (t1->debug_line_offset > t2->debug_line_offset)
  1095        return 1;
  1096
  1097	  return 0;
  1098    }
  1099
  1100    int
  1101    internal_function
  1102    __libdw_getsrclines (Dwarf *dbg, Dwarf_Off debug_line_offset,
  (gdb) list __libdw_getsrclines
  1100    int
  1101    internal_function
  1102    __libdw_getsrclines (Dwarf *dbg, Dwarf_Off debug_line_offset,
  1103                         const char *comp_dir, unsigned address_size,
  1104                         Dwarf_Lines **linesp, Dwarf_Files **filesp)
  1105    {
  1106	  struct files_lines_s fake = { .debug_line_offset = debug_line_offset };
  1107	  struct files_lines_s **found = tfind (&fake, &dbg->files_lines,
  1108                                            files_lines_compare);
  1109	  if (found == NULL)
  (gdb)
  1110        {
  1111          Elf_Data *data = __libdw_checked_get_data (dbg, IDX_debug_line);
  1112          if (data == NULL
  1113              || __libdw_offset_in_section (dbg, IDX_debug_line,
  1114                                            debug_line_offset, 1) != 0)
  1115            return -1;
  1116
  1117          const unsigned char *linep = data->d_buf + debug_line_offset;
  1118          const unsigned char *lineendp = data->d_buf + data->d_size;
  1119
  (gdb)
  1120          struct files_lines_s *node = libdw_alloc (dbg, struct files_lines_s,
  1121                                                    sizeof *node, 1);
  1122
  1123          if (read_srclines (dbg, linep, lineendp, comp_dir, address_size,
  1124                             &node->lines, &node->files) != 0)
  1125            return -1;
  1126
  1127          node->debug_line_offset = debug_line_offset;
  1128
  1129          found = tsearch (node, &dbg->files_lines, files_lines_compare);
  (gdb)

Signed-off-by: Arnaldo Carvalho de Melo <[email protected]>
acmel added a commit that referenced this issue Jan 28, 2022
@acmel
fprintf: Fix division by zero for uninitialized conf_fprintf->cacheli…
46cec35 
…ne_size field

tldr;

  gdb pfunct
  (gdb) run --compile tcp.o
  Program received signal SIGFPE, Arithmetic exception.
  0x00007ffff7f18551 in class__fprintf_cacheline_boundary (conf=0x7fffffffda10, offset=0, fp=0x7ffff7e17520 <_IO_2_1_stdout_>) at /var/home/acme/git/pahole/dwarves_fprintf.c:1319
  1319		uint32_t cacheline = offset / conf->cacheline_size;
  (gdb) bt
  #0  0x00007ffff7f18551 in class__fprintf_cacheline_boundary (conf=0x7fffffffda10, offset=0, fp=0x7ffff7e17520 <_IO_2_1_stdout_>) at /var/home/acme/git/pahole/dwarves_fprintf.c:1319
  #1  0x00007ffff7f16af2 in class_member__fprintf (member=0x45de10, union_member=false, type=0x45dfb0, cu=0x435a40, conf=0x7fffffffda10, fp=0x7ffff7e17520 <_IO_2_1_stdout_>) at /var/home/acme/git/pahole/dwarves_fprintf.c:869
  #2  0x00007ffff7f1717b in struct_member__fprintf (member=0x45de10, type=0x45dfb0, cu=0x435a40, conf=0x7fffffffda10, fp=0x7ffff7e17520 <_IO_2_1_stdout_>) at /var/home/acme/git/pahole/dwarves_fprintf.c:983
  #3  0x00007ffff7f1945c in __class__fprintf (class=0x45dcc0, cu=0x435a40, conf=0x7fffffffdbb0, fp=0x7ffff7e17520 <_IO_2_1_stdout_>) at /var/home/acme/git/pahole/dwarves_fprintf.c:1583
  #4  0x00007ffff7f1a6bd in tag__fprintf (tag=0x45dcc0, cu=0x435a40, conf=0x7fffffffdc70, fp=0x7ffff7e17520 <_IO_2_1_stdout_>) at /var/home/acme/git/pahole/dwarves_fprintf.c:1906
  #5  0x00007ffff7fbf022 in type__emit (tag=0x45dcc0, cu=0x435a40, prefix=0x0, suffix=0x0, fp=0x7ffff7e17520 <_IO_2_1_stdout_>) at /var/home/acme/git/pahole/dwarves_emit.c:333
  #6  0x00007ffff7fbed3d in tag__emit_definitions (tag=0x6b21e0, cu=0x435a40, emissions=0x408300 <emissions>, fp=0x7ffff7e17520 <_IO_2_1_stdout_>) at /var/home/acme/git/pahole/dwarves_emit.c:265
  #7  0x00007ffff7fbef45 in type__emit_definitions (tag=0x6b20c0, cu=0x435a40, emissions=0x408300 <emissions>, fp=0x7ffff7e17520 <_IO_2_1_stdout_>) at /var/home/acme/git/pahole/dwarves_emit.c:315
  #8  0x00007ffff7fbed15 in tag__emit_definitions (tag=0x6b3b40, cu=0x435a40, emissions=0x408300 <emissions>, fp=0x7ffff7e17520 <_IO_2_1_stdout_>) at /var/home/acme/git/pahole/dwarves_emit.c:264
  #9  0x00007ffff7fbef45 in type__emit_definitions (tag=0x6b31d0, cu=0x435a40, emissions=0x408300 <emissions>, fp=0x7ffff7e17520 <_IO_2_1_stdout_>) at /var/home/acme/git/pahole/dwarves_emit.c:315
  #10 0x00007ffff7fbed15 in tag__emit_definitions (tag=0x4cb920, cu=0x435a40, emissions=0x408300 <emissions>, fp=0x7ffff7e17520 <_IO_2_1_stdout_>) at /var/home/acme/git/pahole/dwarves_emit.c:264
  #11 0x00007ffff7fbef45 in type__emit_definitions (tag=0x4cb7d0, cu=0x435a40, emissions=0x408300 <emissions>, fp=0x7ffff7e17520 <_IO_2_1_stdout_>) at /var/home/acme/git/pahole/dwarves_emit.c:315
  #12 0x0000000000403592 in function__emit_type_definitions (func=0x738ad0, cu=0x435a40, fp=0x7ffff7e17520 <_IO_2_1_stdout_>) at /var/home/acme/git/pahole/pfunct.c:353
  #13 0x0000000000403670 in function__show (func=0x738ad0, cu=0x435a40) at /var/home/acme/git/pahole/pfunct.c:371
  #14 0x00000000004038e9 in cu_function_iterator (cu=0x435a40, cookie=0x0) at /var/home/acme/git/pahole/pfunct.c:404
  #15 0x00007ffff7f1296b in cus__for_each_cu (cus=0x4369e0, iterator=0x403869 <cu_function_iterator>, cookie=0x0, filter=0x0) at /var/home/acme/git/pahole/dwarves.c:1919
  #16 0x000000000040432a in main (argc=3, argv=0x7fffffffe1f8) at /var/home/acme/git/pahole/pfunct.c:776
  (gdb) p conf->cacheline_size
  $2 = 0

We need to pass a conf_fprintf pointer to the chain starting with
function__emit_type_definitions(), i.e. dwarves_emit.c needs to receive
the printing configuration instead of, right at type__emit() synthesize
a conf_fprintf without initializing conf_fprintf->cacheline_size which
ends up in a division by zero.

But to fix this quicker just add a helper that checks if it is zero and
uses the conf_fprintf__defaults.cacheline_size field that is being
initialized by all tools via:

  dwarves__resolve_cacheline_size(&conf_load, 0);

Fixes: 772725a ("dwarves_fprintf: Move cacheline_size into struct conf_fprintf")
Cc: Douglas Raillard <[email protected]>
Signed-off-by: Arnaldo Carvalho de Melo <[email protected]>
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