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* [PATCH] Binutils support for split-dwarf and dwarf-5
@ 2022-06-02 14:55 Kumar N, Bhuvanendra
  2022-06-03 12:04 ` Jan Beulich
  0 siblings, 1 reply; 3+ messages in thread
From: Kumar N, Bhuvanendra @ 2022-06-02 14:55 UTC (permalink / raw)
  To: binutils; +Cc: Nick Clifton, George, Jini Susan, Natarajan, Kavitha

[-- Attachment #1: Type: text/plain, Size: 19640 bytes --]

[Public]

Hi,

Binutils support for split-dwarf and dwarf5 is now added for gcc and clang. There are 2 patches. Basic sections dump like .debug_info.dwo, .debug_abbrev.dwo, .debug_str.dwo etc are supported in patch 1/2. location list and ranges list sections dump with split-dwarf and dwarf5 are supported in patch 2/2 and patch 2/2 is continuation of patch 1/2. Both the patches are attached and also inlined below. Separating these issues as individual patches might be easy to review, hence 2 patches are there.

Issues fixed in patch 1/2 :
There are few differences b/w dwarf4 and dwarf5 as shared below, w.r.t. split-dwarf support added like different attributes/forms used to represent DWO name and ID, .debug_str_offsets section etc. All these are addressed. I have tested these changes with gcc and clang compiled objects with split-dwarf and dwarf-5.

DWARF4:

  *   DW_AT_GNU_dwo_name [DW_FORM_strp]
  *   DW_AT_GNU_dwo_id [DW_FORM_data8]
  *   Above attribute are part of DW_TAG_compile_unit

DWARF5:

  *   DW_AT_dwo_name [DW_FORM_strp]
  *   Above attribute is part of DW_TAG_skeleton_unit
  *   .debug_str_offsets is used to refer to .debug_str section

NOTE: DWO ID is not printed for dwarf 5 during initial dwo file dump information summary. But its dumped under .debug_info section dump. Because now there is no separate attribute in dwarf5 for DWO ID like it was there in dwarf4(DW_AT_GNU_dwo_id).

Issues fixed in patch 2/2 :
.debug_loclists.dwo and .debug_rnglists.dwo section dumps are taken care. I have tested these changes for clang compiled objects with split-dwarf and dwarf-5, where .debug_loclists.dwo and .debug_rnglists.dwo sections exist in the separate debug file (.dwo files)

Regards,
bhuvan

Patch 1/2 inlined:

From 1bda1e144f43d1f41fe30a934ba008561083dc07 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=E2=80=9Cbhkumarn=E2=80=9D?= Bhuvanendra.KumarN@amd.com<mailto:Bhuvanendra.KumarN@amd.com>
Date: Thu, 2 Jun 2022 17:44:02 +0530
Subject: [PATCH] [PATCH 1/2] Binutils support for split-dwarf and dwarf-5.

This fix adds support for split-dwarf and dwarf5, for both gcc and clang.
There are 2 patches. Basic sections dump like .debug_info.dwo,
.debug_abbrev.dwo, .debug_str.dwo etc are supported in this patch 1/2.
But location list and ranges list sections dump with split-dwarf and dwarf5
are supported in the next patch 2/2.

There are few differences b/w dwarf4 and dwarf5, w.r.t. split-dwarf support
added like different attributes/forms used to represent DWO name and ID,
.debug_str_offsets section etc. All these are addressed.

      * dwarf.c (fetch_indexed_string): Use str_offsets_base to calculate
      the string offset.
      (read_and_display_attr_value): Set str_offsets_base i.e. string offset
      table base address.
      (process_debug_info): Include DW_TAG_skeleton_unit.
      (load_separate_debug_files): Load .debug_str_offsets if exists.
      Skip DWO ID dump for dwarf-5.
      * testsuite/binutils-all/readelf.exp: Added new test point.
      * testsuite/binutils-all/readelf.k5: New file.
      * testsuite/binutils-all/dwo_5.s: New file.
---
binutils/dwarf.c                            |  11 +-
binutils/testsuite/binutils-all/dwo_5.s     | 257 ++++++++++++++++++++
binutils/testsuite/binutils-all/readelf.exp |  12 +
binutils/testsuite/binutils-all/readelf.k5  |   7 +
4 files changed, 285 insertions(+), 2 deletions(-)
create mode 100644 binutils/testsuite/binutils-all/dwo_5.s
create mode 100644 binutils/testsuite/binutils-all/readelf.k5

diff --git a/binutils/dwarf.c b/binutils/dwarf.c
index caa3ce48d00..e8f0ea4cf0c 100644
--- a/binutils/dwarf.c
+++ b/binutils/dwarf.c
@@ -118,6 +118,8 @@ int dwarf_cutoff_level = -1;
unsigned long dwarf_start_die;
 int dwarf_check = 0;
+static dwarf_vma str_offsets_base = 0;
+#define DEBUG_STR_OFFSETS_HEADER_LEN 8
 /* Convenient constant, to avoid having to cast -1 to dwarf_vma when
    testing whether e.g. a locview list is present.  */
@@ -779,7 +781,7 @@ fetch_indexed_string (dwarf_vma idx, struct cu_tu_set *this_set,
       return _("<index offset is too big>");
     }
-  str_offset = byte_get (curr + index_offset, offset_size);
+  str_offset = byte_get (curr + index_offset + str_offsets_base, offset_size);
   str_offset -= str_section->address;
   if (str_offset >= str_section->size)
     {
@@ -2485,6 +2487,8 @@ read_and_display_attr_value (unsigned long           attribute,
     case DW_FORM_GNU_ref_alt:
     case DW_FORM_GNU_strp_alt:
       SAFE_BYTE_GET_AND_INC (uvalue, data, offset_size, end);
+      if (attribute == DW_AT_str_offsets_base)
+        str_offsets_base = uvalue - DEBUG_STR_OFFSETS_HEADER_LEN;
       break;
     case DW_FORM_flag_present:
@@ -4016,6 +4020,7 @@ process_debug_info (struct dwarf_section * section,
           need_base_address = 0;
           break;
         case DW_TAG_compile_unit:
+         case DW_TAG_skeleton_unit:
           need_base_address = 1;
           need_dwo_info = do_loc;
           break;
@@ -4059,6 +4064,7 @@ process_debug_info (struct dwarf_section * section,
                               level);
         }
+       str_offsets_base = 0;
       /* If a locview attribute appears before a location one,
          make sure we don't associate it with an earlier
          loclist. */
@@ -11889,6 +11895,7 @@ load_separate_debug_files (void * file, const char * filename)
       && load_debug_section (abbrev, file)
       && load_debug_section (info, file))
     {
+      load_debug_section (str_index, file);
       free_dwo_info ();
       if (process_debug_info (& debug_displays[info].section, file, abbrev,
@@ -11948,7 +11955,7 @@ load_separate_debug_files (void * file, const char * filename)
                printf (_("  Directory: %s\n"), dir ? dir : _("<not-found>"));
                if (id != NULL)
                display_data (printf (_("  ID:       ")), (unsigned char *) id, 8);
-                else
+                else if (debug_information[0].dwarf_version != 5)
                printf (_("  ID:        <not specified>\n"));
                printf ("\n\n");
              }
diff --git a/binutils/testsuite/binutils-all/dwo_5.s b/binutils/testsuite/binutils-all/dwo_5.s
new file mode 100644
index 00000000000..e394467c2be
--- /dev/null
+++ b/binutils/testsuite/binutils-all/dwo_5.s
@@ -0,0 +1,257 @@
+     .file "a.c"
+     .text
+.Ltext0:
+     .globl     a
+     .type a, @function
+a:
+.LFB0:
+     .file 1 "a.c"
+     .loc 1 1 13
+     .cfi_startproc
+     pushq %rbp
+     .cfi_def_cfa_offset 16
+     .cfi_offset 6, -16
+     movq %rsp, %rbp
+     .cfi_def_cfa_register 6
+     .loc 1 1 22
+     movl $111, %eax
+     .loc 1 1 1
+     popq %rbp
+     .cfi_def_cfa 7, 8
+     ret
+     .cfi_endproc
+.LFE0:
+     .size a, .-a
+.Letext0:
+     .section   .debug_addr,"",@progbits
+     .long 0xc
+     .value     0x5
+     .byte 0x8
+     .byte 0
+.Ldebug_addr0:
+     .quad .LFB0
+     .section   .debug_info.dwo,"e",@progbits
+.Ldebug_info0:
+     .long 0x35
+     .value     0x5
+     .byte 0x5
+     .byte 0x8
+     .long .Ldebug_abbrev0
+     .byte 0x46
+     .byte 0x1c
+     .byte 0xf1
+     .byte 0xfb
+     .byte 0xe5
+     .byte 0x96
+     .byte 0x7d
+     .byte 0x2b
+     .uleb128 0x1
+     .uleb128 0x1
+     .byte 0x1d
+     .string    "a.c"
+     .uleb128 0
+     .uleb128 0x2
+     .string    "a"
+     .byte 0x1
+     .byte 0x1
+     .byte 0x5
+     .long 0x31
+     .uleb128 0
+     .quad .LFE0-.LFB0
+     .uleb128 0x1
+     .byte 0x9c
+     .uleb128 0x3
+     .byte 0x4
+     .byte 0x5
+     .string    "int"
+     .byte 0
+     .section   .debug_info,"",@progbits
+.Lskeleton_debug_info0:
+     .long 0x31
+     .value     0x5
+     .byte 0x4
+     .byte 0x8
+     .long .Lskeleton_debug_abbrev0
+     .byte 0x46
+     .byte 0x1c
+     .byte 0xf1
+     .byte 0xfb
+     .byte 0xe5
+     .byte 0x96
+     .byte 0x7d
+     .byte 0x2b
+     .uleb128 0x1
+     .quad .Ltext0
+     .quad .Letext0-.Ltext0
+     .long .Ldebug_line0
+     .long .LASF0
+     .long .LASF1
+     .long .Ldebug_addr0
+     .section   .debug_abbrev,"",@progbits
+.Lskeleton_debug_abbrev0:
+     .uleb128 0x1
+     .uleb128 0x4a
+     .byte 0
+     .uleb128 0x11
+     .uleb128 0x1
+     .uleb128 0x12
+     .uleb128 0x7
+     .uleb128 0x10
+     .uleb128 0x17
+     .uleb128 0x76
+     .uleb128 0xe
+     .uleb128 0x1b
+     .uleb128 0xe
+     .uleb128 0x2134
+     .uleb128 0x19
+     .uleb128 0x73
+     .uleb128 0x17
+     .byte 0
+     .byte 0
+     .byte 0
+     .section   .debug_abbrev.dwo,"e",@progbits
+.Ldebug_abbrev0:
+     .uleb128 0x1
+     .uleb128 0x11
+     .byte 0x1
+     .uleb128 0x25
+     .uleb128 0x1a
+     .uleb128 0x13
+     .uleb128 0xb
+     .uleb128 0x3
+     .uleb128 0x8
+     .uleb128 0x1b
+     .uleb128 0x1a
+     .byte 0
+     .byte 0
+     .uleb128 0x2
+     .uleb128 0x2e
+     .byte 0
+     .uleb128 0x3f
+     .uleb128 0x19
+     .uleb128 0x3
+     .uleb128 0x8
+     .uleb128 0x3a
+     .uleb128 0xb
+     .uleb128 0x3b
+     .uleb128 0xb
+     .uleb128 0x39
+     .uleb128 0xb
+     .uleb128 0x27
+     .uleb128 0x19
+     .uleb128 0x49
+     .uleb128 0x13
+     .uleb128 0x11
+     .uleb128 0x1b
+     .uleb128 0x12
+     .uleb128 0x7
+     .uleb128 0x40
+     .uleb128 0x18
+     .uleb128 0x7a
+     .uleb128 0x19
+     .byte 0
+     .byte 0
+     .uleb128 0x3
+     .uleb128 0x24
+     .byte 0
+     .uleb128 0xb
+     .uleb128 0xb
+     .uleb128 0x3e
+     .uleb128 0xb
+     .uleb128 0x3
+     .uleb128 0x8
+     .byte 0
+     .byte 0
+     .byte 0
+     .section   .debug_gnu_pubnames,"",@progbits
+     .long 0x15
+     .value     0x2
+     .long .Lskeleton_debug_info0
+     .long 0x39
+     .long 0x1c
+     .byte 0x30
+     .string    "a"
+     .long 0
+     .section   .debug_gnu_pubtypes,"",@progbits
+     .long 0x17
+     .value     0x2
+     .long .Lskeleton_debug_info0
+     .long 0x39
+     .long 0x31
+     .byte 0x90
+     .string    "int"
+     .long 0
+     .section   .debug_aranges,"",@progbits
+     .long 0x2c
+     .value     0x2
+     .long .Lskeleton_debug_info0
+     .byte 0x8
+     .byte 0
+     .value     0
+     .value     0
+     .quad .Ltext0
+     .quad .Letext0-.Ltext0
+     .quad 0
+     .quad 0
+     .section   .debug_line,"",@progbits
+.Ldebug_line0:
+     .section   .debug_line.dwo,"e",@progbits
+.Lskeleton_debug_line0:
+     .long .LELT0-.LSLT0
+.LSLT0:
+     .value     0x5
+     .byte 0x8
+     .byte 0
+     .long .LELTP0-.LASLTP0
+.LASLTP0:
+     .byte 0x1
+     .byte 0x1
+     .byte 0x1
+     .byte 0xf6
+     .byte 0xf2
+     .byte 0xd
+     .byte 0
+     .byte 0x1
+     .byte 0x1
+     .byte 0x1
+     .byte 0x1
+     .byte 0
+     .byte 0
+     .byte 0
+     .byte 0x1
+     .byte 0
+     .byte 0
+     .byte 0x1
+     .byte 0x1
+     .uleb128 0x1
+     .uleb128 0x8
+     .uleb128 0x1
+     .string    "/tmp"
+     .byte 0x2
+     .uleb128 0x1
+     .uleb128 0x8
+     .uleb128 0x2
+     .uleb128 0xb
+     .uleb128 0x2
+     .string    "a.c"
+     .byte 0
+     .string    "a.c"
+     .byte 0
+.LELTP0:
+.LELT0:
+     .section   .debug_str,"MS",@progbits,1
+.LASF1:
+     .string    "/tmp"
+.LASF0:
+     .string    "a.dwo"
+     .section      .debug_str_offsets.dwo,"e",@progbits
+     .long 0xc
+     .value     0x5
+     .value     0
+     .long 0
+     .long 0x5
+     .section   .debug_str.dwo,"e",@progbits
+     .string    "/tmp"
+     .string    "GNU C17 10.0.0 20190813 (experimental) -mtune=generic -march=x86-64 -gdwarf-5 -gsplit-dwarf"
+     .ident     "GCC: (GNU) 10.0.0 20190813 (experimental)"
+     .section   .note.GNU-stack,"",@progbits
diff --git a/binutils/testsuite/binutils-all/readelf.exp b/binutils/testsuite/binutils-all/readelf.exp
index 0f7a1f3b5a0..b68224d5019 100644
--- a/binutils/testsuite/binutils-all/readelf.exp
+++ b/binutils/testsuite/binutils-all/readelf.exp
@@ -572,6 +572,18 @@ if {![binutils_assemble $srcdir/$subdir/dwo.s tmpdir/dwo.o]} then {
     readelf_test {--debug-dump=links --debug-dump=no-follow-links} $tempfile readelf.k2
}
+if {![binutils_assemble $srcdir/$subdir/dwo_5.s tmpdir/dwo_5.o]} then {
+    unsupported "readelf --debug-dump=links (failed to assemble dwo_5.s)"
+} else {
+    if ![is_remote host] {
+        set tempfile tmpdir/dwo_5.o
+    } else {
+        set tempfile [remote_download host tmpdir/dwo_5.o]
+    }
+
+    readelf_test {--debug-dump=links --debug-dump=no-follow-links} $tempfile readelf.k5
+}
+
if {![binutils_assemble $srcdir/$subdir/zero-sec.s tmpdir/zero-sec.o]} then {
     unsupported "readelf --enable-checks (failed to assemble zero-sec.s)"
} else {
diff --git a/binutils/testsuite/binutils-all/readelf.k5 b/binutils/testsuite/binutils-all/readelf.k5
new file mode 100644
index 00000000000..49779224f2c
--- /dev/null
+++ b/binutils/testsuite/binutils-all/readelf.k5
@@ -0,0 +1,7 @@
+The .debug_info section contains link\(s\) to dwo file\(s\):
+
+  Name:      a.dwo
+  Directory: /tmp
+
+
+
--
2.17.1


Patch 2/2 inlined:
From dab73681a6e19c16c799d150cc79cace3f8f894c Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=E2=80=9Cbhkumarn=E2=80=9D?= Bhuvanendra.KumarN@amd.com<mailto:Bhuvanendra.KumarN@amd.com>
Date: Thu, 2 Jun 2022 19:19:13 +0530
Subject: [PATCH] [PATCH 2/2] Binutils support for split-dwarf and dwarf-5.

This fix adds support for split-dwarf and dwarf5. There are 2 patches.
Basic sections dump like .debug_info.dwo, .debug_abbrev.dwo, .debug_str.dwo
etc are supported in the previous patch 1/2. location list and ranges list
sections dump with split-dwarf and dwarf5 are supported in this patch 2/2
and its continuation of patch 1/2.

.debug_loclists.dwo and .debug_rnglists.dwo section dumps are taken care in
this patch 2/2.

      * dwarf.c(read_and_display_attr_value): Handle DW_FORM_loclistx
      and DW_FORM_rnglistx for .dwo files.
      (process_debug_info): Load .debug_loclists.dwo and
      .debug_rnglists.dwo if exists.
      (load_separate_debug_files): Load .debug_loclists and
      .debug_rnglists if exists.
      Include 2 entries in debug_displays table.
      * dwarf.h (enum dwarf_section_display_enum): Include 2 entries.
---
binutils/dwarf.c | 39 +++++++++++++++++++++++++++++++++++++--
binutils/dwarf.h |  2 ++
2 files changed, 39 insertions(+), 2 deletions(-)

diff --git a/binutils/dwarf.c b/binutils/dwarf.c
index e8f0ea4cf0c..7b4bb445da4 100644
--- a/binutils/dwarf.c
+++ b/binutils/dwarf.c
@@ -120,6 +120,7 @@ unsigned long dwarf_start_die;
int dwarf_check = 0;
static dwarf_vma str_offsets_base = 0;
#define DEBUG_STR_OFFSETS_HEADER_LEN 8
+#define DEBUG_LOC_RNGLISTS_SEC_HDR_LEN 12
 /* Convenient constant, to avoid having to cast -1 to dwarf_vma when
    testing whether e.g. a locview list is present.  */
@@ -2792,7 +2793,34 @@ read_and_display_attr_value (unsigned long           attribute,
        offset = base + uvalue * pointer_size;
-       if (do_wide)
+       const char *suffix = strrchr (section->name, '.');
+       bool dwo = suffix && strcmp (suffix, ".dwo") == 0;
+
+       if (form == DW_FORM_loclistx)
+         {
+           if (!dwo)
+             printf (_("%c(index: 0x%s): %s"), delimiter,
+                     dwarf_vmatoa ("x", uvalue),
+                     dwarf_vmatoa ("x", debug_info_p->loc_offsets [uvalue]));
+           else
+             printf (_("%c(index: 0x%s): %s"), delimiter,
+                     dwarf_vmatoa ("x", uvalue),
+                     dwarf_vmatoa ("x", fetch_indexed_value (uvalue, loclists_dwo)
+                                        + DEBUG_LOC_RNGLISTS_SEC_HDR_LEN));
+         }
+       else if (form == DW_FORM_rnglistx)
+         {
+           if (!dwo)
+             printf (_("%c(index: 0x%s): %s"), delimiter,
+                     dwarf_vmatoa ("x", uvalue),
+                     dwarf_vmatoa ("x", debug_info_p->range_lists [uvalue]));
+           else
+             printf (_("%c(index: 0x%s): %s"), delimiter,
+                     dwarf_vmatoa ("x", uvalue),
+                     dwarf_vmatoa ("x", fetch_indexed_value (uvalue, rnglists_dwo)
+                                        + DEBUG_LOC_RNGLISTS_SEC_HDR_LEN));
+         }
+       else if (do_wide)
         /* We have already displayed the form name.  */
         printf (_("%c(index: 0x%s): %s"), delimiter,
              dwarf_vmatoa ("x", uvalue),
@@ -3608,7 +3636,9 @@ process_debug_info (struct dwarf_section * section,
   load_debug_section_with_follow (abbrev_sec, file);
   load_debug_section_with_follow (loclists, file);
   load_debug_section_with_follow (rnglists, file);
-
+  load_debug_section_with_follow (loclists_dwo, file);
+  load_debug_section_with_follow (rnglists_dwo, file);
+
   if (debug_displays [abbrev_sec].section.start == NULL)
     {
       warn (_("Unable to locate %s section!\n"),
@@ -11896,6 +11926,9 @@ load_separate_debug_files (void * file, const char * filename)
       && load_debug_section (info, file))
     {
       load_debug_section (str_index, file);
+      load_debug_section (loclists, file);
+      load_debug_section (rnglists, file);
+
       free_dwo_info ();
       if (process_debug_info (& debug_displays[info].section, file, abbrev,
@@ -12265,10 +12298,12 @@ struct dwarf_section_display debug_displays[] =
   { { ".debug_line_str",    ".zdebug_line_str",      "",  NO_ABBREVS },      display_debug_str,         &do_debug_str,  false },
   { { ".debug_loc",      ".zdebug_loc",         ".dwloc",  NO_ABBREVS },      display_debug_loc,          &do_debug_loc,    true },
   { { ".debug_loclists",    ".zdebug_loclists",      "",  NO_ABBREVS },      display_debug_loc,         &do_debug_loc,  true },
+  { { ".debug_loclists.dwo", ".zdebug_loclists.dwo", "",         NO_ABBREVS },      display_debug_loc,      &do_debug_loc,      true },
   { { ".debug_pubtypes",    ".zdebug_pubtypes",      ".dwpbtyp", NO_ABBREVS },      display_debug_pubnames, &do_debug_pubtypes, false },
   { { ".debug_gnu_pubtypes", ".zdebug_gnu_pubtypes", "", NO_ABBREVS },      display_debug_gnu_pubnames, &do_debug_pubtypes, false },
   { { ".debug_ranges",        ".zdebug_ranges",      ".dwrnges", NO_ABBREVS },      display_debug_ranges,   &do_debug_ranges,   true },
   { { ".debug_rnglists",    ".zdebug_rnglists",      "",  NO_ABBREVS },      display_debug_ranges,   &do_debug_ranges,     true },
+  { { ".debug_rnglists.dwo", ".zdebug_rnglists.dwo", "",         NO_ABBREVS },      display_debug_ranges,   &do_debug_ranges,   true },
   { { ".debug_static_func", ".zdebug_static_func",   "",  NO_ABBREVS },      display_debug_not_supported, NULL,          false },
   { { ".debug_static_vars", ".zdebug_static_vars",   "",  NO_ABBREVS },      display_debug_not_supported, NULL,          false },
   { { ".debug_types",         ".zdebug_types",       "",  ABBREV (abbrev) }, display_debug_types,    &do_debug_info, true },
diff --git a/binutils/dwarf.h b/binutils/dwarf.h
index 040e674c6ce..86b635ef3c2 100644
--- a/binutils/dwarf.h
+++ b/binutils/dwarf.h
@@ -92,10 +92,12 @@ enum dwarf_section_display_enum
   line_str,
   loc,
   loclists,
+  loclists_dwo,
   pubtypes,
   gnu_pubtypes,
   ranges,
   rnglists,
+  rnglists_dwo,
   static_func,
   static_vars,
   types,
--
2.17.1





[-- Attachment #2: 0001-PATCH-1-2-Binutils-support-for-split-dwarf-and-dwarf.patch --]
[-- Type: application/octet-stream, Size: 9886 bytes --]

From 1bda1e144f43d1f41fe30a934ba008561083dc07 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=E2=80=9Cbhkumarn=E2=80=9D?= <Bhuvanendra.KumarN@amd.com>
Date: Thu, 2 Jun 2022 17:44:02 +0530
Subject: [PATCH] [PATCH 1/2] Binutils support for split-dwarf and dwarf-5.

This fix adds support for split-dwarf and dwarf5, for both gcc and clang.
There are 2 patches. Basic sections dump like .debug_info.dwo,
.debug_abbrev.dwo, .debug_str.dwo etc are supported in this patch 1/2.
But location list and ranges list sections dump with split-dwarf and dwarf5
are supported in the next patch 2/2.

There are few differences b/w dwarf4 and dwarf5, w.r.t. split-dwarf support
added like different attributes/forms used to represent DWO name and ID,
.debug_str_offsets section etc. All these are addressed.

	* dwarf.c (fetch_indexed_string): Use str_offsets_base to calculate
	the string offset.
	(read_and_display_attr_value): Set str_offsets_base i.e. string offset
	table base address.
	(process_debug_info): Include DW_TAG_skeleton_unit.
	(load_separate_debug_files): Load .debug_str_offsets if exists.
	Skip DWO ID dump for dwarf-5.
	* testsuite/binutils-all/readelf.exp: Added new test point.
	* testsuite/binutils-all/readelf.k5: New file.
	* testsuite/binutils-all/dwo_5.s: New file.
---
 binutils/dwarf.c                            |  11 +-
 binutils/testsuite/binutils-all/dwo_5.s     | 257 ++++++++++++++++++++
 binutils/testsuite/binutils-all/readelf.exp |  12 +
 binutils/testsuite/binutils-all/readelf.k5  |   7 +
 4 files changed, 285 insertions(+), 2 deletions(-)
 create mode 100644 binutils/testsuite/binutils-all/dwo_5.s
 create mode 100644 binutils/testsuite/binutils-all/readelf.k5

diff --git a/binutils/dwarf.c b/binutils/dwarf.c
index caa3ce48d00..e8f0ea4cf0c 100644
--- a/binutils/dwarf.c
+++ b/binutils/dwarf.c
@@ -118,6 +118,8 @@ int dwarf_cutoff_level = -1;
 unsigned long dwarf_start_die;
 
 int dwarf_check = 0;
+static dwarf_vma str_offsets_base = 0;
+#define DEBUG_STR_OFFSETS_HEADER_LEN 8
 
 /* Convenient constant, to avoid having to cast -1 to dwarf_vma when
    testing whether e.g. a locview list is present.  */
@@ -779,7 +781,7 @@ fetch_indexed_string (dwarf_vma idx, struct cu_tu_set *this_set,
       return _("<index offset is too big>");
     }
 
-  str_offset = byte_get (curr + index_offset, offset_size);
+  str_offset = byte_get (curr + index_offset + str_offsets_base, offset_size);
   str_offset -= str_section->address;
   if (str_offset >= str_section->size)
     {
@@ -2485,6 +2487,8 @@ read_and_display_attr_value (unsigned long           attribute,
     case DW_FORM_GNU_ref_alt:
     case DW_FORM_GNU_strp_alt:
       SAFE_BYTE_GET_AND_INC (uvalue, data, offset_size, end);
+      if (attribute == DW_AT_str_offsets_base)
+        str_offsets_base = uvalue - DEBUG_STR_OFFSETS_HEADER_LEN;
       break;
 
     case DW_FORM_flag_present:
@@ -4016,6 +4020,7 @@ process_debug_info (struct dwarf_section * section,
 	      need_base_address = 0;
 	      break;
 	    case DW_TAG_compile_unit:
+	    case DW_TAG_skeleton_unit:
 	      need_base_address = 1;	
 	      need_dwo_info = do_loc;
 	      break;
@@ -4059,6 +4064,7 @@ process_debug_info (struct dwarf_section * section,
 					    level);
 	    }
 
+	  str_offsets_base = 0;
 	  /* If a locview attribute appears before a location one,
 	     make sure we don't associate it with an earlier
 	     loclist. */
@@ -11889,6 +11895,7 @@ load_separate_debug_files (void * file, const char * filename)
       && load_debug_section (abbrev, file)
       && load_debug_section (info, file))
     {
+      load_debug_section (str_index, file);
       free_dwo_info ();
 
       if (process_debug_info (& debug_displays[info].section, file, abbrev,
@@ -11948,7 +11955,7 @@ load_separate_debug_files (void * file, const char * filename)
 		      printf (_("  Directory: %s\n"), dir ? dir : _("<not-found>"));
 		      if (id != NULL)
 			display_data (printf (_("  ID:       ")), (unsigned char *) id, 8);
-		      else
+		      else if (debug_information[0].dwarf_version != 5)
 			printf (_("  ID:        <not specified>\n"));
 		      printf ("\n\n");
 		    }
diff --git a/binutils/testsuite/binutils-all/dwo_5.s b/binutils/testsuite/binutils-all/dwo_5.s
new file mode 100644
index 00000000000..e394467c2be
--- /dev/null
+++ b/binutils/testsuite/binutils-all/dwo_5.s
@@ -0,0 +1,257 @@
+	.file	"a.c"
+	.text
+.Ltext0:
+	.globl	a
+	.type	a, @function
+a:
+.LFB0:
+	.file 1 "a.c"
+	.loc 1 1 13
+	.cfi_startproc
+	pushq	%rbp
+	.cfi_def_cfa_offset 16
+	.cfi_offset 6, -16
+	movq	%rsp, %rbp
+	.cfi_def_cfa_register 6
+	.loc 1 1 22
+	movl	$111, %eax
+	.loc 1 1 1
+	popq	%rbp
+	.cfi_def_cfa 7, 8
+	ret
+	.cfi_endproc
+.LFE0:
+	.size	a, .-a
+.Letext0:
+	.section	.debug_addr,"",@progbits
+	.long	0xc
+	.value	0x5
+	.byte	0x8
+	.byte	0
+.Ldebug_addr0:
+	.quad	.LFB0
+	.section	.debug_info.dwo,"e",@progbits
+.Ldebug_info0:
+	.long	0x35
+	.value	0x5
+	.byte	0x5
+	.byte	0x8
+	.long	.Ldebug_abbrev0
+	.byte	0x46
+	.byte	0x1c
+	.byte	0xf1
+	.byte	0xfb
+	.byte	0xe5
+	.byte	0x96
+	.byte	0x7d
+	.byte	0x2b
+	.uleb128 0x1
+	.uleb128 0x1
+	.byte	0x1d
+	.string	"a.c"
+	.uleb128 0
+	.uleb128 0x2
+	.string	"a"
+	.byte	0x1
+	.byte	0x1
+	.byte	0x5
+	.long	0x31
+	.uleb128 0
+	.quad	.LFE0-.LFB0
+	.uleb128 0x1
+	.byte	0x9c
+	.uleb128 0x3
+	.byte	0x4
+	.byte	0x5
+	.string	"int"
+	.byte	0
+	.section	.debug_info,"",@progbits
+.Lskeleton_debug_info0:
+	.long	0x31
+	.value	0x5
+	.byte	0x4
+	.byte	0x8
+	.long	.Lskeleton_debug_abbrev0
+	.byte	0x46
+	.byte	0x1c
+	.byte	0xf1
+	.byte	0xfb
+	.byte	0xe5
+	.byte	0x96
+	.byte	0x7d
+	.byte	0x2b
+	.uleb128 0x1
+	.quad	.Ltext0
+	.quad	.Letext0-.Ltext0
+	.long	.Ldebug_line0
+	.long	.LASF0
+	.long	.LASF1
+	.long	.Ldebug_addr0
+	.section	.debug_abbrev,"",@progbits
+.Lskeleton_debug_abbrev0:
+	.uleb128 0x1
+	.uleb128 0x4a
+	.byte	0
+	.uleb128 0x11
+	.uleb128 0x1
+	.uleb128 0x12
+	.uleb128 0x7
+	.uleb128 0x10
+	.uleb128 0x17
+	.uleb128 0x76
+	.uleb128 0xe
+	.uleb128 0x1b
+	.uleb128 0xe
+	.uleb128 0x2134
+	.uleb128 0x19
+	.uleb128 0x73
+	.uleb128 0x17
+	.byte	0
+	.byte	0
+	.byte	0
+	.section	.debug_abbrev.dwo,"e",@progbits
+.Ldebug_abbrev0:
+	.uleb128 0x1
+	.uleb128 0x11
+	.byte	0x1
+	.uleb128 0x25
+	.uleb128 0x1a
+	.uleb128 0x13
+	.uleb128 0xb
+	.uleb128 0x3
+	.uleb128 0x8
+	.uleb128 0x1b
+	.uleb128 0x1a
+	.byte	0
+	.byte	0
+	.uleb128 0x2
+	.uleb128 0x2e
+	.byte	0
+	.uleb128 0x3f
+	.uleb128 0x19
+	.uleb128 0x3
+	.uleb128 0x8
+	.uleb128 0x3a
+	.uleb128 0xb
+	.uleb128 0x3b
+	.uleb128 0xb
+	.uleb128 0x39
+	.uleb128 0xb
+	.uleb128 0x27
+	.uleb128 0x19
+	.uleb128 0x49
+	.uleb128 0x13
+	.uleb128 0x11
+	.uleb128 0x1b
+	.uleb128 0x12
+	.uleb128 0x7
+	.uleb128 0x40
+	.uleb128 0x18
+	.uleb128 0x7a
+	.uleb128 0x19
+	.byte	0
+	.byte	0
+	.uleb128 0x3
+	.uleb128 0x24
+	.byte	0
+	.uleb128 0xb
+	.uleb128 0xb
+	.uleb128 0x3e
+	.uleb128 0xb
+	.uleb128 0x3
+	.uleb128 0x8
+	.byte	0
+	.byte	0
+	.byte	0
+	.section	.debug_gnu_pubnames,"",@progbits
+	.long	0x15
+	.value	0x2
+	.long	.Lskeleton_debug_info0
+	.long	0x39
+	.long	0x1c
+	.byte	0x30
+	.string	"a"
+	.long	0
+	.section	.debug_gnu_pubtypes,"",@progbits
+	.long	0x17
+	.value	0x2
+	.long	.Lskeleton_debug_info0
+	.long	0x39
+	.long	0x31
+	.byte	0x90
+	.string	"int"
+	.long	0
+	.section	.debug_aranges,"",@progbits
+	.long	0x2c
+	.value	0x2
+	.long	.Lskeleton_debug_info0
+	.byte	0x8
+	.byte	0
+	.value	0
+	.value	0
+	.quad	.Ltext0
+	.quad	.Letext0-.Ltext0
+	.quad	0
+	.quad	0
+	.section	.debug_line,"",@progbits
+.Ldebug_line0:
+	.section	.debug_line.dwo,"e",@progbits
+.Lskeleton_debug_line0:
+	.long	.LELT0-.LSLT0
+.LSLT0:
+	.value	0x5
+	.byte	0x8
+	.byte	0
+	.long	.LELTP0-.LASLTP0
+.LASLTP0:
+	.byte	0x1
+	.byte	0x1
+	.byte	0x1
+	.byte	0xf6
+	.byte	0xf2
+	.byte	0xd
+	.byte	0
+	.byte	0x1
+	.byte	0x1
+	.byte	0x1
+	.byte	0x1
+	.byte	0
+	.byte	0
+	.byte	0
+	.byte	0x1
+	.byte	0
+	.byte	0
+	.byte	0x1
+	.byte	0x1
+	.uleb128 0x1
+	.uleb128 0x8
+	.uleb128 0x1
+	.string	"/tmp"
+	.byte	0x2
+	.uleb128 0x1
+	.uleb128 0x8
+	.uleb128 0x2
+	.uleb128 0xb
+	.uleb128 0x2
+	.string	"a.c"
+	.byte	0
+	.string	"a.c"
+	.byte	0
+.LELTP0:
+.LELT0:
+	.section	.debug_str,"MS",@progbits,1
+.LASF1:
+	.string	"/tmp"
+.LASF0:
+	.string	"a.dwo"
+	.section	.debug_str_offsets.dwo,"e",@progbits
+	.long	0xc
+	.value	0x5
+	.value	0
+	.long	0
+	.long	0x5
+	.section	.debug_str.dwo,"e",@progbits
+	.string	"/tmp"
+	.string	"GNU C17 10.0.0 20190813 (experimental) -mtune=generic -march=x86-64 -gdwarf-5 -gsplit-dwarf"
+	.ident	"GCC: (GNU) 10.0.0 20190813 (experimental)"
+	.section	.note.GNU-stack,"",@progbits
diff --git a/binutils/testsuite/binutils-all/readelf.exp b/binutils/testsuite/binutils-all/readelf.exp
index 0f7a1f3b5a0..b68224d5019 100644
--- a/binutils/testsuite/binutils-all/readelf.exp
+++ b/binutils/testsuite/binutils-all/readelf.exp
@@ -572,6 +572,18 @@ if {![binutils_assemble $srcdir/$subdir/dwo.s tmpdir/dwo.o]} then {
     readelf_test {--debug-dump=links --debug-dump=no-follow-links} $tempfile readelf.k2
 }
 
+if {![binutils_assemble $srcdir/$subdir/dwo_5.s tmpdir/dwo_5.o]} then {
+    unsupported "readelf --debug-dump=links (failed to assemble dwo_5.s)"
+} else {
+    if ![is_remote host] {
+        set tempfile tmpdir/dwo_5.o
+    } else {
+        set tempfile [remote_download host tmpdir/dwo_5.o]
+    }
+
+    readelf_test {--debug-dump=links --debug-dump=no-follow-links} $tempfile readelf.k5
+}
+
 if {![binutils_assemble $srcdir/$subdir/zero-sec.s tmpdir/zero-sec.o]} then {
     unsupported "readelf --enable-checks (failed to assemble zero-sec.s)"
 } else {
diff --git a/binutils/testsuite/binutils-all/readelf.k5 b/binutils/testsuite/binutils-all/readelf.k5
new file mode 100644
index 00000000000..49779224f2c
--- /dev/null
+++ b/binutils/testsuite/binutils-all/readelf.k5
@@ -0,0 +1,7 @@
+The .debug_info section contains link\(s\) to dwo file\(s\):
+
+  Name:      a.dwo
+  Directory: /tmp
+
+
+
-- 
2.17.1


[-- Attachment #3: 0001-PATCH-2-2-Binutils-support-for-split-dwarf-and-dwarf.patch --]
[-- Type: application/octet-stream, Size: 5927 bytes --]

From dab73681a6e19c16c799d150cc79cace3f8f894c Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=E2=80=9Cbhkumarn=E2=80=9D?= <Bhuvanendra.KumarN@amd.com>
Date: Thu, 2 Jun 2022 19:19:13 +0530
Subject: [PATCH] [PATCH 2/2] Binutils support for split-dwarf and dwarf-5.

This fix adds support for split-dwarf and dwarf5. There are 2 patches.
Basic sections dump like .debug_info.dwo, .debug_abbrev.dwo, .debug_str.dwo
etc are supported in the previous patch 1/2. location list and ranges list
sections dump with split-dwarf and dwarf5 are supported in this patch 2/2
and its continuation of patch 1/2.

.debug_loclists.dwo and .debug_rnglists.dwo section dumps are taken care in
this patch 2/2.

	* dwarf.c(read_and_display_attr_value): Handle DW_FORM_loclistx
	and DW_FORM_rnglistx for .dwo files.
	(process_debug_info): Load .debug_loclists.dwo and
	.debug_rnglists.dwo if exists.
	(load_separate_debug_files): Load .debug_loclists and
	.debug_rnglists if exists.
	Include 2 entries in debug_displays table.
	* dwarf.h (enum dwarf_section_display_enum): Include 2 entries.
---
 binutils/dwarf.c | 39 +++++++++++++++++++++++++++++++++++++--
 binutils/dwarf.h |  2 ++
 2 files changed, 39 insertions(+), 2 deletions(-)

diff --git a/binutils/dwarf.c b/binutils/dwarf.c
index e8f0ea4cf0c..7b4bb445da4 100644
--- a/binutils/dwarf.c
+++ b/binutils/dwarf.c
@@ -120,6 +120,7 @@ unsigned long dwarf_start_die;
 int dwarf_check = 0;
 static dwarf_vma str_offsets_base = 0;
 #define DEBUG_STR_OFFSETS_HEADER_LEN 8
+#define DEBUG_LOC_RNGLISTS_SEC_HDR_LEN 12
 
 /* Convenient constant, to avoid having to cast -1 to dwarf_vma when
    testing whether e.g. a locview list is present.  */
@@ -2792,7 +2793,34 @@ read_and_display_attr_value (unsigned long           attribute,
 
 	  offset = base + uvalue * pointer_size;
 
-	  if (do_wide)
+	  const char *suffix = strrchr (section->name, '.');
+	  bool dwo = suffix && strcmp (suffix, ".dwo") == 0;
+
+	  if (form == DW_FORM_loclistx)
+	    {
+	      if (!dwo)
+	        printf (_("%c(index: 0x%s): %s"), delimiter,
+	                dwarf_vmatoa ("x", uvalue),
+	                dwarf_vmatoa ("x", debug_info_p->loc_offsets [uvalue]));
+	      else
+	        printf (_("%c(index: 0x%s): %s"), delimiter,
+	                dwarf_vmatoa ("x", uvalue),
+	                dwarf_vmatoa ("x", fetch_indexed_value (uvalue, loclists_dwo)
+	                                   + DEBUG_LOC_RNGLISTS_SEC_HDR_LEN));
+	    }
+	  else if (form == DW_FORM_rnglistx)
+	    {
+	      if (!dwo)
+	        printf (_("%c(index: 0x%s): %s"), delimiter,
+	                dwarf_vmatoa ("x", uvalue),
+	                dwarf_vmatoa ("x", debug_info_p->range_lists [uvalue]));
+	      else
+	        printf (_("%c(index: 0x%s): %s"), delimiter,
+	                dwarf_vmatoa ("x", uvalue),
+	                dwarf_vmatoa ("x", fetch_indexed_value (uvalue, rnglists_dwo)
+	                                   + DEBUG_LOC_RNGLISTS_SEC_HDR_LEN));
+	    }
+	  else if (do_wide)
 	    /* We have already displayed the form name.  */
 	    printf (_("%c(index: 0x%s): %s"), delimiter,
 		    dwarf_vmatoa ("x", uvalue),
@@ -3608,7 +3636,9 @@ process_debug_info (struct dwarf_section * section,
   load_debug_section_with_follow (abbrev_sec, file);
   load_debug_section_with_follow (loclists, file);
   load_debug_section_with_follow (rnglists, file);
-  
+  load_debug_section_with_follow (loclists_dwo, file);
+  load_debug_section_with_follow (rnglists_dwo, file);
+
   if (debug_displays [abbrev_sec].section.start == NULL)
     {
       warn (_("Unable to locate %s section!\n"),
@@ -11896,6 +11926,9 @@ load_separate_debug_files (void * file, const char * filename)
       && load_debug_section (info, file))
     {
       load_debug_section (str_index, file);
+      load_debug_section (loclists, file);
+      load_debug_section (rnglists, file);
+
       free_dwo_info ();
 
       if (process_debug_info (& debug_displays[info].section, file, abbrev,
@@ -12265,10 +12298,12 @@ struct dwarf_section_display debug_displays[] =
   { { ".debug_line_str",    ".zdebug_line_str",	     "",	 NO_ABBREVS },	    display_debug_str,	    &do_debug_str,	false },
   { { ".debug_loc",	    ".zdebug_loc",	     ".dwloc",	 NO_ABBREVS },	    display_debug_loc,	    &do_debug_loc,	true },
   { { ".debug_loclists",    ".zdebug_loclists",	     "",	 NO_ABBREVS },	    display_debug_loc,	    &do_debug_loc,	true },
+  { { ".debug_loclists.dwo", ".zdebug_loclists.dwo", "",         NO_ABBREVS },      display_debug_loc,      &do_debug_loc,      true },
   { { ".debug_pubtypes",    ".zdebug_pubtypes",	     ".dwpbtyp", NO_ABBREVS },	    display_debug_pubnames, &do_debug_pubtypes, false },
   { { ".debug_gnu_pubtypes", ".zdebug_gnu_pubtypes", "",	 NO_ABBREVS },	    display_debug_gnu_pubnames, &do_debug_pubtypes, false },
   { { ".debug_ranges",	    ".zdebug_ranges",	     ".dwrnges", NO_ABBREVS },	    display_debug_ranges,   &do_debug_ranges,	true },
   { { ".debug_rnglists",    ".zdebug_rnglists",	     "",	 NO_ABBREVS },	    display_debug_ranges,   &do_debug_ranges,	true },
+  { { ".debug_rnglists.dwo", ".zdebug_rnglists.dwo", "",         NO_ABBREVS },      display_debug_ranges,   &do_debug_ranges,   true },
   { { ".debug_static_func", ".zdebug_static_func",   "",	 NO_ABBREVS },	    display_debug_not_supported, NULL,		false },
   { { ".debug_static_vars", ".zdebug_static_vars",   "",	 NO_ABBREVS },	    display_debug_not_supported, NULL,		false },
   { { ".debug_types",	    ".zdebug_types",	     "",	 ABBREV (abbrev) }, display_debug_types,    &do_debug_info,	true },
diff --git a/binutils/dwarf.h b/binutils/dwarf.h
index 040e674c6ce..86b635ef3c2 100644
--- a/binutils/dwarf.h
+++ b/binutils/dwarf.h
@@ -92,10 +92,12 @@ enum dwarf_section_display_enum
   line_str,
   loc,
   loclists,
+  loclists_dwo,
   pubtypes,
   gnu_pubtypes,
   ranges,
   rnglists,
+  rnglists_dwo,
   static_func,
   static_vars,
   types,
-- 
2.17.1


^ permalink raw reply	[flat|nested] 3+ messages in thread

* Re: [PATCH] Binutils support for split-dwarf and dwarf-5
  2022-06-02 14:55 [PATCH] Binutils support for split-dwarf and dwarf-5 Kumar N, Bhuvanendra
@ 2022-06-03 12:04 ` Jan Beulich
  2022-06-10 17:34   ` Kumar N, Bhuvanendra
  0 siblings, 1 reply; 3+ messages in thread
From: Jan Beulich @ 2022-06-03 12:04 UTC (permalink / raw)
  To: Kumar N, Bhuvanendra; +Cc: George, Jini Susan, Natarajan, Kavitha, binutils

On 02.06.2022 16:55, Kumar N, Bhuvanendra via Binutils wrote:
> Patch 1/2 inlined:
> 
> From 1bda1e144f43d1f41fe30a934ba008561083dc07 Mon Sep 17 00:00:00 2001
> From: =?UTF-8?q?=E2=80=9Cbhkumarn=E2=80=9D?= Bhuvanendra.KumarN@amd.com<mailto:Bhuvanendra.KumarN@amd.com>
> Date: Thu, 2 Jun 2022 17:44:02 +0530
> Subject: [PATCH] [PATCH 1/2] Binutils support for split-dwarf and dwarf-5.
> 
> This fix adds support for split-dwarf and dwarf5, for both gcc and clang.
> There are 2 patches. Basic sections dump like .debug_info.dwo,
> .debug_abbrev.dwo, .debug_str.dwo etc are supported in this patch 1/2.
> But location list and ranges list sections dump with split-dwarf and dwarf5
> are supported in the next patch 2/2.

Just as a remark: "patch 1/2" and "next patch" and alike aren't very
meaningful in commit messages. The individual commits may end up far
apart in the repo.

> --- a/binutils/dwarf.c
> +++ b/binutils/dwarf.c
> @@ -118,6 +118,8 @@ int dwarf_cutoff_level = -1;
> unsigned long dwarf_start_die;
>  int dwarf_check = 0;
> +static dwarf_vma str_offsets_base = 0;
> +#define DEBUG_STR_OFFSETS_HEADER_LEN 8

Aiui 8 is correct for 32-bit Dwarf, but 16 would need using for 64-bit.

> @@ -2485,6 +2487,8 @@ read_and_display_attr_value (unsigned long           attribute,
>      case DW_FORM_GNU_ref_alt:
>      case DW_FORM_GNU_strp_alt:
>        SAFE_BYTE_GET_AND_INC (uvalue, data, offset_size, end);
> +      if (attribute == DW_AT_str_offsets_base)
> +        str_offsets_base = uvalue - DEBUG_STR_OFFSETS_HEADER_LEN;

Can this legitimately be stored in a static variable? Don't you need
to collect the value(s) into debug_info_p just like is done for
DW_AT_loclists_base?

> @@ -11889,6 +11895,7 @@ load_separate_debug_files (void * file, const char * filename)
>        && load_debug_section (abbrev, file)
>        && load_debug_section (info, file))
>      {
> +      load_debug_section (str_index, file);

What if this fails? Immediately preceding load_debug_section() uses
have their return values checked.

> --- /dev/null
> +++ b/binutils/testsuite/binutils-all/dwo_5.s
> @@ -0,0 +1,257 @@
> +     .file "a.c"
> +     .text
> +.Ltext0:
> +     .globl     a
> +     .type a, @function
> +a:
> +.LFB0:
> +     .file 1 "a.c"
> +     .loc 1 1 13
> +     .cfi_startproc
> +     pushq %rbp
> +     .cfi_def_cfa_offset 16
> +     .cfi_offset 6, -16
> +     movq %rsp, %rbp
> +     .cfi_def_cfa_register 6
> +     .loc 1 1 22
> +     movl $111, %eax
> +     .loc 1 1 1
> +     popq %rbp
> +     .cfi_def_cfa 7, 8
> +     ret
> +     .cfi_endproc
> +.LFE0:
> +     .size a, .-a
> +.Letext0:
> +     .section   .debug_addr,"",@progbits
> +     .long 0xc
> +     .value     0x5
> +     .byte 0x8
> +     .byte 0
> +.Ldebug_addr0:
> +     .quad .LFB0
> +     .section   .debug_info.dwo,"e",@progbits
> +.Ldebug_info0:
> +     .long 0x35
> +     .value     0x5
> +     .byte 0x5
> +     .byte 0x8
> +     .long .Ldebug_abbrev0
> +     .byte 0x46
> +     .byte 0x1c
> +     .byte 0xf1
> +     .byte 0xfb
> +     .byte 0xe5
> +     .byte 0x96
> +     .byte 0x7d
> +     .byte 0x2b
> +     .uleb128 0x1
> +     .uleb128 0x1
> +     .byte 0x1d
> +     .string    "a.c"
> +     .uleb128 0
> +     .uleb128 0x2
> +     .string    "a"
> +     .byte 0x1
> +     .byte 0x1
> +     .byte 0x5
> +     .long 0x31
> +     .uleb128 0
> +     .quad .LFE0-.LFB0
> +     .uleb128 0x1
> +     .byte 0x9c
> +     .uleb128 0x3
> +     .byte 0x4
> +     .byte 0x5
> +     .string    "int"
> +     .byte 0
> +     .section   .debug_info,"",@progbits
> +.Lskeleton_debug_info0:
> +     .long 0x31
> +     .value     0x5
> +     .byte 0x4
> +     .byte 0x8
> +     .long .Lskeleton_debug_abbrev0
> +     .byte 0x46
> +     .byte 0x1c
> +     .byte 0xf1
> +     .byte 0xfb
> +     .byte 0xe5
> +     .byte 0x96
> +     .byte 0x7d
> +     .byte 0x2b
> +     .uleb128 0x1
> +     .quad .Ltext0
> +     .quad .Letext0-.Ltext0
> +     .long .Ldebug_line0
> +     .long .LASF0
> +     .long .LASF1
> +     .long .Ldebug_addr0
> +     .section   .debug_abbrev,"",@progbits
> +.Lskeleton_debug_abbrev0:
> +     .uleb128 0x1
> +     .uleb128 0x4a
> +     .byte 0
> +     .uleb128 0x11
> +     .uleb128 0x1
> +     .uleb128 0x12
> +     .uleb128 0x7
> +     .uleb128 0x10
> +     .uleb128 0x17
> +     .uleb128 0x76
> +     .uleb128 0xe
> +     .uleb128 0x1b
> +     .uleb128 0xe
> +     .uleb128 0x2134
> +     .uleb128 0x19
> +     .uleb128 0x73
> +     .uleb128 0x17
> +     .byte 0
> +     .byte 0
> +     .byte 0
> +     .section   .debug_abbrev.dwo,"e",@progbits
> +.Ldebug_abbrev0:
> +     .uleb128 0x1
> +     .uleb128 0x11
> +     .byte 0x1
> +     .uleb128 0x25
> +     .uleb128 0x1a
> +     .uleb128 0x13
> +     .uleb128 0xb
> +     .uleb128 0x3
> +     .uleb128 0x8
> +     .uleb128 0x1b
> +     .uleb128 0x1a
> +     .byte 0
> +     .byte 0
> +     .uleb128 0x2
> +     .uleb128 0x2e
> +     .byte 0
> +     .uleb128 0x3f
> +     .uleb128 0x19
> +     .uleb128 0x3
> +     .uleb128 0x8
> +     .uleb128 0x3a
> +     .uleb128 0xb
> +     .uleb128 0x3b
> +     .uleb128 0xb
> +     .uleb128 0x39
> +     .uleb128 0xb
> +     .uleb128 0x27
> +     .uleb128 0x19
> +     .uleb128 0x49
> +     .uleb128 0x13
> +     .uleb128 0x11
> +     .uleb128 0x1b
> +     .uleb128 0x12
> +     .uleb128 0x7
> +     .uleb128 0x40
> +     .uleb128 0x18
> +     .uleb128 0x7a
> +     .uleb128 0x19
> +     .byte 0
> +     .byte 0
> +     .uleb128 0x3
> +     .uleb128 0x24
> +     .byte 0
> +     .uleb128 0xb
> +     .uleb128 0xb
> +     .uleb128 0x3e
> +     .uleb128 0xb
> +     .uleb128 0x3
> +     .uleb128 0x8
> +     .byte 0
> +     .byte 0
> +     .byte 0
> +     .section   .debug_gnu_pubnames,"",@progbits
> +     .long 0x15
> +     .value     0x2
> +     .long .Lskeleton_debug_info0
> +     .long 0x39
> +     .long 0x1c
> +     .byte 0x30
> +     .string    "a"
> +     .long 0
> +     .section   .debug_gnu_pubtypes,"",@progbits
> +     .long 0x17
> +     .value     0x2
> +     .long .Lskeleton_debug_info0
> +     .long 0x39
> +     .long 0x31
> +     .byte 0x90
> +     .string    "int"
> +     .long 0
> +     .section   .debug_aranges,"",@progbits
> +     .long 0x2c
> +     .value     0x2
> +     .long .Lskeleton_debug_info0
> +     .byte 0x8
> +     .byte 0
> +     .value     0
> +     .value     0
> +     .quad .Ltext0
> +     .quad .Letext0-.Ltext0
> +     .quad 0
> +     .quad 0
> +     .section   .debug_line,"",@progbits
> +.Ldebug_line0:
> +     .section   .debug_line.dwo,"e",@progbits
> +.Lskeleton_debug_line0:
> +     .long .LELT0-.LSLT0
> +.LSLT0:
> +     .value     0x5
> +     .byte 0x8
> +     .byte 0
> +     .long .LELTP0-.LASLTP0
> +.LASLTP0:
> +     .byte 0x1
> +     .byte 0x1
> +     .byte 0x1
> +     .byte 0xf6
> +     .byte 0xf2
> +     .byte 0xd
> +     .byte 0
> +     .byte 0x1
> +     .byte 0x1
> +     .byte 0x1
> +     .byte 0x1
> +     .byte 0
> +     .byte 0
> +     .byte 0
> +     .byte 0x1
> +     .byte 0
> +     .byte 0
> +     .byte 0x1
> +     .byte 0x1
> +     .uleb128 0x1
> +     .uleb128 0x8
> +     .uleb128 0x1
> +     .string    "/tmp"
> +     .byte 0x2
> +     .uleb128 0x1
> +     .uleb128 0x8
> +     .uleb128 0x2
> +     .uleb128 0xb
> +     .uleb128 0x2
> +     .string    "a.c"
> +     .byte 0
> +     .string    "a.c"
> +     .byte 0
> +.LELTP0:
> +.LELT0:
> +     .section   .debug_str,"MS",@progbits,1
> +.LASF1:
> +     .string    "/tmp"
> +.LASF0:
> +     .string    "a.dwo"
> +     .section      .debug_str_offsets.dwo,"e",@progbits
> +     .long 0xc
> +     .value     0x5
> +     .value     0
> +     .long 0
> +     .long 0x5
> +     .section   .debug_str.dwo,"e",@progbits
> +     .string    "/tmp"
> +     .string    "GNU C17 10.0.0 20190813 (experimental) -mtune=generic -march=x86-64 -gdwarf-5 -gsplit-dwarf"
> +     .ident     "GCC: (GNU) 10.0.0 20190813 (experimental)"
> +     .section   .note.GNU-stack,"",@progbits

I'm a little worried about the maintainability (and reviewability) of
such testcases: This looks to be compiler output, even with non-
essential pieces left in. That's fine in principle, but without any
comments it's close to unreadable. Plus it's then unclear whether the
compiler-generated directives are actually all correct; after all
compilers can also have bugs, and the compiler used wasn't even a
released version, and even quite early a major-10 version.

Jan


^ permalink raw reply	[flat|nested] 3+ messages in thread

* RE: [PATCH] Binutils support for split-dwarf and dwarf-5
  2022-06-03 12:04 ` Jan Beulich
@ 2022-06-10 17:34   ` Kumar N, Bhuvanendra
  0 siblings, 0 replies; 3+ messages in thread
From: Kumar N, Bhuvanendra @ 2022-06-10 17:34 UTC (permalink / raw)
  To: Jan Beulich; +Cc: George, Jini Susan, Natarajan, Kavitha, binutils

[-- Attachment #1: Type: text/plain, Size: 19530 bytes --]

[AMD Official Use Only - General]

Hi,

Thanks for the review comments. I could address your review comments in the updated patch which is attached and also inlined below.

> Can this legitimately be stored in a static variable? Don't you need to collect the value(s) into debug_info_p just like is done for DW_AT_loclists_base?

I have moved this to debug_information or debug_info_p. During this I observed, debug_information struct is allocated and initialized inside function process_debug_info(), under the condition " if (do_loc || do_debug_loc || do_debug_ranges)". Now I have added do_debug_info to this list of checks for my requirement and it helps during readelf -wi and its working fine.

> What if this fails? Immediately preceding load_debug_section() uses have their return values checked.
I have added the proper comment now. If we don’t have the .debug_str_offsets section, then it simply ignores.

regards,
bhuvan

Updated patch inlined:

From 4d90b859146b7aacc1067ff1a77c123e77391ee0 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=E2=80=9Cbhkumarn=E2=80=9D?= <Bhuvanendra.KumarN@amd.com>
Date: Fri, 10 Jun 2022 22:00:34 +0530
Subject: [PATCH] [PATCH] Binutils support for split-dwarf and dwarf-5.

This patch adds support for split-dwarf and dwarf5, for both gcc and clang.
Basic sections dump like .debug_info.dwo, .debug_abbrev.dwo, .debug_str.dwo
etc are supported in this patch.

There are few differences b/w dwarf4 and dwarf5, w.r.t. split-dwarf like
different attributes/forms used to represent DWO name and ID,
.debug_str_offsets section etc. All these are addressed.

	* dwarf.c (fetch_indexed_string): Added new parameter str_offsets_base
	to calculate the string offset.
	(read_and_display_attr_value): Read DW_AT_str_offsets_base attribute.
	(process_debug_info): While allocating memory and initializing
	debug_information, do it for do_debug_info also, if its true.
	(load_separate_debug_files): Load .debug_str_offsets if exists.
	* dwarf.h (struct debug_info): Add str_offsets_base field.
---
 binutils/dwarf.c | 54 ++++++++++++++++++++++++++++++++----------------
 binutils/dwarf.h |  1 +
 2 files changed, 37 insertions(+), 18 deletions(-)

diff --git a/binutils/dwarf.c b/binutils/dwarf.c
index e8f0ea4cf0c..6d2541039e5 100644
--- a/binutils/dwarf.c
+++ b/binutils/dwarf.c
@@ -118,8 +118,6 @@ int dwarf_cutoff_level = -1;
 unsigned long dwarf_start_die;
 
 int dwarf_check = 0;
-static dwarf_vma str_offsets_base = 0;
-#define DEBUG_STR_OFFSETS_HEADER_LEN 8
 
 /* Convenient constant, to avoid having to cast -1 to dwarf_vma when
    testing whether e.g. a locview list is present.  */
@@ -693,7 +691,7 @@ fetch_indirect_line_string (dwarf_vma offset)
 
 static const char *
 fetch_indexed_string (dwarf_vma idx, struct cu_tu_set *this_set,
-		      dwarf_vma offset_size, bool dwo)
+		      dwarf_vma offset_size, bool dwo, dwarf_vma str_offsets_base)
 {
   enum dwarf_section_display_enum str_sec_idx = dwo ? str_dwo : str;
   enum dwarf_section_display_enum idx_sec_idx = dwo ? str_index_dwo : str_index;
@@ -781,6 +779,13 @@ fetch_indexed_string (dwarf_vma idx, struct cu_tu_set *this_set,
       return _("<index offset is too big>");
     }
 
+  if (str_offsets_base > 0 )
+    {
+      if (offset_size == 8)
+        str_offsets_base -= 16;
+      else
+        str_offsets_base -= 8;
+    }
   str_offset = byte_get (curr + index_offset + str_offsets_base, offset_size);
   str_offset -= str_section->address;
   if (str_offset >= str_section->size)
@@ -2487,8 +2492,6 @@ read_and_display_attr_value (unsigned long           attribute,
     case DW_FORM_GNU_ref_alt:
     case DW_FORM_GNU_strp_alt:
       SAFE_BYTE_GET_AND_INC (uvalue, data, offset_size, end);
-      if (attribute == DW_AT_str_offsets_base)
-        str_offsets_base = uvalue - DEBUG_STR_OFFSETS_HEADER_LEN;
       break;
 
     case DW_FORM_flag_present:
@@ -2737,11 +2740,13 @@ read_and_display_attr_value (unsigned long           attribute,
 	    /* We have already displayed the form name.  */
 	    printf (_("%c(offset: 0x%s): %s"), delimiter,
 		    dwarf_vmatoa ("x", uvalue),
-		    fetch_indexed_string (uvalue, this_set, offset_size, dwo));
+		    fetch_indexed_string (uvalue, this_set, offset_size, dwo,
+	                                  debug_info_p->str_offsets_base));
 	  else
 	    printf (_("%c(indexed string: 0x%s): %s"), delimiter,
 		    dwarf_vmatoa ("x", uvalue),
-		    fetch_indexed_string (uvalue, this_set, offset_size, dwo));
+		    fetch_indexed_string (uvalue, this_set, offset_size, dwo,
+	                                  debug_info_p->str_offsets_base));
 	}
       break;
 
@@ -2816,7 +2821,7 @@ read_and_display_attr_value (unsigned long           attribute,
       break;
     }
 
-  if ((do_loc || do_debug_loc || do_debug_ranges)
+  if ((do_loc || do_debug_loc || do_debug_ranges || do_debug_info)
       && num_debug_info_entries == 0
       && debug_info_p != NULL)
     {
@@ -2829,6 +2834,13 @@ read_and_display_attr_value (unsigned long           attribute,
 	  debug_info_p->loclists_base = uvalue;
 	  break;
 
+	case DW_AT_str_offsets_base:
+	  if (debug_info_p->str_offsets_base)
+	    warn (_("CU @ 0x%s has multiple str_offsets_base values"),
+		  dwarf_vmatoa ("x", debug_info_p->cu_offset));
+	  debug_info_p->str_offsets_base = uvalue;
+	  break;
+
 	case DW_AT_frame_base:
 	  have_frame_base = 1;
 	  /* Fall through.  */
@@ -2967,7 +2979,8 @@ read_and_display_attr_value (unsigned long           attribute,
 	      case DW_FORM_strx2:
 	      case DW_FORM_strx3:
 	      case DW_FORM_strx4:
-		add_dwo_name (fetch_indexed_string (uvalue, this_set, offset_size, false), cu_offset);
+		add_dwo_name (fetch_indexed_string (uvalue, this_set, offset_size, false,
+		                                    debug_info_p->str_offsets_base), cu_offset);
 		break;
 	      case DW_FORM_string:
 		add_dwo_name ((const char *) orig_data, cu_offset);
@@ -2999,7 +3012,8 @@ read_and_display_attr_value (unsigned long           attribute,
 	      case DW_FORM_strx2:
 	      case DW_FORM_strx3:
 	      case DW_FORM_strx4:
-		add_dwo_dir (fetch_indexed_string (uvalue, this_set, offset_size, false), cu_offset);
+		add_dwo_dir (fetch_indexed_string (uvalue, this_set, offset_size, false,
+		                                   debug_info_p->str_offsets_base), cu_offset);
 		break;
 	      case DW_FORM_string:
 		add_dwo_dir ((const char *) orig_data, cu_offset);
@@ -3319,6 +3333,7 @@ read_and_display_attr_value (unsigned long           attribute,
       /* Fall through.  */
     case DW_AT_location:
     case DW_AT_loclists_base:
+    case DW_AT_str_offsets_base:
     case DW_AT_string_length:
     case DW_AT_return_addr:
     case DW_AT_data_member_location:
@@ -3337,8 +3352,10 @@ read_and_display_attr_value (unsigned long           attribute,
       if ((dwarf_version < 4
 	   && (form == DW_FORM_data4 || form == DW_FORM_data8))
 	  || form == DW_FORM_sec_offset
-	  || form == DW_FORM_loclistx)
-	printf (_(" (location list)"));
+	  || form == DW_FORM_loclistx) {
+	if (attribute != DW_AT_str_offsets_base)
+	  printf (_(" (location list)"));
+      }
       /* Fall through.  */
     case DW_AT_allocated:
     case DW_AT_associated:
@@ -3569,7 +3586,7 @@ process_debug_info (struct dwarf_section * section,
       return false;
     }
 
-  if ((do_loc || do_debug_loc || do_debug_ranges)
+  if ((do_loc || do_debug_loc || do_debug_ranges || do_debug_info)
       && num_debug_info_entries == 0
       && ! do_types)
     {
@@ -3804,7 +3821,7 @@ process_debug_info (struct dwarf_section * section,
 	  continue;
 	}
 
-      if ((do_loc || do_debug_loc || do_debug_ranges)
+      if ((do_loc || do_debug_loc || do_debug_ranges || do_debug_info)
 	  && num_debug_info_entries == 0
 	  && alloc_num_debug_info_entries > unit
 	  && ! do_types)
@@ -3825,6 +3842,7 @@ process_debug_info (struct dwarf_section * section,
 	  debug_information [unit].range_lists = NULL;
 	  debug_information [unit].max_range_lists= 0;
 	  debug_information [unit].num_range_lists = 0;
+	  debug_information [unit].str_offsets_base = 0;
 	}
 
       if (!do_loc && dwarf_start_die == 0)
@@ -4064,7 +4082,6 @@ process_debug_info (struct dwarf_section * section,
 					    level);
 	    }
 
-	  str_offsets_base = 0;
 	  /* If a locview attribute appears before a location one,
 	     make sure we don't associate it with an earlier
 	     loclist. */
@@ -4097,7 +4114,7 @@ process_debug_info (struct dwarf_section * section,
 
   /* Set num_debug_info_entries here so that it can be used to check if
      we need to process .debug_loc and .debug_ranges sections.  */
-  if ((do_loc || do_debug_loc || do_debug_ranges)
+  if ((do_loc || do_debug_loc || do_debug_ranges || do_debug_info)
       && num_debug_info_entries == 0
       && ! do_types)
     {
@@ -6245,7 +6262,7 @@ display_debug_macro (struct dwarf_section *section,
 	      READ_ULEB (lineno, curr, end);
 	      READ_ULEB (offset, curr, end);
 	      string = (const unsigned char *)
-		fetch_indexed_string (offset, NULL, offset_size, false);
+		fetch_indexed_string (offset, NULL, offset_size, false, 0);
 	      if (op == DW_MACRO_define_strx)
 		printf (" DW_MACRO_define_strx ");
 	      else
@@ -7860,7 +7877,7 @@ display_debug_str_offsets (struct dwarf_section *section,
 	  SAFE_BYTE_GET_AND_INC (offset, curr, entry_length, entries_end);
 	  if (dwo)
 	    string = (const unsigned char *)
-	      fetch_indexed_string (idx, NULL, entry_length, dwo);
+	      fetch_indexed_string (idx, NULL, entry_length, dwo, 0);
 	  else
 	    string = fetch_indirect_string (offset);
 
@@ -11895,6 +11912,7 @@ load_separate_debug_files (void * file, const char * filename)
       && load_debug_section (abbrev, file)
       && load_debug_section (info, file))
     {
+      /* Load .debug_str_offsets section, if exists.  */
       load_debug_section (str_index, file);
       free_dwo_info ();
 
diff --git a/binutils/dwarf.h b/binutils/dwarf.h
index 040e674c6ce..ce38858d609 100644
--- a/binutils/dwarf.h
+++ b/binutils/dwarf.h
@@ -192,6 +192,7 @@ typedef struct
   dwarf_vma *    range_lists;
   unsigned int   num_range_lists;
   unsigned int   max_range_lists;
+  dwarf_vma      str_offsets_base;
 }
 debug_info;
 
-- 
2.17.1


-----Original Message-----
From: Jan Beulich <jbeulich@suse.com> 
Sent: Friday, June 3, 2022 5:34 PM
To: Kumar N, Bhuvanendra <Bhuvanendra.KumarN@amd.com>
Cc: George, Jini Susan <JiniSusan.George@amd.com>; Natarajan, Kavitha <Kavitha.Natarajan@amd.com>; binutils@sourceware.org
Subject: Re: [PATCH] Binutils support for split-dwarf and dwarf-5

[CAUTION: External Email]

On 02.06.2022 16:55, Kumar N, Bhuvanendra via Binutils wrote:
> Patch 1/2 inlined:
>
> From 1bda1e144f43d1f41fe30a934ba008561083dc07 Mon Sep 17 00:00:00 2001
> From: =?UTF-8?q?=E2=80=9Cbhkumarn=E2=80=9D?= 
> Bhuvanendra.KumarN@amd.com<mailto:Bhuvanendra.KumarN@amd.com>
> Date: Thu, 2 Jun 2022 17:44:02 +0530
> Subject: [PATCH] [PATCH 1/2] Binutils support for split-dwarf and dwarf-5.
>
> This fix adds support for split-dwarf and dwarf5, for both gcc and clang.
> There are 2 patches. Basic sections dump like .debug_info.dwo, 
> .debug_abbrev.dwo, .debug_str.dwo etc are supported in this patch 1/2.
> But location list and ranges list sections dump with split-dwarf and 
> dwarf5 are supported in the next patch 2/2.

Just as a remark: "patch 1/2" and "next patch" and alike aren't very meaningful in commit messages. The individual commits may end up far apart in the repo.

> --- a/binutils/dwarf.c
> +++ b/binutils/dwarf.c
> @@ -118,6 +118,8 @@ int dwarf_cutoff_level = -1; unsigned long 
> dwarf_start_die;  int dwarf_check = 0;
> +static dwarf_vma str_offsets_base = 0; #define 
> +DEBUG_STR_OFFSETS_HEADER_LEN 8

Aiui 8 is correct for 32-bit Dwarf, but 16 would need using for 64-bit.

> @@ -2485,6 +2487,8 @@ read_and_display_attr_value (unsigned long           attribute,
>      case DW_FORM_GNU_ref_alt:
>      case DW_FORM_GNU_strp_alt:
>        SAFE_BYTE_GET_AND_INC (uvalue, data, offset_size, end);
> +      if (attribute == DW_AT_str_offsets_base)
> +        str_offsets_base = uvalue - DEBUG_STR_OFFSETS_HEADER_LEN;

Can this legitimately be stored in a static variable? Don't you need to collect the value(s) into debug_info_p just like is done for DW_AT_loclists_base?

> @@ -11889,6 +11895,7 @@ load_separate_debug_files (void * file, const char * filename)
>        && load_debug_section (abbrev, file)
>        && load_debug_section (info, file))
>      {
> +      load_debug_section (str_index, file);

What if this fails? Immediately preceding load_debug_section() uses have their return values checked.

> --- /dev/null
> +++ b/binutils/testsuite/binutils-all/dwo_5.s
> @@ -0,0 +1,257 @@
> +     .file "a.c"
> +     .text
> +.Ltext0:
> +     .globl     a
> +     .type a, @function
> +a:
> +.LFB0:
> +     .file 1 "a.c"
> +     .loc 1 1 13
> +     .cfi_startproc
> +     pushq %rbp
> +     .cfi_def_cfa_offset 16
> +     .cfi_offset 6, -16
> +     movq %rsp, %rbp
> +     .cfi_def_cfa_register 6
> +     .loc 1 1 22
> +     movl $111, %eax
> +     .loc 1 1 1
> +     popq %rbp
> +     .cfi_def_cfa 7, 8
> +     ret
> +     .cfi_endproc
> +.LFE0:
> +     .size a, .-a
> +.Letext0:
> +     .section   .debug_addr,"",@progbits
> +     .long 0xc
> +     .value     0x5
> +     .byte 0x8
> +     .byte 0
> +.Ldebug_addr0:
> +     .quad .LFB0
> +     .section   .debug_info.dwo,"e",@progbits
> +.Ldebug_info0:
> +     .long 0x35
> +     .value     0x5
> +     .byte 0x5
> +     .byte 0x8
> +     .long .Ldebug_abbrev0
> +     .byte 0x46
> +     .byte 0x1c
> +     .byte 0xf1
> +     .byte 0xfb
> +     .byte 0xe5
> +     .byte 0x96
> +     .byte 0x7d
> +     .byte 0x2b
> +     .uleb128 0x1
> +     .uleb128 0x1
> +     .byte 0x1d
> +     .string    "a.c"
> +     .uleb128 0
> +     .uleb128 0x2
> +     .string    "a"
> +     .byte 0x1
> +     .byte 0x1
> +     .byte 0x5
> +     .long 0x31
> +     .uleb128 0
> +     .quad .LFE0-.LFB0
> +     .uleb128 0x1
> +     .byte 0x9c
> +     .uleb128 0x3
> +     .byte 0x4
> +     .byte 0x5
> +     .string    "int"
> +     .byte 0
> +     .section   .debug_info,"",@progbits
> +.Lskeleton_debug_info0:
> +     .long 0x31
> +     .value     0x5
> +     .byte 0x4
> +     .byte 0x8
> +     .long .Lskeleton_debug_abbrev0
> +     .byte 0x46
> +     .byte 0x1c
> +     .byte 0xf1
> +     .byte 0xfb
> +     .byte 0xe5
> +     .byte 0x96
> +     .byte 0x7d
> +     .byte 0x2b
> +     .uleb128 0x1
> +     .quad .Ltext0
> +     .quad .Letext0-.Ltext0
> +     .long .Ldebug_line0
> +     .long .LASF0
> +     .long .LASF1
> +     .long .Ldebug_addr0
> +     .section   .debug_abbrev,"",@progbits
> +.Lskeleton_debug_abbrev0:
> +     .uleb128 0x1
> +     .uleb128 0x4a
> +     .byte 0
> +     .uleb128 0x11
> +     .uleb128 0x1
> +     .uleb128 0x12
> +     .uleb128 0x7
> +     .uleb128 0x10
> +     .uleb128 0x17
> +     .uleb128 0x76
> +     .uleb128 0xe
> +     .uleb128 0x1b
> +     .uleb128 0xe
> +     .uleb128 0x2134
> +     .uleb128 0x19
> +     .uleb128 0x73
> +     .uleb128 0x17
> +     .byte 0
> +     .byte 0
> +     .byte 0
> +     .section   .debug_abbrev.dwo,"e",@progbits
> +.Ldebug_abbrev0:
> +     .uleb128 0x1
> +     .uleb128 0x11
> +     .byte 0x1
> +     .uleb128 0x25
> +     .uleb128 0x1a
> +     .uleb128 0x13
> +     .uleb128 0xb
> +     .uleb128 0x3
> +     .uleb128 0x8
> +     .uleb128 0x1b
> +     .uleb128 0x1a
> +     .byte 0
> +     .byte 0
> +     .uleb128 0x2
> +     .uleb128 0x2e
> +     .byte 0
> +     .uleb128 0x3f
> +     .uleb128 0x19
> +     .uleb128 0x3
> +     .uleb128 0x8
> +     .uleb128 0x3a
> +     .uleb128 0xb
> +     .uleb128 0x3b
> +     .uleb128 0xb
> +     .uleb128 0x39
> +     .uleb128 0xb
> +     .uleb128 0x27
> +     .uleb128 0x19
> +     .uleb128 0x49
> +     .uleb128 0x13
> +     .uleb128 0x11
> +     .uleb128 0x1b
> +     .uleb128 0x12
> +     .uleb128 0x7
> +     .uleb128 0x40
> +     .uleb128 0x18
> +     .uleb128 0x7a
> +     .uleb128 0x19
> +     .byte 0
> +     .byte 0
> +     .uleb128 0x3
> +     .uleb128 0x24
> +     .byte 0
> +     .uleb128 0xb
> +     .uleb128 0xb
> +     .uleb128 0x3e
> +     .uleb128 0xb
> +     .uleb128 0x3
> +     .uleb128 0x8
> +     .byte 0
> +     .byte 0
> +     .byte 0
> +     .section   .debug_gnu_pubnames,"",@progbits
> +     .long 0x15
> +     .value     0x2
> +     .long .Lskeleton_debug_info0
> +     .long 0x39
> +     .long 0x1c
> +     .byte 0x30
> +     .string    "a"
> +     .long 0
> +     .section   .debug_gnu_pubtypes,"",@progbits
> +     .long 0x17
> +     .value     0x2
> +     .long .Lskeleton_debug_info0
> +     .long 0x39
> +     .long 0x31
> +     .byte 0x90
> +     .string    "int"
> +     .long 0
> +     .section   .debug_aranges,"",@progbits
> +     .long 0x2c
> +     .value     0x2
> +     .long .Lskeleton_debug_info0
> +     .byte 0x8
> +     .byte 0
> +     .value     0
> +     .value     0
> +     .quad .Ltext0
> +     .quad .Letext0-.Ltext0
> +     .quad 0
> +     .quad 0
> +     .section   .debug_line,"",@progbits
> +.Ldebug_line0:
> +     .section   .debug_line.dwo,"e",@progbits
> +.Lskeleton_debug_line0:
> +     .long .LELT0-.LSLT0
> +.LSLT0:
> +     .value     0x5
> +     .byte 0x8
> +     .byte 0
> +     .long .LELTP0-.LASLTP0
> +.LASLTP0:
> +     .byte 0x1
> +     .byte 0x1
> +     .byte 0x1
> +     .byte 0xf6
> +     .byte 0xf2
> +     .byte 0xd
> +     .byte 0
> +     .byte 0x1
> +     .byte 0x1
> +     .byte 0x1
> +     .byte 0x1
> +     .byte 0
> +     .byte 0
> +     .byte 0
> +     .byte 0x1
> +     .byte 0
> +     .byte 0
> +     .byte 0x1
> +     .byte 0x1
> +     .uleb128 0x1
> +     .uleb128 0x8
> +     .uleb128 0x1
> +     .string    "/tmp"
> +     .byte 0x2
> +     .uleb128 0x1
> +     .uleb128 0x8
> +     .uleb128 0x2
> +     .uleb128 0xb
> +     .uleb128 0x2
> +     .string    "a.c"
> +     .byte 0
> +     .string    "a.c"
> +     .byte 0
> +.LELTP0:
> +.LELT0:
> +     .section   .debug_str,"MS",@progbits,1
> +.LASF1:
> +     .string    "/tmp"
> +.LASF0:
> +     .string    "a.dwo"
> +     .section      .debug_str_offsets.dwo,"e",@progbits
> +     .long 0xc
> +     .value     0x5
> +     .value     0
> +     .long 0
> +     .long 0x5
> +     .section   .debug_str.dwo,"e",@progbits
> +     .string    "/tmp"
> +     .string    "GNU C17 10.0.0 20190813 (experimental) -mtune=generic -march=x86-64 -gdwarf-5 -gsplit-dwarf"
> +     .ident     "GCC: (GNU) 10.0.0 20190813 (experimental)"
> +     .section   .note.GNU-stack,"",@progbits

I'm a little worried about the maintainability (and reviewability) of such testcases: This looks to be compiler output, even with non- essential pieces left in. That's fine in principle, but without any comments it's close to unreadable. Plus it's then unclear whether the compiler-generated directives are actually all correct; after all compilers can also have bugs, and the compiler used wasn't even a released version, and even quite early a major-10 version.

Jan

[-- Attachment #2: 0001-PATCH-Binutils-support-for-split-dwarf-and-dwarf-5.patch --]
[-- Type: application/octet-stream, Size: 9278 bytes --]

From 4d90b859146b7aacc1067ff1a77c123e77391ee0 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=E2=80=9Cbhkumarn=E2=80=9D?= <Bhuvanendra.KumarN@amd.com>
Date: Fri, 10 Jun 2022 22:00:34 +0530
Subject: [PATCH] [PATCH] Binutils support for split-dwarf and dwarf-5.

This patch adds support for split-dwarf and dwarf5, for both gcc and clang.
Basic sections dump like .debug_info.dwo, .debug_abbrev.dwo, .debug_str.dwo
etc are supported in this patch.

There are few differences b/w dwarf4 and dwarf5, w.r.t. split-dwarf like
different attributes/forms used to represent DWO name and ID,
.debug_str_offsets section etc. All these are addressed.

	* dwarf.c (fetch_indexed_string): Added new parameter str_offsets_base
	to calculate the string offset.
	(read_and_display_attr_value): Read DW_AT_str_offsets_base attribute.
	(process_debug_info): While allocating memory and initializing
	debug_information, do it for do_debug_info also, if its true.
	(load_separate_debug_files): Load .debug_str_offsets if exists.
	* dwarf.h (struct debug_info): Add str_offsets_base field.
---
 binutils/dwarf.c | 54 ++++++++++++++++++++++++++++++++----------------
 binutils/dwarf.h |  1 +
 2 files changed, 37 insertions(+), 18 deletions(-)

diff --git a/binutils/dwarf.c b/binutils/dwarf.c
index e8f0ea4cf0c..6d2541039e5 100644
--- a/binutils/dwarf.c
+++ b/binutils/dwarf.c
@@ -118,8 +118,6 @@ int dwarf_cutoff_level = -1;
 unsigned long dwarf_start_die;
 
 int dwarf_check = 0;
-static dwarf_vma str_offsets_base = 0;
-#define DEBUG_STR_OFFSETS_HEADER_LEN 8
 
 /* Convenient constant, to avoid having to cast -1 to dwarf_vma when
    testing whether e.g. a locview list is present.  */
@@ -693,7 +691,7 @@ fetch_indirect_line_string (dwarf_vma offset)
 
 static const char *
 fetch_indexed_string (dwarf_vma idx, struct cu_tu_set *this_set,
-		      dwarf_vma offset_size, bool dwo)
+		      dwarf_vma offset_size, bool dwo, dwarf_vma str_offsets_base)
 {
   enum dwarf_section_display_enum str_sec_idx = dwo ? str_dwo : str;
   enum dwarf_section_display_enum idx_sec_idx = dwo ? str_index_dwo : str_index;
@@ -781,6 +779,13 @@ fetch_indexed_string (dwarf_vma idx, struct cu_tu_set *this_set,
       return _("<index offset is too big>");
     }
 
+  if (str_offsets_base > 0 )
+    {
+      if (offset_size == 8)
+        str_offsets_base -= 16;
+      else
+        str_offsets_base -= 8;
+    }
   str_offset = byte_get (curr + index_offset + str_offsets_base, offset_size);
   str_offset -= str_section->address;
   if (str_offset >= str_section->size)
@@ -2487,8 +2492,6 @@ read_and_display_attr_value (unsigned long           attribute,
     case DW_FORM_GNU_ref_alt:
     case DW_FORM_GNU_strp_alt:
       SAFE_BYTE_GET_AND_INC (uvalue, data, offset_size, end);
-      if (attribute == DW_AT_str_offsets_base)
-        str_offsets_base = uvalue - DEBUG_STR_OFFSETS_HEADER_LEN;
       break;
 
     case DW_FORM_flag_present:
@@ -2737,11 +2740,13 @@ read_and_display_attr_value (unsigned long           attribute,
 	    /* We have already displayed the form name.  */
 	    printf (_("%c(offset: 0x%s): %s"), delimiter,
 		    dwarf_vmatoa ("x", uvalue),
-		    fetch_indexed_string (uvalue, this_set, offset_size, dwo));
+		    fetch_indexed_string (uvalue, this_set, offset_size, dwo,
+	                                  debug_info_p->str_offsets_base));
 	  else
 	    printf (_("%c(indexed string: 0x%s): %s"), delimiter,
 		    dwarf_vmatoa ("x", uvalue),
-		    fetch_indexed_string (uvalue, this_set, offset_size, dwo));
+		    fetch_indexed_string (uvalue, this_set, offset_size, dwo,
+	                                  debug_info_p->str_offsets_base));
 	}
       break;
 
@@ -2816,7 +2821,7 @@ read_and_display_attr_value (unsigned long           attribute,
       break;
     }
 
-  if ((do_loc || do_debug_loc || do_debug_ranges)
+  if ((do_loc || do_debug_loc || do_debug_ranges || do_debug_info)
       && num_debug_info_entries == 0
       && debug_info_p != NULL)
     {
@@ -2829,6 +2834,13 @@ read_and_display_attr_value (unsigned long           attribute,
 	  debug_info_p->loclists_base = uvalue;
 	  break;
 
+	case DW_AT_str_offsets_base:
+	  if (debug_info_p->str_offsets_base)
+	    warn (_("CU @ 0x%s has multiple str_offsets_base values"),
+		  dwarf_vmatoa ("x", debug_info_p->cu_offset));
+	  debug_info_p->str_offsets_base = uvalue;
+	  break;
+
 	case DW_AT_frame_base:
 	  have_frame_base = 1;
 	  /* Fall through.  */
@@ -2967,7 +2979,8 @@ read_and_display_attr_value (unsigned long           attribute,
 	      case DW_FORM_strx2:
 	      case DW_FORM_strx3:
 	      case DW_FORM_strx4:
-		add_dwo_name (fetch_indexed_string (uvalue, this_set, offset_size, false), cu_offset);
+		add_dwo_name (fetch_indexed_string (uvalue, this_set, offset_size, false,
+		                                    debug_info_p->str_offsets_base), cu_offset);
 		break;
 	      case DW_FORM_string:
 		add_dwo_name ((const char *) orig_data, cu_offset);
@@ -2999,7 +3012,8 @@ read_and_display_attr_value (unsigned long           attribute,
 	      case DW_FORM_strx2:
 	      case DW_FORM_strx3:
 	      case DW_FORM_strx4:
-		add_dwo_dir (fetch_indexed_string (uvalue, this_set, offset_size, false), cu_offset);
+		add_dwo_dir (fetch_indexed_string (uvalue, this_set, offset_size, false,
+		                                   debug_info_p->str_offsets_base), cu_offset);
 		break;
 	      case DW_FORM_string:
 		add_dwo_dir ((const char *) orig_data, cu_offset);
@@ -3319,6 +3333,7 @@ read_and_display_attr_value (unsigned long           attribute,
       /* Fall through.  */
     case DW_AT_location:
     case DW_AT_loclists_base:
+    case DW_AT_str_offsets_base:
     case DW_AT_string_length:
     case DW_AT_return_addr:
     case DW_AT_data_member_location:
@@ -3337,8 +3352,10 @@ read_and_display_attr_value (unsigned long           attribute,
       if ((dwarf_version < 4
 	   && (form == DW_FORM_data4 || form == DW_FORM_data8))
 	  || form == DW_FORM_sec_offset
-	  || form == DW_FORM_loclistx)
-	printf (_(" (location list)"));
+	  || form == DW_FORM_loclistx) {
+	if (attribute != DW_AT_str_offsets_base)
+	  printf (_(" (location list)"));
+      }
       /* Fall through.  */
     case DW_AT_allocated:
     case DW_AT_associated:
@@ -3569,7 +3586,7 @@ process_debug_info (struct dwarf_section * section,
       return false;
     }
 
-  if ((do_loc || do_debug_loc || do_debug_ranges)
+  if ((do_loc || do_debug_loc || do_debug_ranges || do_debug_info)
       && num_debug_info_entries == 0
       && ! do_types)
     {
@@ -3804,7 +3821,7 @@ process_debug_info (struct dwarf_section * section,
 	  continue;
 	}
 
-      if ((do_loc || do_debug_loc || do_debug_ranges)
+      if ((do_loc || do_debug_loc || do_debug_ranges || do_debug_info)
 	  && num_debug_info_entries == 0
 	  && alloc_num_debug_info_entries > unit
 	  && ! do_types)
@@ -3825,6 +3842,7 @@ process_debug_info (struct dwarf_section * section,
 	  debug_information [unit].range_lists = NULL;
 	  debug_information [unit].max_range_lists= 0;
 	  debug_information [unit].num_range_lists = 0;
+	  debug_information [unit].str_offsets_base = 0;
 	}
 
       if (!do_loc && dwarf_start_die == 0)
@@ -4064,7 +4082,6 @@ process_debug_info (struct dwarf_section * section,
 					    level);
 	    }
 
-	  str_offsets_base = 0;
 	  /* If a locview attribute appears before a location one,
 	     make sure we don't associate it with an earlier
 	     loclist. */
@@ -4097,7 +4114,7 @@ process_debug_info (struct dwarf_section * section,
 
   /* Set num_debug_info_entries here so that it can be used to check if
      we need to process .debug_loc and .debug_ranges sections.  */
-  if ((do_loc || do_debug_loc || do_debug_ranges)
+  if ((do_loc || do_debug_loc || do_debug_ranges || do_debug_info)
       && num_debug_info_entries == 0
       && ! do_types)
     {
@@ -6245,7 +6262,7 @@ display_debug_macro (struct dwarf_section *section,
 	      READ_ULEB (lineno, curr, end);
 	      READ_ULEB (offset, curr, end);
 	      string = (const unsigned char *)
-		fetch_indexed_string (offset, NULL, offset_size, false);
+		fetch_indexed_string (offset, NULL, offset_size, false, 0);
 	      if (op == DW_MACRO_define_strx)
 		printf (" DW_MACRO_define_strx ");
 	      else
@@ -7860,7 +7877,7 @@ display_debug_str_offsets (struct dwarf_section *section,
 	  SAFE_BYTE_GET_AND_INC (offset, curr, entry_length, entries_end);
 	  if (dwo)
 	    string = (const unsigned char *)
-	      fetch_indexed_string (idx, NULL, entry_length, dwo);
+	      fetch_indexed_string (idx, NULL, entry_length, dwo, 0);
 	  else
 	    string = fetch_indirect_string (offset);
 
@@ -11895,6 +11912,7 @@ load_separate_debug_files (void * file, const char * filename)
       && load_debug_section (abbrev, file)
       && load_debug_section (info, file))
     {
+      /* Load .debug_str_offsets section, if exists.  */
       load_debug_section (str_index, file);
       free_dwo_info ();
 
diff --git a/binutils/dwarf.h b/binutils/dwarf.h
index 040e674c6ce..ce38858d609 100644
--- a/binutils/dwarf.h
+++ b/binutils/dwarf.h
@@ -192,6 +192,7 @@ typedef struct
   dwarf_vma *    range_lists;
   unsigned int   num_range_lists;
   unsigned int   max_range_lists;
+  dwarf_vma      str_offsets_base;
 }
 debug_info;
 
-- 
2.17.1


^ permalink raw reply	[flat|nested] 3+ messages in thread

end of thread, other threads:[~2022-06-10 17:34 UTC | newest]

Thread overview: 3+ messages (download: mbox.gz / follow: Atom feed)
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2022-06-02 14:55 [PATCH] Binutils support for split-dwarf and dwarf-5 Kumar N, Bhuvanendra
2022-06-03 12:04 ` Jan Beulich
2022-06-10 17:34   ` Kumar N, Bhuvanendra

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