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From 201a71ce18734b1cebc337225f345fd754a6414f Mon Sep 17 00:00:00 2001
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Message-Id: <201a71ce18734b1cebc337225f345fd754a6414f.1573552234.git.pmatilai@redhat.com>
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In-Reply-To: <ce6e8556a8f93327d6de0446f21ac5e549861d82.1573552234.git.pmatilai@redhat.com>
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References: <ce6e8556a8f93327d6de0446f21ac5e549861d82.1573552234.git.pmatilai@redhat.com>
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From: Mark Wielaard <mark@klomp.org>
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Date: Mon, 17 Jun 2019 11:23:25 +0200
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Subject: [PATCH 2/3] Handle .debug_macro in debugedit.
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When compiling with -g3 gcc will generate a .debug_macro section
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which has pointers to the .debug_str section. Since we might rewrite
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the .debug_str section, we also need to update any .debug_macro
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pointers.
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Updated the debugedit.at testcase by building everything with -g
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and add various checks to see the .debug_macro section looks OK
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after running debugedit. Added a new rpmbuild.at testcase to check
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handing of .debug_macro in the whole rpmbuild debuginfo pipeline
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to double check the separate .debug file also contains the macros.
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Original patch by Michael Schroeder <mls@suse.de>. Extended by
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Mark Wielaard <mark@klomp.org> to deal with relocations and possible
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multiple COMDAT .debug_macro sections.
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---
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 tests/Makefile.am              |   1 +
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 tests/data/SPECS/hello-g3.spec |  60 ++++++++++
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 tests/debugedit.at             |  79 ++++++++++++-
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 tests/rpmbuild.at              |  33 ++++++
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 tools/debugedit.c              | 196 +++++++++++++++++++++++++++++++--
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 5 files changed, 356 insertions(+), 13 deletions(-)
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 create mode 100644 tests/data/SPECS/hello-g3.spec
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[ test-suite part edited out, too painful to backport ]
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diff --git a/tools/debugedit.c b/tools/debugedit.c
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index cf9cc3ca9..84483ef5e 100644
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--- a/tools/debugedit.c
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+++ b/tools/debugedit.c
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@@ -41,6 +41,7 @@
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 #include <gelf.h>
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 #include <dwarf.h>
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+
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 /* Unfortunately strtab manipulation functions were only officially added
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    to elfutils libdw in 0.167.  Before that there were internal unsupported
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    ebl variants.  While libebl.h isn't supported we'll try to use it anyway
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@@ -432,6 +433,7 @@ typedef struct debug_section
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     int sec, relsec;
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     REL *relbuf;
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     REL *relend;
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+    struct debug_section *next; /* Only happens for COMDAT .debug_macro.  */
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   } debug_section;
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 static debug_section debug_sections[] =
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@@ -1989,11 +1991,35 @@ edit_dwarf2 (DSO *dso)
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 	    for (j = 0; debug_sections[j].name; ++j)
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 	      if (strcmp (name, debug_sections[j].name) == 0)
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 	 	{
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+		  struct debug_section *debug_sec = &debug_sections[j];
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 		  if (debug_sections[j].data)
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 		    {
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-		      error (0, 0, "%s: Found two copies of %s section",
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-			     dso->filename, name);
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-		      return 1;
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+		      if (j != DEBUG_MACRO)
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+			{
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+			  error (0, 0, "%s: Found two copies of %s section",
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+				 dso->filename, name);
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+			  return 1;
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+			}
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+		      else
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+			{
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+			  /* In relocatable files .debug_macro might
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+			     appear multiple times as COMDAT
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+			     section.  */
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+			  struct debug_section *sec;
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+			  sec = calloc (sizeof (struct debug_section), 1);
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+			  if (sec == NULL)
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+			    error (1, errno,
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+				   "%s: Could not allocate more macro sections",
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+				   dso->filename);
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+			  sec->name = ".debug_macro";
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+
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+			  struct debug_section *macro_sec = debug_sec;
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+			  while (macro_sec->next != NULL)
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+			    macro_sec = macro_sec->next;
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+
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+			  macro_sec->next = sec;
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+			  debug_sec = sec;
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+			}
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 		    }
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 		  scn = dso->scn[i];
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@@ -2002,10 +2028,10 @@ edit_dwarf2 (DSO *dso)
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 		  assert (elf_getdata (scn, data) == NULL);
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 		  assert (data->d_off == 0);
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 		  assert (data->d_size == dso->shdr[i].sh_size);
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-		  debug_sections[j].data = data->d_buf;
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-		  debug_sections[j].elf_data = data;
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-		  debug_sections[j].size = data->d_size;
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-		  debug_sections[j].sec = i;
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+		  debug_sec->data = data->d_buf;
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+		  debug_sec->elf_data = data;
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+		  debug_sec->size = data->d_size;
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+		  debug_sec->sec = i;
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 		  break;
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 		}
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@@ -2028,7 +2054,26 @@ edit_dwarf2 (DSO *dso)
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 			  + (dso->shdr[i].sh_type == SHT_RELA),
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 			  debug_sections[j].name) == 0)
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 	 	{
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-		  debug_sections[j].relsec = i;
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+		  if (j == DEBUG_MACRO)
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+		    {
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+		      /* Pick the correct one.  */
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+		      int rel_target = dso->shdr[i].sh_info;
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+		      struct debug_section *macro_sec = &debug_sections[j];
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+		      while (macro_sec != NULL)
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+			{
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+			  if (macro_sec->sec == rel_target)
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+			    {
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+			      macro_sec->relsec = i;
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+			      break;
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+			    }
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+			  macro_sec = macro_sec->next;
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+			}
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+		      if (macro_sec == NULL)
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+			error (0, 1, "No .debug_macro reloc section: %s",
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+			       dso->filename);
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+		    }
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+		  else
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+		    debug_sections[j].relsec = i;
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 		  break;
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 		}
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 	  }
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@@ -2062,6 +2107,7 @@ edit_dwarf2 (DSO *dso)
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       struct abbrev_tag tag, *t;
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       int phase;
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       bool info_rel_updated = false;
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+      bool macro_rel_updated = false;
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       for (phase = 0; phase < 2; phase++)
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 	{
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@@ -2279,6 +2325,113 @@ edit_dwarf2 (DSO *dso)
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 		}
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 	    }
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+	  /* The .debug_macro section also contains offsets into the
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+	     .debug_str section and references to the .debug_line
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+	     tables, so we need to update those as well if we update
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+	     the strings or the stmts.  */
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+	  if ((need_strp_update || need_stmt_update)
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+	      && debug_sections[DEBUG_MACRO].data)
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+	    {
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+	      /* There might be multiple (COMDAT) .debug_macro sections.  */
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+	      struct debug_section *macro_sec = &debug_sections[DEBUG_MACRO];
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+	      while (macro_sec != NULL)
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+		{
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+		  setup_relbuf(dso, macro_sec, &reltype);
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+		  rel_updated = false;
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+
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+		  ptr = macro_sec->data;
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+		  endsec = ptr + macro_sec->size;
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+		  int op = 0, macro_version, macro_flags;
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+		  int offset_len = 4, line_offset = 0;
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+
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+		  while (ptr < endsec)
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+		    {
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+		      if (!op)
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+			{
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+			  macro_version = read_16 (ptr);
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+			  macro_flags = read_8 (ptr);
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+			  if (macro_version < 4 || macro_version > 5)
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+			    error (1, 0, "unhandled .debug_macro version: %d",
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+				   macro_version);
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+			  if ((macro_flags & ~2) != 0)
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+			    error (1, 0, "unhandled .debug_macro flags: 0x%x",
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+				   macro_flags);
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+
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+			  offset_len = (macro_flags & 0x01) ? 8 : 4;
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+			  line_offset = (macro_flags & 0x02) ? 1 : 0;
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+
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+			  if (offset_len != 4)
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+			    error (0, 1,
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+				   "Cannot handle 8 byte macro offsets: %s",
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+				   dso->filename);
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+
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+			  /* Update the line_offset if it is there.  */
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+			  if (line_offset)
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+			    {
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+			      if (phase == 0)
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+				ptr += offset_len;
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+			      else
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+				{
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+				  size_t idx, new_idx;
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+				  idx = do_read_32_relocated (ptr);
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+				  new_idx = find_new_list_offs (&dso->lines,
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+								idx);
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+				  write_32_relocated (ptr, new_idx);
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+				}
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+			    }
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+			}
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+
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+		      op = read_8 (ptr);
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+		      if (!op)
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+			continue;
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+		      switch(op)
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+			{
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+			case DW_MACRO_GNU_define:
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+			case DW_MACRO_GNU_undef:
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+			  read_uleb128 (ptr);
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+			  ptr = ((unsigned char *) strchr ((char *) ptr, '\0')
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+				 + 1);
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+			  break;
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+			case DW_MACRO_GNU_start_file:
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+			  read_uleb128 (ptr);
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+			  read_uleb128 (ptr);
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+			  break;
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+			case DW_MACRO_GNU_end_file:
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+			  break;
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+			case DW_MACRO_GNU_define_indirect:
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+			case DW_MACRO_GNU_undef_indirect:
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+			  read_uleb128 (ptr);
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+			  if (phase == 0)
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+			    {
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+			      size_t idx = read_32_relocated (ptr);
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+			      record_existing_string_entry_idx (&dso->strings,
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+								idx);
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+			    }
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+			  else
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+			    {
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+			      struct stridxentry *entry;
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+			      size_t idx, new_idx;
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+			      idx = do_read_32_relocated (ptr);
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+			      entry = string_find_entry (&dso->strings, idx);
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+			      new_idx = strent_offset (entry->entry);
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+			      write_32_relocated (ptr, new_idx);
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+			    }
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+			  break;
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+			case DW_MACRO_GNU_transparent_include:
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+			  ptr += offset_len;
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+			  break;
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+			default:
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+			  error (1, 0, "Unhandled DW_MACRO op 0x%x", op);
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+			  break;
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+			}
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+		    }
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+
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+		  if (rel_updated)
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+		    macro_rel_updated = true;
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+		  macro_sec = macro_sec->next;
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+		}
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+	    }
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+
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 	  /* Same for the debug_str section. Make sure everything is
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 	     in place for phase 1 updating of debug_info
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 	     references. */
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@@ -2308,10 +2461,24 @@ edit_dwarf2 (DSO *dso)
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 	 new strp, strings and/or linep offsets.  */
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       if (need_strp_update || need_string_replacement || need_stmt_update)
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 	dirty_section (DEBUG_INFO);
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+      if (need_strp_update || need_stmt_update)
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+	dirty_section (DEBUG_MACRO);
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+      if (need_stmt_update)
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+	dirty_section (DEBUG_LINE);
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-      /* Update any debug_info relocations addends we might have touched. */
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+      /* Update any relocations addends we might have touched. */
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       if (info_rel_updated)
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 	update_rela_data (dso, &debug_sections[DEBUG_INFO]);
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+
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+      if (macro_rel_updated)
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+	{
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+	  struct debug_section *macro_sec = &debug_sections[DEBUG_MACRO];
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+	  while (macro_sec != NULL)
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+	    {
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+	      update_rela_data (dso, macro_sec);
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+	      macro_sec = macro_sec->next;
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+	    }
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+	}
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     }
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   return 0;
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@@ -2843,6 +3010,17 @@ main (int argc, char *argv[])
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   destroy_lines (&dso->lines);
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   free (dso);
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+  /* In case there were multiple (COMDAT) .debug_macro sections,
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+     free them.  */
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+  struct debug_section *macro_sec = &debug_sections[DEBUG_MACRO];
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+  macro_sec = macro_sec->next;
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+  while (macro_sec != NULL)
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+    {
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+      struct debug_section *next = macro_sec->next;
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+      free (macro_sec);
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+      macro_sec = next;
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+    }
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+
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   poptFreeContext (optCon);
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   return 0;
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-- 
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2.23.0
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