RE: [PATCH] bfd: Fix issues with files in debug_line table with dwarf5.

["Potharla, Rupesh" <Rupesh.Potharla@amd.com>]

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[Public]


Thanks Jan for reviewing the code changes,


>> -      /* Skip the first "zero entry", which is the compilation dir/file.  */
>> -      if (datai != 0)
>> -         if (!callback (table, fe.name, fe.dir, fe.time, fe.size))
>> -           return false;
>> +      if (!callback (table, fe.name, fe.dir, fe.time, fe.size))
>> +        return false;
>>      }
>
>How come this change doesn't add a version check?
>
Since the function read_formatted_entries is only called for version 5 in the file, I thought the version check is not needed. Now I have added the condition and updated the patch. 
 
>To help being certain this is the right way of changing things, can you please
>add up to two testcases (readelf and/or objdump), one for a version < 5
>(unless one such already exists and hence it would be visible there that you
>don't unduly alter handling of those older versions) and one for version 5?
>

Readelf and objdump are not using dwarf2.c file under bfd directory these tools are using dwarf.c under binutils directory.  Currently I am using addr2line to test and validate my code changes manually. There are no testcases for addr2line and I did not find any testcases for bfd library as well.  Please let me know your suggestions .
 
Regards,
Rupesh P

---
 bfd/dwarf2.c | 13 +++++++++++--
 1 file changed, 11 insertions(+), 2 deletions(-)

diff --git a/bfd/dwarf2.c b/bfd/dwarf2.c
index f6b0183720b..c5b5d14fc9f 100644
--- a/bfd/dwarf2.c
+++ b/bfd/dwarf2.c
@@ -1572,6 +1572,7 @@ struct line_info_table
   unsigned int		num_files;
   unsigned int		num_dirs;
   unsigned int		num_sequences;
+  unsigned int 		version;
   char *		comp_dir;
   char **		dirs;
   struct fileinfo*	files;
@@ -1792,6 +1793,8 @@ concat_filename (struct line_info_table *table, unsigned int file)
 {
   char *filename;
 
+  if (table->version >= 5)
+    file = file + 1;
   if (table == NULL || file - 1 >= table->num_files)
     {
       /* FILE == 0 means unknown.  */
@@ -2414,7 +2417,7 @@ read_formatted_entries (struct comp_unit *unit, bfd_byte **bufp,
 	}
 
       /* Skip the first "zero entry", which is the compilation dir/file.  */
-      if (datai != 0)
+      if (table->version < 5 && datai != 0)
 	if (!callback (table, fe.name, fe.dir, fe.time, fe.size))
 	  return false;
     }
@@ -2581,6 +2584,7 @@ decode_line_info (struct comp_unit *unit)
   table->sequences = NULL;
 
   table->lcl_head = NULL;
+  table->version = lh.version;
 
   if (lh.version >= 5)
     {
@@ -2623,7 +2627,12 @@ decode_line_info (struct comp_unit *unit)
       /* State machine registers.  */
       bfd_vma address = 0;
       unsigned char op_index = 0;
-      char * filename = table->num_files ? concat_filename (table, 1) : NULL;
+      char *filename;
+      if (table->version >= 5)
+	filename = table->num_files ? concat_filename (table, 0) : NULL;
+      else
+	filename = table->num_files ? concat_filename (table, 1) : NULL;
+
       unsigned int line = 1;
       unsigned int column = 0;
       unsigned int discriminator = 0;
-- 
2.17.1



>-----Original Message-----
>From: Jan Beulich <jbeulich@suse.com>
>Sent: Wednesday, May 18, 2022 6:07 PM
>To: Potharla, Rupesh <Rupesh.Potharla@amd.com>; Potharla, Rupesh via
>Binutils <binutils@sourceware.org>
>Cc: George, Jini Susan <JiniSusan.George@amd.com>; Parasuraman,
>Hariharan <Hariharan.Parasuraman@amd.com>; Natarajan, Kavitha
><Kavitha.Natarajan@amd.com>
>Subject: Re: [PATCH] bfd: Fix issues with files in debug_line table with dwarf5.
>
>[CAUTION: External Email]
>
>On 09.05.2022 09:03, Potharla, Rupesh via Binutils wrote:
>> [Public]
>>
>>
>>
>> While working on the implementation of DW_FORM_strx forms could not
>print file names even after the implementation of strx forms. I found an issue
>with adding the file names to the file table with dwarf5 and clang.
>>
>> With dwarf5 debug line version the file index is starting with zero, but the
>code is expecting it to be 1 which is the case with other dwarf versions.
>>
>> From the contents of .debug_line compiled with clang and dwarf5, the file
>names array index is starting with zero.
>>
>> standard_opcode_lengths[DW_LNS_set_isa] = 1 include_directories[  0] =
>> "/home/rupesh/addr2line"
>> file_names[  0]:
>>            name: "prog1.c"
>>       dir_index: 0
>>    md5_checksum: da4ea4c312af96d39b13557acdf23f05
>>
>> Address            Line   Column File   ISA Discriminator Flags
>> ------------------ ------ ------ ------ --- -------------
>> -------------
>>
>>
>> The below line skipping zero entry was added as part of commit
>19d80e5fec548e681c453d15b4ae5b49bc080acc is ignoring the file names in
>the zeroth index. I have no idea why this line was added. Removing the line is
>working for programs compiled with clang using dwarf5. With my fix, I am not
>seeing any issues with GCC and dwarf5 moreover currently GCC's debug_line
>version is 3 even when compiled with dwarf5.
>>
>>       /* Skip the first "zero entry", which is the compilation dir/file.  */
>>       if (datai != 0)
>>         if (!callback (table, fe.name, fe.dir, fe.time, fe.size))
>>           return false;
>>
>> Made code changes to fix this issue. Can you review the code changes and
>send in your comments/suggestions?
>>
>> Regards,
>> Rupesh P
>
>Much of the above wants to go ...
>
>> From 28e92539dfe5319e7bdfea32c4ee46f55ff51053 Mon Sep 17 00:00:00
>2001
>> From: rupothar
>rupesh.potharla@amd.com<mailto:rupesh.potharla@amd.com>
>> Date: Mon, 9 May 2022 12:10:48 +0530
>> Subject: [PATCH] bfd: Fix issues with files in debug_line table with dwarf5.
>>
>> ---
>
>... above this marker, to become the actual commit message.
>
>> @@ -2270,10 +2273,8 @@ read_formatted_entries (struct comp_unit *unit,
>bfd_byte **bufp,
>>              }
>>          }
>>
>> -      /* Skip the first "zero entry", which is the compilation dir/file.  */
>> -      if (datai != 0)
>> -         if (!callback (table, fe.name, fe.dir, fe.time, fe.size))
>> -           return false;
>> +      if (!callback (table, fe.name, fe.dir, fe.time, fe.size))
>> +        return false;
>>      }
>
>How come this change doesn't add a version check?
>
>To help being certain this is the right way of changing things, can you please
>add up to two testcases (readelf and/or objdump), one for a version < 5
>(unless one such already exists and hence it would be visible there that you
>don't unduly alter handling of those older versions) and one for version 5?
>
>Jan

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From 1898ad99680a70e81e9cc2ca4aa69285599fea21 Mon Sep 17 00:00:00 2001
From: rupothar <rupesh.potharla@amd.com>
Date: Wed, 25 May 2022 09:22:48 +0530
Subject: [PATCH]  bfd: Fix issues with files in debug_line table with dwarf5.

---
 bfd/dwarf2.c | 13 +++++++++++--
 1 file changed, 11 insertions(+), 2 deletions(-)

diff --git a/bfd/dwarf2.c b/bfd/dwarf2.c
index f6b0183720b..c5b5d14fc9f 100644
--- a/bfd/dwarf2.c
+++ b/bfd/dwarf2.c
@@ -1572,6 +1572,7 @@ struct line_info_table
   unsigned int		num_files;
   unsigned int		num_dirs;
   unsigned int		num_sequences;
+  unsigned int 		version;
   char *		comp_dir;
   char **		dirs;
   struct fileinfo*	files;
@@ -1792,6 +1793,8 @@ concat_filename (struct line_info_table *table, unsigned int file)
 {
   char *filename;
 
+  if (table->version >= 5)
+    file = file + 1;
   if (table == NULL || file - 1 >= table->num_files)
     {
       /* FILE == 0 means unknown.  */
@@ -2414,7 +2417,7 @@ read_formatted_entries (struct comp_unit *unit, bfd_byte **bufp,
 	}
 
       /* Skip the first "zero entry", which is the compilation dir/file.  */
-      if (datai != 0)
+      if (table->version < 5 && datai != 0)
 	if (!callback (table, fe.name, fe.dir, fe.time, fe.size))
 	  return false;
     }
@@ -2581,6 +2584,7 @@ decode_line_info (struct comp_unit *unit)
   table->sequences = NULL;
 
   table->lcl_head = NULL;
+  table->version = lh.version;
 
   if (lh.version >= 5)
     {
@@ -2623,7 +2627,12 @@ decode_line_info (struct comp_unit *unit)
       /* State machine registers.  */
       bfd_vma address = 0;
       unsigned char op_index = 0;
-      char * filename = table->num_files ? concat_filename (table, 1) : NULL;
+      char *filename;
+      if (table->version >= 5)
+	filename = table->num_files ? concat_filename (table, 0) : NULL;
+      else
+	filename = table->num_files ? concat_filename (table, 1) : NULL;
+
       unsigned int line = 1;
       unsigned int column = 0;
       unsigned int discriminator = 0;
-- 
2.17.1