[committed,gdb/testsuite] Fix exec_is_pie with gold linker

Message ID 20200525100237.GA6162@delia
State New
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  • [committed,gdb/testsuite] Fix exec_is_pie with gold linker
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Commit Message

Tom de Vries May 25, 2020, 10:02 a.m.
Hi,

When running test-case gdb.base/break-interp.exp with target board gold, we
run into:
...
gdb compile failed, pie failed to generate PIE executable
...

The problem is that the proc exec_is_pie uses the PIE flag in the readelf -d
output, which doesn't seem to be set by the gold linker.

Instead, use the "Type" field in the readelf -h output.

Tested on x86_64-linux.

Committed to trunk.

Thanks,
- Tom

[gdb/testsuite] Fix exec_is_pie with gold linker

gdb/testsuite/ChangeLog:

2020-05-25  Tom de Vries  <tdevries@suse.de>

	PR testsuite/26031
	* lib/gdb.exp (exec_is_pie): Test readelf -h output.

---
 gdb/testsuite/lib/gdb.exp | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

Comments

Simon Marchi via Gdb-patches May 25, 2020, 2:54 p.m. | #1
On 5/25/20 11:02 AM, Tom de Vries wrote:
> Hi,

> 

> When running test-case gdb.base/break-interp.exp with target board gold, we

> run into:

> ...

> gdb compile failed, pie failed to generate PIE executable

> ...

> 

> The problem is that the proc exec_is_pie uses the PIE flag in the readelf -d

> output, which doesn't seem to be set by the gold linker.


Seems like a Gold bug?  A comment in exec_is_pie explaining why we don't
do the more obvious thing would be helpful, IMO.

> @@ -5509,11 +5509,12 @@ proc exec_is_pie { executable } {

>  	return -1

>      }

>      set readelf_program [gdb_find_readelf]

> -    set res [catch {exec $readelf_program -d $executable} output]

> +    set res [catch {exec $readelf_program -h $executable} output]

>      if { $res != 0 } {

>  	return -1

>      }

> -    set res [regexp -line {\(FLAGS_1\).*Flags:.* PIE($| )} $output]

> +    set res [regexp -line {^[ \t]*Type:[ \t]*DYN \(Shared object file\)$} \

> +		 $output]

>      if { $res == 1 } {

>  	return 1

>      }

> 


Thanks,
Pedro Alves
Tom de Vries May 25, 2020, 3:29 p.m. | #2
On 25-05-2020 16:54, Pedro Alves wrote:
> On 5/25/20 11:02 AM, Tom de Vries wrote:

>> Hi,

>>

>> When running test-case gdb.base/break-interp.exp with target board gold, we

>> run into:

>> ...

>> gdb compile failed, pie failed to generate PIE executable

>> ...

>>

>> The problem is that the proc exec_is_pie uses the PIE flag in the readelf -d

>> output, which doesn't seem to be set by the gold linker.

> 

> Seems like a Gold bug?


Yeah, Andreas Schwab had the same comment in bugzilla, so I filed
PR26039 - "gold doesn't add PIE flag" (
https://sourceware.org/bugzilla/show_bug.cgi?id=26039 ).	

> A comment in exec_is_pie explaining why we don't

> do the more obvious thing would be helpful, IMO.

> 


Fixed in attached patch, committed.

Thanks,
- Tom
[gdb/testsuite] Add comment in exec_is_pie

Add comment to exec_is_pie explaining why readelf -d output is not used.

gdb/testsuite/ChangeLog:

2020-05-25  Tom de Vries  <tdevries@suse.de>

	* lib/gdb.exp (exec_is_pie): Add comment.

---
 gdb/testsuite/lib/gdb.exp | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/gdb/testsuite/lib/gdb.exp b/gdb/testsuite/lib/gdb.exp
index 7177be941b..8e22941f0b 100644
--- a/gdb/testsuite/lib/gdb.exp
+++ b/gdb/testsuite/lib/gdb.exp
@@ -5509,6 +5509,9 @@ proc exec_is_pie { executable } {
 	return -1
     }
     set readelf_program [gdb_find_readelf]
+    # We're not testing readelf -d | grep "FLAGS_1.*Flags:.*PIE"
+    # because the PIE flag is not set by all versions of gold, see PR
+    # binutils/26039.
     set res [catch {exec $readelf_program -h $executable} output]
     if { $res != 0 } {
 	return -1

Patch

diff --git a/gdb/testsuite/lib/gdb.exp b/gdb/testsuite/lib/gdb.exp
index f7d20bd94f..7177be941b 100644
--- a/gdb/testsuite/lib/gdb.exp
+++ b/gdb/testsuite/lib/gdb.exp
@@ -5509,11 +5509,12 @@  proc exec_is_pie { executable } {
 	return -1
     }
     set readelf_program [gdb_find_readelf]
-    set res [catch {exec $readelf_program -d $executable} output]
+    set res [catch {exec $readelf_program -h $executable} output]
     if { $res != 0 } {
 	return -1
     }
-    set res [regexp -line {\(FLAGS_1\).*Flags:.* PIE($| )} $output]
+    set res [regexp -line {^[ \t]*Type:[ \t]*DYN \(Shared object file\)$} \
+		 $output]
     if { $res == 1 } {
 	return 1
     }