[committed,gdb/testsuite] Fail in gdb_compile if pie results in non-PIE executable
Commit Message
[ was: Re: [PATCH][gdb/testsuite] Fail in gdb_compile if nopie results
in PIE executable ]
On 30-07-19 03:20, Simon Marchi wrote:
> On 2019-07-29 5:57 a.m., Alan Hayward wrote:
>>> OK for trunk?
>>
>> LGTM (but I’m not a global maintainer).
>>
>> I tried this on an Ubuntu18.04 (which defaults gcc to use PIE), and everything
>> looks fine.
> Thanks, LGTM too, please push.
Hi,
this follow-up patch deals with the opposite: Fail in gdb_compile if pie
results in non-PIE executable.
Thanks,
- Tom
[gdb/testsuite] Fail in gdb_compile if pie results in non-PIE executable
When running gdb.base/break-idempotent.exp with
--target_board=unix/-fno-PIE/-no-pie, we get:
...
nr of expected passes 140
...
The test-case is compiled once with nopie and once with pie, but in both cases
we end up with a non-PIE executable. The "-fno-PIE -no-pie" options specified
using the target_board are interpreted by dejagnu as multilib_flags, and end up
overriding the pie flags.
Fix this by checking in gdb_compile if the resulting exec is non-PIE despite of
a pie setting, and if so return an error:
...
Running gdb/testsuite/gdb.base/break-idempotent.exp ...
gdb compile failed, pie failed to generate PIE executable
=== gdb Summary ===
nr of expected passes 70
nr of untested testcases 1
...
Tested on x86_64-linux.
gdb/testsuite/ChangeLog:
2019-08-05 Tom de Vries <tdevries@suse.de>
* lib/gdb.exp (version_at_least): Factor out of ...
(tcl_version_at_least): ... here.
(gdb_compile): Fail if pie results in non-PIE executable.
(readelf_version, readelf_prints_pie): New proc.
(exec_is_pie): Return -1 if unknown.
---
gdb/testsuite/lib/gdb.exp | 78 ++++++++++++++++++++++++++++++++++++++---------
1 file changed, 64 insertions(+), 14 deletions(-)
@@ -1103,21 +1103,27 @@ proc gdb_test { args } {
}]
}
-# Return 1 if tcl version used is at least MAJOR.MINOR
-proc tcl_version_at_least { major minor } {
- global tcl_version
- regexp {^([0-9]+)\.([0-9]+)$} $tcl_version \
- dummy tcl_version_major tcl_version_minor
- if { $tcl_version_major > $major } {
+# Return 1 if version MAJOR.MINOR is at least AT_LEAST_MAJOR.AT_LEAST_MINOR.
+proc version_at_least { major minor at_least_major at_least_minor} {
+ if { $major > $at_least_major } {
return 1
- } elseif { $tcl_version_major == $major \
- && $tcl_version_minor >= $minor } {
+ } elseif { $major == $at_least_major \
+ && $minor >= $at_least_minor } {
return 1
} else {
return 0
}
}
+# Return 1 if tcl version used is at least MAJOR.MINOR
+proc tcl_version_at_least { major minor } {
+ global tcl_version
+ regexp {^([0-9]+)\.([0-9]+)$} $tcl_version \
+ dummy tcl_version_major tcl_version_minor
+ return [version_at_least $tcl_version_major $tcl_version_minor \
+ $major $minor]
+}
+
if { [tcl_version_at_least 8 5] == 0 } {
# lrepeat was added in tcl 8.5. Only add if missing.
proc lrepeat { n element } {
@@ -3803,9 +3809,13 @@ proc gdb_compile {source dest type options} {
regsub "\[\r\n\]*$" "$result" "" result
regsub "^\[\r\n\]*" "$result" "" result
- if { $type == "executable" && $result == "" && $nopie != -1 } {
- if { [exec_is_pie "$dest"] } {
+ if { $type == "executable" && $result == "" \
+ && ($nopie != -1 || $pie != -1) } {
+ set is_pie [exec_is_pie "$dest"]
+ if { $nopie != -1 && $is_pie == 1 } {
set result "nopie failed to prevent PIE executable"
+ } elseif { $pie != -1 && $is_pie == 0 } {
+ set result "pie failed to generate PIE executable"
}
}
@@ -5209,13 +5219,53 @@ proc exec_has_index_section { executable } {
return 0
}
-# Return true if EXECUTABLE is a Position Independent Executable.
+# Return list with major and minor version of readelf, or an empty list.
+gdb_caching_proc readelf_version {
+ set readelf_program [gdb_find_readelf]
+ set res [catch {exec $readelf_program --version} output]
+ if { $res != 0 } {
+ return [list]
+ }
+ set lines [split $output \n]
+ set line [lindex $lines 0]
+ set res [regexp {[ \t]+([0-9]+)[.]([0-9]+)[^ \t]*$} \
+ $line dummy major minor]
+ if { $res != 1 } {
+ return [list]
+ }
+ return [list $major $minor]
+}
+
+# Return 1 if readelf prints the PIE flag, 0 if is doesn't, and -1 if unknown.
+proc readelf_prints_pie { } {
+ set version [readelf_version]
+ if { [llength $version] == 0 } {
+ return -1
+ }
+ set major [lindex $version 0]
+ set minor [lindex $version 1]
+ # It would be better to construct a PIE executable and test if the PIE
+ # flag is printed by readelf, but we cannot reliably construct a PIE
+ # executable if the multilib_flags dictate otherwise
+ # (--target_board=unix/-no-pie/-fno-PIE).
+ return [version_at_least $major $minor 2 26]
+}
+
+# Return 1 if EXECUTABLE is a Position Independent Executable, 0 if it is not,
+# and -1 if unknown.
proc exec_is_pie { executable } {
+ set res [readelf_prints_pie]
+ if { $res != 1 } {
+ return -1
+ }
set readelf_program [gdb_find_readelf]
- set res [catch {exec $readelf_program -d $executable \
- | grep -E "(FLAGS_1).*Flags:.* PIE($| )" }]
- if { $res == 0 } {
+ set res [catch {exec $readelf_program -d $executable} output]
+ if { $res != 0 } {
+ return -1
+ }
+ set res [regexp -line {\(FLAGS_1\).*Flags:.* PIE($| )} $output]
+ if { $res == 1 } {
return 1
}
return 0