[PATCH v5 0/4] gdb: add gdb_attach to fix failed testcases

[PATCH v5 0/4] gdb: add gdb_attach to fix failed testcases

[Tiezhu Yang]

Please review this v5 patchset, thank you.

Tiezhu Yang (4):
  gdb: testsuite: remove attach test from can_spawn_for_attach
  gdb: testsuite: add new gdb_attach to check "attach" command
  gdb: testsuite: use gdb_attach to fix attach-pie-noexec.exp
  gdb: testsuite: use gdb_attach to fix jit-elf.exp

 gdb/testsuite/gdb.base/attach-pie-noexec.exp |  5 +-
 gdb/testsuite/gdb.base/jit-elf.exp           | 24 ++++++----
 gdb/testsuite/lib/gdb.exp                    | 72 +++++++++++++---------------
 3 files changed, 52 insertions(+), 49 deletions(-)

-- 
2.1.0

[PATCH v5 1/4] gdb: testsuite: remove attach test from can_spawn_for_attach

[Tiezhu Yang]

As Pedro Alves said, caching procs should not issue pass/fail [1],
this commit removes attach test from can_spawn_for_attach, at the
same time, use "verbose -log" instead of "unsupported" to get a
trace about why a test run doesn't support spawning for attach.

[1] https://sourceware.org/pipermail/gdb-patches/2022-March/186311.html

Signed-off-by: Tiezhu Yang <yangtiezhu@loongson.cn>
---
 gdb/testsuite/lib/gdb.exp | 52 ++++++++---------------------------------------
 1 file changed, 9 insertions(+), 43 deletions(-)

diff --git a/gdb/testsuite/lib/gdb.exp b/gdb/testsuite/lib/gdb.exp
index 729bded..892bf07 100644
--- a/gdb/testsuite/lib/gdb.exp
+++ b/gdb/testsuite/lib/gdb.exp
@@ -5122,12 +5122,12 @@ proc gdb_exit { } {
 # Return true if we can spawn a program on the target and attach to
 # it.
 
-gdb_caching_proc can_spawn_for_attach {
+proc can_spawn_for_attach { } {
     # We use exp_pid to get the inferior's pid, assuming that gives
     # back the pid of the program.  On remote boards, that would give
     # us instead the PID of e.g., the ssh client, etc.
     if [is_remote target] then {
-	unsupported "skip attach tests (target is remote)"
+	verbose -log "can't spawn for attach (target is remote)"
 	return 0
     }
 
@@ -5135,50 +5135,10 @@ gdb_caching_proc can_spawn_for_attach {
     # stub-like, where GDB finds the program already started on
     # initial connection.
     if {[target_info exists use_gdb_stub]} {
-	unsupported "skip attach tests (target is stub)"
+	verbose -log "can't spawn for attach (target is stub)"
 	return 0
     }
 
-    set me "can_spawn_for_attach"
-    set src { int main (void) { sleep (600); return 0; } }
-    if {![gdb_simple_compile $me $src executable]} {
-        return 0
-    }
-
-    set test_spawn_id [spawn_wait_for_attach $obj]
-    set test_pid [spawn_id_get_pid $test_spawn_id]
-
-    gdb_start
-    file delete $obj
-    gdb_test_multiple "attach $test_pid" "can spawn for attach" {
-        -re -wrap "Attaching to process $test_pid\r\n.*No executable file now.*" {
-          pass $gdb_test_name
-          kill_wait_spawned_process $test_spawn_id
-          return 1
-        }
-        -re -wrap "Attaching to process $test_pid\r\n.*ptrace: Operation not permitted\\." {
-          unsupported "$gdb_test_name (Operation not permitted)"
-          kill_wait_spawned_process $test_spawn_id
-          return 0
-        }
-        -re -wrap "Attaching to process $test_pid\r\n.*Attaching to process $test_pid failed" {
-          unsupported "$gdb_test_name (Attaching to process failed)"
-          kill_wait_spawned_process $test_spawn_id
-          return 0
-        }
-        -re -wrap "Attaching to process $test_pid\r\n.*XML support was disabled at compile time.*" {
-          pass $gdb_test_name
-          kill_wait_spawned_process $test_spawn_id
-          return 1
-        }
-        -re "A program is being debugged already.  Kill it. .y or n. " {
-          send_gdb "y\n"
-          exp_continue
-        }
-    }
-
-    kill_wait_spawned_process $test_spawn_id
-
     # Assume yes.
     return 1
 }
@@ -5228,6 +5188,12 @@ proc spawn_id_get_pid { spawn_id } {
 proc spawn_wait_for_attach { executable_list } {
     set spawn_id_list {}
 
+    if ![can_spawn_for_attach] {
+	# The caller should have checked can_spawn_for_attach itself
+	# before getting here.
+	error "can't spawn for attach with this target/board"
+    }
+
     foreach {executable} $executable_list {
 	# Note we use Expect's spawn, not Tcl's exec, because with
 	# spawn we control when to wait for/reap the process.  That
-- 
2.1.0

[PATCH v5 2/4] gdb: testsuite: add new gdb_attach to check "attach" command

[Tiezhu Yang]

This commit adds new gdb_attach to centralize the failure checking of
"attach" command. Return 0 if attach failed, otherwise return 1.

Signed-off-by: Tiezhu Yang <yangtiezhu@loongson.cn>
---
 gdb/testsuite/lib/gdb.exp | 26 ++++++++++++++++++++++++++
 1 file changed, 26 insertions(+)

diff --git a/gdb/testsuite/lib/gdb.exp b/gdb/testsuite/lib/gdb.exp
index 892bf07..d8015fb 100644
--- a/gdb/testsuite/lib/gdb.exp
+++ b/gdb/testsuite/lib/gdb.exp
@@ -5143,6 +5143,32 @@ proc can_spawn_for_attach { } {
     return 1
 }
 
+# Centralize the failure checking of "attach" command.
+# Return 0 if attach failed, otherwise return 1.
+
+proc gdb_attach { testpid args } {
+    parse_args {
+	{pattern ""}
+    }
+
+    if { [llength $args] != 0 } {
+	error "Unexpected arguments: $args"
+    }
+
+    gdb_test_multiple "attach $testpid" "attach" {
+	-re -wrap "Attaching to.*ptrace: Operation not permitted\\." {
+	    unsupported "$gdb_test_name (Operation not permitted)"
+	    return 0
+	}
+	-re -wrap "$pattern" {
+	    pass $gdb_test_name
+	    return 1
+	}
+    }
+
+    return 0
+}
+
 # Kill a progress previously started with spawn_wait_for_attach, and
 # reap its wait status.  PROC_SPAWN_ID is the spawn id associated with
 # the process.
-- 
2.1.0

[PATCH v5 3/4] gdb: testsuite: use gdb_attach to fix attach-pie-noexec.exp

[Tiezhu Yang]

If /proc/sys/kernel/yama/ptrace_scope is 1, when execute the following
command without superuser:

  make check-gdb TESTS="gdb.base/attach-pie-noexec.exp"

we can see the following messages in gdb/testsuite/gdb.log:

  (gdb) attach 6500
  Attaching to process 6500
  ptrace: Operation not permitted.
  (gdb) PASS: gdb.base/attach-pie-noexec.exp: attach

It is obviously wrong, the expected result should be UNSUPPORTED in such
a case.

With this patch, we can see "Operation not permitted" in the log info,
and then we can do the following processes to test:
(1) set ptrace_scope as 0
    $ echo 0 | sudo tee /proc/sys/kernel/yama/ptrace_scope
    $ make check-gdb TESTS="gdb.base/attach-pie-noexec.exp"
(2) use sudo
    $ sudo make check-gdb TESTS="gdb.base/attach-pie-noexec.exp"

Signed-off-by: Tiezhu Yang <yangtiezhu@loongson.cn>
---
 gdb/testsuite/gdb.base/attach-pie-noexec.exp | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/gdb/testsuite/gdb.base/attach-pie-noexec.exp b/gdb/testsuite/gdb.base/attach-pie-noexec.exp
index 4712824..33238db 100644
--- a/gdb/testsuite/gdb.base/attach-pie-noexec.exp
+++ b/gdb/testsuite/gdb.base/attach-pie-noexec.exp
@@ -59,7 +59,10 @@ set testpid [spawn_id_get_pid $test_spawn_id]
 
 gdb_start
 file delete -- $binfile
-gdb_test "attach $testpid" "Attaching to process $testpid\r\n.*" "attach"
+if { ![gdb_attach $testpid] } {
+    kill_wait_spawned_process $test_spawn_id
+    return
+}
 gdb_test "set architecture $arch" "The target architecture is set to \"$arch\"\\."
 gdb_test "info shared" "From\[ \t\]+To\[ \t\]+Syms Read\[ \t\]+Shared Object Library\r\n0x.*"
 
-- 
2.1.0

[PATCH v5 4/4] gdb: testsuite: use gdb_attach to fix jit-elf.exp

[Tiezhu Yang]

If /proc/sys/kernel/yama/ptrace_scope is 1, when execute the following
command without superuser:

  make check-gdb TESTS="gdb.base/jit-elf.exp"

we can see the following messages in gdb/testsuite/gdb.log:

  (gdb) attach 1650108
  Attaching to program: /home/yangtiezhu/build/gdb/testsuite/outputs/gdb.base/jit-elf/jit-elf-main, process 1650108
  ptrace: Operation not permitted.
  (gdb) FAIL: gdb.base/jit-elf.exp: attach: one_jit_test-2: break here 1: attach

use gdb_attach to fix the above issue, at the same time, the clean_reattach
proc should return a value to indicate whether it worked, and the callers
should return early as well on failure.

Signed-off-by: Tiezhu Yang <yangtiezhu@loongson.cn>
---
 gdb/testsuite/gdb.base/jit-elf.exp | 24 ++++++++++++++++--------
 1 file changed, 16 insertions(+), 8 deletions(-)

diff --git a/gdb/testsuite/gdb.base/jit-elf.exp b/gdb/testsuite/gdb.base/jit-elf.exp
index 8a4c5b7..4b75188 100644
--- a/gdb/testsuite/gdb.base/jit-elf.exp
+++ b/gdb/testsuite/gdb.base/jit-elf.exp
@@ -38,6 +38,7 @@ set jit_solib_basename jit-elf-solib
 set jit_solib_srcfile ${srcdir}/${subdir}/${jit_solib_basename}.c
 
 # Detach, restart GDB, and re-attach to the program.
+# Return 0 if attach failed, otherwise return 1.
 proc clean_reattach {} {
     global decimal gdb_prompt
     global main_binfile main_srcfile
@@ -57,18 +58,18 @@ proc clean_reattach {} {
 
     clean_restart ${main_binfile}
 
-    set test "attach"
-    gdb_test_multiple "attach $testpid" "$test" {
-	-re "Attaching to program.*.*main.*at .*$main_srcfile:.*$gdb_prompt $" {
-	    pass "$test"
-	}
+    if { ![gdb_attach $testpid \
+	      -pattern "main.*at .*$::main_srcfile:.*"] } {
+	return 0
     }
 
     gdb_test_no_output "set var wait_for_gdb = 0"
+    return 1
 }
 
 # Continue to LOCATION in the program.  If REATTACH, detach and
 # re-attach to the program from scratch.
+# Return 0 if clean_reattach failed, otherwise return 1.
 proc continue_to_test_location {location reattach} {
     global main_srcfile
 
@@ -76,9 +77,12 @@ proc continue_to_test_location {location reattach} {
     gdb_continue_to_breakpoint $location
     if {$reattach} {
 	with_test_prefix "$location" {
-	    clean_reattach
+	    if { ![clean_reattach] } {
+		return 0
+	    }
 	}
     }
+    return 1
 }
 
 proc one_jit_test {jit_solibs_target match_str reattach} {
@@ -114,7 +118,9 @@ proc one_jit_test {jit_solibs_target match_str reattach} {
 	gdb_continue_to_breakpoint "break here 0"
 
 
-	continue_to_test_location "break here 1" $reattach
+	if { ![continue_to_test_location "break here 1" $reattach] } {
+	    return
+	}
 
 	gdb_test "info function ^jit_function" "$match_str"
 
@@ -124,7 +130,9 @@ proc one_jit_test {jit_solibs_target match_str reattach} {
 	    gdb_test "maintenance info break"
 	}
 
-	continue_to_test_location "break here 2" $reattach
+	if { ![continue_to_test_location "break here 2" $reattach] } {
+	    return
+	}
 
 	# All jit librares must have been unregistered
 	gdb_test "info function jit_function" \
-- 
2.1.0

Re: [PATCH v5 0/4] gdb: add gdb_attach to fix failed testcases

[Pedro Alves]

On 2022-03-22 06:41, Tiezhu Yang wrote:
> Please review this v5 patchset, thank you.

Looks fine to me.

BTW, I tried setting ptrace_scope=1 and then running gdb.base/attach.exp, as probably the main attach testcase, and it
unsurprisingly FAILs:

 $ echo 1 | sudo tee /proc/sys/kernel/yama/ptrace_scope
 $ make check TESTS="gdb.base/attach.exp"
 ...
 Running /home/pedro/gdb/build/gdb/testsuite/../../../src/gdb/testsuite/gdb.base/attach.exp ...
 FAIL: gdb.base/attach.exp: do_attach_tests: attach1, after setting file
 FAIL: gdb.base/attach.exp: do_attach_tests: attach1 detach (the program is no longer running)
 FAIL: gdb.base/attach.exp: do_attach_tests: attach2, with no file
 FAIL: gdb.base/attach.exp: do_attach_tests: after attach2, set should_exit
 FAIL: gdb.base/attach.exp: do_attach_tests: continue to breakpoint: postloop (the program is no longer running)
 FAIL: gdb.base/attach.exp: do_attach_tests: continue until exit at after attach2, exit (the program is no longer running)
 FAIL: gdb.base/attach.exp: do_attach_tests: attach when process' a.out not in cwd
 ...


The curious thing is that the first FAIL is already a gdb_test_multiple:

    set test "attach1, after setting file"
    gdb_test_multiple "attach $testpid" "$test" {
	-re "Attaching to program.*`?$escapedbinfile'?, process $testpid.*main.*at .*$srcfile:.*$gdb_prompt $" {
	    pass "$test"
	}
	-re "Attaching to program.*`?$escapedbinfile\.exe'?, process $testpid.*\[Switching to thread $testpid\..*\].*$gdb_prompt $" {
	    # Response expected on Cygwin
	    pass "$test"
	}
    }

So I really think we will want to do the idea at 
<https://sourceware.org/pipermail/gdb-patches/2022-March/186795.html>.  But it can be
done after your patches are in.  I'm fine with you merging what you have as is.