RE: [PATCH] gdb fix for catch-syscall.exp

[Carl Love via Gdb-patches <gdb-patches@sourceware.org>]

Simon:

I split the latest patch so there is a separate revert patch and a
patch to make the Powerepc test a xfail.  Note, the revert patch only
reverts the part of the original patch that causes the regression test
on amd64.  

Let me know if the first patch looks OK to commit to mainline.

We can continue to discuss the second patch to decide if there is a
better implementation to add the xfail and if it really is a kernel
failure.

                     Carl 
--------------------------------------------------------------------
[PATCH 1/2] gdb: Revert change to gdb.base/catch-syscall.exp

The previous commit:
   commit ab198279120fe7937c0970a8bb881922726678f9
   Author: Carl Love <cel@us.ibm.com>
   Date:   Wed Nov 17 22:29:33 2021 +0000

       gdb fix for catch-syscall.exp

Fixed the test failure on PowerPC but broke the test on amd64.  The issue is
both messages:

    Catchpoint 1 (call to syscall execve), ....
    Catchpoint 1 (returned from syscall execve),  ....

are seen on amd64 whereas on PowerPC only the "call to syscall execve" is
seen.  Based on the discussion on the mailing list, it is felt that this
is really an issue with the PowerPC kernel support not reporting both events.

This patch just reverts the part of the commit that caused the regression
failure on amd64.  The change for the istarget powerpc64-*-linux* is not
being reverted.
---
 gdb/testsuite/gdb.base/catch-syscall.exp | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/gdb/testsuite/gdb.base/catch-syscall.exp b/gdb/testsuite/gdb.base/catch-syscall.exp
index 016d0a698a6..cdd5e2aec47 100644
--- a/gdb/testsuite/gdb.base/catch-syscall.exp
+++ b/gdb/testsuite/gdb.base/catch-syscall.exp
@@ -348,9 +348,7 @@ proc test_catch_syscall_execve {} {
 	# Check for entry/return across the execve, making sure that the
 	# syscall_state isn't lost when turning into a new process.
 	insert_catch_syscall_with_arg "execve"
-
-	# Check that the execve is called.
-	check_call_to_syscall "execve"
+	check_continue "execve"
 
 	# Continue to main so extended-remote can read files as needed.
 	# (Otherwise that "Reading" output confuses gdb_continue_to_end.)
-- 
2.30.2

-----------------------------------------------------------------------
[PATCH 2/2] gdb: Powerpc mark xfail in gdb.base/catch-syscall.exp

Powerpc is not reporting the

  Catchpoint 1 (returned from syscall execve),  ....

as expected.  The issue appears to be with the kernel not returning the
expected result.  This patch marks the test failure as an xfail.

See gdb bugzilla https://sourceware.org/bugzilla/show_bug.cgi?id=28623
---
 gdb/testsuite/gdb.base/catch-syscall.exp | 37 ++++++++++++++++++++----
 1 file changed, 31 insertions(+), 6 deletions(-)

diff --git a/gdb/testsuite/gdb.base/catch-syscall.exp b/gdb/testsuite/gdb.base/catch-syscall.exp
index cdd5e2aec47..0693f7afe27 100644
--- a/gdb/testsuite/gdb.base/catch-syscall.exp
+++ b/gdb/testsuite/gdb.base/catch-syscall.exp
@@ -127,7 +127,24 @@ proc check_return_from_syscall { syscall { pattern "" } } {
     }
 
     set thistest "syscall $syscall has returned"
-    gdb_test "continue" "Catchpoint $decimal \\(returned from syscall ${pattern}\\).*" $thistest
+    if { $pattern eq "execve" } {
+	gdb_test_multiple "continue" $thistest {
+	    -re -wrap "Catchpoint $decimal \\(returned from syscall ${pattern}\\).*" {
+		pass $thistest
+		return 1
+	    }
+	    -re -wrap ".*Breakpoint $decimal, main .*" {
+		# On Powerpc kernel does not report the returned from syscall
+		# as expected by the test.  GDB bugzilla 28623.
+		xfail $thistest
+		return 0
+	    }
+	}
+
+    } else {
+	gdb_test "continue" "Catchpoint $decimal \\(returned from syscall ${pattern}\\).*" $thistest
+	return 1
+    }
 }
 
 # Internal procedure that performs two 'continue' commands and checks if
@@ -142,7 +159,11 @@ proc check_continue { syscall { pattern "" } } {
     # Testing if the inferior has called the syscall.
     check_call_to_syscall $syscall $pattern
     # And now, that the syscall has returned.
-    check_return_from_syscall $syscall $pattern
+    if [check_return_from_syscall $syscall $pattern] {
+	return 1
+    } else {
+	return 0
+    }
 }
 
 # Inserts a syscall catchpoint with an argument.
@@ -348,11 +369,15 @@ proc test_catch_syscall_execve {} {
 	# Check for entry/return across the execve, making sure that the
 	# syscall_state isn't lost when turning into a new process.
 	insert_catch_syscall_with_arg "execve"
-	check_continue "execve"
+	if [check_continue "execve"] {
+	    # The check_continue test generates an XFAIL on Powerpc.  In
+	    # that case, gdb is already at main so don't do the continue.
 
-	# Continue to main so extended-remote can read files as needed.
-	# (Otherwise that "Reading" output confuses gdb_continue_to_end.)
-	gdb_continue "main"
+
+	    # Continue to main so extended-remote can read files as needed.
+	    # (Otherwise that "Reading" output confuses gdb_continue_to_end.)
+	    gdb_continue "main"
+	}
 
 	# Now can we finish?
 	check_for_program_end
-- 
2.30.2