[PATCH 2/2] gdb, testsuite: Handle unexpected PRKU value in linux corefiles.

[Christina Joos <christina.joos@intel.com>]

I observed that for linux corefiles the value of PKRU register is
sometimes the default value (0x55555554), introduced with commit
"x86/pkeys: Default to a restrictive init PKRU" [1] in linux kernel
v4.9. even though we expect a different value at this point.

I have seen the default init value on Ubuntu 24.04.4 LTS with linux
kernel version 6.8.0, but the expected value (0x12345678) on Ubuntu
26.04 LTS with linux kernel version 7.0.0.

Accepts both values for now until the reason is identified and we can
change it to an appropriate xfail.

[1] https://github.com/torvalds/linux/commit/acd547b29880800d29222c4632d2c145e401988c
---
 gdb/testsuite/gdb.arch/i386-pkru.exp | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/gdb/testsuite/gdb.arch/i386-pkru.exp b/gdb/testsuite/gdb.arch/i386-pkru.exp
index c455891b8de..ce9e17a4493 100644
--- a/gdb/testsuite/gdb.arch/i386-pkru.exp
+++ b/gdb/testsuite/gdb.arch/i386-pkru.exp
@@ -119,7 +119,12 @@ proc test_corefile {core_filename} {
     gdb_test "core $core_filename" "Core was generated by .*" \
 	"load corefile"
 
-    gdb_test "info register pkru" ".*pkru.*$::val1.*" \
+    set pkru_val_re $::val1
+    if { [istarget *-*-linux*] } {
+	# Some linux kernel write the default PKRU value to the register.
+	set pkru_val_re ($pkru_val_re|0x55555554)
+    }
+    gdb_test "info register pkru" ".*pkru.*$pkru_val_re.*" \
 	"read pkru register"
 }
 
-- 
2.53.0

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