[gdb/testsuite] Factor out proc linux_kernel_version

Factor out new proc linux_kernel_version from test-case
gdb.arch/i386-pkru.exp.

Tested on x86_64-linux.

2 files changed, 29 insertions, 14 deletions

diff --git a/gdb/testsuite/gdb.arch/i386-pkru.exp b/gdb/testsuite/gdb.arch/i386-pkru.exp
index 90d8c1d..1f047df 100644
--- a/gdb/testsuite/gdb.arch/i386-pkru.exp
+++ b/gdb/testsuite/gdb.arch/i386-pkru.exp
@@ -59,20 +59,12 @@ if { !$supports_pkru } {
 # the PKRU using ptrace, see commit 4a804c4f8356 ("x86/fpu: Allow PKRU to be
 # (once again) written by ptrace.").
 set have_xfail 0
-if { [istarget *-*-linux*] } {
-    set res [remote_exec target "uname -r"]
-    set status [lindex $res 0]
-    set output [lindex $res 1]
-
-    set re ^($decimal)\\.($decimal)\\.($decimal)
-    if { $status == 0
-	 && [regexp $re $output dummy v1 v2 v3] == 1 } {
-	set v [list $v1 $v2 $v3]
-	set have_xfail \
-	    [expr \
-		 [version_compare [list 5 14 0] <= $v] \
-		 && [version_compare $v < [list 6 2 0]]]
-    }
+set v [linux_kernel_version]
+if { $v != {} } {
+    set have_xfail \
+	[expr \
+	     [version_compare [list 5 14 0] <= $v] \
+	     && [version_compare $v < [list 6 2 0]]]
 }
 
 # Test pkru register at startup
diff --git a/gdb/testsuite/lib/gdb.exp b/gdb/testsuite/lib/gdb.exp
index 7f98f08..e48228e 100644
--- a/gdb/testsuite/lib/gdb.exp
+++ b/gdb/testsuite/lib/gdb.exp
@@ -9374,5 +9374,28 @@ proc has_dependency { file dep } {
     return [regexp $dep $output]
 }
 
+# Detect linux kernel version and return as list of 3 numbers: major, minor,
+# and patchlevel.  On failure, return an empty list.
+
+gdb_caching_proc linux_kernel_version {
+    if { ![istarget *-*-linux*] } {
+	return {}
+    }
+
+    set res [remote_exec target "uname -r"]
+    set status [lindex $res 0]
+    set output [lindex $res 1]
+    if { $status != 0 } {
+	return {}
+    }
+
+    set re ^($::decimal)\\.($::decimal)\\.($::decimal)
+    if { [regexp $re $output dummy v1 v2 v3] != 1 } {
+	return {}
+    }
+
+    return [list $v1 $v2 $v3]
+}
+
 # Always load compatibility stuff.
 load_lib future.exp