[gdb/testsuite] Fix gdb.arch/arm-single-step-kernel-helper.exp

On arm-linux I run into:
...
(gdb) p *kernel_user_helper_version^M
Cannot access memory at address 0xffff0ffc^M
(gdb) FAIL: gdb.arch/arm-single-step-kernel-helper.exp: check kernel helper version
...

What the test-case is trying to do, is to access a special address in the arm
linux kernel [1] using ptrace, which doesn't seem to work.

This is with kernel version 6.1.55.  Perhaps this used to work, but the kernel
was modified to be more strict with respect to access to this special address.

Fix this by making the inferior access that special address instead.

Tested on arm-linux.

Approved-By: Luis Machado <luis.machado@arm.com>
PR testsuite/32070
Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=32070

[1] https://www.kernel.org/doc/Documentation/arm/kernel_user_helpers.txt

diff --git a/gdb/testsuite/gdb.arch/arm-single-step-kernel-helper.c b/gdb/testsuite/gdb.arch/arm-single-step-kernel-helper.c
index 393004e623a009b52d455de9376542f850df537b..9b5e137992da8cb642ebfdcf76c82cf92aaa21ff 100644 (file)
--- a/gdb/testsuite/gdb.arch/arm-single-step-kernel-helper.c
+++ b/gdb/testsuite/gdb.arch/arm-single-step-kernel-helper.c
@@ -15,7 +15,8 @@
    You should have received a copy of the GNU General Public License
    along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
 
-static int *kernel_user_helper_version = (int *) 0xffff0ffc;
+static int *kernel_user_helper_version_ptr = (int *) 0xffff0ffc;
+static int kernel_user_helper_version;
 
 typedef void * (kernel_user_func_t)(void);
 #define kernel_user_get_tls (*(kernel_user_func_t *) 0xffff0fe0)
@@ -25,6 +26,8 @@ main (void)
 {
   int i;
 
+  kernel_user_helper_version = *kernel_user_helper_version_ptr;
+
   for (i = 0; i < 8; i++)
     kernel_user_get_tls ();
 }

diff --git a/gdb/testsuite/gdb.arch/arm-single-step-kernel-helper.exp b/gdb/testsuite/gdb.arch/arm-single-step-kernel-helper.exp
index 27be5d56883e43b71e4c00ae1a3e59ef07a93391..788bc86379933280217326843eacbf855c770e6c 100644 (file)
--- a/gdb/testsuite/gdb.arch/arm-single-step-kernel-helper.exp
+++ b/gdb/testsuite/gdb.arch/arm-single-step-kernel-helper.exp
@@ -26,10 +26,13 @@ if { ![runto_main] } {
     return -1
 }
 
+# Initialize kernel_user_helper_version.
+gdb_test "next" "for .*"
+
 # Check kernel helpers are supported or not.
 
 set kernel_helper_supported 0
-gdb_test_multiple "p *kernel_user_helper_version" \
+gdb_test_multiple "p kernel_user_helper_version" \
     "check kernel helper version" {
        -re " = ($decimal)\r\n$gdb_prompt $" {
            if { $expect_out(1,string) >= 1 } {