Re: [PATCH 15/14] selftests: futex: Add tests for robust unlock within the critical section.

[André Almeida]

Em 04/04/2026 06:39, Sebastian Andrzej Siewior escreveu:
> From: Sebastian Andrzej Siewior <sebastian@xxxxxxxxxxxxx>
>
> I took Thomas’ initial test case from the cover letter and reworked it
> so that it uses ptrace() to single‑step through the VDSO unlock
> operation. The test expects the lock to remain locked, with
> `list_op_pending' pointing somewhere, when entering the VDSO unlock
> path. Once execution steps into the critical section, it expects the
> kernel to perform the fixup that is, to unlock the lock and clear
> `list_op_pending'.
>
> The test requires VDSO debug symbols, typically provided by
> vdso64.so.dbg or vdso32.so.dbg. It attempts to locate the appropriate
> file automatically, but the user may override this by setting the
> VDSO_DBG environment variable. If neither method succeeds, libelf falls
> back to its usual lookup mechanism under /usr/lib/debug/.build-id/

Tested on x86 and arm64 and it worked, thanks!

> Signed-off-by: Sebastian Andrzej Siewior <sebastian@xxxxxxxxxxxxx>
> ---
>   .../selftests/futex/functional/Makefile       |   3 +-
>   .../futex/functional/robust_list_critical.c   | 402 ++++++++++++++++++
>   2 files changed, 404 insertions(+), 1 deletion(-)
>   create mode 100644 tools/testing/selftests/futex/functional/robust_list_critical.c

Missing the addition to .gitignore.

[...]

> +static bool pc_is_within(struct user_regs_struct *regs, uint64_t start, uint64_t end)
> +{
> +	unsigned long pc;
> +
> +#if defined(__x86_64__)
> +	pc = regs->rip;
> +#elif defined(__riscv)
> +	pc = reg->pc;

I think this should be regs as well.

And this is what I changed to make it work with arm64:

---
 .../futex/functional/robust_list_critical.c   | 24 +++++++++++++++++--
 1 file changed, 22 insertions(+), 2 deletions(-)

diff --git 
a/tools/testing/selftests/futex/functional/robust_list_critical.c 
b/tools/testing/selftests/futex/functional/robust_list_critical.c
index b9490d24eb10..89062c921054 100644
--- a/tools/testing/selftests/futex/functional/robust_list_critical.c
+++ b/tools/testing/selftests/futex/functional/robust_list_critical.c
@@ -67,6 +67,9 @@ static bool pc_is_within(struct user_regs_struct 
*regs, uint64_t start, uint64_t
 	pc = regs->rip;
 #elif defined(__riscv)
 	pc = reg->pc;
+#elif defined(__aarch64__)
+	pc = regs->pc;
+#else
 # error Missing ptrace support
 #endif
 	if (pc >= (long) start && pc < end)
@@ -219,6 +222,23 @@ enum trace_state {
 	STATE_LEAVE_VDSO,
 };

+static int ptrace_get_regs(struct user_regs_struct *regs, pid_t child)
+{
+#if defined(__x86_64__)
+
+	return ptrace(PTRACE_GETREGS, child, 0, regs);
+
+#elif defined(__aarch64__)
+
+	struct iovec io;
+	io.iov_base = regs;
+	io.iov_len = sizeof(struct user_regs_struct);
+
+	return ptrace(PTRACE_GETREGSET, child, NT_PRSTATUS, &io);
+
+#endif
+}
+
 static void trace_child(struct __test_metadata *_metadata, pid_t 
child, bool is_32bit)
 {
 	int state = STATE_WAIT;
@@ -247,8 +267,8 @@ static void trace_child(struct __test_metadata 
*_metadata, pid_t child, bool is_
 			return;
 		}

-		if (ptrace(PTRACE_GETREGS, child, 0, &regs) != 0)
-			errx(1, "PTRACE_GETREGS");
+		if (ptrace_get_regs(&regs, child) == -1)
+			errx(1, "ptrace_get_regs");

 		if (is_32bit) {
 			in_vdso = pc_is_within(&regs, (long)frtu32, frtu32_end);
--
2.54.0