On 04/09/2019 12:49, Dave Martin wrote:

On Mon, Sep 02, 2019 at 12:29:32pm +0100, Cristian Marussi wrote:

quoted

Add a simple fake_sigreturn testcase which places a valid sigframe on a
non-16 bytes aligned SP. Expects a SIGSEGV on test PASS.

Signed-off-by: Cristian Marussi <cristian.marussi@arm.com>
---
v3 --> v4
- fix commit
- use new fake_sigreturn misalig_bytes params
- removed TODO
- added test description
---
 .../testcases/fake_sigreturn_misaligned_sp.c  | 37 +++++++++++++++++++
 1 file changed, 37 insertions(+)
 create mode 100644 tools/testing/selftests/arm64/signal/testcases/fake_sigreturn_misaligned_sp.c

diff --git a/tools/testing/selftests/arm64/signal/testcases/fake_sigreturn_misaligned_sp.c b/tools/testing/selftests/arm64/signal/testcases/fake_sigreturn_misaligned_sp.c
new file mode 100644
index 000000000000..1e089e66f9f3
--- /dev/null
+++ b/tools/testing/selftests/arm64/signal/testcases/fake_sigreturn_misaligned_sp.c

@@ -0,0 +1,37 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2019 ARM Limited
+ *
+ * Place a fake sigframe on the stack at a misaligned SP: on sigreturn
+ * Kernel must spot this attempt and the test case is expected to be
+ * terminated via SEGV.
+ */
+
+#include <signal.h>
+#include <ucontext.h>
+
+#include "test_signals_utils.h"
+#include "testcases.h"
+
+struct fake_sigframe sf;
+
+static int fake_sigreturn_misaligned_run(struct tdescr *td,
+					 siginfo_t *si, ucontext_t *uc)
+{
+	/* just to fill the ucontext_t with something real */
+	if (!get_current_context(td, &sf.uc))
+		return 1;
+
+	/* Forcing sigframe on misaligned SP (16 + 3) */
+	fake_sigreturn(&sf, sizeof(sf), 3);

Can we add tests on the TODO list for other misalignments?

 a) 4 (i.e., __alignof__(struct _aarch64_ctx))
 b) 8 (i.e., sizeof(struct _aarch64_ctx))

This may help catch potential wrong-bitmask bugs in the kernel when
checking the alignment.  Similarly to my suggestion on patch 10, these
can go on the TODO list and added later (probably macro-ised).

Ok

For now, let's get this series settled as-is -- so, after responding to
nits:

Reviewed-by: Dave Martin <Dave.Martin@arm.com>

Thanks

Cristian

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