Hi
On 6/21/19 11:35 AM, Dave Martin wrote:
On Thu, Jun 13, 2019 at 12:13:30PM +0100, Cristian Marussi wrote:
Added a simple mangle testcase which messes with the ucontext_t
from within the sig_handler, trying to toggle PSTATE SSBS bit.
Expect SIGILL if SSBS feature unsupported or that the value set in
PSTATE.SSBS is preserved on test PASS.
Signed-off-by: Cristian Marussi <cristian.marussi@xxxxxxx>
---
.../arm64/signal/testcases/.gitignore | 1 +
.../testcases/mangle_pstate_ssbs_regs.c | 41 +++++++++++++++++++
2 files changed, 42 insertions(+)
create mode 100644 tools/testing/selftests/arm64/signal/testcases/mangle_pstate_ssbs_regs.c
diff --git a/tools/testing/selftests/arm64/signal/testcases/.gitignore b/tools/testing/selftests/arm64/signal/testcases/.gitignore
index e7a1d998b650..c2972c3f33ca 100644
--- a/tools/testing/selftests/arm64/signal/testcases/.gitignore
+++ b/tools/testing/selftests/arm64/signal/testcases/.gitignore
@@ -5,3 +5,4 @@ mangle_pstate_invalid_state_toggle
mangle_pstate_invalid_mode_el1
mangle_pstate_invalid_mode_el2
mangle_pstate_invalid_mode_el3
+mangle_pstate_ssbs_regs
diff --git a/tools/testing/selftests/arm64/signal/testcases/mangle_pstate_ssbs_regs.c b/tools/testing/selftests/arm64/signal/testcases/mangle_pstate_ssbs_regs.c
new file mode 100644
index 000000000000..d997ebf742d9
--- /dev/null
+++ b/tools/testing/selftests/arm64/signal/testcases/mangle_pstate_ssbs_regs.c
@@ -0,0 +1,41 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/* Copyright (C) 2019 ARM Limited */
+
+#include "test_signals_utils.h"
+#include "testcases.h"
+
+static int mangle_invalid_pstate_ssbs_run(struct tdescr *td,
+ siginfo_t *si, ucontext_t *uc)
+{
+ ASSERT_GOOD_CONTEXT(uc);
+
+ /* toggle bit value */
+ uc->uc_mcontext.pstate ^= PSR_SSBS_BIT;
+ /* Save after mangling...it should be preserved */
+ td->saved_uc = *uc;
+
+ return 1;
+}
+
+static int pstate_ssbs_bit_checks(struct tdescr *td)
+{
+ uint64_t val = 0;
+
+ get_regval(MRS_SSBS_SYSREG, val);
+ /* pass when preserved */
+ td->pass = (!!(val & MRS_SSBS_BIT) ==
+ !!(td->saved_uc.uc_mcontext.pstate & PSR_SSBS_BIT));
Nit: there's a redundant level of ! here, and the outer () are unnecessary:
(!!a == !!b) -> !a == !b
This was me badly convinced (not sure where I got this) that the bitpos
of PSR_SSBS_BIT in pstate was different from the bitpos as reported in
the output of MRS SSBS, so I was trying to normalize the comparison to 1
== 1 or 0 == 0
...but in fact bitpos is the same between PSTATE and MSR SSBS so it can
be compared directly.
[...]
Can we trigger a second signal after the first returns, to grab the
updated ucontext and check SSBS in there directly?
Checking that the updated value is _also_ visible via MRS remains
useful though, so we should keep that.
I have added an informational message that reports the PSTATE and the
status of SSBS as grabbed from uc via an induced SIGUSR2.
Test outcome is anyway determined on MRS SSBS result.
If HWCAP_SSBS is available the feature is considered available and so
MRS SSBS MUST work.
If instead feature is NOT supported as stated in HWCAP_SSBS the test is
anyway run but the MRS SSBS is expected to cause a SIGILL (COULD not
SHOULD...since HW_CAP could be reporting wrong caps and so MRS SSBS will
still work)
Moreover I fixed a small glitch: I was toggling the SSBS bit in uc
PSTATE, BUT this make no sense...toggling to zero there's NO way I can
check if Kernel preserve it to zero...so now I'm setting to 1 and then
check if it has been preserved by Kernel
Cristian
Cheers
---Dave
